JP2008238638A - Liquid discharging device and leakage judgment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mechanism which can judge the presence or absence of leakage without utilizing a special instrument other than various detecting devices equipped as standard in an ink jet printer. <P>SOLUTION: The liquid ejector is equipped with a recording head, a tank, a channel, a temperature detecting means which detects the temperature of the recording head, a pressure detecting means which detects whether or not the pressure reaches a threshold value, a liquid supply means which sends the pressurized air to the tank to supply a liquid in the tank to the recording head, and a judging means which specifies an actual time after the tank pressure becomes higher than the threshold value before it becomes lower than the threshold value, and specifies a permissible time as a threshold value of the presence or absence of leakage on the basis of the detected temperature and a volume of the air, thereby judging the presence or absence of leakage according to a relationship between the actual time and the permissible time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid ejection device and a leakage determination method.

  A so-called off-carriage type ink jet printer pressurizes a main tank (ink cartridge) provided in a housing to supply ink stored therein from a sub tank in the carriage to a recording head. ing. The recording head forms an image on the recording paper by ejecting ink while reciprocating in the direction substantially orthogonal to the conveying direction of the recording paper together with the carriage. The pressurization of the main tank is performed by sending air whose pressure has been increased by a pump to the inside. Therefore, if the tube connecting the pump and the main tank or the outer shell of the main tank itself is damaged and air leaks from the damaged portion, the main tank cannot be pressurized sufficiently and the supply of ink is stagnated. For this reason, in the maintenance of the ink jet printer, so-called leak determination for confirming the presence or absence of air leak is essential.

Patent Document 1 discloses a mechanism that can be applied to this leak determination. The apparatus disclosed in this document estimates the time required for refilling ink from the remaining amount of ink. Conventionally, a dedicated jig for detecting such ink remaining amount and pressure in the tube is mounted on the ink jet printer, and the presence or absence of air leakage is determined according to the detection result.
Japanese Patent Laid-Open No. 06-316085

  However, the dedicated jig used for determining such a leak is not provided as standard in the ink jet printer itself. For this reason, the determination of the presence or absence of a leak has a problem that the service engineer must bring a dedicated jig to the installation site of the printer, leading to a high cost of after-sales service.

  The present invention has been devised under such a background, and can determine whether or not there is a leak without using any special equipment other than various detection equipment that is standard equipment in the liquid ejection device. The purpose is to provide a mechanism.

  A liquid ejection apparatus according to a preferred aspect of the present invention includes a recording head that ejects liquid from a nozzle opening, a tank that supplies the liquid, a flow path that connects the tank and the recording head, and a temperature that detects the temperature of the recording head. Detection means, pressure detection means for detecting whether or not the pressure at a predetermined pressure detection position inside the tank, recording head, or flow path has reached the threshold value, and detects that the pressure is below the threshold value Liquid supply means for supplying pressurized air to the tank and supplying the liquid in the tank to the recording head via the flow path, and a threshold value after the pressure applied to the tank exceeds the threshold value. And the allowable time that is the threshold for the presence or absence of air leakage based on the detected temperature and the volume of air sent into the tank by the operation of the liquid supply means. , Real time identified Characterized in that it comprises a determination means for determining the presence or absence of leakage in accordance with the relationship between the allowable time. According to the present invention, the presence or absence of ink leakage is determined according to the detection results of the temperature detection means and the pressure detection means that are standard equipment in a normal printer. Therefore, it is possible to determine the presence or absence of ink leakage without using special equipment such as a dedicated jig for measuring the pressure in the flow path.

  In addition, the judgment means subtracts the estimated time from when the pressure exceeds the threshold value until it reaches the ideal pressure from the specified real time, and compares the time obtained by the subtraction with the allowable time according to the result of the leakage. The presence or absence may be determined. According to this, the presence / absence of leakage is determined based on the time obtained by subtracting the estimated time from the actual time from when the pressure exceeds the threshold value to below the threshold value. Therefore, the timing at which the pressure that has reached the ideal pressure starts to decrease is taken into consideration, and the presence or absence of leakage can be more reliably determined.

  Further, the apparatus further includes a memory that stores each combination of the temperature of the recording head and the volume of the air fed into the tank and the permissible time, and a consumption detection unit that detects the consumption of ink. The determination means specifies the volume of air in the tank based on the consumption detected by the consumption detection means, and is stored in the memory in association with the combination of the volume and the temperature detected by the temperature detection means. The allowable time may be read out, and it may be determined that there is a leak when the time obtained by subtraction is larger than the read allowable time. According to this, the allowable time corresponding to the detected combination of temperature and consumption is specified by referring to the memory in which each combination of the print head temperature and the ink consumption is associated with the allowable time. Therefore, it is possible to appropriately reflect the relationship between the temperature, the amount of consumption, and the allowable time, which has been obtained in advance by actual measurement, in the determination of the presence or absence of leakage.

  Further, the liquid supply means may send pressurized air into the tank until an estimated time elapses after it is detected that the pressure exceeds a threshold value. According to this, air is fed into the tank until the estimated time elapses. Therefore, the air pressure in the tank can surely reach the ideal air pressure regardless of the volume of air in the tank and the magnitude of the temperature fluctuation range.

  According to another aspect of the present invention, there is provided a leakage determination method, comprising: a recording head that discharges liquid from a nozzle opening; a tank that supplies liquid; a flow path that connects the tank and the recording head; Temperature detecting means for detecting, pressure detecting means for detecting whether or not the pressure at a predetermined pressure detecting position inside the tank, the recording head, or the flow path has reached the threshold value, and the pressure is below the threshold value Is detected by a liquid discharge apparatus having liquid supply means for supplying pressurized air to the tank and supplying the liquid in the tank to the recording head via the flow path. The actual time from when the pressure applied to the tank exceeds the threshold to below the threshold is specified, and based on the detected temperature and the volume of air fed into the tank by the operation of the liquid supply means Air leakage Identifying the allowable time as the presence or absence of a threshold, characterized by having a decision step for determining the presence or absence of leakage in accordance with the relationship between the permissible time and the actual time specified. Also according to the present invention, the presence or absence of ink leakage is determined according to the detection results of the temperature detection means and the pressure detection means provided as standard in a normal printer. Therefore, it is possible to determine the presence or absence of ink leakage without using special equipment such as a dedicated jig for measuring the pressure in the flow path.

(Embodiment of the Invention)
Embodiments of the present invention will be described below with reference to the drawings.
The feature of the ink jet printer as the liquid ejection device according to the present embodiment is that the pressurized air is sent into the sub-tank every time the pressure in the main tank falls below the threshold value. While supplying ink (equivalent to liquid) intermittently, leaks depending on the relationship between the allowable time calculated according to the pressurized volume in the main tank and its temperature and the actual time interval of pressurization of the main tank This is the point of judging whether or not.

<Schematic configuration of inkjet printer>
FIG. 1 is a top view showing details of a recording head of an ink jet printer and various members supporting driving thereof. Each element constituting the printer according to the present embodiment can be broadly classified into a recording head driving system including a recording head and various members that support driving the recording head, and a control system including a member that controls the operation of the recording head. As shown in FIG. 1, walls 11, 12, and 13 are provided on the upper surface of the printer casing so as to surround the left, right, and rear sides, and from the right wall 11 toward the left. A sheet feeding member 14 is provided continuously. Then, an image of ink dots is formed on the upper surface of the sheet conveyed on the sheet feeding member (platen) 14.

  In FIG. 1, a drive pulley 15 and a driven pulley 16 are respectively provided at a position slightly left from the right end of the rear wall 12 of the housing, and at a position slightly right from the left end in FIG. A belt 17 is wound around the pulleys 15 and 16. Further, a shaft-shaped guide member 18 is spanned between the left side wall 11 and the right side wall 13 in front of the carriage 19 so that the carriage 19 can slide along the guide member 18. Has been. The two connecting members 21 and 22 provided at the rear of the carriage 19 are fixed so as to sandwich a predetermined position of the belt 17. The rotation shaft of the drive pulley 15 is attached to the motor 22. Therefore, when the drive pulley 15 rotates forward and backward by the motor 22, the carriage 19 is guided to the guide member 18 and reciprocates left and right.

  The carriage 19 includes sub tanks 25y, 25m, 25c, and 25k (hereinafter, appropriately referred to as “sub tanks 25”) corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (K). A recording head 60 (see FIG. 2) is provided under these sub tanks 25. The recording head 60 includes a nozzle plate 62 having a series of nozzle openings, a piezoelectric element 63 that expands and contracts in response to charge and discharge, and a cavity 64 that is sandwiched between the nozzle plate 62 and the piezoelectric element 63 to form an ink storage space. Have Note that the sub tank 25 is not limited to the four colors of YMCK, and may correspond to any number of colors such as six colors including light cyan (LC) and light magenta (LM).

  In FIG. 1, a cap 26 and a wiper 27 are provided on the right side of the paper feeding member 14. The cap 26 and the wiper 27 function when a cleaning operation is performed.

  The cleaning operation is executed according to the following procedure. First, the carriage 19 is moved rightward in FIG. 1 to a position where the nozzle plate 62 of the recording head 60 and the cap 26 face each other (hereinafter, this position is referred to as “home position”), and then the cap 26 is raised. The nozzle plate 62 is sealed with the cap 26. Next, a negative pressure is generated in an airtight space created by sealing the cap 26 to the nozzle plate 62. As a result, the ink in the cavity 64 (see FIG. 3) of the recording head 60 is sucked together with the bubbles mixed therein and absorbed by the waste liquid absorbent 79 (see FIG. 3). When the ink suction is finished, the cap 26 is lowered after the negative pressure state is eliminated. Further, the wiper 27 is raised to a height where it contacts the nozzle plate 62, and the carriage 19 is moved leftward from the home position. At this time, the wiper 27 wipes the nozzle plate 62, the ink meniscus on the lower side is adjusted, and the cleaning operation is completed.

  In FIG. 1, main tanks 28y, 28m, 28c, and 28k (hereinafter referred to as “main tank 28” as appropriate) corresponding to the respective colors of YMCK are mounted on the right of the right wall 13. These main tanks 28 are filled with ink of each color YMCK. The main tank 28 for each color is connected to each of the sub tanks 25 for each color mounted on the carriage 19 via a first tube 31. A pressurizing pump 30 is mounted above the main tank 28.

  FIG. 2 is a diagram schematically showing an ink supply system from the main tank 28 to the recording head 60 via the sub tank 25. As shown in FIG. 2, the main tank 28 is loaded with an ink pack 35 formed of a flexible material. A pressure relief valve 37 is provided in the outer shell 36 of the main tank 28, and a pressure sensor 39 (corresponding to “pressure detection means” in the claims) is provided in an airtight space 38 between the outer shell 36 and the ink pack 35. Is provided. The pressure sensor 39 is, for example, a light projecting / receiving sensor, and when the light projecting / receiving state changes when a predetermined threshold is exceeded, the pressure in the airtight space 38 is set to a predetermined threshold (in the example described below, 8 kg). Detect whether or not (Pascal) is reached. The air port 43 of the main tank 28 is connected to the pressurizing pump 30 through the second tube 44, and the pressurizing pump 30 is connected to the airtight space 38 between the outer shell 36 of the main tank 28 and the ink pack 35. Air having a pressure sufficiently higher than the pressure in the space can be fed.

  Further, the ink outlet 45 of the main tank 28 and the ink inlet 46 of the sub tank 25 are connected via the first tube 31 described above, and the ink outlet 47 of the sub tank 25 and the recording head 60 are connected via the third tube 49. It is connected. The recording head 60 is provided with a temperature sensor 61 (corresponding to “temperature detection means” in the claims). The temperature sensor 61 detects the temperature of the recording head 60. The pressurization pump 30 repeats intermittent air supply with increased pressure under the control of an ink supply control unit 82 described later. Such intermittent delivery of air into the airtight space 38 of the main tank 28 is called “additional pressurization” or the like. By repeating this additional pressurization with the assistance of the pressure sensor 39, supply of ink to the recording head 60 without excess or deficiency is realized.

  The principle of ink supply by the pressure pump 30 will be described in detail. When the pressurizing pump 30 is driven and air having a pressure sufficiently higher than that space is fed into the airtight space 38 of the main tank 28, the internal pressure of the airtight space 38 becomes higher than the internal pressure of the ink pack 35. The pack 35 is crushed. When the ink pack 35 is crushed, the volume of the ink pack 35 is shrunk, and a part of the ink that is no longer stored and partitioned inside the ink pack 35 is pushed out from the ink outlet 45 into the first tube 31. 46 to the sub tank 25.

  Further, when the sub tank 25 is filled with the ink supplied from the main tank 28 and the internal pressure increases to a certain level, the ink in the sub tank 25 is pushed out from the ink outlet 47 into the third tube 49, and the pushed ink is discharged. Supplied to the recording head 60. When the ink is pushed out and the ink pack 35 contracts, the airtight space 38 of the main tank 28 expands its volume in exchange for the contraction, and the pressure in the airtight space 38 decreases due to the expansion. In this example, when the pressure in the hermetic space 38 falls below the lower limit threshold value (for example, 8 kilopascals), the supply of ink to the recording head 60 stagnate, while the pressure is the upper limit threshold value (for example, 12 kg). If it exceeds (Pascal), the ink supply to the recording head 60 becomes excessive. For this reason, the printer according to the present embodiment drives the pressurizing pump 30 each time the pressure in the airtight space 38 of the main tank 28 detected by the pressure sensor 39 falls below 8 kilopascals, and also releases the pressure of the main tank 28. By setting the valve opening threshold of the valve 37 to about 12 kilopascals, the pressure fluctuation range is within the range between the two.

  The volume of the main tank 28 is 300 cc, for example, and the volume of the ink pack 35 contained therein is 200 cc, for example. Therefore, the volume of the initial airtight space 38 in which the ink pack 35 is loaded is 100 cc, and when the ink is pushed out from the ink pack 35, the volume of the airtight space 38 increases accordingly.

  FIG. 3 is a diagram showing details of the control system of the ink jet printer. As shown in FIG. 3, the control system of this printer is mounted separately from the first pump driving unit 70 that drives the above-described pressurizing pump 30 to send air to the airtight space 38 of the main tank 28 and the pump 30. The second pump drive unit 72 that switches the pressure of the airtight space 38 obtained by driving the suction pump 71 and sealing the cap 26 to the nozzle plate 62, and the carriage drive that drives the motor 22 to move the carriage 19 left and right In addition to the unit 73, the head driving unit 74 that drives the recording head 60 to discharge ink, the actuator driving unit 76 that drives the actuator 75 to move the cap 26 and the wiper 27 up and down, the timer 80, the print control unit 81, and the ink supply A control unit 82, a cleaning control unit 83, and a leak determination control unit 84 are provided. Each of these control units may be configured by hardware logic such as a customized ASIC (Application Specific Integrated Circuit), or by software logic using a CPU, a RAM, and a program developed on the RAM. May be.

  The functions of the timer 80 and each control unit will be described in detail. The timer 80 receives a query from each unit and outputs a signal indicating the time. The print control unit 81 controls both the carriage drive unit 73 and the head drive unit 74 based on the print data, thereby forming an image corresponding to the print data on the recording paper. The processing executed by the print control unit 81 is specifically shown as follows. When the print control unit 81 is supplied with print data generated by the printer driver 91 of the host computer 90 or a printer driver (not shown) of the printer (not shown) that the printer itself has, the print control unit 81 supplies it. The print data is converted into raster data. Subsequently, the address and density of each pixel constituting the raster data are specified. Further, control signals for forming dots at the addresses of the respective pixels at those densities are supplied to the carriage driving unit 73 and the head driving unit 74.

  The print control unit 81 calculates ink consumption based on raster data generated by itself. Specifically, each time print data is converted into raster data, the number of on dots of the raster data is counted, and the number of on dots counted is multiplied by the ink consumption per dot, thereby obtaining one raster data. The ink consumption amount is calculated. An area for storing the total amount of ink consumption is secured in the memory in the print control unit 81, and the ink consumption amount is added to the total amount each time the ink consumption amount corresponding to each raster data is calculated. Is done. The print control unit 81 corresponds to “consumption amount detection means” in the claims.

  The cleaning control unit 83 is a module that performs a cleaning operation. The cleaning control unit 83 gives an instruction to start the cleaning operation when a cleaning button (not shown) is pressed or the time counted by the timer 80 reaches a specified time. When the cleaning control unit 83 instructs the start of the cleaning operation, the carriage 19 is moved to the home position, the cap 26 is raised, the negative pressure is applied, the negative pressure is released, the cap 26 is lowered, and the wiper 27 is raised. Then, a control signal for performing the above-described series of operations of moving the carriage 19 to the outside of the home position is sequentially supplied to the carriage driving unit 73, the actuator driving unit 76, and the second pump driving unit 72.

  The ink supply control unit 82 is a module that controls supply of ink by additional pressure. A signal indicating that the pressure in the airtight space 38 of the main tank 28 has exceeded the lower limit threshold value of 8 kilopascals and a signal indicating that the pressure has been decreased below the threshold value are supplied from the pressure sensor 39 to the ink supply control unit 82. Supplied. When a signal indicating that the pressure in the airtight space 38 is below the lower limit threshold is supplied, the ink supply control unit 82 supplies a control signal to the first pump driving unit 70 to the airtight space 38 in the main tank 28. The air supply is started, and the supply is stopped when a predetermined time (for example, 10 seconds) has elapsed since the signal indicating that the pressure exceeded the lower limit threshold was supplied. When a signal indicating that the pressure has fallen below the lower limit threshold is supplied again, the supply of air to the airtight space 38 of the main tank 28 is started. By repeating such a routine, the pressure in the airtight space 38 of the main tank 28 changes between 8 kilopascals and 12 kilopascals. The ink supply control unit 81 corresponds to “ink supply means” in the claims.

  FIG. 4 is a diagram showing the relationship between the driving state of the pressurizing pump 30 and the pressure in the airtight space 38 of the main tank 28. As described above, the driving of the pressurizing pump 30 is triggered by the fact that the pressure in the airtight space 38 has fallen below the lower limit threshold. When the pressurizing pump 30 is driven and the pressurized air is sent into the airtight space 38 of the main tank 28, the pressure soon exceeds 8 kilopascals and rises as it is to reach 12 kilopascals. As described above, since the threshold of the pressure relief valve 37 of the main tank 28 is set to 12 kilopascals, the pressure of the airtight space 38 that has reached 12 kilopascals does not increase beyond that.

  The time required for the pressure in the airtight space 38 to reach 12 kilopascals after exceeding 8 kilopascals varies depending on the volume and temperature of the airtight space 38. On the other hand, as a matter of course, the driving time of the pressurizing pump 30 has a margin to ensure that the pressure can reach 12 kilopascals regardless of the fluctuation of the volume of the airtight space 38. It is desirable to set. In addition, as an example of the time with a margin, there is a case where the time for which the pressurization pump 30 is continuously driven is set to about 10 seconds, for example. In this case, how the volume of the airtight space 38 varies. Regardless, its volume can reach 12 kilopascals.

  When the pressure in the hermetic space 38 reaches 12 kilopascals and the drive of the pressurizing pump 30 is stopped, the pressure rapidly decreases immediately thereafter, and then gradually decreases. The slope of the pressure drop immediately after the drive of the pressurizing pump 30 is stopped is that the tube forming a part of the flow path from the main tank 28 to the recording head 60 is somewhat after the pressurization is stopped. This is because it expands and shifts to an equilibrium state. A predetermined time after this pressure is suddenly reduced is called “balance time” or the like. When the pressure in the airtight space 38 falls below 8 kilopascals, the pressure transition as shown in the envelope of FIG. Note that the time required for the pressure to drop below 8 kilopascals after this balance time also varies depending on the volume and temperature of the airtight space 38.

  Returning to the description of FIG. The leak determination control unit 84 is a module that controls determination of air leaks. The leak determination control unit 84 corresponds to “determination means” in the claims. The leak determination control unit 84 is supplied with a signal indicating the temperature of the recording head 60 from the temperature sensor 61, and indicates whether the pressure in the airtight space 38 of the main tank 28 is above or below the lower limit threshold. Is supplied from the pressure sensor 39. Further, a signal indicating the total amount of ink consumption stored in the memory is supplied from the print control unit 81. A leak determination time value table is stored in the memory of the leak determination control unit 84.

  FIG. 5 is a diagram showing a leak determination time value table stored in the memory of the leak determination control unit 84. This table shows discrete values (10 ° C., 15 ° C., 20 ° C., 25 ° C., 30 ° C., 35 ° C.) indicating the temperature of the airtight space 38 of the main tank 28 in increments of 5 ° C. and discrete values indicating the volumes in increments of 50 cc. Each combination of values (100 cc, 150 cc, 200 cc, 250 cc, 300 cc) and an allowable time are stored in association with each other. The allowable time stored in each field of this table is a time used as a threshold for determining whether or not the air supplied from the pressurizing pump 30 to the airtight space 38 is leaking. The time until the pressure of the airtight space 38 falls below the threshold value (8 kilopascals) after the pressure pump 30 is operated in each environment where the temperature and the volume are different from each other and the balance time is passed (time t1 shown in FIG. 4). Is set based on the actual measurement result.

  In FIG. 5, there is a relationship of A <B <C <D <E. Further, since the viscosity of air increases as the temperature rises, there is a relationship of N15 <N20 <N25 <N30 <N35. Here, N is any one of A to E.

  As described above, the allowable time must be prepared for each combination of the volume and temperature of the airtight space 38 for the following reason. As described at the beginning, the present embodiment is characterized in that the presence or absence of a leak is determined according to the relationship between the allowable time and the actual time interval of pressurization of the main tank 28. That is, when the time corresponding to the time t1 in FIG. 4 is extremely earlier than that measured during normal operation, damage is caused to any part on the air supply path from the pressurizing pump 30 to the airtight space 38. It is determined that a site (a wound) has occurred and air has leaked from the wound. However, as described above, the time corresponding to t1 in FIG. 4 varies depending on the volume and temperature of the hermetic space 38.

  In general, the lower the temperature, the lower the viscosity of air, and the higher the temperature, the higher the viscosity. For this reason, the pressure drop when a leak occurs at a low temperature is steeper than the pressure drop when a leak occurs at a high temperature. Further, the larger the volume of air in the hermetic space 38, the smaller the volume of leak that occupies that volume, so the slope of the decrease in atmospheric pressure becomes gentler, and the smaller the volume of air in the hermetic space 38, the larger the volume. Since the volume of leak is increased, the slope of the decrease in pressure becomes steep. In view of such circumstances, in the present embodiment, if a leak occurs based on the result of actual measurement by operating the pressurization pump 30 in each environment where the volume and temperature of the airtight space 38 are different. The threshold times that may be judged are individually determined, and the determined times are collected as an allowable time table shown in FIG.

<Flow of processing executed by leak judgment control unit>
Next, the process executed by the leak determination control unit 84 will be described in detail with reference to the flowchart of FIG. In the series of processes shown in the figure, activation of the leak determination mode is instructed by a timer interrupt process or the like in the CPU when a mode transition button (not shown) is pressed or ink is not supplied. Note that the state where ink is not supplied refers to a state where ink ejection from the recording head 60 is stopped and the operation of the suction pump 71 is stopped.

  When the activation of the leak determination mode is instructed (S100: Yes), the leak determination control unit 84 specifies the volume of the airtight space 38 (S110). The volume of the airtight space 38 is specified by adding the total amount of ink consumption indicated by the signal supplied from the print control unit 81 to the volume (100 cc) of the airtight space 38 when the ink tank is loaded. Next, the leak determination control unit 84 reads the allowable time corresponding to the combination of the temperature indicated by the signal supplied from the temperature sensor 61 and the volume specified in step S110 from the leak determination time value table (S120).

  Next, the leak determination control unit 84 supplies a control signal to the pressurizing pump 30 to start the supply of air into the airtight space 38 of the main tank 28 (S130). When the inflow of air into the airtight space 38 is started, the pressure increases. When a signal indicating that the pressure has exceeded the lower limit threshold value of 8 kilopascals is supplied from the pressure sensor 39 (S140: Yes), when a predetermined time has elapsed from that time (S150: Yes), Air supply from the pressure pump 30 to the airtight space 38 is stopped (S160). This predetermined time (corresponding to “estimated time” in the claims) can ensure that the pressure reaches 12 kilopascals (corresponding to “ideal pressure” in the claims) regardless of the change in the volume of the airtight space 38. It is about a time (for example, about 10 seconds as described above).

  When the supply of air from the pressurizing pump 30 to the hermetic space 38 is stopped, the air pressure in the hermetic space 38 decreases after a balance time. Before the balance time elapses, time measurement by the timer 80 is started (not shown). However, the time may be measured by the timer 80 after the balance time has passed. In view of the short operation time of the pressurizing pump 30, the time measurement by the timer 80 may be started from the start of driving of the pressurizing pump 30.

  When the pressure falls below the lower limit threshold value of 8 kilopascals, a signal indicating that is supplied from the pressure sensor 39 to the leak determination control unit 84. The leak determination control unit 84 that has received the signal supply (S170: Yes) balances from the time from when the timer 80 is activated until the signal indicating that the pressure falls below the lower limit threshold is supplied. The offset value corresponding to time is subtracted (S180). By this subtraction, the actual time corresponding to t1 in FIG. 4 is obtained. The leak determination control unit 84 compares the actual time obtained in step S180 with the allowable time read in step S120. When the actual time obtained in step S180 is smaller than the allowable time (S190: Yes), a message indicating that a leak has occurred is output to the host computer 90 (S200).

  In the present embodiment described above, ink is intermittently transferred from the main tank 28 to the carriage 19 by sending pressurized air into the main tank 28 whenever the pressure in the main tank 28 falls below the lower limit threshold. Supply. Then, by referring to the table based on the combination of the airtight space 38 of the main tank 28 pressurized by the pressurizing pump 30 and the temperature of the recording head 60, the allowable time serving as a threshold for determining the leak is specified, and the main When the time obtained by subtracting the balance time from the time interval from when the pressure in the tank 28 exceeds the lower limit threshold to below it falls below the allowable time, it is determined that a leak has occurred. In this way, by preparing a table in which each combination of the pressurized volume and temperature and the permissible time are associated, various types of detection that are standard on the ink jet printer, such as the pressure sensor 39 and the temperature sensor 61, are prepared. Whether or not there is a leak can be determined using only the device.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and various modifications can be made.

  The printer according to the above embodiment measures the time from when the pressure in the airtight space 38 of the main tank 28 exceeds the lower limit threshold until it falls below the lower limit threshold, and then calculates an offset value corresponding to the balance time from that time. Subtraction is performed, and the magnitude relationship between the real time obtained by the subtraction and the allowable time is compared. On the other hand, the presence or absence of a leak may be determined by comparing the time from when the pressure in the airtight space 38 of the main tank 28 exceeds the lower limit threshold to when it falls below the allowable time. In this modification, the pressure pump 30 is driven in each environment in which the volume and temperature of the airtight space 38 are different, and the pressure exceeds the lower limit threshold (8 kilopascals) until it falls below the lower limit threshold. This can be realized by storing the time, that is, the allowable time set based on the sum of the time t1, the balance time, and the drive time of the movable pump shown in FIG. 4 in each field of the table.

  The printer according to the above-described embodiment is configured to send and stop air to the airtight space 38 of the main tank 28 by driving and stopping the pressurizing pump 30. On the other hand, while the pressure pump 30 is driven, a valve is provided in the second tube 44 between the pressure pump 30 and the airtight space 38, and air to the airtight space 38 is opened and closed. You may make it switch between sending and stopping.

  In the printer according to the embodiment, the temperature sensor 61 is mounted on the recording head 60. On the other hand, a temperature sensor may be mounted on the main tank, the sub tank, or the flow path from these tanks to the recording head 60, and the allowable time may be read from the table according to the detection value of the temperature sensor.

  Further, in the above-described embodiment, activation of the leak determination mode is instructed in a state where ink ejection from the recording head 60 is stopped. However, in view of the fact that the amount of ink discharged from the recording head 60 is very small, the leak determination mode may be activated even when the recording head 60 is operating.

  Further, the liquid ejection device is not limited to an ink jet printer. Examples of the liquid ejection device other than the ink jet printer include a device for ejecting liquid used for manufacturing a liquid crystal display, an EL display, and the like. In addition, the liquid may be a liquid other than ink. For example, in a device for ejecting a liquid used for a liquid crystal display or an EL display, the color material and the electrode material are liquid.

FIG. 3 is a diagram illustrating details of a recording head of an ink jet printer according to an embodiment of the present invention and various members that support driving thereof. FIG. 3 is a diagram schematically illustrating an ink supply system from a main tank to a recording head. It is a figure which shows the detail of the control system of the printer shown in FIG. It is a figure which shows the relationship between the drive state of a pressurization pump, and the pressure of the airtight space of a main tank. It is a figure which shows the time value table for leak judgment. It is a flowchart which shows the process which a leak judgment control part performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11, 12, 13 ... Wall, 14 ... Paper feed member, 15 ... Drive pulley, 16 ... Drive pulley, 17 ... Belt, 18 ... Guide member, 19 ... Carriage, 25 ... Sub tank, 60 ... Recording head, 62 ... Nozzle plate 63 ... Piezoelectric element, 64 ... Cavity, 26 ... Cap, 27 ... Wiper, 35 ... Ink pack, 36 ... Outer shell, 38 ... Airtight space, 39 ... Pressure sensor (corresponding to "pressure detection means" in claims), 31 ... 1st tube, 44 ... 2nd tube, 43 ... Air port, 45, 47 ... Ink outlet, 49 ... 3rd tube, 61 ... Temperature sensor (equivalent to "temperature detection means" in claims), 70 ... 1st Pump drive unit 72 ... second pump drive unit 22 ... motor 74 ... head drive unit 75 ... actuator 76 ... actuator drive unit 80 ... watch 81 ... print control unit 82... Ink supply control unit (corresponding to “ink supply unit” in claims), 83... Cleaning control unit, 84... Leak judgment control unit (corresponding to “judgment means” in claims) , 90: Host computer, 91: Printer driver

Claims (5)

A recording head for discharging liquid from the nozzle opening;
A tank for supplying the liquid;
A flow path connecting the tank and the recording head;
Temperature detecting means for detecting the temperature of the recording head;
Pressure detection means for detecting whether the pressure at a predetermined pressure detection position inside the tank, the recording head, or the flow path has reached a threshold value;
When it is detected that the pressure is below the threshold value, liquid supply means for supplying pressurized air to the tank and supplying the liquid in the tank to the recording head via the flow path When,
The actual time from when the pressure applied to the tank exceeds the threshold value to below the threshold value is specified, and based on the detected temperature and the volume of air fed into the tank by the operation of the liquid supply means. In addition, a determination unit that specifies an allowable time that is a threshold for the presence or absence of air leakage and determines the presence or absence of leakage according to the relationship between the specified real time and the allowable time,
A liquid ejecting apparatus comprising: The determination means includes
The estimated time until the ideal pressure is reached after the pressure exceeds the threshold value is subtracted from the specified actual time, and the presence or absence of leakage is determined according to the result of comparing the time obtained by the subtraction with the allowable time. To
The liquid ejection apparatus according to claim 1, wherein A memory storing each combination of the temperature of the recording head and the volume of air sent into the tank and the permissible time;
Consumption detection means for detecting the consumption of ink;
Further comprising
The determination means includes
The volume of air in the tank is specified based on the consumption detected by the consumption detection means, and is stored in the memory in association with the combination of the volume and the temperature detected by the temperature detection means. Read the allowable time, and determine that there is a leak when the time obtained by the subtraction is larger than the read allowable time,
The liquid discharge apparatus according to claim 2, wherein The liquid supply means includes
Injecting pressurized air into the tank between the time when the estimated time elapses after it is detected that the pressure is above a threshold;
The liquid discharge apparatus according to claim 2, wherein the liquid discharge apparatus is a liquid discharge apparatus. A recording head for discharging liquid from a nozzle opening; a tank for supplying the liquid; a flow path connecting the tank and the recording head; a temperature detecting means for detecting the temperature of the recording head; the tank; When it is detected that the pressure at the predetermined pressure detection position in the head or the flow path has reached the threshold value, and the pressure is detected to be below the threshold value, A method that is executed in a liquid ejection apparatus that includes a liquid supply unit that sends pressurized air into the tank and supplies liquid in the tank to the recording head via the flow path.
The actual time from when the pressure applied to the tank exceeds the threshold value to below the threshold value is specified, and based on the detected temperature and the volume of air fed into the tank by the operation of the liquid supply means. In addition, a determination process for identifying an allowable time as a threshold for the presence or absence of air leakage and determining the presence or absence of leakage according to the relationship between the specified real time and the allowable time,
A leakage judgment method characterized by comprising:

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