JP6198419B2 - Ink jet recording apparatus and ink amount detection method - Google Patents

Description

  The present invention relates to a recording apparatus and an ink amount detection method. The present invention particularly relates to, for example, an ink jet recording apparatus including an ink tank for storing ink and a sub tank, and an ink amount detection method for the sub tank.

  In recent years, an ink jet recording apparatus has been used for recording on a recording medium having a large size such as A1 or A0. Its applications range from black line drawings to photographic image recording. In particular, when a relatively high duty image such as a photographic image is recorded, a large amount of ink is consumed for recording one sheet. As a result, ink tanks are frequently replaced. When the ink tank replacement frequency increases, not only the time loss due to the interruption of the recording operation increases, but also the image quality such as color unevenness caused by the time difference due to the interruption of the recording operation may be caused.

  Therefore, in order to avoid ink tank replacement accompanying interruption of the recording operation, for example, as disclosed in Patent Document 1, an ink jet recording apparatus in which a sub tank different from the ink tank is mounted has been proposed. According to Patent Document 1, ink is moved from an ink tank to a sub tank (hereinafter referred to as sub tank filling), and ink is supplied from the sub tank to the recording head to perform a recording operation. With such a configuration, even when the ink in the ink tank is used up, recording can be continued with the ink in the sub tank.

  If the ink tank is replaced while recording is performed while consuming ink in the sub tank, the recording operation is not interrupted, so that time loss and image quality deterioration can be prevented. Further, according to the cited document 1, a volume changing member (diaphragm valve) that also serves as a valve that shuts off the flow path is provided between the sub tank and the recording head, and after the ink in the sub tank is consumed, the sub tank is set to a negative pressure. In this way, ink is supplied from the ink tank to the sub tank.

JP 2010-208151 A

  However, if an attempt is made to use a sub-tank having a configuration different from that disclosed in Patent Document 1, there is a problem in that the amount of ink in the sub-tank cannot be accurately measured during ink supply from the ink tank to the sub-tank. Specifically, even if the sensor detects that the sub-tank is filled with ink, the sub-tank is actually not filled with ink.

  In other words, the configuration disclosed in Patent Document 1 has a problem in that there is no degree of freedom in selecting a subtank and it is not possible to use subtanks having configurations different in shape and configuration.

  The present invention has been made in view of the above-described conventional example, and provides an ink jet recording apparatus and an ink amount detecting method capable of accurately measuring the ink amount in the sub tank even when the sub tank having another configuration is used. For the purpose.

  In order to achieve the above object, an ink jet recording apparatus of the present invention has the following configuration.

That is, the i Nkutanku for storing ink, a sub tank for storing ink supplied from the ink tank, a recording head for recording on a recording medium by discharging an ink supplied from the sub tank, before Symbol sub-tank and the recording disposed between the head, a supply means for supplying operation of supplying a predetermined amount of ink in the first interval to the sub tank from the ink tank by changing the volume pair which is provided in an upper portion of the sub-tank comprising of the electrode, and a detection means for performing the second distance detection operation for detecting a current flowing upon application of a voltage value or the constant voltage of which was obtained by applying a constant current to the pair of electrodes, the detection the supply operation is stopped on the basis of the means of detection result, wherein the second interval than the first interval is long, the second distance is different from an integral multiple of the first interval And wherein the door.

Also, look at the present invention from another aspect, the recording performed and Lee Nkutanku for storing ink, a sub tank for storing ink supplied from the ink tank, a recording medium by discharging an ink supplied from the sub tank a head, disposed between said recording head and the sub tank, a supply means for supplying operation of supplying a predetermined amount of ink in the first interval to the sub tank from the ink tank by changing the volume, the an ink amount detecting method in the ink jet recording apparatus having a pair of electrodes provided on the upper portion of the sub tank, a current flowing upon application of a voltage value or the constant voltage of which was obtained by applying a constant current to said pair of electrodes performs a detection operation for detecting the value in the second interval, the feed operation is stopped based on the detection result of the previous SL detection operation, than the first distance Serial second distance is long, the second interval comprises an ink amount detecting method of being different from an integral multiple of the first interval.

  Therefore, according to the present invention, there is an effect that the ink amount in the sub tank can be accurately measured by changing the execution timing of the ink supply to the sub tank and the ink amount detection of the sub tank.

1 is a partially broken perspective view showing a schematic configuration of an ink jet recording apparatus that is a typical embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of an ink supply system of the recording apparatus illustrated in FIG. 1. FIG. 2 is a block diagram illustrating a control configuration of the recording apparatus illustrated in FIG. 1. FIG. 4 is a diagram illustrating a state of an ink supply system in a state where a recording operation is executed using the ink in an ink tank and using ink in a sub tank (stopless recording). It is a figure which shows the control sequence of stopless recording. It is a figure which shows the state of the ink supply system after replacing | exchanging an ink tank. It is a flowchart which shows the detailed process sequence of sub tank filling control required during stopless recording control. It is a figure which shows the relationship between the measurement voltage of the ink amount detection in a sub tank, and sub tank filling time. It is a figure which shows the change of the ink amount in the sub tank 4 corresponding to each of three area | regions shown to Fig.8 (a). It is a figure explaining setting conditions. It is a figure which shows the specific example of the time change of a voltage. It is a figure which shows the relationship between an ink supply operation | movement, ink amount detection operation, and a sub tank filling time, and a figure which shows the relationship between the measurement voltage by the ink amount detection in a sub tank, and a sub tank filling time. FIG. 6 is a diagram illustrating a state in which the timing of ink supply operation and the timing of ink amount detection are made different.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the already demonstrated part and duplication description is abbreviate | omitted.

  In this specification, “recording” (sometimes referred to as “printing”) is not limited to the case of forming significant information such as characters and graphics, but may be significant. It also represents the case where an image, a pattern, a pattern, etc. are widely formed on a recording medium, or the medium is processed, regardless of whether it is manifested so that humans can perceive it visually. .

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Further, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording (printing)”. Therefore, by being applied on the recording medium, it is used for formation of images, patterns, patterns, etc., processing of the recording medium, or ink processing (for example, solidification or insolubilization of the colorant in the ink applied to the recording medium). It shall represent a liquid that can be made.

  Furthermore, unless otherwise specified, the “nozzle” collectively refers to an ejection port or a liquid channel communicating with the ejection port and an element that generates energy used for ink ejection.

  The recording head substrate (head substrate) used below does not indicate a simple substrate made of a silicon semiconductor but indicates a configuration in which each element, wiring, and the like are provided.

  Further, the term “on the substrate” means not only the element substrate but also the surface of the element substrate and the inside of the element substrate near the surface. In addition, the term “built-in” as used in the present invention is not a term indicating that each individual element is simply arranged separately on the surface of the substrate, but each element is manufactured in a semiconductor circuit. It shows that it is integrally formed and manufactured on an element plate by a process or the like.

  Next, examples of the ink jet recording apparatus will be described. This recording apparatus uses a continuous sheet (recording medium) wound in a roll shape, and performs large format printing in which an image of B0 or A0 size is recorded on the sheet. Needless to say, a cut sheet may be used as the recording medium to be used.

  FIG. 1 is a partially broken perspective view showing a schematic configuration of an ink jet recording apparatus which is a typical embodiment of the present invention.

  As shown in FIG. 1, an ink jet recording apparatus (hereinafter referred to as a recording apparatus) 50 is fixed so as to straddle the upper ends of two leg portions 55 facing each other. The recording head 1 is mounted on the carriage 60. During recording, the recording medium set in the transport roll holder unit 52 is fed to the recording position, and the carriage 60 reciprocates in the direction indicated by arrow B (main scanning direction) from the carriage motor (not shown) and the belt 62. Ink droplets are ejected from each nozzle of the recording head 1. When the carriage 60 moves to one end of the recording medium, the conveyance roller 51 conveys the recording medium by a predetermined amount in the direction indicated by the arrow A (sub-scanning direction). In this way, an image is formed on the entire recording medium by alternately repeating the recording operation and the conveying operation. After the image formation, the recording medium is cut by a cutter (not shown), and the cut recording medium is stacked on the stacker 53.

  The ink supply unit 63 is provided with an ink tank 5 that is separated for each ink color such as black, cyan, magenta, and yellow (removable to the apparatus), and the ink tank 5 is connected to the supply tube 2. . In addition, the supply tube 2 is bundled by a tube guide 61 so that it does not run out when the carriage 60 reciprocates.

  A surface of the recording head 1 facing the recording medium has a plurality of nozzle rows (not shown) in a direction substantially orthogonal to the main scanning direction, and is connected to the supply tube 2 in units of nozzle rows.

  Further, a recovery unit 70 is provided at a position outside the recording medium range in the main scanning direction and facing the nozzle surface of the recording head 1. The recovery unit 70 performs a cleaning operation for sucking out ink or air from the nozzle surface of the recording head 1 and a suction operation for forcibly sucking out air accumulated in the recording head as necessary.

  An operation panel 54 is provided on the right side of the recording apparatus 50. When the ink in the ink tank 5 becomes empty, a warning message is displayed to notify the user and prompt the user to replace the ink tank 5. be able to.

  FIG. 2 is a diagram illustrating a configuration of an ink supply system of the recording apparatus illustrated in FIG. 1. As described above, the recording apparatus 50 uses a plurality of colors of ink. However, since the configuration of the ink supply system is common to the plurality of inks, only one color ink supply system is shown here.

  As shown in FIG. 2, the fixed-volume ink tank 5 that can be attached to and detached from the recording apparatus has two joint portions at the bottom, and the joint portions are the first hollow tube 8 and the second hollow portion of the apparatus. The hollow tube 9 is connected. The first hollow tube 8 and the second hollow tube 9 are constituted by hollow metal needles. A standing wall 42 is formed around the second hollow tube 9 in the ink tank 5 from the bottom surface of the ink tank. With this structure, when a minute current (constant current) is passed between the first hollow tube and the second hollow tube, the amount of ink remaining stored is lower than the standing wall 42. As a result, the current flow through the ink is hindered, and the resistance value between the two hollow tubes increases. As a result, it is possible to detect that the ink tank 5 is almost out of ink.

  Further, when the ink tank 5 is removed from the recording apparatus, the resistance value between the two hollow tubes increases, and after the ink tank 5 is replaced with a new ink tank 5, the resistance between the two hollow tubes is increased. Since the resistance value is lowered, it is possible to detect the attachment / detachment of the ink tank from such a change in the resistance value.

  The second hollow tube 9 communicates with the atmosphere communication chamber 6, and the ink tank 5 communicates with the atmosphere via the atmosphere communication passage 7 in the atmosphere communication chamber 6. Further, the bottom surface 45 of the ink tank 5 and the top surface 46 of the sub-tank 4 having a constant volume are communicated by the first hollow tube 8, and the sub-tank 4 and the recording head 1 are communicated via the supply tube 2. The sub-tank 4 is configured by an inclined surface 49 having a cross-sectional area that increases in the vertical direction in the substantially entire area of the top surface, and is connected to the first hollow tube 8 at the highest position (that is, the top surface 46). . An electrode portion (solid tube) 10 made of metal is provided in the upper portion of the sub tank 4. When a minute current (constant current) is caused to flow between the first hollow tube 8 and the electrode portion 10, whether or not the ink in the sub tank is full is detected based on the resistance value between them.

  The ink outlet from the sub tank 4 is provided at the lowest position 48 of the side surface 47. Between the sub tank 4 and the supply tube 2, there is provided an on-off valve 3 constituted by a flexible member capable of changing the volume capable of opening / closing the supply flow path. The on-off valve 3 is always urged in the opening direction by a compression spring 38, and the lever 39 is pushed by the cam 37 and is closed by rotating around the central shaft 40. The cam 37 is configured to be positioned by a photo sensor 41, and the rotation is controlled via a gear 36 by a DC motor 35 as a drive source. Here, a configuration in which the on-off valve 3 is provided in the sub tank 4 is shown, but the on-off valve 3 may be provided in the ink supply tube 2 between the sub tank 4 and the recording head 1.

  FIG. 3 is a block diagram showing a control configuration of the recording apparatus shown in FIG.

  As shown in FIG. 3, the recording apparatus 50 includes a CPU 11 that controls the entire apparatus, a user interface 12 that includes an operation panel that displays keys and information operated by the user, and a ROM 13 that contains control software. Further, the recording apparatus 50 includes a RAM 14 that is temporarily used when operating the control software, an I / O port 15 that inputs / outputs control signals, sensor signals, recording signals, and the like, and a drive unit 16 as mentioned in FIG. The ink remaining amount sensor 17 for detecting the remaining amount of the ink tank is provided.

  The ink remaining amount sensor 17 monitors the resistance value between the first hollow tube 8 and the second hollow tube 9 when a small current is passed between them, and the ink runs out. Detect that. The ink tank mounting sensor 18 that detects the attachment / detachment of the ink tank 5 determines the attachment / detachment based on the read value from the EEPROM 20 provided in the ink tank 5. Further, the content of the EEPROM 20 is rewritten via the ink tank mounting sensor 18.

  FIG. 4 is a diagram showing a state of the ink supply system in a state where the ink in the ink tank 5 is used up and the recording operation is executed using the ink in the sub tank 4 (stopless recording). In FIG. 4, the same reference numerals are given to the components already described with reference to FIG. 2, and description thereof is omitted.

  FIG. 5 is a diagram showing a control sequence of stopless recording.

  When the recording device 50 uses up the ink in the ink tank 5, the image formation can be continued using the ink in the sub tank 4. When the ink in the sub tank 4 is consumed, the ink tank 5 is removed from the atmosphere communication path 7. Via, air is introduced into the sub tank 4. As shown in FIG. 4, the introduced air accumulates above the sub tank 4. If the ink in the sub tank 4 is further consumed in such a state, the ink surface in the sub tank 4 is lowered, and the first hollow tube 8 and the electrode portion 10 are electrically connected via the ink. Disappear. As a result, it becomes difficult for current to flow between them.

  Accordingly, in step S201, the ink in the sub tank 4 is consumed by passing a minute current between the first hollow tube 8 and the electrode unit 10 and measuring the voltage value between them (that is, in step S201). , The sub tank is not full). Here, if it is determined that the ink in the sub tank 4 is consumed, it indicates that the ink tank 5 has been emptied, and the process proceeds to step S202, where the ink tank 5 is empty to the user. This is notified through the operation panel to prompt the user to replace the ink tank.

  Until the ink tank 5 is replaced, the image formation is allowed to continue up to the ink use allowable amount in the sub tank 4 and is continued. In this embodiment, the allowable amount is about 11 ml, and when the recording apparatus 50 records at a density of 100% on the maximum recordable size paper, at least one sheet corresponds to the recordable ink amount. The following method is used to determine whether or not the ink usage allowance has been used. That is, the ink consumption allowable amount in the sub tank 4 is stored in advance in the recording apparatus, and the ink consumption amount is calculated by counting the number of ink droplets ejected from the recording head 1. Next, the consumption amount is compared with an allowable amount. If the consumption amount is less than the allowable amount, recording is permitted. If the consumption amount exceeds the allowable amount, image formation is stopped and the ink tank 5 is empty. While notifying that there is, wait for replacement of the ink tank 5. Here, the method of converting the ink remaining amount of the sub tank 4 into the ink discharge amount without providing the detecting means is used, but the ink remaining amount detecting means may be provided in the sub tank 4.

  In step S203, it is checked whether or not the ink tank has been replaced before the ink use allowable amount in the sub tank 4 has been consumed. If it is determined that the ink tank has been replaced, the process proceeds to step S204 to determine whether or not image formation is in progress. Investigate. If it is determined that the image is being formed, the end of the image formation is awaited. After confirming that image formation has stopped, the process proceeds to step S205, and ink is filled into the sub tank 4 before the start of the next image formation. Details of the ink filling control to the sub tank will be described later. After the filling, the next image formation is started. In this way, ink is filled into the sub tank during image formation (for example, during recording of a certain page and the next page).

  On the other hand, if it is determined in step S203 that the ink tank 5 has not yet been replaced, the process proceeds to step S207, and it is further checked whether or not the allowable ink use amount in the sub tank 4 has been consumed. If it is determined that the allowable amount has been consumed, the process proceeds to step S207, and the recording operation is immediately stopped. This is because if recording is not stopped, air is mixed into the recording head 1 from the sub tank 4 via the ink supply flow path, resulting in an ink ejection failure and a deterioration in the quality of the recorded image. In step S208, a message prompting replacement of the ink tank 5 is displayed.

  FIG. 6 is a diagram illustrating a state of the ink supply system after the ink tank 5 is replaced.

  6A shows a state where the on-off valve 3 is opened from the closed state, and FIG. 6B shows a state where the on-off valve 3 is opened from the closed state. In this embodiment, when the volume of the on-off valve 3 is V1, and the volume of the first hollow tube is V2, the relationship V1> V2 is established. In this example, V1 = about 0.45 ml and V2 = about 0.09 ml. Accordingly, as shown in FIG. 6A, when the on-off valve 3 is changed from the closed state to the opened state, the ink of the volume V1-V2 (about 0.36 ml) can be drawn from the ink tank 5 to the sub tank 4 ( Inflow of ink). This volume is V3 (= V1-V2). At that time, air is drawn into the ink tank 5 by the volume V3 from the atmosphere communication chamber 6 (outflow of air).

  Thereafter, as shown in FIG. 6 (b), the cam 37 is rotated by the DC motor 35 and the on-off valve 3 is pressed by the lever 39 to change from the open state to the closed state. It is pushed out from the sub tank 4 to the ink tank 5 by the amount. At this time, the ink corresponding to the volume V3 is pushed out from the ink tank 5 to the atmosphere communication chamber 6. At this time, since the pressure loss of the ink supply flow path from the on-off valve 3 to the recording head 1 is much larger than the pressure loss from the on-off valve 3 to the ink tank 5, the ink hardly flows to the recording head 1 side.

  Thereafter, as shown in FIG. 6A again, when the cam 37 is rotated by the DC motor 35 and the lever 39 is urged by the compression spring 38, the on-off valve 3 is changed from the closed state to the opened state. At that time, when ink is drawn from the atmosphere communication chamber 6 to the ink tank 5 for V3, ink is drawn from the ink tank 5 to the sub tank 4 at that time. Thereafter, the DC motor 35 is rotated again to bring the on-off valve 3 from the open state to the closed state as shown in FIG. That is, a predetermined amount of ink is filled from the ink tank 5 to the sub tank 4 by one opening / closing operation of the opening / closing valve 3.

  FIG. 7 is a flowchart showing a detailed processing sequence of sub tank filling control required during stopless recording control.

  In this embodiment, in step S301, the opening / closing operation (for filling) of the opening / closing valve 3 is repeatedly controlled. In step S302, it is confirmed whether or not the sub tank 4 is filled with ink for each opening / closing operation. As described above, a minute electric current is passed between the first hollow tube 8 and the electrode portion 10 provided in the sub tank 4 as described above, and as a result, the first hollow tube 8 and the electrode portion 10 are obtained. It can be confirmed by measuring the voltage value between.

  If it is determined that the ink is not filled, the process advances to step S303 to check whether there is ink in the ink tank 5. If it is determined that there is ink, the process returns to step S301, and the opening / closing operation (for filling) of the opening / closing valve 3 is repeated. On the other hand, if it is determined that there is no ink in the ink tank 5, the process proceeds to step S304, prompts the user to replace the ink tank 5, and waits for completion of the ink tank replacement in step S305. If the replacement of the ink tank 5 is confirmed, the process returns to step S301, and the opening / closing operation (for filling) of the opening / closing valve 3 is repeated again.

  Whether ink is present in the ink tank 5 is determined by measuring the voltage value between the first hollow tube 8 and the second hollow tube 9 when a minute current is passed between them. Based on this, it is determined that the ink is almost out. Also, the determination of when the ink is almost out and the remaining amount is close to zero (near end) is made based on the remaining amount information stored in the EEPROM 20 of the ink tank 5. That is, since the capacity of V3 (about 0.36 ml) can be introduced from the ink tank 5 to the sub tank 4 by one opening / closing operation of the opening / closing valve 3, it is determined by calculating from the information indicating the remaining amount stored in the EEPROM 20. To do.

  When it is confirmed in step S302 that the sub tank 4 is filled with ink, the process ends.

  In this embodiment, an on-off valve that also functions as an ink reservoir for supplying ink is used. However, the ink supply means and the on-off valve may be separated. In that case, it is desirable to provide the ink supply means between the sub tank and the on-off valve. The ink supply means may be in the form of a bellows or a diaphragm, and may be formed of a flexible member whose volume can be changed.

  In the sub-tank filling control shown in FIG. 7, in this embodiment, the detection interval for detecting the ink amount in the sub-tank 4 is controlled separately from the execution interval of the opening / closing operation of the on-off valve 3 for filling the sub-tank 4 with ink. To do. That is, when the sub-tank filling control is started, the opening / closing operation of the on-off valve 3 and the ink amount detection in the sub-tank 4 are continuously executed at respective intervals.

  FIG. 8 is a diagram showing the relationship between the measurement voltage for detecting the ink amount in the sub tank and the sub tank filling time.

  In FIG. 8, (a) shows the measurement result of the ink amount detection in the sub tank 4 (a weak current was passed between the hollow tube 8 and the electrode part (solid tube) 10) when the sub tank filling control was executed. The time change of the voltage value measurement result at the time is shown. In FIG. 8A, the change over time of the detection voltage is divided into three regions. That is, the region 1 is a region from when the voltage from the start of the sub tank filling operation starts until the voltage starts to decrease, the region 2 is a region where the voltage is decreasing while fluctuating, and the region 3 is stable because the voltage is decreasing It is an area.

  FIG. 9 is a diagram showing a change in the ink amount in the sub tank 4 corresponding to each of the three regions shown in FIG. The state of the ink in the sub tank 4 in each region can be explained as follows.

  That is, the region 1 is in a state where ink is not supplied up to the height of the solid tube 10 as shown in FIG. In the region 2, as shown in FIG. 9B, ink is supplied up to the height of the solid tube 10, and the ink flows as shown by the arrow each time the opening / closing valve 3 is opened and closed, so that the hollow tube 8 and the solid tube 10 The voltage value between and fluctuates. Region 3 is a state in which the sub tank 4 is filled with ink as shown in FIG.

  Thus, in the case of the ink flow path configuration as shown in FIG. 2, the region 3 in which the sub tank 4 is filled with ink from the behavior of the voltage value between the hollow tube 8 and the solid tube 10 during filling of the sub tank. The condition for detecting is set.

  FIG. 10 is a diagram for explaining setting conditions. That is, as shown in FIG. 10, the condition 1 is set such that the detection voltage in the region 1 is a value not more than a predetermined voltage (2.1 V or less in this embodiment). Also, as condition 2, it is set to continuously detect that the absolute value of the difference from the previous measurement voltage is not more than a predetermined threshold value (0.1 V or less in this embodiment) for a predetermined number of times (5 times in this embodiment). To do. When both of these two conditions are satisfied, it is determined that the sub tank 4 is filled with ink.

  FIG. 8B is a diagram illustrating a result of determination using the two conditions illustrated in FIG. 10 with respect to the behavior of the voltage change illustrated in FIG. According to FIG. 8B, the region 1 does not satisfy the condition 1 shown in FIG. 10 and the region 2 does not satisfy the condition 2 shown in FIG. At this point, it is determined that the sub tank 4 is filled with ink.

  However, the inventor has found that there is a case where it is determined that the ink is filled even though the sub tank is not actually filled with ink.

  FIG. 11 is a diagram showing a change with time of voltage showing a specific example.

  As shown in FIG. 11, even if the determination is made using the two conditions shown in FIG. 10, the determination that the sub tank 4 is filled with ink is inaccurate. In region 2 shown in FIG. 11, the difference between the current measured voltage value and the previous measured voltage value is small, and therefore Condition 2 is satisfied at the point of arrow D. However, since the sub tank is actually filled with ink at the time indicated by arrow E, the sub tank 4 is not filled with ink at the timing of arrow D.

  Here, when the opening / closing state of the opening / closing valve 3 at the timing when the detection of the ink amount in the sub tank 4 was detected by the photosensor 41, the opening / closing valve 3 repeated the same state.

  FIG. 12 is a diagram showing the relationship between the ink supply operation, the ink amount detection operation, and the sub tank filling time, and the relationship between the measurement voltage by the ink amount detection in the sub tank and the sub tank filling time.

  12A shows the detection interval of the ink amount detection operation and the execution interval of the ink supply operation when the measurement shown in FIG. 11 is performed. In the case shown in FIG. 12A, the result of the photosensor 41 (that is, the ink supply timing) and the ink amount detection timing are aligned as indicated by the positions of the arrows and ●. This is considered to be due to the fact that a current flows between the hollow tube 8 and the solid tube 10 via the ink flow in the sub tank, etc., even though the sub tank is not filled with ink. It is done. Furthermore, since all the ink amount detection operations are performed at the timing when the open / close state of the on-off valve 3 is the same, the ink flow between the hollow tube 8 and the solid tube 10 is similar each time. To do. For this reason, since the same amount of current flows every time, it is considered that the fluctuation of the voltage value is reduced.

  The inventors have considered this point, and have found that this can be avoided by controlling the open / close state of the on-off valve 3 at a timing when the ink amount detection operation in the sub tank 4 is executed to be different each time.

  Specifically, in the sub tank filling control shown in FIG. 7, the detection interval of the ink amount detection operation in the sub tank 4 is controlled separately from the execution interval of the opening / closing operation of the on / off valve 3 that fills the sub tank 4 with ink. . By controlling the detection interval of the ink amount detection operation to be different from an integral multiple of the execution interval of the opening / closing operation of the opening / closing valve 3, the open / close state of the opening / closing valve 3 at the timing when the ink amount detection operation in the sub tank 4 is executed. Make them different.

  For example, as shown in FIG. 12B, by setting the detection interval (Tp) of the ink amount detection operation to 2.31 seconds and the execution interval (Ts) of the ink supply operation to 0.32 seconds, Tp is Set so that 7.2 times Ts does not become an integer multiple. As a result, the open / close state of the open / close valve 3 is different at each ink amount detection timing. Therefore, even if there is an ink flow or the like in the sub-tank and a current flows between the hollow tube 8 and the solid tube 10, it can be avoided that the same amount of current flows every time. Can cause fluctuations.

  FIG. 12C shows a voltage change measured by ink amount detection when the execution intervals of the ink amount detection operation and the ink supply operation are controlled as shown in FIG. As shown in FIG. 12C, condition 2 is not satisfied because the voltage in region 2 fluctuates more than 0.1 V, and the two conditions shown in FIG. It is determined that it is satisfied. That is, the determination is made correctly when the sub tank 4 is filled with ink.

  In the above-described embodiment, the ink amount detection in the sub-tank 4 has been described using only one color ink. However, the present invention is not limited to this. For example, during the detection interval of the ink amount detection operation, measurement may be performed by switching the ink to be detected, or measurement may be performed by switching between the ink tank and the sub tank.

  Thus, in this embodiment, when it is determined whether the sub tank 4 is filled with ink under the conditions shown in FIG. 10 during the sub tank filling control shown in FIG. Is controlled so as to be different from an integral multiple of the execution interval of the opening / closing operation. As a result, when the determination is made under the conditions shown in FIG. 10, it is possible to accurately measure the ink amount in the sub tank during filling of the sub tank.

  Next, a method for setting each interval when the detection interval of the ink amount detection operation in the sub tank 4 is controlled to be different from an integral multiple of the execution interval of the opening / closing operation of the on-off valve 3 will be described.

  The open / close state of the open / close valve 3 at the ink amount detection timing can be varied by setting the intervals. Due to the change in the open / close state, the voltage value at the ink amount detection timing changes. Therefore, in this embodiment, by defining the setting range of each interval, the ink amount measurement in the sub tank is made more accurate by maximizing the fluctuation of the open / close state.

  When the detection interval of the ink amount detection operation is longer than the execution interval of the opening / closing operation of the opening / closing valve 3, the ink amount detection interval (Tp) is set so that the opening / closing state of the opening / closing valve 3 varies at each ink amount detection timing. It is not necessary to be an integer (N) times the execution interval (Ts) of the opening / closing operation of the opening / closing valve 3.

That is,
Tp ≠ (Ts × N) (1)
It is necessary to satisfy the relationship. Here, N is the quotient of Ts divided by Tp.

  FIG. 13 is a diagram illustrating a state in which the timing of the ink supply operation is different from the timing of detecting the ink amount. In FIG. 13, the difference in the open / close state of the open / close valve 3 at each ink amount detection timing is the difference between the positions of ● and arrows (timing), and the open / close state is delayed by (Tp−Ts × N). This delay time (Tp−Ts × N) changes the way the ink flows between the hollow tube 8 and the solid tube 10 in the sub-tank 4 and changes the degree of variation in the measured value.

Since the determination shown in FIG. 10 is used for the determination that the ink in the sub tank 4 is filled, the total delay time of the on / off state of the on-off valve 3 during the ink amount detection is continuously performed Cr times (Tp− Ts × N) × Cr. When this total (Tp−Ts × N) × Cr is equal to or longer than the execution interval (Ts) of the opening / closing operation of the opening / closing valve 3 as in the condition indicated by the expression (2), the delay time of the opening / closing state of the opening / closing valve 3 is 3 of the opening / closing operation of 3 or more. That is, the open / close state of the on-off valve 3 that maximizes the variation in the ink flow between the hollow tube 8 and the solid tube 10 in the sub tank 4 is included in the Cr ink amount detection measurement. It will be. The conditions indicated by the formula (2) are as follows. That is,
(Tp−Ts × N) × Cr ≧ Ts (2)
It is.

  If the sub tank 4 is not filled with ink, the voltage value fluctuates during the ink amount detection measurement of Cr times and the condition shown in FIG. 10 is not satisfied, and the sub tank filling control is continued.

Now, when both sides of the formula (2) are divided by Cr, the formula (3) is obtained. That is,
(Tp−Ts × N) ≧ (Ts / Cr) (3)
It is. Formula (3) is the delay time (Tp−Ts × N) of the open / close state of the open / close valve 3 generated at each ink amount detection timing, which is a value obtained by dividing the execution interval of the open / close operation of the open / close valve 3 by Cr of the number of continuous measurements Ts / Cr) or more is desirable.

  Considering this, in this embodiment, when the execution interval (Ts) of the opening / closing operation of the opening / closing valve 3 is Ts = 0.32 seconds, the number of continuous measurements (Cr) is 5, and N = 7, the expression (3) Accordingly, the detection interval (Tp) for detecting the amount of ink in the sub tank 4 was set to 2.304 seconds or more.

  In addition, when the execution interval (Ts) of the ink supply operation has a certain range of apparatus variation as suggested by the equation (2), the detection interval (Tp) for detecting the ink amount is the upper limit of the variation in Ts ( It is desirable to set a value larger than Ts1). Note that the device variation shown in Equation (2) is due to the influence of a motor or the like, and therefore the variation upper limit value (Ts1) can be obtained by intentionally creating and measuring a configuration that maximizes the detection interval. it can.

  As described above, when the detection interval of the ink amount detection operation is controlled to be different from an integral multiple of the execution interval of the opening / closing operation of the on-off valve, the detection interval (Tp) and the execution interval (Ts) are the number of continuous measurements. Using (Cr) and an integer (N), control is performed so as to satisfy the relationship of Expression (3). Note that the number of continuous measurements (Cr) is preferably 10 or less in order to shorten the measurement time.

  Therefore, according to the embodiment described above, since the measurement can be performed in one cycle or more of the opening / closing operation of the opening / closing valve 3 at the Cr ink amount detection timing, and the fluctuation of the measurement voltage can be maximized, the ink in the sub tank Quantity measurement can be performed accurately.

  In this embodiment, a voltage value when a minute current (constant current) is passed between the first middle space 8 and the electrode portion 10 is detected, and energization via ink is performed from the detected change in the voltage value. Is detected to determine the ink amount. However, the present invention is not limited to this. For example, the current value that flows when a constant voltage is applied between the first middle space 8 and the electrode unit 10 may be detected, and the ink amount may be determined from the change in the detected current value. In this case, it is predetermined that the detected current value is equal to or greater than a predetermined current, and the absolute value of the difference between the two current values is continuously equal to or less than the predetermined current value. It can be determined that the sub-tank is filled with ink when the number of times is continuously detected.

Claims (11)

And stomach Nkutanku for storing ink,
A sub tank for storing ink supplied from the ink tank ;
A recording head that discharges ink supplied from the sub-tank and performs recording on a recording medium;
Disposed between the front Symbol subtank the recording head, a supply means for supplying operation of supplying a predetermined amount of ink in the first interval to the sub tank from the ink tank by changing the volume,
A pair of electrodes provided on the upper portion of the sub-tank,
Detecting means for detecting a voltage value when a constant current is passed through the pair of electrodes at a second interval ;
Stop the supply operation based on the detection result of the detection means,
The inkjet recording apparatus , wherein the second interval is longer than the first interval, and the second interval is different from an integer multiple of the first interval . Before SL and voltage than predetermined is sensed voltage value by the detection means, and said plurality of with respect to the voltage value detected by the detection means, the absolute of the difference between the detected two voltage values successively the number of times that the value is less than the threshold value predetermined ink jet recording apparatus according to claim 1, wherein the sub-tank when it is continuously detected, characterized in that determined to have been filled with ink. The second interval is Tp,
The first interval is Ts,
The predetermined number of times is Cr,
The integral quotient when divided by the Tp in the Ts, in case of a N,
(Tp−Ts × N) ≧ (Ts / Cr)
The inkjet recording apparatus according to claim 2 , wherein: And stomach Nkutanku for storing ink,
A sub tank for storing ink supplied from the ink tank ;
A recording head for recording on a recording medium by discharging ink supplied from the sub tank;
Disposed between the front Symbol subtank the recording head, a supply means for supplying operation of supplying a predetermined amount of ink in the first interval to the sub tank from the ink tank by changing the volume,
A pair of electrodes provided on the upper portion of the sub-tank,
And a detection means for performing a detection operation for detecting a current flowing upon application of a constant voltage to the pair of electrodes in the second interval,
Stop the supply operation based on the detection result of the detection means,
The inkjet recording apparatus , wherein the second interval is longer than the first interval, and the second interval is different from an integer multiple of the first interval . Or less prior SL current value the current value detected is predetermined by the detection means, and said relates plurality of current value detected by the detection means, the difference between the detected two current values are continuously number of times a predetermined absolute value is less than the threshold value, the ink jet recording apparatus according to claim 4, wherein the sub-tank when it is continuously detected, characterized in that determined to have been filled with ink. The second interval is Tp,
The first interval is Ts,
The predetermined number of times is Cr,
The integral quotient when divided by the Tp in the Ts, in case of a N,
(Tp−Ts × N) ≧ (Ts / Cr)
The inkjet recording apparatus according to claim 5 , wherein: Said supply means, between the pre-Symbol sub-tank and the ink tank has an opening and closing valve for controlling the inflow and outflow of air or ink, that the volume is changed by the inflow and outflow of the air or ink the ink-jet recording apparatus according to any one of claims 1 to 6, wherein. Before SL sub tank is still unmet if in ink-jet recording apparatus according to any one of claims 1 to 7 wherein the supply means and performing the feed operation. To any one of claims 1 to 8, characterized in that the recording by the ink the recording head by supply from the sub-tank in the supply operation by the ink ink is not supplied to the sub tank from the tank if The ink jet recording apparatus described. And b Nkutanku for storing ink, a sub tank for storing ink supplied from the ink tank, a recording head for recording on a recording medium by discharging an ink supplied from the sub-tank, and the recording head and the sub-tank arranged between a supply unit for supplying operation of supplying a predetermined amount of ink in the first interval to the sub tank from the ink tank by changing the volume, and a pair of electrodes provided on the upper portion of the sub-tank an ink amount detecting method in the inkjet recording apparatus provided with,
A detection operation for detecting a voltage value when a constant current is passed through the pair of electrodes is performed at a second interval ,
The supply operation is stopped based on the detection result of the previous SL detecting operation,
2. The ink amount detection method according to claim 1, wherein the second interval is longer than the first interval, and the second interval is different from an integral multiple of the first interval . And b Nkutanku for storing ink, a sub tank for storing ink supplied from the ink tank, a recording head for recording on a recording medium by discharging an ink supplied from the sub-tank, and the recording head and the sub-tank arranged between a supply unit for supplying operation of supplying a predetermined amount of ink in the first interval to the sub tank from the ink tank by changing the volume, and a pair of electrodes provided on the upper portion of the sub-tank an ink amount detecting method in the inkjet recording apparatus provided with,
A detection operation for detecting a current value flowing when a constant voltage is applied to the pair of electrodes is performed at a second interval ,
The supply operation is stopped based on the detection result of the previous SL detecting operation,
2. The ink amount detection method according to claim 1, wherein the second interval is longer than the first interval, and the second interval is different from an integral multiple of the first interval .

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