JP2005096152A - Inkjet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet printer that can be continuously operated by permitting the replacement of an ink tank without suspending recording by a recording head, namely an inkjet printer that does not suspend printing for the replacement of an ink tank, does not cause an image degradation due to printing stoppage, uses up an ink in an ink tank without wasting any and does not lower the degree of freedom of layout of the mechanism of the printer. <P>SOLUTION: In the inkjet printer in which an ink is supplied to the recording head through an ink supply channel from an ink tank replaceably provided, two subsidiary tanks capable of storing an ink, respectively are provided in the ink supply channel between the ink tank and the recording head. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink jet printer, and more particularly, to an ink jet printer capable of continuous operation by enabling replacement of an ink tank without interrupting recording by a recording head.

  In an ink jet printer, ink is supplied to a recording head from an ink tank mounted on the printer via an ink supply path. When the ink tank becomes empty due to the consumption of ink during image recording, it is necessary to replace the ink tank, but not only the printing efficiency decreases due to the interruption of the printing operation, but also the ink tank needs to be replaced. Thereafter, when the interrupted printing operation is resumed, there is a problem that the color continuity is lost. For this reason, conventionally, the techniques described in Patent Documents 1 to 10 are known as countermeasures when the ink tank becomes empty during printing or the remaining amount of ink in the ink tank decreases.

  Patent Document 1 discloses that image data is adjusted so that dot formation is controlled when the remaining amount of ink in the ink tank is low.

  Patent Documents 2 and 3 disclose that when black ink is insufficient, image recording is performed using ink of a color other than black.

  Japanese Patent Application Laid-Open No. H10-228688 discloses that when the remaining ink level is exhausted, the processing of the color data is not performed.

  Patent Documents 5, 6 and 7 each have a plurality of ink tanks provided with means for detecting the remaining amount of ink, and when detecting that there is no remaining ink in any of the ink tanks, Switching to perform ink supply is disclosed.

  In Patent Document 8, one ink tank is provided in the vicinity of the recording head, and each of the ink tanks is provided with a means for detecting the remaining amount of ink. It is disclosed to supply.

  Patent Document 9 discloses that a drive waveform is adjusted and color conversion is corrected as the ink remaining amount decreases.

Patent Document 10 discloses that the remaining amount is detected by measuring the weight of a sealed ink tank.
JP-A-11-99670 JP-A-7-178931 JP 2001-191546 A JP 2000-108372 A JP 2003-1842 A JP 2002-29041 A JP-A-8-216426 JP 7-137275 A JP 2002-19091 A JP 2001-260387 A

  However, as disclosed in Patent Documents 1 to 4 and 9, if the image data is processed when the remaining ink amount is low or the remaining ink amount is low, or if ink of another color is substituted, There is a problem that causes image degradation.

  Further, as disclosed in Patent Documents 5 to 7, when one of the ink tanks has run out, the ink is switched to be supplied from another ink tank. It is necessary to provide a space in the printer to load a plurality of ink tanks in a replaceable manner, and the degree of freedom in the layout of the printer mechanism is reduced. In addition, in order to continuously supply ink, it is necessary to switch to another ink tank before the remaining amount of one of the ink tanks becomes completely zero, which causes a problem of wasting ink.

  Further, the one disclosed in Patent Document 8 is such that even if the ink runs out during printing, it is possible to continue printing without the need to replace the ink tank. Need to stop.

  Further, as disclosed in Patent Document 10, even if the remaining amount of ink is detected by measuring the weight of the sealed ink tank, the ink tank is unlikely to be completely in a state where the remaining amount of ink is zero. There is no choice but to determine that there is no ink remaining in the presence of remaining ink, and there is a problem that wasteful ink is generated. In this case, the remaining amount can be detected using one sub tank so that the ink tank can be used until it becomes empty, but there is a problem that printing must be stopped when the empty is detected.

  Therefore, the present invention does not interrupt printing due to ink tank replacement, does not cause image deterioration due to printing stop, and can be used without waste until the ink tank is empty. It is another object of the present invention to provide an ink jet printer that does not reduce the degree of freedom in the layout of the printer mechanism.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

  According to a first aspect of the present invention, in an ink jet printer that supplies ink from an ink tank provided in a replaceable manner to a recording head through an ink supply path, the ink supply path is provided between the ink tank and the recording head. In addition, the inkjet printer has two subtanks each capable of storing ink.

  The invention according to claim 2 is the ink jet printer according to claim 1, wherein the two sub tanks are different in size, and the smaller sub tank is arranged on the upstream side.

  A third aspect of the invention is the ink jet printer according to the first or second aspect, wherein at least an upstream side sub tank of the two sub tanks has an internal volume detecting means.

  According to a fourth aspect of the present invention, there is provided a valve mechanism for opening and closing the ink supply path at least on the upstream side of the upstream subtank of the two subtanks. Inkjet printer.

  According to a fifth aspect of the present invention, the valve mechanism is opened when the internal capacity detecting means determines that the internal capacity is low, and the valve mechanism is closed when the internal capacity is determined to be large. 5. The ink jet printer according to claim 4, further comprising control means for controlling.

  According to a sixth aspect of the present invention, there is provided warning means for warning that there is no remaining amount of the ink tank, and the control means detects the internal capacity detecting means even after a predetermined time has elapsed after opening the valve mechanism. 6. The ink jet printer according to claim 5, wherein when the large capacity is not detected, it is determined that there is no remaining amount of the ink tank, and the warning unit is activated.

  The invention according to claim 7 is the ink jet printer according to claim 1, wherein the two sub-tanks have internal volume detecting means having different determination levels.

  According to the present invention, printing is not interrupted for replacement of the ink tank, there is no possibility of image deterioration due to the printing interruption, and it can be used without waste until the ink tank is empty. Furthermore, it is possible to provide an ink jet printer that does not reduce the degree of freedom of the printer mechanism layout.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a first embodiment of an ink jet printer according to the present invention. In the figure, reference numeral 1 denotes an ink tank, which is in the form of an ink cartridge in which an ink pack storing image recording ink is housed in a housing, and is replaced with a predetermined loading portion of the ink jet printer 100. It is loaded as possible.

  The ink in the ink tank 1 is supplied to the recording head 3 via the ink supply path 2. The recording head 3 is mounted on a carriage 4 provided so as to be able to reciprocate along a main scanning direction orthogonal to a conveyance direction (sub-scanning direction) of a recording medium (not shown). A desired image is recorded on the recording medium by ejecting ink as fine droplets from a number of nozzles arranged on the nozzle surface 31 toward the recording surface of the recording medium.

  In the ink supply path 2 between the ink tank 1 and the recording head 3, an ink supply valve 5, a first sub tank 6, and a second sub tank 7 are interposed in series from the upstream side. The ink in 1 is sequentially supplied to the recording head 3 via the ink supply valve 5, the first sub tank 6, and the second sub tank 7.

  A maintenance unit 8 is disposed at a position where the recording head 3 is removed from a recording medium on which image recording is not performed. In the maintenance unit 8, the suction cap 81 is arranged so as to be in close contact with the nozzle surface 31 of the recording head 3. By depressurizing the ink, ink suction is forcibly performed from the nozzles of the recording head 3. 83 is a waste ink tank for discharging the sucked waste ink, and 84 is an open valve for returning the suction cap 81 decompressed by ink suction from the nozzle surface 31 to the atmospheric pressure. .

  FIG. 2 shows details of the ink supply path 2 through which ink is supplied from the ink tank 1 to the recording head 3 in FIG. FIG. 3 is a configuration block diagram for ink supply control in the inkjet printer 100. In these figures, parts having the same configuration as in FIG.

  The loading unit 10 loaded with the ink tank 1 detects the weight of the ink tank 1 to detect whether the loading unit 10 is loaded with the ink tank 1, that is, the presence or absence of the ink tank 1. An ink tank weight detection sensor 11 is provided. The ink tank weight detection sensor 11 is provided with a shielding plate 113 at the other end of a detection rod 111 whose other end can be moved up and down around a shaft 112 at one end, and an LED or the like so as to sandwich the shielding plate 113 therebetween. The photo sensor 114 is disposed in which a light emitting element made of a light receiving element and a light receiving element made of a photodiode or the like are arranged to face each other.

  The detection rod 111 is constantly urged by the urging spring 115 toward the loading unit 10 around the shaft 112. The upper end 111a of the detection bar 111 is disposed so as to protrude upward from the bottom of the loading unit 10. When the ink tank 1 is loaded in the loading unit 10, the upper end 111a of the detection bar 111 is moved to the ink tank 1. Is pushed downward in the figure against the urging force of the urging spring 115 to move the shielding plate 113 at the other end downward in the figure about the shaft 112. FIG. 2 shows this state. When the ink tank 1 is loaded in the loading unit 10 as described above, the photo sensor 114 detects the presence of the shielding plate 113. Thereby, it is detected that the ink tank 1 is loaded in the loading unit 10. On the other hand, when the ink tank 1 is removed from the loading unit 10, the upper end 111 a of the detection rod 111 protrudes upward from the bottom of the loading unit 10 about the shaft 112 by the biasing force of the biasing spring 115. At this time, the shielding plate 113 is out of the detection range of the photosensor 114, thereby detecting that the ink tank 1 is not loaded in the loading unit 10.

  The detection signal of the ink tank weight detection sensor 11 is output to the control unit 20 shown in FIG.

  The ink supply valve 5 provided on the most upstream side in the ink supply path 2 is configured by a valve mechanism that can be electrically opened and closed such as an electromagnetic valve, for example, and receives a control signal from the control unit 20. By receiving and opening and closing the ink supply path 2, the ink is circulated or blocked.

  The first sub-tank 6 provided downstream of the ink supply valve 5 temporarily stores ink supplied from the ink tank 1 via the ink supply path 2 when the ink supply valve 5 is in the valve open state. It is formed in a sealed bag shape with a flexible material that has the function of expanding when it is filled with ink and contracting when the ink inside is consumed. ing.

  The first sub tank 6 is provided with a full tank detection sensor 12 as an internal capacity detection means. In the present invention, the full tank detection sensor does not necessarily indicate a state where the tank is fully filled, but detects a state set as the ON side determined based on the ON / OFF switching position setting described later. The full tank detection sensor 12 includes a detection rod 121 disposed so as to abut on the surface of the first sub-tank 6 and a light-emitting element such as an LED or the like so as to sandwich one end side of the detection rod 121 therebetween. The photosensor 122 is arranged so as to face a light receiving element made of a diode or the like.

  One end of the detection rod 121 is rotatable about the shaft 123 at the other end, and moves in the left-right direction in FIG. 2 according to the degree of swelling of the first sub tank 6. In FIG. 2, the first sub tank 6 is filled with ink. In this state, the photo sensor 122 detects one end of the detection rod 121. Thus, it is detected that the first sub tank 6 is full. On the other hand, when the ink in the first sub tank 6 is consumed, the detection rod 121 gradually moves in the right direction in FIG. 2 around the shaft 123 as the first sub tank 6 contracts. Eventually, it comes out of the detection range of the photo sensor 122, and thereby it is detected that the remaining amount of ink in the first sub tank 6 has decreased.

  The second sub-tank 7 provided downstream of the first sub-tank 6 functions as a storage tank that temporarily stores ink supplied from the first sub-tank 6 via the ink supply path 2. It is formed into a sealed bag shape by a flexible material having a function of expanding when the ink is filled therein and contracting when the ink inside is consumed.

  The second sub tank 7 is also provided with a full tank detection sensor 13 as an internal capacity detection means. The full tank detection sensor 13 includes a detection rod 131 disposed so as to contact the surface of the second sub-tank 7, and a light-emitting element such as an LED or the like and a photo so as to sandwich one end side of the detection rod 131. The photosensor 132 is configured to face a light receiving element made of a diode or the like.

  One end of the detection rod 131 is rotatable about the shaft 133 at the other end, and moves in the left-right direction in FIG. 2 according to the degree of swelling of the second sub-tank 7. In FIG. 2, the second sub tank 7 is filled with ink. In this state, the photo sensor 132 detects one end of the detection bar 131. Thus, it is detected that the second sub tank 7 is full. On the other hand, when the ink in the second sub tank 7 is consumed, the detection rod 131 gradually moves to the right in FIG. 2 around the shaft 133 as the second sub tank 7 contracts. Eventually, it is out of the detection range of the photo sensor 132, and it is thereby detected that the remaining amount of ink in the second sub tank 7 has decreased.

  The full tank detection sensor 12 of the first sub-tank 6 and the full tank detection sensor 13 of the second sub-tank 7 are detected rods 121 according to the swelling of the first sub-tank 6 and the second sub-tank 7, respectively. By appropriately setting the position where 131 is detected by the photosensors 122 and 132, it is possible to set the ON / OFF switching position of the detection signal. For example, the ON / OFF switching position of the detection signal is set to the ink. It can be set to be just before the remaining amount becomes completely zero. While the full tank detection sensor 13 of the second sub tank 7 is in the ON state, while the full tank detection sensor 12 of the first sub tank 6 is in the OFF state, the ink tank 1 is requested to be replaced. When both the full tank detection sensors 12 and 13 are turned off, the printing is stopped, so that an appropriate measure can be taken before ink is not ejected from the nozzles of the recording head 3. Further, as will be described later, the setting of the switching position can be set immediately before it becomes zero by counting the printing amount or the like if the ink content is known.

  The detection signals of these full tank detection sensors 12 and 13 are output to the control unit 20, respectively.

  In the example shown in FIG. 2, the first sub-tank 6 and the second sub-tank 7 have different sizes, and the first sub-tank 6 has a smaller internal capacity than the second sub-tank 7. ing. The ink tank 1, the ink supply valve 5, the first sub-tank 6 and the second sub-tank 7 are sequentially arranged below, and the ink is supplied to the ink tank by opening the ink supply valve 5. 1 circulates in the ink supply path 2 by natural flow and is stored in the order of the second sub-tank 7 and the first sub-tank 6, and when the image is recorded by the recording head 3, the first sub-tank 6 and the second sub-tank Ink is consumed in the same manner from 7, but the remaining capacity of the first sub-tank 6 is smaller than that of the second sub-tank 7. It has been detected that the amount has decreased.

  In FIG. 3, 14 is a timer, and the control unit 20 monitors the full tank detection sensor 12 of the first sub tank 6 after starting the timer 14. A predetermined time-up time T1 is set in the timer 14, and after the ink supply valve 5 is opened, specifically, the ink supply valve 5 is opened and the ink in the ink tank 1 is transferred to the first time. From the full tank detection sensor 12 provided in the first sub-tank 6 until a sufficient time has passed until it is predicted that the first sub-tank 6 will be full after the supply to the sub-tank 6 is started. When the detection signal is not output, a time-up signal is output to the control unit 20. Accordingly, the control unit 20 can detect that ink is not normally supplied from the ink tank 1, that is, that there is no ink remaining in the ink tank 1.

  Reference numeral 15 denotes a display lamp as warning means for notifying the user that ink has run out. The warning means may sound an alarm buzzer or warning announcement instead of or in addition to the display lamp 15.

  FIG. 4 is a flowchart relating to the ink supply control of the ink jet printer 100, and the ink supply control operation will be described using this flowchart.

  After the power is turned on, the control unit 20 first resets the timer 14 (S1) and then starts the timer 14 (S2). Here, the control unit 20 monitors the remaining amount of ink in the first sub tank 6 by the full tank detection sensor 12 of the first sub tank 6 (S3).

  At this time, when the first sub tank 6 is full, a detection signal is output from the full tank detection sensor 12, so that the control unit 20 can confirm that the first sub tank 6 is full. . The first sub-tank 6 is smaller than the second sub-tank 7, and the first sub-tank 6 and the second sub-tank 7 are connected to each other by the natural flow of ink in the ink supply path 2. When one sub-tank 6 is full, it can be seen that the second sub-tank 7 is also full. When it is confirmed that the first sub tank 6 is full, the control unit 20 closes the ink supply valve 5 (S4) and ends the ink supply control operation.

  If the remaining amount of ink in the first sub-tank 6 is low and no detection signal is output from the full tank detection sensor 12 in step S3, the control unit 20 opens the ink supply valve 5 and starts from the ink tank 1. Ink is circulated through the ink supply path 2 (S5).

  During this time, the timer 14 monitors the elapse of the predetermined time-up time T1 (S6), and the ink is normally stored in the first sub tank 6 before the time-up time T1 elapses. When the detection signal of 12 is output, the control unit 20 proceeds to step S4, closes the ink supply valve 5 (S4), and ends the ink supply control operation. On the other hand, when the time-up time T1 elapses without the ink being normally stored in the first sub tank 6, the control unit 20 determines that the ink tank 1 is out of ink and stops the timer 14 (S7). Next, the ink supply valve 5 is closed (S8), and the display lamp 15 is turned on to notify the user that the ink tank 1 is out of ink and instruct to replace the ink tank 1 (S9). During this time, the user replaces the ink tank 1.

  Here, the control unit 20 monitors the ink remaining amount in the second sub tank 7 by the full tank detection sensor 13 of the second sub tank 7 (S10). At this time, if the remaining amount of ink in the second sub tank 7 is small and no detection signal is output from the full tank detection sensor 13, it is determined that printing cannot be continued and printing is temporarily stopped (S11). .

  On the other hand, when a detection signal is output from the full tank detection sensor 13 in step S10 and sufficient ink is still stored in the second ink tank 7, the control unit 20 uses the ink tank weight detection sensor 11 to It is monitored whether the ink tank 1 has been replaced, that is, whether the detection signal of the ink tank weight detection sensor 11 has changed from ON to OFF to ON (S12).

  Even if the first sub-tank 6 has no remaining ink, the second sub-tank 7 has a larger internal capacity here, so that printing can be continued until the second sub-tank 7 is empty. The control unit 20 continues the processes of step S10 and step S12, and this period is a replacement grace period of the ink tank 1.

  When it is determined in step S12 that the ink tank 1 has been replaced, the control unit 20 opens the ink supply valve 5, and causes ink to flow from the newly loaded ink tank 1 through the ink supply path 2 (S13). ).

  Thereafter, the control unit 20 again monitors whether or not the first sub tank 6 is full by the full sub detection sensor 12 of the first sub tank 6 (S14). Here, as long as the first sub tank 6 is not full, the control unit 20 repeats the processing from step S10 onward, and the first sub tank 6 becomes full and the detection signal from the full detection sensor 12 is reached. Is confirmed, the display lamp 15 is turned off, and the ink tank 1 replacement instruction is canceled (S15). Thereafter, the ink supply valve 5 is closed (S4), and the ink supply control operation is terminated.

  Thus, since the ink jet printer 100 is provided with the two sub tanks, the first sub tank 6 and the second sub tank 7, even if the ink tank 1 is empty, the second sub tank 7 is empty. It is possible to continue printing until. By replacing the ink tank 1 during this time, printing can be continued without stopping printing. The replacement grace time of the ink tank 1 depends on the internal capacity of the second sub-tank 7. Therefore, the replacement grace time can be extended by setting the internal capacity of the second sub-tank 7 large.

  Further, even if the ink tank 1 is emptied, printing can be continued without stopping printing, so there is no risk of image deterioration such as color change when the ink tank 1 is replaced. It can be used until the tank 1 is completely emptied, and ink is not wasted.

  Further, since the ink tank 1 is the only replaceable tank, it is only necessary to arrange the loading unit 10 for loading the ink tank 1 in a place that is easily accessible by the user. There will be no significant loss of freedom.

  The first sub-tank 6 and the second sub-tank 7 described above have different internal capacities, but the present invention is not limited to this, and the internal capacities may be the same. Conversely, the internal capacity of the first sub tank 6 may be larger than that of the second sub tank 7. In these cases, the determination level is set differently so that the full tank detection sensor 12 of the first sub tank 6 is detected OFF earlier than the full tank detection sensor 13 of the second sub tank 7. Thus, the same function as described above can be achieved.

  FIG. 5 shows a second embodiment of the ink supply path 2 through which ink is supplied from the ink tank 1 to the recording head 3. FIG. 6 is a block diagram showing the configuration for ink supply control according to the second embodiment. In these figures, parts having the same configurations as those in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof will be omitted.

  In the second embodiment, a first ink supply valve 16 is interposed upstream of the first sub tank 6 in the ink supply path 2, downstream of the first sub tank 6, and A second ink supply valve 17 is interposed on the upstream side of the second sub tank 7.

  The first ink supply valve 16 and the second ink supply valve 17 are configured by a valve mechanism that can be electrically opened and closed such as an electromagnetic valve, for example, and receives a control signal from the control unit 21. By opening and closing the ink supply path 2, the ink is circulated or blocked.

  In the second embodiment, the second ink supply valve 17 is interposed between the first sub-tank 6 and the second sub-tank 7 and is normally closed. Consumption of ink accompanying recording can be made only from the second sub tank 7. On the other hand, if only the first ink supply valve 16 is opened, the ink in the ink tank 1 is stored only in the first sub tank 6. Therefore, when detecting that there is no ink remaining in the ink tank 1, the detection is purely based on the ink flow time from the ink tank 1 to the first sub tank 6.

  At this time, by keeping the second ink supply valve 17 closed, it is possible to set the ink storage amount of the second sub-tank 7 independently of the first sub-tank 6. The full tank detection sensor 13 of the second sub tank 7 detects ON when the second sub tank 7 is full, and detects low ink by detecting OFF when the remaining amount of ink still remains. It is supposed to be.

  Next, the ink supply control operation of the second embodiment will be described using the flowchart shown in FIG.

  After the power is turned on, the controller 21 first resets the timer 14 (S20) and then starts the timer 14 (S21). Here, the control unit 21 monitors the remaining amount of ink in the second sub tank 7 by the full tank detection sensor 13 of the second sub tank 7 (S22).

  At this time, when the second sub tank 7 is full, a detection signal is output from the full tank detection sensor 13, and therefore the control unit 21 can confirm that the second sub tank 7 is full. . As a result, when it is confirmed that the second sub tank 7 is full, the second ink supply valve 17 is closed (S23), and then the controller 21 is full sensor 1 of the first sub tank 6. Thus, the remaining amount of ink in the first sub tank 6 is monitored (S24). As a result, when it is confirmed that the first sub tank 6 is full, the first ink supply valve 16 is closed (S25), and the ink supply control operation is terminated.

  In step S22, when the remaining amount of ink in the second sub tank 7 is low and no detection signal is output from the full tank detection sensor 13, the control unit 21 opens the second ink supply valve 17, Ink is circulated from the one sub tank 6 through the ink supply path 2 (S26). Thereafter, the control unit 21 proceeds to step S24, and monitors the remaining amount of ink in the first sub tank 6 by the full tank detection sensor 12 of the first sub tank 6 as described above.

  In this step S24, when the remaining amount of ink in the first sub tank 6 is low and no detection signal is output from the full tank detection sensor 12, the control unit 21 closes the second ink supply valve 17 ( S27), the first ink supply valve 16 is opened, and ink is circulated from the ink tank 1 through the ink supply path 2 (S28).

  During this time, the timer 14 monitors the elapse of the predetermined time-up time T1 (S29), and the control unit 21 repeats the processing from step S22. If the ink is normally stored in the first sub-tank 6 and the detection signal of the full tank detection sensor 12 is output before the time-up time T1 elapses, the first ink supply valve 16 is closed ( S25), the ink supply control operation is terminated. On the other hand, when the time-up time T1 elapses without the ink being normally stored in the first sub tank 6, the control unit 21 determines that the ink tank 1 is out of ink, stops the timer 14 (S30), Next, the first ink supply valve 16 is closed (S31), and the display lamp 15 is turned on to notify the user that the ink tank 1 is out of ink and instruct to replace the ink tank 1 (S32). During this time, the user replaces the ink tank 1.

  Here, the control unit 21 monitors the remaining amount of ink in the second sub tank 7 by the full tank detection sensor 13 of the second sub tank 7 (S33). At this time, if the remaining amount of ink in the second sub tank 7 is low and no detection signal is output from the full tank detection sensor 13, it is determined that printing cannot be continued and printing is temporarily stopped (S34). .

  On the other hand, when a detection signal is output from the full tank detection sensor 13 in step S33 and sufficient ink is still stored in the second ink tank 7, the control unit 21 uses the ink tank weight detection sensor 11 to It is monitored whether the ink tank 1 has been replaced, that is, whether the detection signal of the ink tank weight detection sensor 11 has changed from ON to OFF to ON (S35).

  Even when the first sub tank 6 has no ink remaining, ink is supplied from the first sub tank 6 to the second sub tank 7 in the processes of steps S22 and S26. Ink is stored, and printing can be continued until the second sub-tank 7 becomes empty. During this time, the control unit 21 continues the processing of step S33 and step S35, and during this time, the ink tank 1 exchange grace period.

  When it is determined in step S35 that the ink tank 1 has been replaced, the control unit 21 opens the first ink supply valve 16, and circulates ink from the newly loaded ink tank 1 through the ink supply path 2. (S36).

  Thereafter, the control unit 21 again monitors whether or not the first sub tank 6 is full by the full tank detection sensor 12 of the first sub tank 6 (S37). Here, while the first sub tank 6 is not full, the control unit 21 repeats the processing from step S33 onward, and the first sub tank 6 becomes full and the detection signal from the full detection sensor 12 is reached. Is confirmed, the display lamp 15 is turned off and the replacement instruction for the ink tank 1 is canceled (S38). Thereafter, the first ink supply valve 16 is closed (S25), and the ink supply control operation is terminated.

  According to the second embodiment, in addition to the same effects as those of the first embodiment, the following effects can be obtained.

  That is, since the second ink supply valve 17 is interposed between the first sub-tank 6 and the second sub-tank 7, the remaining amount of ink in each of the first sub-tank 6 and the second sub-tank 7 is determined. It is not necessary to provide a difference in the judgment level, and it can be monitored individually.

  Further, for example, the back pressure applied to the recording head 3 by the second sub tank 7 as a flexible container is set without increasing the amount of ink in the second sub tank 7 to a predetermined amount or more (that is, without panning). Is possible.

  During printing, since the ink is consumed only from the second sub-tank 7 by closing the second ink supply valve 17, it is shown in order to detect the remaining amount of ink in the second sub-tank 7. Instead of providing the full tank detection sensor 12, it is also possible to easily detect the remaining amount of ink by counting the ink discharge amount and discharge amount required for printing and head maintenance.

  For example, if the internal capacity of the second sub-tank 7 is 40 ml and the specification of the recording head 3 is 16 pl / dot, 128 nozzles, 1 dot / 50 μsec, then 41 pl / μsec = 41 ml / 1000 sec. Here, if the printing area time during the scanning of the carriage 4 is 1 sec, the turn-back time during the carriage scanning (non-printing area) is 0.5 sec, and bidirectional printing is performed, the printing time ratio during the scanning of the carriage 4 is 66.7%, and the maximum ink consumption is 41 ml / 1500 sec = 41 ml / 25 min. Therefore, after detecting that the ink tank 1 is empty, it may be replaced within 25 minutes.

  Similarly, if the internal capacity of the second sub-tank 7 is 40 ml and the specification of the recording head 3 is 20 pl / dot, 256 nozzles, 1 dot / 55.8 μsec, then 102 pl / μsec = 41 ml / 402 sec. Here, if the printing area time during scanning of the carriage 4 is 2 sec, the time required for folding during the carriage scanning (non-printing area) is 0.5 sec, and bidirectional printing is performed, the printing time ratio during scanning of the carriage 4 is 80%, and the maximum ink consumption is 41 ml / 503 sec = 41 ml / 8 min. Therefore, after detecting that the ink tank 1 is empty, it should be replaced within 8 minutes. If the internal volume of the second sub-tank 7 is 80 ml, the replacement grace time is further extended to 16 minutes.

  Since this is the maximum ink consumption, and it is rare to discharge such a maximum amount in normal printing, the consumption amount is a fraction of 1 to several tens of minutes. Exchange grace time is expected to be several times to several tens of times.

  Further, if a dot count means (not shown) for counting the printing data and counting the number of dots actually ejected for each color is provided, the replacement grace time can be calculated more accurately.

  The detection of the remaining amount of ink by counting the amount of ink ejected and discharged can also be applied to the first embodiment. In this case, it is detected that there is no ink remaining in the first sub tank 6.

  In addition, although the 1st sub tank 6 and the 2nd sub tank 7 in each 1st and 2nd embodiment showed what was formed in the shape of a sealing bag body with the material which has flexibility, what is this? It is not limited to. For example, it may not be flexible and may be a hard box-shaped container.

  In the above description, the ink supply system of one recording head 3 has been described as an example. However, in an inkjet printer that performs full-color image recording, an image is recorded with a plurality of colors such as four colors and eight colors. The plurality of ink tanks for supplying ink of each color and the number of recording heads corresponding to the ink tanks are provided. Therefore, in this case, the same number of ink supply systems as described above are provided for the number of recording heads.

1 is a schematic configuration diagram showing a first embodiment of an inkjet printer according to the present invention. The figure which shows the detail of the ink supply path in FIG. Configuration block diagram for ink supply control Flow chart showing ink supply control operation The figure which shows 2nd Embodiment of an ink supply path. Configuration block diagram for ink supply control of the second embodiment A flowchart showing an ink supply control operation of the second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100: Inkjet printer 1: Ink tank 2: Ink supply path 3: Recording head 4: Carriage 5: Ink supply valve 6: 1st subtank 7: 2nd subtank 8: Maintenance unit 10: Loading part 11: Ink tank weight Detection sensor 12, 13: Full tank detection sensor 14: Timer 15: Display lamp 16: First ink supply valve 17: Second ink supply valve

Claims (7)

In an ink jet printer that supplies ink from a replaceable ink tank to a recording head via an ink supply path,
An ink jet printer comprising: two sub tanks each capable of storing ink in the ink supply path between the ink tank and the recording head.   The inkjet printer according to claim 1, wherein the two sub tanks have different sizes, and a smaller sub tank is disposed on the upstream side.   3. The ink jet printer according to claim 1, further comprising an internal volume detecting unit in at least an upstream side sub tank of the two sub tanks.   4. The ink jet printer according to claim 1, further comprising: a valve mechanism that opens and closes the ink supply path at least upstream of the two sub tanks.   The valve mechanism is opened when the internal capacity detecting means determines that the internal capacity is low, and has control means for controlling the valve mechanism to close when the internal capacity is determined to be high. The ink jet printer according to claim 4, wherein Warning means for warning that there is no remaining ink tank;
The control means determines that the ink tank has no remaining capacity and activates the warning means when the internal volume detection means does not detect a large internal capacity even after a predetermined time has elapsed after opening the valve mechanism. 6. An ink jet printer according to claim 5, wherein the ink jet printer is used.   2. The ink jet printer according to claim 1, wherein the two sub tanks have internal volume detecting means having different determination levels.

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