JP2006188002A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the remaining quantity of an ink can be detected only when the remaining quantity of the ink in a main tank becomes insufficient in a conventional inkjet recording device. <P>SOLUTION: The inkjet recording device has a recording head to make record on a recording medium by discharging ink, a main tank having a main ink bag to hold an ink to be supplied to the recording head, an ink supply route to supply the ink to the recording head from the main tank, a sub tank provided at a halfway point of the ink supply route and to temporarily hold the ink and supply the ink to the recording head, and an ink replenishing pump at the halfway point of the ink supply route of the main tank and the sub tank. The device is characterized in that the device obtains the remaining quantity of the ink in the main tank from the frequency of operation of the ink replenishing pump. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ink jet recording apparatus, and more particularly, to an ink remaining amount detection method for an ink jet recording apparatus that obtains the ink remaining amount of a main tank from the number of operations of an ink refill pump.

  The configuration of a conventional ink supply system will be described with reference to FIG.

  A printing system of an ink jet recording apparatus is roughly divided into a recording head 1 that discharges ink droplets from nozzles to form recording dots and an ink supply system that supplies ink to the recording head 1. An ink tank that is a component of the ink supply system is generally composed of a main tank 10 and a sub tank 5. The sub tank 5 fixed to keep the water head difference h with the recording head 1 constant, and the ink level in the sub tank 5 are detected by a sensor (not shown), and ink is supplied from the main tank 10 when necessary. Yes. The main tank 10 is installed at a position higher than the sub tank 5, and ink is supplied from the main tank 10 to the sub tank 5 by pressurization due to a water head difference. At this time, the solenoid valve 7 and the solenoid valve 11 are driven and controlled. If the solenoid valve 7 is not opened while the solenoid valve 11 is closed, ink will leak from the print head 1 because the water head difference between the main tank 10 and the print head 1 is large. In order to prevent this, when the ink is supplied to the sub tank 5, the solenoid valve 7 is opened and the solenoid valve 11 is closed. Due to such two types of ink tank configurations, ink replenishment can be easily performed by replacing the main tank 10.

  A filter unit 4 equipped with a filter 4a for filtering ink is disposed downstream of the sub tank 5 in the ink flow. The filter 4a prevents inflow of dust or ink aggregates that may cause nozzle clogging of the recording head 1. Single or multiple recording heads 1 are arranged further downstream of the filter unit 4. In the recording head 1, a tube is connected to an inlet 1 a for introducing ink, and ink is supplied from the filter unit 4.

  In the above configuration, the remaining amount of ink in the main tank 10 is detected when the remaining amount of ink in the main tank 10 is low when the replenishment of ink to the sub tank 5 is not completed within a certain time. Therefore, the remaining ink level can be detected only after the remaining ink level in the main tank 10 is reduced.

  As a means to solve the above problems, a soft tube is placed along a casing having an arc-shaped inner wall surface, and a pump mechanism that feeds ink downstream while crushing the tube with a roller attached to the rotor is used to determine the ink from the rotational speed of the rotor. A method has been proposed in which the amount used is determined and the remaining amount of ink in the ink tank is detected (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 8-238783

  The pump mechanism applied to the printer described in Patent Document 1 is inserted in the middle of a tube connecting the ink tank and the head, and the pressure difference between the front and rear of the roller due to the negative pressure generated by the ink discharged from the nozzle portion of the head. Occurs, the roller moves, and as a result, the rotor rotates. However, since the negative pressure generated in the tube by printing and cleaning is small, it is extremely difficult for the rotor to rotate while maintaining a state where the tube is crushed, although a flexible material tube is used. As a result, there is a high possibility that ejection failure will occur due to insufficient supply of ink.

  Further, based on the print information, the rotor is forcibly rotated by motor drive and controlled to supply an amount corresponding to the ink consumption. However, since the ink is incompressible, if the ink is supplied directly to the head, the ink is in a pressurized state due to a slight difference between the ink consumption and the supply amount, and there is a high possibility that an ejection failure will occur. Further, the influence of pressure fluctuation due to ink supply on ink ejection cannot be ignored.

  The present invention has been made in view of such a conventional technical problem, and provides means for supplying ink to a sub tank without affecting the ink ejection performance and constantly monitoring the remaining amount of ink in the main tank. An object of the present invention is to provide an inkjet recording apparatus provided.

  In order to achieve this object, an ink jet recording apparatus of the present invention includes a recording head that discharges ink to perform recording on a recording medium, a main tank that includes a main ink bag that holds ink supplied to the recording head, a main tank, An ink jet recording apparatus comprising: an ink supply path for supplying ink from a tank to a recording head; and a sub tank provided in the middle of the ink supply path for temporarily holding ink and supplying ink to the recording head; An ink replenishment pump is provided in the middle of the ink supply path of the sub tank, and the remaining amount of ink in the main tank is obtained from the number of operations of the ink replenishment pump.

  Also, a recording head that discharges ink to record on a recording medium, a main tank that includes a main ink bag that holds ink to be supplied to the recording head, and an ink supply that supplies ink from the main tank to the recording head A sub-tank that is provided in the middle of the ink supply path, temporarily holds ink and supplies ink to the recording head, a sub-ink bag that is hermetically held in the sub-tank with a single opening, and a sub-ink bag At the same time, it has a communication part with the outside, and has a sealed container that holds and holds the sub ink bag in a sealed manner except for the communication part, and the ink supply path between the main tank and the sub tank is divided into two flow paths downstream of the first solenoid valve. Branched, provided with an ink replenishment pump in the first flow path, a second electromagnetic valve in the second flow path, and a third electromagnetic valve in the ink supply path between the sub tank and the recording head Operation of an ink replenishment pump in an ink jet recording apparatus that has a negative pressure adjusting means that is installed and communicates with a communication portion formed in a sealed container and that allows a space between the sub ink bag and the sealed container to be adjusted to a negative pressure. The remaining amount of ink in the main tank is obtained from the number of times.

  The ink replenishment pump has a built-in check valve that prevents the ink from flowing back in the direction opposite to the transport direction, and the check valve has a negative pressure of about −3000 Pa in the direction in which the ink refill pump transports the liquid. It is a liquid metering pump that can be blocked and held in a state where there is almost no ink leakage when added.

  According to the present invention, ink replenishment from the main tank to the sub-tank can be calculated from the number of operations of the ink replenishment pump by using the ink replenishment pump, so that the remaining amount of ink in the main tank is constantly monitored. It is possible. Accordingly, it is possible to provide an ink jet recording apparatus capable of determining the replacement time of the main tank according to the printing amount.

  Hereinafter, the present invention will be described with reference to examples.

  First, the overall configuration of the ink jet recording apparatus of the present invention will be described with reference to FIG.

  The printing system of the ink jet recording apparatus is roughly divided into a recording head 1 that forms recording dots by ejecting ink droplets from nozzles, and an ink supply system for supplying ink to the recording head 1. An ink tank which is a component of the ink supply system is generally provided with a main tank 10 and a sub tank 5. The sub tank 5 fixed to keep the water head difference h from the recording head 1 constant, and the ink level in the sub tank 5 are detected by the level sensor 36, and ink is supplied from the main tank 10 when necessary. . Ink supply from the main tank 10 to the sub tank 5 is performed by an ink supply pump 21. When ink is supplied to the sub tank 5, the solenoid valve 7 is opened and the solenoid valve 11 is closed. Due to such two types of ink tank configurations, ink replenishment can be easily performed by replacing the main tank 10.

  A filter unit 4 equipped with a filter 4a for filtering ink is disposed downstream of the sub tank 5 in the ink flow. The filter 4a prevents inflow of dust or ink aggregates that may cause nozzle clogging of the recording head 1. Single or multiple recording heads 1 are arranged further downstream of the filter unit 4. In the recording head 1, a tube is connected to an inlet 1 a for introducing ink, and ink is supplied from the filter unit 4.

  Next, a method for detecting the remaining amount of ink in the main tank 10 will be described.

The main tank 10 is always replaced while being filled with a fixed amount of ink. The ink level is detected by the ink level sensor 36 in the sub tank 5, and ink is replenished from the main tank 10 by the ink replenishment pump 21 when necessary. The ink replenishment pump 21 is preferably a fixed discharge liquid pump, for example, a diaphragm pump. The number of operations of the ink replenishment pump 21 due to ink replenishment to the sub tank 5 is counted by the control means 50, and the ink replenishment amount is calculated. Since the initial ink capacity of the main tank 10 is constant, the remaining amount of ink in the main tank 10 is obtained and displayed on the display means 51 as necessary. The display of the remaining amount of ink in the main tank 10 is not limited to a method such as a constant display or a display upon request, but it may be forcibly displayed when the remaining amount of ink reaches about 20 to 30%. preferable.
When removing the main tank 10 for replacement, the number of operations of the ink replenishment pump 21 is reset by a signal from the lock release sensor 9 by releasing a lock mechanism (not shown).

  Another embodiment of the present invention will be described with reference to FIG. In the present embodiment, the ink flow direction will be described with the main tank 10 as the upstream side and the end recording head 1 side as the downstream side.

  The main tank 10 is detachably held by an operator. A first electromagnetic valve 20 is disposed from the most upstream main tank 10, and a first flow path 23 in which an ink replenishment pump 21 for transporting ink is disposed downstream of the first electromagnetic valve 20 and a second electromagnetic valve 22 is disposed. Branches into a second flow path 24. Both the first flow path 23 and the second flow path 24 are connected to the negative pressure reservoir 30. The ink introduction member 31 of the negative pressure reservoir 30 connects the first flow path 23 and the second flow path 24 and integrates them into a single flow path. A sub tank 5 of an aluminum resin laminated bag is connected to the ink introducing member 31 through a single opening. The aluminum resin laminated bag has a single mouth portion that is used as a general shape, and is fixed to the ink introduction member 31 with a screw portion formed on the outer periphery of the mouth portion. For this reason, the ink inlet of the sub tank 5 is single. An airtight container 32 that covers and holds the sub tank 5 is configured to be airtightly held with the ink introduction member 31. The sealed container 32 is provided with an opening 33 connected to a negative pressure adjusting mechanism 40 for generating a negative pressure in the space between the sub tank 5 and the sealed container 32, and is connected by a tube 34 or the like. The negative pressure adjustment mechanism 40 includes an air suction pump 41 using a tube pump or the like, an air replenishment pump 42, an electromagnetic three-way valve 43 that switches to open to the atmosphere, and a pressure sensor 44. The negative pressure adjustment is performed by controlling the operation of the air suction pump 41 and the air replenishment pump 42 by a control circuit (not shown) from the signal of the pressure sensor 44.

  A third electromagnetic valve 35 and the recording head 1 are connected downstream of the negative pressure reservoir 30 through an ink flow path. The ink flow path from the main tank 10 to the recording head 1 uses all stainless steel pipes and joints so as to ensure a deaerated state of the ink for a long period.

  Usually, the negative pressure optimum for the ink in the nozzle portion of the recording head 1 is about −100 to −300 Pa. In order to generate this negative pressure, the air in the sealed container 32 is sucked so that an appropriate negative pressure is applied to the ink in the sub tank 5.

  When the recording head 1 discharges and consumes ink, the ink in the sub tank 5 decreases and the sub tank 5 contracts. For this reason, ink is replenished when necessary from the main tank 10 according to ink consumption. A level sensor 36 for detecting the ink level of the sub tank 5 is installed in the sealed container 32 so as to detect the ink amount.

  Ink supply from the main tank 10 is performed by an ink supply pump 21. When the negative pressure reservoir 30 generates a negative pressure, the ink replenishment pump 21 applies an equivalent negative pressure to the ink in the ink replenishment pump 21 and therefore must be able to hold the ink against the negative pressure. If the pressure cannot be maintained, the negative pressure reservoir 30 continues to suck ink from the main tank 10 due to the negative pressure, and the negative pressure cannot be generated or adjusted. For this reason, the ink replenishment pump 21 must be a pump that counteracts negative pressure and blocks and holds ink.

  For this reason, it is preferable to use a liquid metering pump equipped with a check valve (check valve) that blocks and holds ink even when a certain amount of negative pressure is applied in the infusion direction. Many check valves for this type of liquid metering pump use the duckbill type. The negative pressure that holds and holds the liquid metering pump may be about −3000 Pa, and the ink may be transported in conjunction with ink consumption. Further, when the pressure pulsation of the ink replenishing pump 21 can be as small as about ± 100 Pa, ink replenishment can be performed continuously even while the recording head 1 is printing. The ink replenishment pump 21 is preferably a fixed discharge liquid pump, for example, a diaphragm pump.

  During normal printing, the ink replenishment pump 21 supplements the negative pressure reservoir 30 with ink so that the amount of ink consumed by the recording head 1 is always supplemented, so that the ink flows only through the first flow path. .

  However, a purge operation for sucking out ink from the recording head 1 by a suction mechanism (not shown) is required as a periodic discharge recovery operation of the recording head 1. When the nozzles of the recording head 1 are continuously ejected or left without being ejected for a certain period of time, there are cases where ink ejection is not sufficiently performed due to ink wetting or drying of the nozzle portion. In this case, a purge operation is provided as a maintenance operation for recovering the discharge state. The ink sucked from the recording head 1 by this purge operation is much larger per unit time than the ink consumed by ejection during normal printing. For this reason, a large amount of ink in the negative pressure reservoir 30 is reduced by one purge operation. From this state, it takes time to restore the original ink level again with only the ink refill pump 21.

  For this reason, it is necessary to return to the original ink level, that is, the print standby state in a short time after the purge operation. In order to shorten this time, the second flow path 24 is provided, and the ink is caused to flow to the negative pressure reservoir 30. It may be configured as a bypass path. The second flow path 24 is opened by opening the second electromagnetic valve 22, and the flow rate is high due to the negative pressure of the negative pressure reservoir 30 and the water head difference between the negative pressure reservoir 30 and the main tank 10. it can.

  Next, a method for detecting the remaining amount of ink in the main tank 10 will be described.

  The main tank 10 is always replaced while being filled with a fixed amount of ink. The ink level is detected by the ink level sensor 36 in the sub tank 5, and ink is replenished from the main tank 10 by the ink replenishment pump 21 when necessary. The number of operations of the ink replenishment pump 21 due to ink replenishment to the sub tank 5 is counted by the control means 50, and the ink replenishment amount is calculated. Further, when the ink is replenished using the second path 24 after the purge operation, the unit time is determined by the negative pressure of the negative pressure reservoir 30 and the water head difference between the negative pressure reservoir 30 and the main tank 10 which are obtained in advance. The ink replenishment amount is calculated based on the per-flow rate and the opening time of the second electromagnetic valve 22. Since the initial ink capacity of the in-tank 10 is constant, the remaining amount of ink in the main tank 10 is obtained from the sum of the respective ink replenishment amounts and displayed on the display means 51 as necessary. The display of the remaining amount of ink in the main tank 10 is not limited to a method such as a constant display or a display upon request, but it may be forcibly displayed when the remaining amount of ink reaches about 20 to 30%. preferable.

  When removing the main tank 10 for replacement, the number of operations of the ink replenishment pump 21 and the opening time of the second electromagnetic valve 22 are reset by releasing the lock mechanism (not shown) by the signal of the lock release sensor 9. The

  It can also be applied to devices that take out fluid from various containers and need to detect the remaining amount.

It is the schematic which shows the inkjet recording device of this invention. Example 1 It is the schematic which shows the inkjet recording device of this invention. (Example 2) It is the schematic which shows an example of the conventional inkjet recording device.

Explanation of symbols

1 is a recording head, 1a is an inlet, 4 is a filter unit, 4a is a filter, 5 is a sub tank, 7 is a solenoid valve, 9 is a lock release sensor, 10 is a main tank, 11 is a solenoid valve, and 20 is a first solenoid valve. , 21 is an ink replenishment pump, 22 is a second electromagnetic valve, 22a is an electromagnetic three-way valve, 23 is a first flow path, 24 is a second flow path, 30 is a negative pressure reservoir, 31 is an ink introduction member, 32 Is an airtight container, 33 is an opening, 34 is a tube, 35 is a third electromagnetic valve, 36 is an ink level sensor, 40 is a negative pressure adjustment mechanism, 41 is an air suction pump, 42 is an air replenishment pump, and 43 is an electromagnetic three-way A valve, 50 is a control means, and 51 is a display means.

Claims (3)

  A recording head that discharges ink to perform recording on a recording medium, a main tank that includes a main ink bag that holds ink to be supplied to the recording head, and ink that supplies ink from the main tank to the recording head In an ink jet recording apparatus having a supply path and a sub tank provided in the middle of the ink supply path for temporarily holding ink and supplying ink to the recording head, the ink supply path of the main tank and the sub tank may be in the middle of the ink supply path. An ink jet recording apparatus comprising an ink replenishment pump, wherein the ink remaining amount in a main tank is obtained from the number of operations of the ink replenishment pump.   A recording head that discharges ink to perform recording on a recording medium, a main tank that includes a main ink bag that holds ink to be supplied to the recording head, and ink that supplies ink from the main tank to the recording head A sub-tank that is provided in the middle of the ink supply path, temporarily holds ink and supplies ink to the recording head, a sub-ink bag that is hermetically held in the sub-tank with a single opening, The sub-ink bag is provided with a communicating portion with the outside at the same time, and a sealed container for hermetically holding the sub-ink bag except for the communicating portion, and the ink supply path between the main tank and the sub-tank is connected to the first tank. Branching into two flow paths downstream of the solenoid valve, an ink replenishment pump is provided in the first flow path, and a second solenoid valve is provided in the second flow path. A third electromagnetic valve is installed in the ink supply path between the heads, communicates with the communication portion formed in the sealed container, and the space between the sub ink bag and the sealed container can be adjusted to a negative pressure. An ink jet recording apparatus having a negative pressure adjusting means for obtaining an ink remaining amount in a main tank from the number of operations of an ink replenishment pump. The ink replenishment pump has a built-in check valve that prevents the ink from flowing back in the direction opposite to the transport direction, and the check valve has a negative pressure of about −3000 Pa in the direction in which the ink replenishment pump transports the liquid. 3. An ink jet recording apparatus according to claim 1, further comprising a liquid metering pump capable of being blocked and held in a state where there is almost no ink leakage when added.

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