JP4047156B2 - Inkjet recording device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording apparatus that performs recording by discharging ink from a recording unit to a recording medium, and more particularly to a configuration of a novel ink supply mechanism used in the ink jet recording apparatus.
[0002]
[Prior art]
Recording devices used in homes and offices include printers connected to personal computers, word processor printers, facsimiles, and copiers. As a recording method used in these recording apparatuses, an electrophotographic method, an inkjet recording method, or the like is adopted.
An ink jet recording type recording apparatus (ink jet recording apparatus) that obtains a recorded matter (printed matter etc.) by adhering minute ink droplets ejected from an ejection port to a recording medium such as recording paper, Compared to this recording method, the device is inexpensive and easy to miniaturize, and you can easily obtain a wide range of recorded materials from recording office documents on plain paper to recording photographic images on recording media such as special paper and cloth. It can be widely used. A portable ink jet recording apparatus has also been proposed taking advantage of downsizing.
[0003]
  In such an ink jet recording apparatus, as an ink supply mechanism for supplying ink from an ink reservoir (ink tank) to a recording head, an on-carriage type disposed on a carriage for scanning the recording head, and a carriage A type in which an ink tank (hereinafter referred to as a main tank) is provided at another location and ink is supplied to a sub ink tank (hereinafter referred to as a sub tank) that is configured in the vicinity of the recording head or integrally with the recording head by a resin tube or the like. There are two types.
  Among these, the method of supplying ink from the main tank with a tube or the like does not affect the size and weight of the carriage even if the ink tank capacity is increased, so the scanning accuracy of the carriage is not affected by the remaining amount of ink, In addition, there is an advantage that the running cost can be reduced, and it is mainly used in commercial machines.
  As such prior art, there is JP-A-11-105303.
[0004]
  FIG. 10 shows a state after the ink in the main tank is supplied into the sub tank by operating the negative pressure pump and sucking and discharging the air in the sub tank in one configuration example of the ink supply mechanism of the conventional ink jet recording apparatus. FIG. 11 is a schematic cross-sectional view, and FIG. 11 is a schematic cross-sectional view showing a state in which the ink in the sub tank has returned to the main tank from the state of FIG.
  As such a prior art, there is JP-A-2002-248788.
  In the ink jet recording apparatus, there are various methods for supplying ink from the ink reservoir (main tank) to the sub tank, such as a method for supplying air and ink in the sub tank by simultaneously sucking and discharging from the discharge port. .
[0005]
  That is, as shown in FIG. 10, the air in the sub tank 3 integrally formed with the recording head 1 is sucked and discharged through the suction tube 5 by the negative pressure pump 7, so that the sub tank is supplied from the main tank 9 through the supply tube 11. An ink supply mechanism is employed in which ink is supplied to the inside of the sub tank 3 and the ink liquid level in the sub tank 3 is detected by the sensor 13 to stop the supply operation. Such an ink supply mechanism has an advantage that the ink is not wasted and is economical.
  In the ink supply mechanism shown in FIG. 10, since the supplied ink is prevented from flowing back by a check valve mechanism 17 as an ink backflow preventing means that allows flow only in the direction of the arrow 15, the negative pressure pump 7 The ink pumped into the sub-tank 3 is prevented from returning to the main tank 9 even if the driving is stopped or the inside of the negative pressure pump 7 is opened to the atmosphere.
  As a prior art provided with a valve, there is JP 2001-001536 A.
[0006]
The check valve mechanism 17 is generally composed of a check valve made of an elastic material having a high gas barrier property such as chlorinated butyl rubber, a holder for holding the check valve, and a sealing member for sealing the inside of the holder. It is configured. In the configuration of FIG. 10, in order to further ensure the sealing performance required for the check valve (sealing performance to prevent backflow), the sealing portion (seal portion) of the check valve is sealed with grease or the like. Applying a stopper is performed.
[0007]
[Problems to be solved by the invention]
However, the conventional ink supply mechanism as described above has the following technical problems to be solved.
That is, first, the remaining air in the suction tube 5 expands or contracts in response to a change in the environmental temperature, and the ink level in the sub tank 3 is likely to fluctuate.
Secondly, since the air in the suction tube 5 is always under a negative pressure corresponding to the head pressure, even if the ink in the sub-tank 3 evaporates, the saturated vapor pressure is not reached and the ambient temperature is constant. Even in this case, the gas volume in the sub tank 3 always expands until the ink returns to the main tank 9, and therefore, it is necessary to supply ink from the main tank 9 to the sub tank 3 at a high frequency.
[0008]
Third, the suction tube 5 and the supply tube 11 are made of a highly flexible material such as polyethylene or elastomer so that they can follow flexibly as the carriage scans. Since the gas barrier property is extremely low compared to the plastic forming the main tank 9 and the sub tank 3, and the inside of these tubes has a negative pressure and high humidity, these tubes 5 and 11 are always physically Air will be taken in from the outside of the tube to the inside of the tube, and the technical problem as described above will become more prominent.
[0009]
For the reasons described above, the ink liquid level in the sub tank 3 decreases with the passage of time from the position detected by the sensor. The rate of decrease varies depending on the dimensions of the above members and environmental conditions. For example, the supply tube 11 and the suction tube 5 made of elastomer are made into a tube having an inner diameter of 2 mm, a wall thickness of 1 mm, and a length of 400 mm, and the capacity of the sub tank 3 is 7 cc (when the supply is completed) If the sub-tank head is 150 mm, the ambient temperature is 35 degrees Celsius and the tube is supplied in about 2 hours under a low humidity environment. All the ink in 11 returns to the main tank 9. Such a phenomenon becomes more conspicuous as the region where the inside is in an air state is larger. That is, it can be seen that the volume of the air in the tube is expanded at the site of the suction tube 5 in FIG.
[0010]
When the ink pumped to the sub tank 3 returns to the main tank 9 and enters the state shown in FIG. 11, the negative pressure in the sub tank 3 disappears, and the positive pressure is applied to the discharge ports (nozzles) formed in the recording head. Therefore, there may be a problem that normal ink cannot be ejected from the ejection port, and further, ink drops from the ejection port. As a means for solving such inconvenience, a means for improving the gas barrier property (gas non-permeability) of the tube is conceivable. However, when the tube is formed of a resin having excellent gas barrier property (for example, fluorine resin). This will lead to a significant increase in cost. Moreover, in order to ensure appropriate tube flexibility, the entire tube must be thinly provided on the surface layer, etc., rather than being made of fluororesin, which ensures sufficient gas barrier properties of the tube. It was difficult to do.
[0011]
Further, in a configuration in which ink is supplied again by driving the ink supply means (such as a negative pressure pump) before the ink returns to the main tank 9, it is possible if the recording apparatus is turned on. When the power is turned off, the intended processing operation becomes impossible, and the above-mentioned inconvenience cannot be avoided.
In order to avoid the inconvenience described above, it is conceivable to shorten the execution interval of the ink supply operation. However, in such an operation method, the throughput of the recording operation is required for frequent ink supply operation (ink replenishment operation). Furthermore, since the ink filled in the ejection port is retracted by the negative pressure in the sub tank 3 generated by the ink supply operation, the ink is discharged into the ejection port (nozzle) after the ink supply operation. Ink filling work is required. In this ink filling operation, a processing operation for forcibly discharging ink from the ejection port is performed by a recovery operation such as pressurizing the inside of the sub tank 3 or applying a negative pressure from the ejection port. In addition to the decrease, the running cost is increased due to an increase in wasted ink consumption.
[0012]
The present invention has been made in view of such a technical problem, and an object of the present invention is to provide an ink backflow prevention means having excellent sealing properties by simply providing an ink backflow prevention means at or near the recording means. It is an object of the present invention to provide an ink jet recording apparatus that can be configured simply and inexpensively, can reduce the frequency of ink supply, and can achieve an increase in throughput and a reduction in running cost in a recording operation.
[0013]
[Means for Solving the Problems]
  In order to achieve the above object, the present invention provides an ink storage unit for recording ink by discharging ink from a recording unit to a recording medium, and supplying ink to an ink storage unit that stores ink and the ink discharge unit of the recording unit A sub tank, an ink supply path for supplying ink from the ink reservoir to the sub tank, a negative pressure generating means for applying a negative pressure in the sub tank, and a valve chamber attached to the sub tank. Backflow preventing means provided between the subtank and the valve chamber so as to prevent the flow of air and ink from the subtank to the valve chamber, but preventing the flow in the opposite direction; A first electrode disposed; and a second electrode disposed in a part of a path connecting the valve chamber and the negative pressure generating means; Of inkNot fullThe negative pressure generating means is connected to apply a negative pressure to the sub-tank via the valve chamber, and the ink detecting means causes the ink in the sub-tank to flow.Not fullWhen this is detected, the negative pressure generating means is driven to supply ink from the ink reservoir to the sub tank.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings. Note that the same reference numerals denote the same or corresponding parts throughout the drawings.
FIG. 1 is an external perspective view showing an embodiment of an ink jet recording apparatus suitable for applying the present invention. In FIG. 1, 101 is a carriage unit in which recording means (recording head) (not shown) is detachably mounted, 103 is a recovery system unit (discharge recovery device) for maintaining and recovering the ink discharge performance of the recording head, and 105 is A tank unit in which a main tank as an ink storage unit is loaded, 107 is a frame unit which is a base member for mounting each unit, and 109 is an engine unit of an ink jet recording apparatus constituted by the above units.
[0015]
The recovery system unit 103 is formed of a negative pressure pump (recovery pump) as a negative pressure generation source, a rubber-like elastic body such as rubber, and capping for covering and protecting the ink discharge portion (discharge port surface) of the recording head. Means (cap), wiping means (wiper blade) for wiping off and cleaning foreign matter adhering to the ink discharge portion, and the like.
The ink jet recording apparatus shown in FIG. 1 has a structure in which recording means is mounted on a carriage that can move within a predetermined range. In recording, the carriage is not moved (scanned), and a transport mechanism (not shown) is used. This is a kind of line type recording apparatus that performs recording on a recording medium such as a recording sheet conveyed by the printer.
[0016]
2 is a schematic perspective view showing a part of the overall structure of the recording means (recording head) of the ink jet recording apparatus of FIG. 1, and FIG. 3 is a schematic longitudinal sectional view of the recording means of FIG. 4 is a partially enlarged longitudinal sectional view showing, in an enlarged manner, a check valve mechanism portion (a portion surrounded by a one-dot chain line in FIG. 3) as an ink backflow prevention means in FIG. 2 to 4, each of the recesses (holes) formed at two locations on the side wall portion of the sub tank 25 provided in the recording means 19 has a stopper (made of a rubber-like elastic material such as chlorinated butyl rubber). Plugs) 21A and 21B are mounted in a close contact state (for example, a press-fit state).
[0017]
The hollow needles 47 and 55 on the carriage unit (carriage) 101 are inserted (pierced) into the stoppers 21A and 21B, so that the hollow needle is sealed (sealed). Is configured to penetrate and communicate with the inside. In the present embodiment, the hollow needles 47 and 55 have a distal end shape that is formed by obliquely cutting the hollow shaft in the same manner as the medical injection needles, so that the hollow needle insertion holes and the like are formed in the plugs 21A and 21B. However, for example, when the tip of the hollow needle is rounded, a notch such as a cross may be provided in advance as will be described later.
[0018]
  2 to 4, reference numeral 23 denotes a check valve as an ink backflow prevention means, and an umbrella type valve made of, for example, chlorinated butyl rubber having a rubber hardness of 60 degrees is adopted as the valve body. The check valve 23 is inserted into and attached to an opening (hole) 31 formed in a boundary wall 29 with the valve chamber 27 provided alongside the sub tank 25. A plurality of communication ports (communication holes) 33 are formed around the opening 31 of the boundary wall 29. Then, the check valve (ink backflow prevention means) 23 is configured so that air or ink in the sub tank 25 passes through the plurality of communication ports (communication holes) 33 and is hollow as indicated by an arrow 35.Le 55 (FIG. 7) is allowed to flow, but is prevented from flowing in the opposite direction.
[0019]
Further, since the portion corresponding to the umbrella of the check valve 23 is formed with a thickness of about 0.15 mm, the pressure difference required to open the check valve 23 is less than −0.1 atm. Therefore, when the pressure difference between air and ink is 0.1 atm or more, these fluids are configured to freely flow in the direction of the arrow 35.
On the other hand, when the ink is going to flow backward, that is, when the ink is going to flow in the direction opposite to the arrow 35, the pressure portion causes the umbrella portion of the check valve 23 to be in close contact with the boundary wall 29, and the communication hole. The ridge lines 33 serve as sealing portions (sealing portions) so as to prevent (prevent) the flow of ink. The configuration of the check valve mechanism is not necessarily limited to the illustrated embodiment, and may be another valve mechanism such as a duckbill valve as long as it has a backflow prevention function.
[0020]
An ink discharge portion (discharge unit portion) 37 is provided on the face surface portion (lower portion in the illustrated example) of the recording head 19. The recording means (recording head) 19 in this embodiment uses thermal energy. Ink jet recording means for ejecting ink is provided with an electrothermal converter (heater) for generating thermal energy, so that the ink discharge section 37 is applied by the electrothermal converter. The film is caused to boil in the ink in the ejection port (inside the nozzle) by the applied thermal energy, and the ink is ejected from the ejection port by utilizing the pressure change caused by the growth and contraction of bubbles generated at that time.
[0021]
FIG. 5 is a schematic external perspective view of the main tank 39 as an ink reservoir provided in the tank unit 105 (FIG. 1) attached to the frame 107 (FIG. 1). In FIG. 5, plugs 41 </ b> A formed of rubber-like elastic bodies such as chlorinated butyl rubber are respectively provided at two openings (through holes) formed at two positions on the bottom of the ink storage portion (main tank) 39. 41B is mounted in a close contact state (for example, a press-fit state). The hollow needles 61 and 59 provided at the tips of the atmosphere communication tube 43 and the supply tube 45 are inserted (pierced) into the plugs 41A and 41B, thereby sealing (sealing) the outer peripheral surface of the hollow needle. In this state, the hollow needle penetrates and communicates with the inside of the main tank 39. In this embodiment, since the hollow needles 61 and 59 have a distal end shape that is formed by obliquely cutting the hollow shaft in the same manner as the medical injection needle, the plugs 41A and 41B have holes for inserting the hollow needles and the like. However, for example, when the tip of the hollow needle is rounded, a notch such as a cross may be provided in advance as will be described later.
[0022]
The plugs 41 </ b> A and 41 </ b> B are elastic material plugs (plugs) provided to prevent the ink in the main tank 39 from flowing out and the outside air from entering the main tank 39. The supply tube 45 connected via the plug 41A forms a flow path for supplying ink from the main tank 39 to the sub tank 25 of the recording head 19, and is connected via the plug 41B. The atmosphere communication tube 43 forms an atmosphere communication path for communicating the inside of the main tank 39 with the atmosphere. In the present embodiment, as shown in FIG. 5, the aforementioned cross cuts are provided in advance in the stoppers 41A and 41B.
[0023]
  6 to 9 are schematic cross-sectional views showing the configuration and operation of an ink supply mechanism of an ink jet recording apparatus to which the present invention is applied. FIG. 6 shows a state before a main tank as an ink storage unit is loaded in the recording apparatus. 7 shows a state immediately after the main tank is loaded into the recording apparatus, and FIG. 8 shows the generation of negative pressure from the state of FIG.means9 shows a state after the ink in the main tank is supplied into the sub tank by sucking and discharging the air in the sub tank by operating the negative pressure pump as shown in FIG. A state when the ink level in the sub tank is lowered due to air expansion in the sub tank or the like is shown.
[0024]
6 to 9, reference numeral 43 is for introducing air into the ink storage unit 39 corresponding to the ink volume supplied from the ink storage unit (main tank) 39 to the sub tank 25 in the recording means (recording head) 19. The atmosphere communication tube 45 is a supply tube constituting an ink supply path from the main tank 39 to the sub tank 25.
Hollow needles 47 and 55 are provided on the carriage (see the carriage unit 101 in FIG. 1). One hollow needle 47 is a hollow needle for supply that is provided at an end of the supply tube 45 on the sub tank 25 side and functions as a joint formed of a material that can be pierced (inserted) into the stopper 21B. The other hollow needle 55 is a suction hollow needle that is provided at the end of the suction tube 51 on the sub tank 25 side and functions as a joint formed of a conductive material that can be pierced (inserted) into the stopper 21A. is there.
[0025]
  The supply tube 45 communicates with the sub tank 25 through the supply hollow needle 47, and the suction tube 51 passes through the suction hollow needle 55.5The valve chamber 27 is formed adjacent to the valve chamber 27. The other end of the supply tube 45 communicates with the main tank 39 through a hollow needle 59, and a negative pressure pump 49 as a negative pressure generating means is connected to the other end of the suction tube 51. That is, the suction tube 51 forms a flow path that connects the negative pressure pump 49 and the sub tank 25, and the supply tube 45 forms a flow path that connects the main tank 39 and the sub tank 25. To do.
[0026]
  A check valve mechanism (FIG. 4) having a check valve 23 as a backflow prevention means is provided on a partition wall portion on the sub tank 25 side of the valve chamber 27 formed in the sub tank 25. Between the ink backflow prevention means (check valve) 23 and the negative pressure generating means (negative pressure pump) 49 (in the illustrated example, the portion of the suction hollow needle 55),Valve chamber 27Electrodes constituting the ink detection means 57 for detecting the presence or absence of ink in the inside (in this embodiment, the suction hollow needle 55 is used) are provided. The ink detection means 57 in the present embodiment detects ink conduction by detecting electrical continuity between an electrode using the suction hollow needle 55 and an electrode (not shown) provided in the sub tank 25. It is comprised so that the presence or absence of may be detected. The driving and stopping of the negative pressure generating means 49 are controlled according to the detection result of the ink detecting means 57.
[0027]
When the main tank 39 is loaded into a predetermined portion in the recording apparatus from the state of FIG. 6, the hollow needle 59 provided at the front end of the supply tube 45 on the main tank side is one plug 41A of the main tank 39 as shown in FIG. The hollow needle 61 provided at the front end of the atmospheric communication tube 43 on the main tank side is inserted (pierced) into the other plug 41B of the main tank 39. As a result, the supply tube 45 and the atmosphere communication tube 43 are connected to the inside of the main tank 39, and the ink in the main tank 39 is balanced until the air pressure in the main tank 39 and the head pressure of the ink in the main tank 39 are balanced. Flows into the supply tube 45 and the atmosphere communication tube 43.
[0028]
  From the state shown in FIG.means) When the air in the sub tank 25 is sucked and discharged by operating 49, the ink in the main tank 39 is supplied to the sub tank 25 and the valve chamber is passed through the check valve (back flow preventing means) 23 as shown in FIG. 27 (FIG. 4). Then, the ink detecting means 57 using the suction hollow needle 55 as an electrode detects the arrival of ink (a predetermined amount of inflow into the valve chamber 27). When the arrival of the ink is detected, the operation of the negative pressure pump 49 is stopped. FIG. 8 shows a state immediately after the negative pressure pump 49 is stopped after ink supply in this way. At this time, the ink flowing into the valve chamber 27 through the communication port 33 (FIG. 4) of the check valve mechanism also adheres to the seal portion (sealing portion) of the check valve 23, and the sealant of the seal portion Play a role. As a result, it is possible to eliminate the necessity of applying sealing grease or the like to the seal portion of the check valve 23 (in this embodiment, the umbrella portion of the check valve) (the effort required in the prior art).
[0029]
When the negative pressure pump 49 is stopped when the state shown in FIG. 8 is reached, the negative pressure pump 49 is opened to the atmosphere. Therefore, when the check valve 23 is not present, the ink pumped into the sub tank 25 is returned again into the main tank 39 to be in the state shown in FIG. 7 (the state before driving the negative pressure pump 49). However, in the present embodiment, since the check valve 23 is provided, the pressure corresponding to the water head difference 63 generated by pumping the ink into the sub tank 25 is the check valve even in the state of FIG. 4 acts in the direction opposite to the arrow 35 in FIG. 4, the ink flow path (the communication port 33 in FIG. 4) between the valve chamber 27 and the sub tank 25 is blocked by the check valve 23, Therefore, even if the negative pressure pump 4 is stopped in the state shown in FIG. 8, the backflow of ink from the sub tank 25 to the main tank 39 does not occur (is prevented).
[0030]
As described above, according to the configuration of this embodiment, when the negative pressure pump 4 is stopped in the state of FIG. 8, the ink discharge port portion (discharge unit portion) 37 of the recording head 19 only corresponds to the water head difference 63. Thus, the ink filled in the ejection port can form an appropriate meniscus, and the recording head 19 is maintained in a state where ink can be ejected stably. Further, when the ink in the sub tank 25 is consumed as the ink is ejected, the air corresponding to the consumed ink amount flows into the main tank 39 from the atmosphere communication tube 43 and has the same volume as this. Ink is supplied from the main tank 39 into the sub tank 25. In this way, the height of the ink surface in the sub tank 25 is always maintained in a stable and appropriate state, so that the ink ejection from the recording head 19 is also maintained in a stable and appropriate state.
[0031]
However, in actuality, as shown in FIG. 9, due to the expansion of air in the sub-tank 25 due to environmental temperature changes, the air in the sub-tank 25 that slightly flows in through the components such as the check valve 23 and the sub-tank 25, etc. The ink liquid level may be lower than that shown in FIG. When such a phenomenon further progresses, the inside of the supply tube 45 is replaced with air, and a positive pressure is applied to the discharge port portion of the recording head 19, which makes normal ink discharge difficult, or from the discharge port. There may be a situation in which the occurrence of problems such as ink dripping (leaking) may occur.
Therefore, if there is a concern about the occurrence of such a malfunction, the ink detection means 57 detects that the ink in the sub tank 25 is not full before the situation causing such a malfunction occurs. Accordingly, the negative pressure pump 49 is operated to supply (supplement) ink from the main tank 39 into the sub tank 25, so that an operation of returning to the full state as shown in FIG. 8 is preferably executed. .
[0032]
  However, in such an operation, time is wasted for supplying ink from the main tank 39 to the sub-tank 25, or the ink filled in the discharge ports by applying a negative pressure in the sub-tank 25 is sub tank 25. Therefore, after the ink supply as described with reference to FIG. 8 is performed, it is preferable to perform discharge recovery processing by, for example, the discharge recovery means, that is, the recovery system unit 103 (FIG. 1).
  The main configuration and operation of the recovery system unit 103 is to seal the discharge port by bringing a cap made of rubber-like elastic material such as rubber into close contact with the discharge port surface (face surface on which the discharge port is formed) of the recording head 19 ( Capping) and generating negative pressure such as tube pumpsourceBy applying a negative pressure to the cap and forcibly sucking and discharging ink from the discharge port, the discharge port is filled with ink, dust clogged in the discharge port, bubbles generated in the discharge port, and discharge port The ink ejection performance of the recording head 19 is maintained and recovered by removing foreign matters such as thickened ink whose viscosity has increased due to drying of nearby ink.
[0033]
On the other hand, when the time interval for supplying ink from the main tank 39 to the sub tank 25 is shortened, the processing time and the waste of ink due to the discharge recovery process increase, resulting in inconveniences such as a decrease in throughput and an increase in running cost. Will occur. Therefore, in order to eliminate the possibility of such an inconvenience, in this embodiment, a part having the lowest gas barrier property (for example, a part filled with high-temperature gas) is physically separated by the check valve 23 or the like. By doing so, the region (area) of the portion that may take in outside air is greatly reduced, and further, the check valve 23 is formed of chlorinated butyl rubber or the like having a high gas barrier property to greatly improve the gas barrier property in the sub tank 25. Thus, the ink supply time is shortened and the ink waste is suppressed.
[0034]
In addition, although a small amount of ink is supplied to the sub tank 25, the ink may enter the suction tube 51. In this embodiment, the ink (waste ink) sucked and discharged from the discharge port by the negative pressure pump 49 is used. ) Is disposed at the discharge destination (collection destination) of the ink absorber (not shown). However, as another embodiment, the negative pressure pump 49 is also used as a pump (recovery pump) provided as a part of the recovery system (discharge recovery device), so that a new pump or the like is not required. It is also possible to take.
[0035]
Furthermore, in the present embodiment, the ink detection means (ink liquid level detection means) 57 is provided integrally with the suction hollow needle 55, but the configuration of the present invention is not limited to this, and is provided in another part. The provided ink detection means may be used. Further, without providing the ink liquid level detecting means, the negative pressure pump 49 may be operated by a predetermined amount after a predetermined time has elapsed from the previous ink supply operation, and the suction operation for ink supply may be executed. .
Further, according to the present embodiment, since it is not necessary to make the gas barrier property of the suction tube 51 so high, by forming the suction tube 51 with a cheaper material or with a thinner wall tube, By making the gas barrier property of the suction tube 51 lower than the gas barrier property of the supply tube 45, the cost can be reduced.
[0036]
In this embodiment, the ink backflow prevention means including the check valve 23 is arranged in the sub tank 25. However, the arrangement of the backflow prevention means is not limited to this. For example, the ink backflow prevention means is arranged in a portion adjacent to the sub tank 25. Further, as long as it is in the vicinity of the sub tank 25, it may be arranged at a desired site such as a carriage (see the carriage unit 101 in FIG. 1) on which the recording head 19 is mounted.
The ink discharge means in the embodiment described above may be any discharge method as long as it is a means for discharging ink from the discharge port. For example, a so-called bubble using ink film boiling by an electrothermal transducer is used. A jet method may be used, and other discharge methods such as a method using an electromechanical transducer such as a piezoelectric element may be used.
[0037]
  In the embodiments described above, embodiments of the present invention as listed below are described.
  Embodiment 1 In an inkjet recording apparatus that performs recording by discharging ink from a recording unit to a recording medium, an ink storage unit that stores ink, a sub tank for supplying ink to the ink discharge unit of the recording unit, and An ink supply path for supplying ink from the ink reservoir to the sub tank, a negative pressure generating means for applying a negative pressure in the sub tank, a valve chamber provided in the sub tank, and the air and ink A flow from the sub tank to the valve chamber is allowed, but a reverse flow preventing means provided between the sub tank and the valve chamber so as to prevent a reverse flow, and a first electrode disposed in the sub tank And a second electrode disposed in a part of a path connecting the valve chamber and the negative pressure generating means, and the ink in the sub tank isNot fullThe negative pressure generating means is connected to apply a negative pressure to the sub-tank via the valve chamber, and the ink detecting means causes the ink in the sub-tank to flow.Not fullWhen this is detected, the negative pressure generating means is driven to supply ink from the ink reservoir to the sub tank.
  According to the configuration of the first embodiment, the recording means or the vicinity thereofReverseBy simply providing a flow prevention means, it is possible to easily and inexpensively configure an ink backflow prevention means excellent in sealing performance, to reduce the frequency of ink supply, and to improve the throughput and running of the recording operation. An ink jet recording apparatus capable of achieving cost reduction is provided.
[0038]
  Embodiment 2: Generation of the negative pressuremeansThe ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is also used as a negative pressure generating source used in an ejection recovery means for maintaining and recovering the ink ejection performance of the recording means.
  Embodiment 3: The sub tank and the negative pressure generationmeans3. The ink jet recording apparatus according to claim 1, wherein a gas barrier property of a suction tube connecting between the main tank and the sub tank is lower than a gas barrier property of a supply tube connecting between the main tank and the sub tank.
  Embodiment 4: The ink jet recording apparatus according to any one of Embodiments 1 to 3, wherein the ink backflow prevention means is a check valve disposed in the sub tank.
  Embodiment 5: In any one of Embodiments 1 to 4, the sub-tank is detachable from the recording apparatus, and a joint member for attaching and detaching constitutes a part of the ink detecting means. Inkjet recording device.
[0039]
In the above embodiment, a line system for recording only by transporting the recording medium (sub-scanning, paper feeding) using a line-type recording means (carriage unit) having a length that covers the entire width or part of the recording medium. However, the present invention is similarly applied to the case of a serial type ink jet recording apparatus that records while moving a recording head as a recording means in the main scanning direction. It is possible to achieve the same actions and effects.
In addition, the present invention can be freely implemented regardless of the number of recording heads and the number of ink discharge portions, and in addition to an ink jet recording apparatus using one recording head (or ink discharge portion), inks of different colors Ink-jet recording apparatus for color recording using a plurality of recording heads (or ink discharge units) that use the same, or for gradation recording using a plurality of recording heads (or ink discharge units) that use the same color and different concentrations of ink The present invention can also be applied to the ink jet recording apparatus of the present invention, and further to the ink jet recording apparatus in which these are combined, and the same operation and effect can be achieved.
[0040]
Furthermore, the present invention provides a recording head including a configuration using a replaceable head cartridge in which the recording head and the ink tank are integrated, a configuration in which the recording head and the ink tank are separated, and a connection between them is made with an ink supply tube or the like. The present invention can be similarly applied to any arrangement of the ink tanks, and the same effect can be obtained.
In addition to the inkjet recording apparatus that uses an inkjet recording head that ejects ink using thermal energy, the present invention employs a scheme that ejects ink using an electromechanical transducer such as a piezo element. The present invention can be similarly provided to an ink jet recording apparatus using another ink discharge method, such as an ink jet recording apparatus using an ink jet recording head, and the same operation and effect can be achieved.
[0041]
【The invention's effect】
  As is apparent from the above description, according to the present invention,,RecordRecording means or its vicinityReverseBy simply providing a flow prevention means, it is possible to easily and inexpensively configure an ink backflow prevention means excellent in sealing performance, to reduce the frequency of ink supply, and to improve the throughput and running of the recording operation. An ink jet recording apparatus capable of achieving cost reduction is provided.
[Brief description of the drawings]
FIG. 1 is an external perspective view showing an embodiment of an ink jet recording apparatus to which the present invention is applied.
2 is a schematic perspective view showing a part of the entire configuration of the recording means of the ink jet recording apparatus of FIG. 1; FIG.
3 is a schematic longitudinal sectional view of the recording means of FIG.
4 is a partially enlarged longitudinal sectional view showing an enlarged view of a check valve mechanism in FIG. 3. FIG.
FIG. 5 is a schematic external perspective view of an ink storage section (main tank) provided in a tank unit attached to the frame of the recording apparatus of FIG.
FIG. 6 is a schematic cross-sectional view showing a state before an ink reservoir (main tank) is loaded in the recording apparatus in the ink supply mechanism of the inkjet recording apparatus to which the present invention is applied.
7 is a schematic cross-sectional view showing a state immediately after the ink storage unit (main tank) is loaded in the recording apparatus in the ink supply mechanism of FIG.
8 is a schematic cross-sectional view showing a state after the ink in the ink storage section (main tank) is supplied into the sub tank by operating the negative pressure pump from the state of FIG. 7 and sucking and discharging the air in the sub tank. FIG.
9 is a schematic cross-sectional view showing a state when the ink liquid level in the sub tank is lowered due to air expansion or the like in the sub tank accompanying the environmental temperature change or the like from the state of FIG.
FIG. 10 shows a state after supplying ink in the main tank into the sub tank by operating the negative pressure pump and sucking and discharging the air in the sub tank in one configuration example of the ink supply mechanism of the conventional ink jet recording apparatus. It is a typical sectional view shown.
FIG. 11 is a schematic cross-sectional view showing a state where ink in the sub tank has returned to the main tank from the state of FIG.
[Explanation of symbols]
  15 Ink flow direction
  19 Recording means (recording head)
  21A, 21B Plug (plug)
  23 Backflow prevention means (check valve)
  25 Sub tank
  27 Valve chamber
  29 Boundary Wall
  31 opening (hole)
  33 Communication port (communication hole)
  35 Ink flow direction
  37 Ink Ejection Unit (Ejection Unit)
  39 Ink reservoir (main tank)
  41A, 41B Plug (plug)
  43 Atmospheric communication tube
  45 Supply tube
  47 Hollow needle for supply
  49Negative pressure pump (negative pressure generating means)
  51 Suction tube
  55 Hollow Needle for Suction
  57 Ink detection means
  59 Hollow needle
  61 Hollow needle
  63 water head difference
  65 ink drops
  101 Carriage unit
  103 Recovery system unit (discharge recovery device)
  105 Tank unit
  107 Frame unit
  109 Engine unit

Claims (1)

In an inkjet recording apparatus that performs recording by discharging ink from a recording unit to a recording medium,
An ink reservoir for containing ink;
A sub tank for supplying ink to the ink discharge portion of the recording means;
An ink supply path for supplying ink from the ink reservoir to the sub tank;
Negative pressure generating means for applying a negative pressure in the sub tank;
A valve chamber attached to the sub-tank;
Backflow prevention means provided between the subtank and the valve chamber so as to allow the flow of air and ink from the subtank to the valve chamber but allow the flow in the opposite direction;
A first electrode disposed in the sub-tank, and a second electrode disposed in a part of a path connecting the valve chamber and the negative pressure generating means, and the ink in the sub-tank is not full Ink detection means for detecting
With
The negative pressure generating means is connected to apply a negative pressure to the sub tank via the valve chamber,
An ink jet recording apparatus, wherein when the ink detecting means detects that the ink in the sub tank is not full, the negative pressure generating means is driven to supply ink from the ink reservoir to the sub tank.

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