JP2004188914A - Ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ink jet recorder in which sealing performance of an ink supply mechanism is enhanced by an inexpensive arrangement of simply providing an ink backflow preventing means, e.g. a check valve, and throughput of recording operation is enhanced while reducing the frequency of ink supply and the cost. <P>SOLUTION: In the ink jet recorder arranged such that a main tank 39 is connected through a tube 45 with a subtank 25 provided in a recording head 19 and a negative pressure is generated in the subtank by means of a negative pressure pump 49, a backflow preventing means 23 is provided in the vicinity of the subtank or in the subtank between the subtank and the negative pressure pump, a means 57 for detecting ink supply into the subtank is provided between the backflow preventing means and the negative pressure pump and driving/stopping of the negative pressure pump is controlled depending on the detection results of the detecting means. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording apparatus that performs recording by ejecting ink from a recording unit to a recording medium, and 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, printer units of word processors, facsimile machines, copiers, and the like. As a recording method used in these recording apparatuses, an electrophotographic method, an ink jet recording method, or the like is adopted.
A recording apparatus (inkjet recording apparatus) of an ink jet recording system for obtaining a recorded matter (printed matter or the like) by attaching minute ink droplets ejected from an ejection port to a recording medium such as a recording paper is other than an electrophotographic recording apparatus. The device is inexpensive and easy to miniaturize compared to the conventional recording method, and easily obtains a wide range of recorded materials from recording office documents on plain paper to recording photographic images on recording media such as special paper or cloth. It is widely spread because it can be used. In addition, a portable ink jet recording apparatus has been proposed, taking advantage of the advantage of miniaturization.
[0003]
In such an ink jet recording apparatus, an on-carriage type, which is provided on a carriage for scanning the recording head, and a carriage, as an ink supply mechanism for supplying ink from an ink storage unit (ink tank) to the recording head, are described below. 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) integrally formed with the print head by a resin tube or the like; There are two types.
Of these methods, 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, Furthermore, there are advantages such as a reduction in running cost, and they are mainly used for business machines.
[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 to suck and discharge the air in the sub-tank in an example of the configuration of the ink supply mechanism of the conventional ink jet recording apparatus. FIG. 11 is a schematic sectional view showing a state in which the ink in the sub tank has returned to the main tank from the state shown in FIG.
In an ink jet recording apparatus, there are various types of means for supplying ink from an ink storage unit (main tank) to the sub-tank, such as a method in which air and ink in the sub-tank are simultaneously sucked and discharged from a discharge port. .
[0005]
That is, as shown in FIG. 10, the air in the sub tank 3 formed integrally 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 3 is supplied from the main tank 9 through the supply tube 11. An ink supply mechanism configured to supply ink into the sub tank 3 and stop the supply operation by detecting the ink level in the sub tank 3 by the sensor 13 is adopted. Such an ink supply mechanism has an advantage that waste of the ink is small and it is economical.
In the ink supply mechanism shown in FIG. 10, the supplied ink is prevented from flowing backward only by the check valve mechanism 17 serving as an ink backflow preventing means that allows flow only in the direction of the arrow 15. The ink pumped into the sub-tank 3 is prevented from returning to the main tank 9 even if the driving of the pump is stopped or the inside of the negative pressure pump 7 is opened to the atmosphere.
[0006]
The check valve mechanism 17 generally includes 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 shown in FIG. 10, in order to further secure the sealing performance (sealing performance for preventing backflow) required for the check valve, the sealing portion (seal portion) of the check valve is sealed with grease or the like. It has been practiced to apply a blocking agent.
[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 residual air in the suction tube 5 expands or contracts in response to a change in the environmental temperature, and the liquid level of the ink in the sub tank 3 tends to fluctuate.
Second, since a negative pressure corresponding to the water head pressure is constantly applied to the air in the suction tube 5, even if the ink in the sub-tank 3 evaporates, it does not reach the saturated vapor pressure, and the environmental temperature is constant. Even so, the gas volume in the sub-tank 3 will always continue to expand until the ink returns to the main tank 9, so that it is necessary to supply the 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 formed of a highly flexible material such as polyethylene or an elastomer so that the suction tube 5 and the supply tube 11 can flexibly follow the scanning of the carriage. Has extremely low gas barrier properties as compared with the plastic forming the main tank 9 and the sub-tank 3, and furthermore, these tubes 5 and 11 are always physically Since air is taken in from the outside of the tube to the inside of the tube, the above-described technical problem becomes more remarkable.
[0009]
For the above-mentioned reason, the ink level in the sub tank 3 decreases with time from the position detected by the sensor. The lowering speed varies depending on the dimensions of the above-mentioned members and environmental conditions. For example, the supply tube 11 and the suction tube 5 made of an elastomer are 2 mm in inner diameter, 1 mm in thickness, and 400 mm in length, and the capacity of the sub tank 3 is 7 cc (when the supply is completed). Under the condition that the head pressure of the sub-tank is 150 mm, if the environment temperature is 35 degrees Celsius and the environment is left in a low humidity environment, the supply tube will take about 2 hours. All the ink in 11 returns to the main tank 9. Such a phenomenon is more remarkable as the region where the inside is in the air state is larger. That is, it can be seen that the volume of air in the tube is expanded at the site of the suction tube 5 in FIG. 10 for the above-described reason.
[0010]
Then, when the ink pumped into the sub tank 3 returns to the main tank 9 and the state shown in FIG. 11 is reached, the negative pressure in the sub tank 3 disappears, and the positive pressure is applied to the discharge port (nozzle) formed in the recording head. However, there is a possibility that normal ink cannot be ejected from the ejection port, and that the ink drips 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 considered. However, when the tube is formed of a resin having excellent gas barrier property (for example, a fluororesin or the like). This leads to a significant increase in cost. Moreover, in order to ensure an appropriate flexibility of the tube, the entire tube must be thinly provided on a surface layer or the like instead of using a fluororesin. In this case, a sufficient gas barrier property of the tube is ensured. It was difficult to do.
[0011]
In a configuration in which the ink is supplied again by driving the ink supply means (a negative pressure pump or the like) before the ink returns to the main tank 9, it is possible to limit the recording apparatus to a power-on state. 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 above-described inconvenience, 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 increased due to the frequent ink supply operation (ink replenishment operation). Further, since the ink filled in the ejection openings recedes due to the negative pressure in the sub-tank 3 generated by the ink supply operation, the ink enters the ejection openings (nozzles) after the ink supply operation. Ink filling operation is required. In this ink filling operation, a processing operation of forcibly discharging ink from the discharge port is performed by a recovery operation such as pressurizing the inside of the sub-tank 3 or applying a negative pressure from the discharge port. In addition to the decrease, the running cost is increased due to an increase in wasteful 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 preventing means excellent in sealing property only by providing an ink backflow preventing means at or near a recording means. An object of the present invention is to provide an ink jet recording apparatus which can be configured simply and inexpensively, can reduce the frequency of ink supply, and can achieve an improvement 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 jet recording apparatus that performs recording by discharging ink from a recording unit to a recording medium, and an ink storage unit that stores the ink; A sub-tank disposed between the sub-tank and a negative pressure generating means for applying a negative pressure to the inside of the sub-tank, and an ink is provided between the sub-tank and the negative pressure generating means and near or inside the sub-tank. Backflow prevention means, ink detection means for detecting the presence or absence of ink between the ink backflow prevention means and the negative pressure generation means, and driving of the negative pressure generation source in accordance with the detection result of the ink detection means And stopping is controlled.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.
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 on which a recording unit (recording head) (not shown) is detachably mounted, 103 is a recovery unit (discharge recovery device) for maintaining and recovering the ink discharge performance of the recording head, and 105 is a recovery unit. 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 the 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 material such as rubber, and capping for covering and protecting the ink discharge portion (discharge port surface) of the recording head. Means (cap), a wiping means (wiper blade) for wiping off and cleaning foreign matter adhered to the ink discharge section, and the like.
Note that the inkjet 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. However, during recording, the carriage is not moved (scanned), and a transport mechanism (not shown) is used. Is a type of line-type recording apparatus that performs recording on a recording medium such as recording paper conveyed by a printer.
[0016]
FIG. 2 is a schematic perspective view showing a partial exploded view of the entire configuration 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. FIG. 4 is a partially enlarged longitudinal sectional view showing a check valve mechanism portion (a portion surrounded by a dashed line in FIG. 3) as an ink backflow prevention means in FIG. In FIG. 2 to FIG. 4, each of two concave portions (hole portions) formed on the side wall portion of the sub tank 25 provided in the recording means 19 has a stopper (a plug made of a rubber-like elastic material such as chlorinated butyl rubber). The plugs 21A and 21B are mounted in a contact state (for example, a press-fit state).
[0017]
By inserting (piercing) the hollow needles 47 and 55 on the carriage unit (carriage) 101 into these stoppers 21A and 21B, the hollow needles are sealed in a state where the outer peripheral surfaces of the hollow needles are sealed. Are configured to penetrate and communicate with the inside. In the present embodiment, the tip of the hollow needles 47 and 55 has a shape in which the hollow shaft is obliquely cut similarly to the medical injection needle, and therefore the holes for inserting the hollow needles into the stoppers 21A and 21B. Is not necessarily provided in advance, but for example, when the tip of the hollow needle is rounded for safety of the user, a notch such as a cross may be provided in advance as described later.
[0018]
In FIG. 2 to FIG. 4, reference numeral 23 denotes a check valve as an ink backflow prevention means, and an umbrella type valve made of chlorinated butyl rubber having a rubber hardness of 60 degrees, for example, is adopted as the valve body. The check valve 23 is inserted and attached to an opening (hole) 31 formed in a boundary wall 29 with a valve chamber 27 provided in 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 preventing means) 23 directs the air and ink in the sub tank 25 through the plurality of communication ports (communication holes) 33 toward the hollow needles 47 and 55 (FIG. 7) as indicated by an arrow 35. It is configured to allow flow but not flow in the opposite direction.
[0019]
Also, 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 the air and the ink is 0.1 atm or more, these fluids are configured to freely flow in the arrow 35 direction.
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 head of the check valve 23 comes into close contact with the boundary wall 29 due to the pressure, and the communication hole The configuration is such that the ridge line 33 serves as a sealing portion (seal portion) to prevent (prevent) the flow of ink. The configuration of the check valve mechanism is not necessarily limited to the illustrated embodiment, but may be another valve mechanism such as a duckbill valve as long as the valve mechanism has a backflow prevention function.
[0020]
An ink ejection unit (ejection unit) 37 is provided on the face surface portion (the lower part in the illustrated example) of the recording head 19. The recording unit (recording head) 19 in this embodiment uses thermal energy. An ink-jet recording means for ejecting ink by means of an electrothermal converter (heater) for generating thermal energy. The thermal energy generated causes film boiling in the ink in the ejection port (in the nozzle), and the ink is ejected from the ejection port using a pressure change due to the growth and shrinkage of bubbles generated at that time.
[0021]
FIG. 5 is a schematic external perspective view of a main tank 39 as an ink storage section provided in a tank unit 105 (FIG. 1) attached to the frame 107 (FIG. 1). In FIG. 5, two openings (through holes) formed at the bottom of the ink storage section (main tank) 39 have plugs (plugs) 41A formed of a rubber-like elastic material such as chlorinated butyl rubber, respectively. 41B is attached in a close contact state (for example, a press-fit state). By inserting (piercing) the hollow needles 61 and 59 provided at the distal ends of the atmosphere communication tube 43 and the supply tube 45 into these stoppers 41A and 41B, the outer peripheral surface of the hollow needle is sealed (sealed). In this state, the hollow needle penetrates and communicates with the inside of the main tank 39. In the present embodiment, the hollow needles 61 and 59 also have the distal end formed into a shape obtained by obliquely cutting the hollow shaft similarly to the medical injection needle, so that the hollow needle insertion holes and the like are inserted into the stoppers 41A and 41B. It is not always necessary to provide a notch in advance, but for example, if the tip of the hollow needle is rounded for safety of the user, a notch such as a cross may be provided in advance as described later.
[0022]
The stoppers 41A and 41B are elastic material stoppers (plugs) provided to prevent the ink in the main tank 39 from flowing out and the outside air from entering the inside of the main tank 39. The supply tube 45 connected via the stopper 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 stopper 41B. The atmosphere communication tube 43 forms an atmosphere communication passage for communicating the inside of the main tank 39 with the atmosphere. In this embodiment, as shown in FIG. 5, the plugs 41A and 41B are provided with the above-described cross cuts in advance.
[0023]
6 to 9 are schematic 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. FIG. 7 shows a state immediately after the main tank is loaded in the recording apparatus. FIG. 8 shows a state in which the negative pressure pump as a negative pressure generating source is operated from the state of FIG. 7 to suck and discharge air in the sub tank. 9 shows a state after the ink in the main tank is supplied into the sub tank. FIG. 9 shows a state in which the ink level in the sub tank has decreased from the state in FIG. The state at the time is shown.
[0024]
6 to 9, reference numeral 43 denotes air for introducing the volume of ink supplied from the inside of the ink storage section (main tank) 39 to the sub tank 25 in the recording means (recording head) 19 into the ink storage section 39. Reference numeral 45 denotes 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 supply hollow needle that is provided at an end of the supply tube 45 on the sub tank 25 side and that functions as a joint formed of a material that can be pierced (insertable) into the plug 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 that functions as a joint formed of a conductive material that can be pierced (insertable) 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 communicates with the valve chamber 27 formed adjacent to the sub-tank 23 through the suction hollow needle 55. Have been. The other end of the supply tube 45 communicates with the inside of the main tank 39 through a hollow needle 59, and the other end of the suction tube 51 is connected to a negative pressure pump 49 as a negative pressure source. That is, the suction tube 51 forms a flow path connecting the negative pressure pump 49 and the sub tank 25, and the supply tube 45 forms a flow path connecting the main tank 39 and the sub tank 25. Is what you do.
[0026]
A check valve mechanism (FIG. 4) having a check valve 23 as a backflow prevention means is provided on a partition wall of the valve chamber 27 formed in the sub tank 25 on the side of the sub tank 25. In addition, 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), the ink in the valve chamber 27 is provided. There is provided an ink detecting means 57 for detecting the presence / absence of the negative pressure generation source 49 in accordance with the detection result of the ink detecting means 57. The ink detecting means 57 in the present embodiment detects the presence or absence of ink by detecting the electrical continuity between the suction hollow needle 55 and an electrode (not shown) provided in the sub-tank 25. Is configured.
[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 tip of the supply tube 45 on the main tank side is connected to one stopper 41A of the main tank 39 as shown in FIG. The hollow needle 61 provided at the tip of the atmosphere communication tube 43 on the main tank side is inserted (pierced) into the other stopper 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 maintained 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]
When the negative pressure pump (negative pressure generating source) 49 is operated from the state of FIG. 7 to suck and discharge the air in the sub tank 25, the ink in the main tank 39 is supplied to the sub tank 25 as shown in FIG. At the same time, it is also supplied to the inside of the valve chamber 27 (FIG. 4) through the check valve (backflow prevention means) 23. Then, the ink detecting means 57 using the suction hollow needle 55 as an electrode detects 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 the ink supply. 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 is removed. Play a role. As a result, the necessity of applying sealing grease or the like to the seal portion of the check valve 23 (in the present embodiment, the umbrella portion of the check valve) can be eliminated (required in the prior art).
[0029]
When the state of FIG. 8 is reached, when the negative pressure pump 49 is stopped, the negative pressure pump 49 is opened to the atmosphere. Therefore, when the check valve 23 does not exist, the ink pumped into the sub tank 25 is returned to the main tank 39 again to be in the state of FIG. 7 (before the negative pressure pump 49 is driven). However, in the present embodiment, since the check valve 23 is provided, the pressure corresponding to the head difference 63 generated by pumping the ink into the sub-tank 25 does not exceed the check valve even in the state of FIG. 4, the ink flow path (communication port 33 in FIG. 4) between the valve chamber 27 and the sub tank 25 is closed by the check valve 23. Therefore, even if the negative pressure pump 4 stops in the state of 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 the present embodiment, when the negative pressure pump 4 is stopped in the state of FIG. 8, the ink ejection port portion (ejection unit portion) 37 of the recording head 19 has only a head difference 63. Is applied, the ink filled in the discharge port can form an appropriate meniscus, and the recording head 19 is maintained in a state where the ink can be discharged stably. When the ink in the sub-tank 25 is consumed due to the ink ejection, 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. As described above, the height of the ink liquid level 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, the air in the sub-tank 25 is expanded due to the air expansion in the sub-tank 25 due to a change in the environmental temperature, or the air that flows through the check valve 23 and the sub-tank 25 gradually. The ink level may be lower than the state 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 of the recording head 19, so that normal ink discharge becomes difficult, There is a case where a problem may occur such as ink dripping (leakage).
Therefore, if there is a concern that such a problem may occur, the ink detecting means 57 detects that the ink in the sub-tank 25 is not full before entering a state where such a problem occurs. Accordingly, it is preferable to operate the negative pressure pump 49 to supply (replenish) the ink from the main tank 39 to the sub tank 25 to perform an operation for returning to the full state as shown in FIG. 8 again. .
[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 port is reduced by applying a negative pressure to the sub-tank 25. After the ink supply as described with reference to FIG. 8 is performed, it is preferable to perform the discharge recovery process by, for example, the discharge recovery unit, that is, the recovery system unit 103 (FIG. 1).
The main configuration and operation of the recovery system unit 103 are as follows. A cap made of a rubber-like elastic material such as rubber is brought into close contact with the ejection port surface of the recording head 19 (the face surface on which the ejection port is formed) to seal the ejection port ( Capping) and applying negative pressure to the cap by means of a negative pressure generating means such as a tube pump to forcibly suck and discharge ink from the discharge port, thereby filling the discharge port with ink or clogging the discharge port. The ink ejection performance of the recording head 19 is maintained and recovered by removing foreign substances such as dust, bubbles generated in the ejection openings, and ink having increased viscosity due to drying of ink near the ejection openings. is there.
[0033]
On the other hand, shortening the time interval at which the ink is supplied from the main tank 39 to the sub-tank 25 increases the processing time and the waste of ink due to the ejection recovery processing, and causes disadvantages such as a decrease in throughput and an increase in running cost. Will happen. In order to eliminate the possibility of occurrence of such inconvenience, in the present embodiment, a portion having the lowest gas barrier property (for example, a portion whose inside is filled with a high-temperature gas) is physically separated by the check valve 23 or the like. By doing so, the area (area) of a portion that may take in outside air is greatly reduced, and the check valve 23 is formed of chlorinated butyl rubber or the like having a high gas barrier property to greatly enhance the gas barrier property in the sub tank 25. Thus, the ink supply time is reduced and the waste of ink is suppressed.
[0034]
In supplying ink to the sub-tank 25, although a small amount of ink may enter the suction tube 51, in this embodiment, the ink sucked and discharged from the discharge port by the negative pressure pump 49 (waste ink) An absorber (not shown) capable of absorbing and holding the ink is provided at the discharge destination (collection destination). However, as another embodiment, by using the negative pressure pump 49 also as a pump (recovery pump) provided as a part of the recovery system (discharge recovery device), a configuration that does not require a new pump or the like is provided. It is also possible to take.
[0035]
Further, in the present embodiment, the ink detecting means (ink level detecting means) 57 is provided integrally with the hollow needle 55 for suction, but the configuration of the present invention is not limited to this, and may be provided at another portion. The provided ink detecting means may be used. In addition, without providing the ink liquid level detecting means, it is also possible to control so that the suction operation for ink supply is performed by operating the negative pressure pump 49 by a predetermined amount after a predetermined time has elapsed from the previous ink supply operation. .
Further, according to the present embodiment, since it is not necessary to increase the gas barrier properties of the suction tube 51 so much, it is possible to form the suction tube 51 with a cheaper material or with a thinner tube. By making the gas barrier property of the suction tube 51 lower than that of the supply tube 45, it is possible to reduce the cost.
[0036]
Further, 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. Alternatively, if it is in the vicinity of the sub tank 25, it may be arranged at a desired portion such as a carriage on which the recording head 19 is mounted (see the carriage unit 101 in FIG. 1).
In addition, as the ink discharging means in the embodiment described above, any discharging method may be used as long as it is a means for discharging ink from a discharge port, for example, a so-called bubble using ink film boiling by an electrothermal converter. A jet method may be used, or another ejection method such as a method using an electromechanical transducer such as a piezo element may be used.
[0037]
In the embodiments described above, embodiments of the present invention as described below are described.
Embodiment 1: In an ink jet recording apparatus that performs recording by discharging ink from a recording unit to a recording medium, an ink storage unit that stores the ink is disposed between the ink storage unit and the ink discharge unit of the recording unit. A sub-tank, and a negative pressure generating means for applying a negative pressure in the sub-tank, and an ink backflow preventing means is provided between the sub-tank and the negative pressure generating means and near or inside the sub-tank, Providing an ink detection means for detecting the presence or absence of ink between the ink backflow prevention means and the negative pressure generation means, and controlling the driving and stopping of the negative pressure generation source according to the detection result of the ink detection means. Characteristic inkjet recording device.
According to the configuration of the first embodiment, it is possible to simply and inexpensively configure the ink backflow prevention means having excellent sealing properties simply by providing the ink backflow prevention means at or near the recording means. An ink jet printing apparatus is provided, which can reduce the frequency of performing printing, and can achieve an improvement in throughput in printing operation and a reduction in running cost.
[0038]
Embodiment 2: The inkjet according to Embodiment 1, wherein the negative pressure generation source is also used as a negative pressure generation source used for an ejection recovery unit for maintaining and recovering the ink ejection performance of the recording unit. Recording device.
Embodiment 3: The gas barrier property of a suction tube connecting between the sub tank and the negative pressure source is lower than the gas barrier property of a supply tube connecting between the main tank and the sub tank. 3. The ink jet recording apparatus according to 1 or 2.
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 provided in the sub tank.
Embodiment 5: The sub-tank is detachable from the recording apparatus, and a joint member for attachment / detachment forms a part of the ink detecting means. Ink jet recording device.
[0039]
In the above-described embodiment, the line method in which the recording is performed only by transporting the recording medium (sub-scanning and paper feeding) using a line-type recording unit (carriage unit) having a length covering the entire width or a part of the recording medium. Although the present invention has been described by taking the case of an ink jet recording apparatus as an example, the present invention can be similarly applied to the case of a serial type ink jet recording apparatus that performs recording while moving a recording head as recording means in the main scanning direction. To achieve the same functions and effects.
Further, the present invention can be freely carried out regardless of the number of recording heads and the number of ink ejection units. In addition to an ink jet recording apparatus using one recording head (or ink ejection unit), inks of different colors Inkjet recording apparatus for color recording using a plurality of recording heads (or ink ejection units) using the same or for gradation recording using a plurality of recording heads (or ink ejection units) using the same color and different density inks In addition, the present invention can be similarly applied to the case of an ink jet recording apparatus described above and an ink jet recording apparatus obtained by combining them, and the same operation and effect can be achieved.
[0040]
Further, 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 space between the recording head and the ink tank is connected by an ink supply tube or the like. The present invention can be similarly applied to any arrangement of the ink tank and the ink tank, and the same effect can be obtained.
In addition, the present invention provides, in addition to an ink jet recording apparatus using an ink jet recording head of a method of discharging ink using thermal energy, for example, a method of discharging 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 ejection method, such as an ink jet recording apparatus using an ink jet recording head, and can achieve the same operation and effect.
[0041]
【The invention's effect】
As is apparent from the above description, according to the present invention, in an ink jet recording apparatus that performs recording by discharging ink from a recording unit to a recording medium, an ink storage unit that stores ink, the ink storage unit, and the recording unit A sub-tank disposed between the sub-tank and a negative pressure generating means for applying a negative pressure in the sub-tank, between the sub-tank and the negative pressure generating means and in the vicinity of the sub-tank or Ink backflow prevention means is provided inside, and ink detection means for detecting the presence or absence of ink is provided between the ink backflow prevention means and the negative pressure generation means, and the negative pressure generation is performed according to the detection result of the ink detection means. Since the driving and stopping of the source are configured,
By simply providing the ink backflow prevention means at or near the recording means, it is possible to easily and inexpensively configure the ink backflow prevention means having excellent sealing properties, and reduce the frequency of ink supply. An ink jet recording apparatus capable of achieving an improvement in operation throughput and a reduction in running cost 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.
FIG. 2 is a schematic perspective view showing a partial exploded view of an entire configuration of a recording unit of the ink jet recording apparatus of FIG.
FIG. 3 is a schematic longitudinal sectional view of the recording means of FIG.
4 is a partially enlarged longitudinal sectional view showing a check valve mechanism in FIG. 3 in an enlarged manner.
5 is a schematic external perspective view of an ink storage section (main tank) provided in a tank unit attached to a frame of the recording apparatus in FIG.
FIG. 6 is a schematic cross-sectional view showing a state before an ink storage unit (main tank) is loaded in the recording apparatus in the ink supply mechanism of the ink jet recording apparatus to which the present invention is applied.
7 is a schematic cross-sectional view illustrating a state immediately after an ink storage unit (main tank) is loaded in a recording apparatus in the ink supply mechanism of FIG. 6;
8 is a schematic cross-sectional view showing a state after the ink in the ink storage unit (main tank) is supplied into the sub tank by operating the negative pressure pump to suck and discharge air in the sub tank from the state in FIG. 7; FIG.
9 is a schematic cross-sectional view showing a state when the ink liquid level in the sub-tank has decreased due to air expansion or the like in the sub-tank due to a change in environmental temperature or the like from the state in FIG.
FIG. 10 shows a state after supplying ink in a main tank to a sub-tank by operating a negative pressure pump to suck and discharge air in a sub-tank in one configuration example of an ink supply mechanism of a conventional ink jet recording apparatus. It is a typical sectional view shown.
11 is a schematic cross-sectional view showing a state where the 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 stopper (plug)
23 Backflow prevention means (check valve)
25 Sub tank
27 Valve room
29 Boundary wall
31 opening (hole)
33 Communication port (communication hole)
35 Ink flow direction
37 Ink ejection section (ejection unit section)
39 Ink reservoir (main tank)
41A, 41B stopper (plug)
43 Atmosphere communication tube
45 Supply tube
47 Hollow Needle for Supply
49 Negative pressure source (negative pressure pump)
51 Suction tube
55 hollow needle for suction
57 Ink detection means
59 hollow needle
61 hollow needle
63 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 storage unit that stores ink, a sub-tank disposed between the ink storage unit and the ink ejection unit of the recording unit, and a negative pressure generation unit that applies a negative pressure to the sub-tank,
Ink detection is provided between the sub-tank and the negative pressure generating means and near or inside the sub-tank to prevent the presence of ink between the ink reverse flow preventing means and the negative pressure generating means. Means for controlling driving and stopping of the negative pressure generating source in accordance with a detection result of the ink detecting means.

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