JP4734710B2 - Inkjet printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet printer, and more particularly to an ink jet printer that can efficiently absorb pressure waves generated in an ink flow path during printing and efficiently store bubbles generated in the ink flow path.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in an inkjet printer that performs a printing operation by ejecting ink from a print head, an ink jet that employs a tube supply format that supplies ink to the print head from an ink tank that stores the ejected ink through an ink supply tube (tube). There is a printer.
[0003]
A conventional ink jet printer 20 using a tube supply format is shown in FIG. FIG. 6 is a perspective view schematically showing the ink jet printer 20. The ink jet printer 20 includes a print head unit 21, a platen roller 22, a carriage 23, an ink tank 24, an ink tube 25, a signal input line 26, and a guide rod 27.
[0004]
The print head unit 21 is mounted with a print head having an ink discharge port that discharges ink based on a signal transmitted via the signal input line 26 and performs printing on a print sheet. Ink is supplied through the ink tube 25. The print head unit 21 is mounted on a carriage 23, and the carriage 23 is attached to a belt. The belt is wound around a roller attached to a motor. Therefore, when the motor rotates, the belt is driven, and the carriage 23 (print head unit 21) can be moved by the driven distance.
[0005]
The guide rod 27 is slidably fitted into the carriage 23 and supports the carriage 23 so as to be movable. Thereby, the print head unit 21 mounted on the carriage 23 can reciprocate in the direction parallel to the guide rod 27, that is, in the longitudinal direction of the inkjet printer 20.
[0006]
In the ink jet printer 20, in order to maintain the print quality in a good state, it is necessary to maintain a constant discharge property of the ink discharged from the ink discharge port. In order to maintain this ink discharge property, the pressure of the ink supplied to the print head is kept constant, and a constant concave meniscus (curved surface) is formed on the ink surface formed at the tip of the nozzle of the ink discharge port. is doing.
[0007]
[Problems to be solved by the invention]
However, when the print head unit 21 performs printing while reciprocating along the guide rod 27, excessive acceleration is applied to the print head unit 21 due to acceleration / deceleration of the carriage 23. For this reason, the higher the speed of the ink jet printer, the more the acceleration is applied to the ink in the ink tube 25 and the pressure wave propagated toward the print head is generated. As a result, there is a problem in that the meniscus formed at the ink discharge port collapses and the discharge property of the ink discharged from the ink discharge port cannot be maintained in a constant state, and the print quality is adversely affected. There is also a problem that air bubbles easily enter from the wall surface of the ink tube 25 and the connecting member, and the ink discharge port is easily blocked by the air bubbles.
[0008]
The present invention has been made to solve the above-described problems, and efficiently absorbs pressure waves generated in the ink flow path during printing and efficiently stores bubbles that are about to flow into the print head. An object of the present invention is to provide an ink jet printer capable of performing the above.
[0009]
[Means for Solving the Problems]
  In order to achieve this object, an ink jet printer according to claim 1 is provided with a print head that prints on a recording medium by discharging ink from one or a plurality of ink discharge ports, and ink supplied to the print head. An ink tank for storing, and an ink flow path for supplying ink from the ink tank to the print headAnd the ink tank provided in the middle of the ink flow pathAn ink inlet through which ink flows from and a supply port for supplying ink to the print head,Air bubbles mixed in inkIs stored in the upper part, and the bubble storage chamberUnderAnd a side portion in a first chamber on the ink tank side and a second chamber on the print head side,Ink can pass through the first chamber and the second chamber in the lower portion of the bubble storage chamber, and the flow resistance when the ink passes is higher than the flow resistance in the upper portion of the bubble storage chamber. Is also bigA partition member;in frontThe first roomA region where a predetermined amount of bubbles is always stored in the upper portion.While leaving moreOne communicates with the ink inlet, and the other forms a third chamber that communicates from the lower side with respect to the region where the predetermined amount of bubbles is always stored.With pressure induction side wallA recovery means for discharging the air bubbles accumulated in the air bubble storage chamber from the ink discharge port to recover the ink discharge state, and whether or not the air bubbles are stored up to a first position below the top of the partition wall member. Determining means for determining, when the determining means determines that bubbles have been stored in the bubble storage chamber up to the first position, recovery processing operating means for operating the recovery means, and A recovery process stop means for stopping the recovery process by the recovery means when ink is stored in the bubble storage chamber up to a second position above the top of the partition member by the recovery process. The pressure induction side wall is disposed higher than the height of the partition wall member, and the second position is higher than the top of the partition wall member and not more than the height of the pressure induction side wall.The
[0010]
According to this ink jet printer, the ink stored in the ink tank is supplied from the ink inlet of the bubble storage chamber to the bubble storage chamber via the ink flow path, and is supplied to the supply port of the bubble storage chamber. To the print head. The ink supplied to the print head is discharged from one or a plurality of ink discharge ports, and printing is performed on the recording medium.
[0011]
Here, in the bubble storage chamber, since the flow path resistance of the lower part of the partition member is large, the bubbles propagated together with the ink from the ink flow path rise and are stored in the upper part. The first chamber of the bubble storage chamber is further provided with the pressure induction side wall leaving the upper portion of the bubble storage chamber, and the pressure wave propagated from the ink flow path is located above the bubble storage chamber by the pressure induction side wall. It is guided to the bubble storage part.
[0013]
  Claim2The ink jet printer described is claimed1In the inkjet printer described above, the third chamber is provided above the ink inlet of the bubble storage chamber.
[0015]
  Claim3The ink jet printer according to claim 1.Or 2In the ink jet printer described above, the bubble storage chamber is provided by the partition member so that the volume of the second chamber is smaller than the volume of the first chamber.
[0016]
  Claim4The ink jet printer according to claim 1.3In the ink jet printer according to any one of the above, the bubble storage chamber is composed of two or more parts so as to be disposed with the partition member interposed therebetween.
[0017]
  Claim5The ink jet printer according to claim 1.4In the ink jet printer according to any one of the above, the inner surface of the second chamber of the bubble storage chamber is made of a material having better wettability than the inner surface of the first chamber.
[0018]
  Claim6The ink jet printer according to claim 1.5In the ink jet printer according to any one of the above, the pressure guide side wall rises from the bottom of the bubble storage chamber and extends to a position spaced from the ceiling, and the partition member sandwiches the first chamber. The ink inlet is in the lower part of the third chamber and the supply port is in the lower part of the second chamber.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a developed side view of an ink jet printer 1 according to an embodiment of the present invention. As shown in FIG. 1, the ink jet printer 1 includes a printer main body 2 formed of a flame retardant plastic in a substantially box-like body, a print head unit 3 detachably mounted on the upper portion thereof, and an ink tank 4a. To 4d, tubes 5a to 5d for communicating the print head unit 3 and the ink tanks 4a to 4d, a purge device 6, and a guide rod 7.
[0023]
The print head unit 3 is mounted with a plurality of print heads 15 (see FIG. 3) that discharge ink and print on the printing paper PP. The print head unit 3 communicates with ink tanks 4a to 4d provided in a lower portion of the printer main body 2 via tubes 5a to 5d, and the tubes 5a to 5d are connected to the ink tanks 4a to 4d. Ink is being supplied through. The print head unit 3 is mounted on a carriage 3a, and the carriage 3a is mounted on a belt as is well known. The belt is wound around a roller attached to a motor. Therefore, when the motor rotates, the belt is driven, and the carriage 3a (print head unit 3) can be moved by the driven distance. Details of the print head unit 3 will be described later with reference to FIGS.
[0024]
The guide rod 7 is slidably fitted into the carriage 3a, and supports the carriage 3a so as to be movable in a direction (A) orthogonal to the conveyance direction of the printing paper PP. Thereby, the print head unit 3 mounted on the carriage 3 a can reciprocate in the direction parallel to the guide rod 7, that is, the longitudinal direction (A) of the printer body 2.
[0025]
The ink tank 4 is for storing ink to be supplied to the print head unit 3, and is disposed below the print head unit 3. The positional relationship between the ink tank 4 and the print head unit 3 is lower than the gravity direction (B). The ink tank 4 is composed of four ink tanks 4a to 4d in which black, yellow, cyan, and magenta inks are sealed in the moving direction of the carriage 3a. Each ink tank 4a to 4d includes black, One ends of tubes 5 a to 5 d for supplying yellow, cyan, and magenta inks to the print head unit 3 are respectively attached. The other ends of the tubes 5a to 5d communicate with the print head unit 3 described above, and the ink filled in the ink tanks 4a to 4d is supplied to the print head unit 3, respectively. The ink is ejected from each print head 15 corresponding to the ink. By ejecting these color inks from the print head 15, full-color printing can be performed on the printing paper PP.
[0026]
A purge device 6 that performs a purge process is disposed at the left end portion of the printer main body 2. The purge process is a process for recovering the ink discharge state from the print head 15, and the purge device 6 that executes the purge process is a suction that can seal a plurality of ink discharge ports of the print head 15. A cap 6a, a wiper 6b for wiping the surface of the ink discharge port, and a suction pump (not shown) for sucking ink from the suction cap 6a through the discharge tube 6c are provided (see FIG. 3). The purge device 6 may be configured to discharge ink from the print head 15 by applying positive pressure to the ink from the ink tank 4 side.
[0027]
When purging is performed by the purge device 6, the motor is driven to move the print head unit 3 on which the print head 15 is mounted to the left side of the ink jet printer 1, so that the ink discharge port in the print head 15 is a suction cap. Seal with 6a. Thereafter, when the suction pump is operated, bubbles or dried and solidified ink is sucked from the ink discharge port and discharged from the discharge tube 6c. Subsequently, by wiping the surface of the print head 15 with the wiper 6b, the discharge state of the ink discharge port of the print head 15 can be recovered. A control circuit board (not shown) on which a CPU, a ROM, a RAM, and the like for controlling the ink jet printer 1 are mounted according to a control program related to the operation contents of the ink jet printer 1 is disposed inside the printer body 2. The purge process in the purge device 6 is also controlled by the control circuit board.
[0028]
Next, the print head unit 3 will be described in detail with reference to FIGS. FIG. 2 is a cross-sectional view of the print head unit 3, and is a view as seen from the back side of the paper surface of FIG. As shown in FIG. 2, a casing 3 b that houses an air trap unit 11 and a joint member 12 is connected to the carriage 3 a. The air trap unit 11 accommodated in the housing 3b is for storing bubbles generated in the ink flow path, and the ink supplied from the ink tank 4 passes through the air trap unit 11. Are supplied to each print head 15. The air trap unit 11 is provided with four air traps 30 to 33 corresponding to the four ink flow paths so as to store bubbles generated in the four ink flow paths corresponding to the four ink tanks 4a to 4d. It has been.
[0029]
Below the air trap unit 11, the air traps 30 to 33 and the tubes 5a to 5d, which are ink supply paths, are connected to a joint member 12 that communicates with each other and supplied from the ink tanks 4a to 4d. The inks flowing through the tubes 5 a to 5 d are introduced into the air traps 30 to 33 from below through the joint member 12.
[0030]
FIG. 3 is a cross-sectional view taken along a cross-sectional line III-III in FIG. 1 and includes the print head unit 3. In FIG. 3, the (B) direction is the gravity direction, and the line connecting the back side and the near side of the paper surface is the moving direction (A) direction of the print head unit 3.
[0031]
The paper feed rollers 16 a to 16 d are rollers for transporting the print paper PP during printing, and are arranged below the print head unit 3 with two rollers 16 c and 16 d disposed above the print head unit 3. The two rollers 16a and 16b are provided. The paper feed rollers 16a to 16d are driven to rotate in response to a signal input from the control circuit board of the printer body 2, and the print paper PP is perpendicular to the movement direction (A) of the print head 15, that is, in the vertical direction (( B) is conveyed in the opposite direction. A conveyance line through which the printing paper PP is conveyed by the paper supply rollers 16a to 16d is indicated by a one-dot chain line in the drawing.
[0032]
The print head unit 3 is disposed at a position corresponding to a conveyance line through which the printing paper PP is conveyed by the paper supply rollers 16a to 16d. The print head unit 3 is provided with the (B) direction, which is the direction of gravity, being downward and parallel to the transport direction of the print paper PP, that is, with the vertical direction being up and down. The print head unit 3 includes a plurality of print heads 15 corresponding to the air traps 30 to 33 on the side on which the printing paper PP is conveyed.
[0033]
Each print head 15 is provided with a plurality of ink ejection openings that open on the side facing the printing paper PP, and the ink supplied from the corresponding air traps 30 to 33 is used as ink for each ink ejection opening in the same manner as known ones. The ink is distributed to the chambers, and ink in the ink chamber is discharged from the ink discharge port by the displacement of the actuator 15a such as a piezoelectric element.
[0034]
The print head 15 is supported by the casing 3 b of the print head unit 3 and communicates with the corresponding air traps 30 to 33 via the communication path 14. Each of the air traps 30 to 33 is composed of three chambers, and is provided in parallel with the casing 3b of the print head unit 3 with the vertical direction being up and down. A second chamber 11b is disposed on the print head 15 side, and a first chamber 11a is connected upstream of the ink flow path of the second chamber 11b, and upstream of the ink flow path of the first chamber 11a. A third chamber 11c is provided continuously. In the upper part of the first chamber 11a to the third chamber 11c, bubbles that are not sucked by the purge process are always stored.
[0035]
The third chamber 11c is located on the most upstream side of the ink flow path in the air traps 30 to 33, and includes an ink inflow port 11c1 below the third chamber 11c. A joint member 12 is directly connected to the ink inlet 11c1 and receives ink supplied from the ink tank 4. The third chamber 11c is provided with a pressure induction side wall 11a1 from the first chamber 11a. The pressure guide side wall 11a1 is disposed so as to rise integrally from the bottom of the third chamber 11c and face upward in the vertical direction.
[0036]
Specifically, the vertical dimension (dimension in the (B) direction) of the pressure guiding side wall 11a1 is configured to be shorter than the inner dimension in the upward direction (the (B) direction) of the air traps 30 to 33. As a result, a space 11a2 in which the pressure guiding side wall 11a1 is not provided is formed in the upper part of the air traps 30 to 33, and the third chamber 11c communicates with the first chamber 11a by this space 11a2. . Bubbles are constantly stored in such a space. Further, the vertical dimension of the pressure guiding side wall 11a1 is arranged to be higher than that of a first filter 13a described later. Further, the pressure guiding side wall 11a1 is connected to the inner walls on both sides in the width direction (direction (A)) of the air traps 30 to 33.
[0037]
Furthermore, since the pressure induction side wall 11a1 is processed with a material and a shape that do not transmit ink and bubbles, the ink and bubbles that flow into the third chamber 11c pass through the pressure induction side wall 11a1 and pass through the first chamber. It cannot flow into 11a. For this reason, the ink that has flowed into the third chamber 11c from the ink inlet 11c1 rises in the third chamber 11c along the pressure guide side wall 11a1, and collides with the bubbles that are steadily stored in the upper portion of the third chamber 11c. . Thereafter, a flow path that flows into the first chamber 11a is formed through the ink flow path in which the bubbles are present.
[0038]
In addition, since a material having good wettability with respect to ink is used for the pressure induction side wall 11a1, bubbles are unlikely to stay on the pressure induction side wall 11a1. The bubble that has entered the third chamber 11c is easily guided upward in the vertical direction of the air trap, rises along the pressure guiding side wall 11a1, and is stored in the upper part.
[0039]
Further, the pressure wave conveyed to the ink from the tubes 5a to 5d similarly rises along the pressure guiding side wall 11a1 and is absorbed by colliding with the regularly stored bubbles in the upper part of the third chamber 11c. Is done. Thus, by interposing bubbles in the ink flow path flowing to the first chamber 11a communicating with the third chamber 11c, pressure waves generated in the tubes 5a to 5d due to acceleration / deceleration of the carriage 3a at the time of printing are generated. It is possible to reliably absorb the air traps 30 to 33 and prevent the pressure wave from being propagated to the print head 15.
[0040]
Since the pressure guiding side wall 11a1 is disposed higher than the first filter 13a, an ink flow path is formed between the first chamber 11a and the second chamber 11b over the first filter 13a. be able to. The ink flow pattern (ink flow path) in the air traps 30 to 33 will be described later with reference to FIG.
[0041]
The first chamber 11a is a chamber provided by the above-described pressure induction side wall 11a1 and the first filter 13a. The first chamber 11a and the second chamber 11b are not completely defined by the first filter 13a, and the upper portion 13e is in communication. Further, the third chamber 11c communicates with the upper portion of the pressure guide side wall 11a1. The ink supplied to the first chamber 11a through the third chamber 11c flows through the first filter 13a and the upper portion 13e and is supplied to the second chamber 11b.
[0042]
The first chamber 11a is provided with a first thermistor sensor 18a and a second thermistor sensor 18b. The first thermistor sensor 18a detects the amount of ink in the first chamber 11a, and is suspended from a ceiling portion in the first chamber 11a to a first predetermined position. The first thermistor sensor 18a is composed of an electrode pair of a positive electrode and a negative electrode, and is always energized. For this reason, when the first thermistor sensor 18a is immersed in the ink, a large temperature rise does not occur. However, if the sensor is exposed from the ink surface due to the decrease in the ink amount in the first chamber 11a, the temperature rises greatly. Occurs. Since the first thermistor sensor 18a undergoes a large resistance change due to a temperature change, the amount of ink can be detected by detecting this resistance change. The lead wire of the first thermistor sensor 18a is connected to the signal line of the control circuit board provided in the main body 2, and when the resistance change is recognized by the detection signal transmitted to the control circuit board, the air trap 30 It is determined that the amount of bubbles stored in .about.33 has exceeded a predetermined amount, and a signal for performing a purge process is transmitted from the control circuit board to the purge device 6. Thereby, the purge process is executed by the purge device 6 and the bubbles stored in the air traps 30 to 33 are removed.
[0043]
The second thermistor sensor 18b is for detecting the amount of bubbles in the first chamber 11a, and is at a predetermined position above the first thermistor sensor 11a (height substantially equal to the upper portion of the pressure guiding side wall 11a1). The first thermistor sensor 18a is suspended. The second thermistor sensor 18b is configured similarly to the first thermistor sensor 18a. Here, when the purge device 6 is operated by the first thermistor sensor 18a and the purge process is performed, when the ink is filled to the second predetermined position, the second thermistor sensor 18b detects the ink. be able to. The detection signal (resistance change) detected by the second thermistor sensor 18b is transmitted to the control circuit board in the same manner as the first thermistor sensor 18a.
[0044]
Here, an increase in the amount of ink stored in the first chamber 11a by the purge device 6 (an increase in the ink liquid level) indicates a decrease in the amount of bubbles stored in the air traps 30 to 33. For this reason, when the resistance change is recognized by the detection signal transmitted to the control circuit board, it is determined that the amount of ink stored in the air traps 30 to 33 has exceeded a predetermined amount, and the purge circuit 6 purges from the control circuit board. A signal for stopping the processing is transmitted. As a result, the execution of the purge process by the purge device 6 is stopped, and a predetermined amount of bubbles remain stored in the air traps 30 to 33. Therefore, it is possible to reliably leave bubbles in the upper part of the air traps 30 to 33 (for example, the part communicating the first chamber 11a and the third chamber 11c in the upper part of the pressure induction side wall 11a1), Pressure waves generated in the ink flow path by the bubbles can be absorbed.
[0045]
The second chamber 11b is a chamber defined by the first chamber 11a and the partition member, for example, the first filter 13a, and located on the print head 15 side (downstream of the ink flow path with respect to the first chamber 11a). is there. A guide nozzle 11b1 is provided below the second chamber 11b, and the guide nozzle 11b1 communicates with the print head 15 via the communication path 14 described above. As a result, ink is supplied from the second chamber 11b to the print head 15.
[0046]
The capacity of the second chamber 11b is configured to be smaller than the capacity of the first chamber 11a. When the air bubbles stored in the air traps 30 to 33 are sucked by the purging process, all the ink remaining in the second chamber 11b is discharged. However, by discharging the second chamber 11b by reducing the capacity thereof, the discharge is performed. By reducing the amount of ink, the amount of wasted ink can be reduced, and ink suction, that is, bubble suction can be performed with a small suction pressure.
[0047]
Further, the inner wall of the second chamber 11b is made of a crystalline resin having good wettability with respect to ink, or is subjected to surface treatment for improving wettability. For this reason, the ink tends to get wet on the wall surface, and the bubbles discharged through the second chamber 11b during the purge process are made difficult to accumulate on the wall surface, so that the bubbles can be quickly discharged.
[0048]
As described above, the first filter 13a is configured to define the first chamber 11a and the second chamber 11b below the air traps 30 to 33, and the capacity of the second chamber 11b is larger than the capacity of the first chamber 11a. At the position where the print head unit 3 is divided into small portions, the print head unit 3 is provided in parallel with the casing 3b so that the vertical direction is up and down. The first filter 13a uses a mesh made of stainless steel metal mesh, and in this embodiment, a mesh having an opening of 16 μm is used and passes through bubbles generated in the ink flow path. It is supposed not to let you.
[0049]
The vertical dimension of the first filter 13a (dimension in the (B) direction) is shorter than the inner dimension of the air traps 30 to 33 in the upward direction (the (B) direction). As a result, a space 13e in which the first filter 13a is not disposed is formed in the upper part of the air traps 30 to 33, and the first chamber 11a and the second chamber 11b are communicated with each other with low flow resistance. Yes. Further, the first filter 13a is connected to the inner walls on both sides in the width direction ((A) direction) of the air traps 30 to 33, and the bubbles that have entered the first chamber 11a are moved from the width direction to the first wall 13a. The entry into the second chamber 11b is prevented. Here, the air traps 30 to 33 and the first filter 13a are arranged so as to face upward in the vertical direction. For this reason, since the air bubbles that have entered the air traps 30 to 33 cannot pass through the first filter 13a, they rise in the first chamber 11a and are stored above the first chamber 11a. Further, as the stainless steel material forming the first filter 13a, a material having good wettability with respect to ink is used, so that the bubbles hardly stay in the first filter 13a, and the bubbles that have entered the first chamber 11a are The first chamber 11a can be easily guided upward in the vertical direction.
[0050]
By configuring the air trap unit 11 as described above, bubbles generated in the ink flow path can be stored by the air traps 30 to 33. The details of the storage method will be described with reference to FIG. Moreover, the air trap unit 11 comprised in this way is comprised by three members of the members 11d-11f from the ease of the shaping | molding. A method for manufacturing the air trap unit 11 will be described later with reference to FIG.
[0051]
The second filter 13 b is for capturing dust mixed in the ink supplied to the print head 15, and the communication path between the guide nozzles 11 b 1 of the air traps 30 to 33 and the print head 15. 14. The second filter 13b is disposed by being thermally welded to a member forming the communication path 14, and is processed into a shape that covers the entire cross-sectional direction of the communication path 14. The second filter 13b is configured with an opening diameter capable of capturing dust and allowing ink and air bubbles during the purge process to pass therethrough.
[0052]
A driver board 17a is disposed above the casing 3b of the print head unit 3. The driver board 17a is controlled by a control circuit board mounted on the printer main body 2 described above. Specifically, a serial signal transmitted from the control circuit board is converted into a parallel signal corresponding to each actuator unit of the actuator 15a to drive each actuator unit. The driver board 17a is placed on a flexible printed wiring board 17c connected to the actuator 15a.
[0053]
The interface board 17b is disposed on the side surface of the housing 3b of the print head unit 3 on the carriage 3a side. The interface board 17b is connected to an end of the printed wiring board 17c, and a connector for connecting a signal line from the control circuit board to the driver board 17a and a noise removing circuit are mounted.
[0054]
FIG. 4 is an exploded perspective view of the air trap unit 11 and the joint member 12. As described above, the air trap unit 11 is formed by three members 11d to 11f in order to facilitate the manufacture thereof. Each of the members 11d to 11f is processed into a shape in which four air traps 30 to 33 corresponding to the four ink flow paths (tubes 5a to 5d) are connected, and has moldability, solvent resistance, contamination resistance, and resistance to resistance. A thermoplastic resin selected in consideration of physical properties such as impact property and wettability with respect to ink is used.
[0055]
The member 11d is a member for forming the four first chambers 11a and the third chamber 11c, and the four first chambers 11a and the third chamber 11c are partitioned in advance by a partition wall 11h (FIG. 2), and It is a member that has been processed into four consecutive shapes. The member 11d has a box shape in which the side on which the first filter 13a is disposed is opened, and includes a coupling portion 11g with the joint member 12 below each third chamber 11c. The coupling portion 11g has a hollow cylindrical projection structure corresponding to the four ink flow paths (tubes 5a to 5d). The joint member 12 has four communication passages 12a to 12d communicating with the respective tubes 5a to 5d, and the communication passages 12a to 12d are fitted to the respective coupling portions 11g, whereby the tube 5a is removed from the ink tank 4. Ink supplied through ˜5d can be introduced into the third chamber 11c of each air trap 30-33.
[0056]
The first filter 13a is heat-sealed to the member 11e, and functions as the first filter 13a of each air trap 30-33. The width direction of the first filter 13a has a dimension in which the width of the four air traps 30 to 33 connected to each other is added to the bonding margins at both ends thereof. Further, the vertical direction of the first filter 13a is configured to have a dimension in which a margin is added to a predetermined length that covers the lower part of the air traps 30 to 33. The first filter 13a having such a size is fixed to the position where the upper portion of the opening portion of the member 11e constituting the second chamber is in a predetermined size opening state by heat-sealing. Thereby, the 1st filter 13a which demarcates the room | chamber interior of each air trap 30-33 by the 1st chamber 11a and the 2nd chamber 11b by one operation | work can be arrange | positioned.
[0057]
The member 11e is one member that forms four connected second chambers 11b, and has four openings that penetrate in the thickness direction. As described above, the first filter 13a is disposed on one surface of the opening, and the four second chambers 11b are formed by ultrasonically welding the member 11f on the other surface. The member 11f is a member that forms the second chamber 11b together with the member 11e, and includes four concave portions corresponding to the four openings of the member 11e. A groove for forming a guide nozzle 11b1 for introducing ink from the second chamber 11b to the print head 15 is formed below each recess. The tip of the groove penetrates to the back surface (the surface opposite to the opening) of the member 11f so that the guide nozzle 11b1 communicates with the communication passage 14.
[0058]
In the air trap unit 11 composed of the members 11d to 11f described above, first, the first filter 13a and the member 11e are thermally fused, and further, the member 11f is ultrasonically fused to form the second chamber 11b. . Next, the member 11d is ultrasonically fused to the first filter 13a side of the produced second chamber 11b to form the first chamber 11a. With this process, the air trap unit 11 including the four air traps 30 to 33 connected to each other can be manufactured. According to this, as compared with the case where the air traps 30 to 33 are formed one by one, the manufacturing process is simple, and the number of parts is small, so that the process management is easy. In addition, since the size of the parts is increased, the air trap unit 11 can be efficiently formed by facilitating the disposition work of the first filter 13a.
[0059]
Next, the pressure wave propagation pattern, the ink flow pattern, and the state in which bubbles are stored in the air trap unit 11 will be described with reference to FIG. FIG. 5 is a longitudinal sectional view schematically showing the air trap function of the print head unit 3 and the function of bubbles stored in the air traps 30 to 33. FIG. 5A is a diagram at the time of initial introduction (immediately after the purge process) in which the air traps 30 to 33 are filled with ink. Even when the ink is filled as shown in FIG. 5A, the upper portion of the air traps 30 to 33 is not filled with the ink by the second thermistor sensor 18b described above, and bubbles are accumulated.
[0060]
In this case, the ink flow pattern in the air traps 30 to 33 is formed as follows. As ink is ejected from the print head 15, the ink surfaces of the first chamber 11a and the second chamber 11b are lowered, and the pressure in both chambers is lowered. As a result, the ink in the ink tank 4, the tubes 5a to 5d, the joint member 12, and the third chamber 11c is pulled up to the upper part of the air traps 30 to 33 along the pressure induction side wall 11a1 and the upper end of the pressure induction side wall 11a1 is moved. After that, it is supplied to the first chamber 11a. A portion 13e in which the first chamber 11a and the second chamber 11b having a small channel resistance in the ink channel communicate with each other (a portion where the first filter 13a at the upper part in the vertical direction of the first filter 13a is not provided). However, since the flow path resistance is smaller than that of the first filter 13a, the ink passes over the upper end of the first filter 13a and flows into the second chamber 11b. The ink that has flowed into the second chamber 11b is supplied to the print head 15 via the guide nozzle 11b1.
[0061]
The pressure wave generated in the tubes 5a to 5d by the acceleration / deceleration of the carriage 3a is propagated from the ink inlet 11c1 to the third chamber 11c via the ink. Therefore, it propagates along the pressure guiding side wall 11a1, collides with the bubbles stored in the upper part of the air traps 30 to 33, and is absorbed.
[0062]
FIG. 5B is a diagram showing a state in which the bubbles stored in the air traps 30 to 33 are slightly increased. Since the ink flowing into the first chamber 11a from the third chamber 11c does not easily flow directly to the second chamber 11b due to the resistance of the first filter 13a, the bubbles contained therein rise due to buoyancy, and the air traps 30 to 33 It is stored in the upper part of. The bubbles are not discharged by the suction force generated when the print head 15 is discharged. For this reason, the air bubbles are filled in the air traps 30 to 33 and push down the liquid level of the ink in the first chamber 11a and the second chamber 11b (from FIG. 5 (b) to (d), Showing the transition).
[0063]
Even if the liquid level of the ink falls below the upper end of the first filter 13a, the ink is supplied from the first chamber 11a to the second chamber 11b through the first filter 13a. The opening diameter and area of the first filter 13a are set so that the ink supply to the print head 15 does not become insufficient even when the ink level drops to a predetermined amount.
[0064]
Even in this state, the pressure waves generated in the tubes 5a to 5d are absorbed by the bubbles stored in the upper portions of the air traps 30 to 33, as in FIG.
[0065]
Shortly before the ink is insufficiently supplied to the print head 15, the thermistor sensor 18a begins to be exposed from the ink surface. As described above, the purge process by the purge device 6 is performed by the resistance change of the thermistor sensor 18a. In the purge process, since a strong suction force is applied to the second chamber 11b, the flow path resistance applied to the ink when passing through the first filter 13a becomes very large. For this reason, the ink is strong ink that passes through the portion 13e where the first chamber 11a and the second chamber 11b communicate with each other (the portion where the first filter 13a at the top in the vertical direction of the first filter 13a is not provided). Is generated, and bubbles stored in the air traps 30 to 33 are discharged from the air traps 30 to 33 by this flow. When the ink level reaches the second predetermined position (detection position of the second thermistor sensor 18b), the second thermistor sensor 18b detects the ink level and the purge process is stopped. Therefore, all the bubbles in the air traps 30 to 33 are not discharged, and even immediately after the purge process is performed, the pressure waves can be absorbed by the bubbles stored in the air traps 30 to 33.
[0066]
For these reasons, the pressure wave generated in the ink flow path is guided by the pressure guiding side wall 11 a 1 and absorbed by the bubbles stored in the upper part of the air traps 30 to 33, and is not propagated to the print head 15. For this reason, the meniscus formed at the ink discharge port is maintained, the ink discharge performance is constant, and the print quality can be kept good.
[0067]
The ink used in this embodiment has a viscosity of 1 to 10 cps and a surface tension of 30 to 50 mN / m. The first filter 13a having an opening diameter of 16 μm is used for the ink having such physical properties.
[0068]
As described above, according to the ink jet printer 1 of the present embodiment, the pressure generated in the ink flow path (tubes 5a to 5d, joint member 12) by providing the pressure guiding side wall 11a1 in the air traps 30 to 33. Waves are absorbed by the air bubbles stored in the air traps 30 to 33, and the pressure waves are absorbed to maintain the meniscus of the ink discharge port, thereby improving the print quality. Further, a large amount of bubbles contained in the ink can be stored by the action of the first filter 13a, so that the discharge state of the print head 15 can be maintained for a long time and the number of purges can be reduced. Furthermore, since the purge process is executed only when necessary by the first thermistor sensor 18a, the ink is not wasted. Furthermore, the second thermistor sensor 18b can store bubbles for absorbing pressure waves in the air traps 30 to 33 even when the purge process is executed.
[0069]
Although the present invention has been described based on the above embodiment, the present invention is not limited to the above embodiment, and various modifications and changes can be easily made without departing from the gist of the present invention. Can be inferred.
[0070]
For example, in the present embodiment, the first filter 13a is used as the partition member, but a plate material in which one or a plurality of holes are formed may be used instead.
[0071]
【The invention's effect】
  The ink jet printer according to claim 1, wherein the pressure wave propagating from the ink flow path is above the bubble reservoir chamber by the pressure guide side wall further defining the first chamber of the bubble reservoir chamber leaving the upper portion of the bubble reservoir chamber. It is guided to the bubble storage part. Therefore, since the pressure wave can be guided by the pressure guide side wall and absorbed by the bubbles stored in the bubble storage chamber, the propagation of the pressure wave to the print head can be suppressed. As a result, it is possible to maintain good print quality while maintaining the ink discharge performance in a constant state. In addition, since the flow path resistance of the lower part of the partition wall member is large, the bubbles propagated together with the ink float and are stored in the upper part, so that the discharge state of the print head can be maintained for a long time. There is an effect that the number of recovery processes can be reduced.
  The bubble storage chamber is provided by a pressure-inducing side wall, and the provided third chamber is directly connected to the ink flow path and is connected to the first chamber in the upper portion of the bubble storage chamber. For this reason, the ink flows from the upper part of the third chamber to the upper part of the first chamber. Here, since the bubbles are stored in the upper portion of the bubble storage chamber, there is an effect that the pressure wave generated in the ink flow path can be easily absorbed by the bubbles.
  Further, if the pressure induction side wall is disposed lower than the partition wall member, an ink flow path is formed in the upper portion of the pressure induction side wall that communicates with the third chamber and the first chamber and is filled with the ink liquid layer. The pressure wave is easily propagated to the first chamber. Therefore, the pressure guide side wall is arranged higher than the partition wall member, and the bubble layer is interposed in the ink flow path above the pressure guide side wall, so that the propagation of the pressure wave generated in the ink flow path toward the print head is effective. There is an effect that it can be suppressed.
  Further, when it is determined by the determination means that the bubbles are stored up to a predetermined position in the bubble storage chamber, the recovery means can be activated. Here, since the normal recovery processing operation performed to recover the ink ejection state is periodically performed, the recovery processing operation is executed even if no bubbles are actually stored, and the recovery processing operation is not performed. If necessary, ink is thrown away. However, when it is determined that bubbles are stored up to a predetermined position in the bubble storage chamber, recovery processing is executed, so that recovery is performed only when recovery processing is necessary (when the ink ejection state needs to be recovered). The processing operation can be executed, and there is an effect that ink is not discarded unnecessarily.
  Further, when the ink is stored in the bubble storage chamber up to the second predetermined position by discharging the bubbles by the recovery means, the recovery process is stopped by the recovery process stop means. Therefore, there is an effect that the bubbles for absorbing the pressure wave can be reliably left in the bubble storage chamber even if the recovery means is operated to discharge the bubbles in the bubble storage chamber.
[0073]
  Claim2The ink jet printer described is claimed1In the described ink jet printer, the third chamber is provided above the ink inlet of the bubble storage chamber. For this reason, the ink flow path of the third chamber is formed from the ink inlet to the upper side of the third chamber, and the pressure wave propagating along the ink flow path is smoothly moved along the pressure induction side wall, so that the bubble storage chamber To the upper part of Therefore, there is an effect that the pressure wave generated in the ink flow path can be efficiently absorbed by the bubbles stored in the bubble storage chamber.
[0075]
  Claim3The ink jet printer according to claim 1.Or 2In addition to the effects exhibited by the inkjet printer described above, the first chamber and the second chamber are defined by the partition member so that the capacity of the second chamber of the bubble storage chamber is smaller than the capacity of the first chamber. When discharging bubbles stored in the upper part of the bubble storage chamber by suction, the ink in the second chamber is discharged together with the bubbles, so the volume of the second chamber is reduced to reduce the amount of ink discharged. As a result, the amount of wasted ink can be reduced.
[0076]
Further, by reducing the capacity of the second chamber, there is an effect that bubbles can be discharged with a small pressure during the recovery process. According to this, for example, since the recovery means can be driven with small power, the energy consumption due to the recovery processing operation can be suppressed, and a small recovery means that can be operated with small power can be used. There is an effect that the main body can be made compact.
[0077]
  Claim4The ink jet printer according to claim 1.3In addition to the effect of the ink jet printer according to any one of the above, the bubble storage chamber includes a first chamber and a second chamber composed of two or more parts, and a partition member is provided between the first chamber and the second chamber. Clamp and install. Therefore, in the bubble storage chamber manufacturing process, the partition member can be easily welded between the first chamber and the second chamber, and the bubble storage chamber can be manufactured easily and efficiently. is there.
[0078]
  Claim5The ink jet printer according to claim 1.4In addition to the effect of the ink jet printer described in any of the above, the inner surface of the second chamber of the bubble storage chamber is made of a material having better wettability than the inner surface of the first chamber. Therefore, bubbles generated in the ink flow path are more easily stored in the first chamber than in the second chamber, and there is an effect of suppressing the stored bubbles from flowing toward the print head during printing. Furthermore, the bubbles accumulated in the bubble storage chamber can be easily moved without stagnation on the side of the second chamber having good wettability by the flow of ink during the recovery process, so that the removal of the bubbles by the recovery process is efficient. There is an effect that can be performed.
[0079]
  Claim6The ink jet printer according to claim 1.5In addition to the effects of the ink jet printer according to any one of the above, the pressure guide side wall rises from the bottom of the bubble storage chamber and extends to a position spaced from the ceiling, and the partition member sandwiches the first chamber. The ink inlet is located in the lower part of the third chamber, and the supply port is arranged in the lower part of the second chamber. Therefore, the pressure wave generated at the time of printing can be efficiently collided with the bubbles stored above the bubble storage chamber and absorbed, and the pressure of the supplied ink is kept constant and the ink discharge performance is maintained well. There is an effect that can be done.
[Brief description of the drawings]
FIG. 1 is a developed side view of an inkjet printer according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view schematically showing that an air trap and a tube are connected by a joint member.
FIG. 3 is a longitudinal sectional view of an air trap, a suction device, and a paper feed roller of the print head unit.
FIG. 4 is an exploded perspective view of the print head unit.
FIG. 5 is a cross-sectional view schematically showing an air trap function of the print head unit.
FIG. 6 is a perspective view schematically showing a conventional inkjet printer.
[Explanation of symbols]
1 Inkjet printer
4a to 4d ink tank
5a to 5d tube (part of ink flow path)
6 Purge device (recovery means)
11 Air trap unit (bubble storage chamber)
11a Room 1
11a1 pressure induction side wall
11b Second chamber
11b1 Guide nozzle (supply port)
11c Room 3
11c1 Ink inlet
12 Joint member (part of ink flow path)
13a First filter (partition wall member)
13e          Upper part of the first chamber (upper part of the bubble reservoir)
15 Print head
17a Driver board
18a First thermistor sensor
18b Second thermistor sensor

Claims (6)

A print head for printing on a recording medium by discharging ink from one or a plurality of ink discharge ports, an ink tank for storing ink supplied to the print head, and supplying ink from the ink tank to the print head an ink flow path, provided in the middle of the ink flow path, an ink flow inlet and the supply port for supplying ink to the print head ink from the ink tank flows, the upper air bubbles mixed into the ink a bubble reservoir chamber for storing the parts, as well as E設under side portion of the bubble storage chamber into a second chamber of the print head side to the first chamber of the ink tank side, said lower portion of said bubble reservoir the first chamber and is capable passes the second chamber and the ink, septum passage resistance is larger than the flow path resistance in the upper part of the bubble storage chamber when the ink passes in And the member, the bubbles always a predetermined amount in the upper portion of the front Symbol first chamber is further E設leaving area being reservoir, one communicating with the ink inlet, bubbles the other of said constant predetermined amount A pressure guiding side wall that forms a third chamber communicating from below with respect to a region in which the water is stored, and a recovery means that discharges the air bubbles accumulated in the air bubble storage chamber from the ink discharge port to restore the ink discharge state And determining means for determining whether or not the bubbles are stored up to a first position below the top of the partition wall member, and that the determining means stores the bubbles in the bubble storage chamber to the first position. When the determination is made, the recovery processing operation means for operating the recovery means, and the bubble recovery processing by the recovery means, the ink is stored in the bubble storage chamber to a second position above the top of the partition wall member. When, in an ink jet printer and a recovery processing stopping means for stopping the recovery processing by the recovery means,
The pressure induction side wall is disposed higher than the height of the partition wall member,
2. The ink jet printer according to claim 1, wherein the second position is a position that is higher than a top portion of the partition wall member and is not more than a height of the pressure guide side wall . The third chamber is an ink jet printer according to claim 1, characterized in that provided above the ink inlet of the bubble reservoir. The bubble reservoir, the ink jet printer according to claim 1 or 2, characterized in that it is E設by the partition member as the capacity of the second chamber is smaller than the capacity of the first chamber. The bubble reservoir, the ink jet printer according to any one of claims 1 to 3, characterized in that to sandwiched the partition member is composed of two or more parts so as to dispose. The bubble storage chamber, the inner surface of the second chamber is an ink jet printer according to any one of 4 from claim 1, characterized in that it is constituted by a material better wettability than the inner surface of the first chamber. The pressure induction side wall rises from the bottom of the bubble reservoir and extends to a position spaced from the ceiling;
The partition member is substantially parallel to the pressure induction side wall across the first chamber;
The ink inlet is at the bottom of the third chamber;
The ink jet printer according to any one of claims 1 to 5, wherein the supply port, characterized in that the bottom of the second chamber.

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