JP2018039179A - Liquid discharge head and recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid discharge head which prevents a gas stored in the liquid discharge head from moving to nozzles and stably performs liquid discharge even if the liquid discharge head changes its posture.SOLUTION: A liquid chamber 5 which stores a liquid to be supplied to nozzles 3 of a liquid discharge head 2 includes: a liquid storage part 51 communicating with a supply port which supplies the liquid to the nozzles; and a gas storage part 52 which communicates with the liquid storage part 51 and can store a predetermined or smaller amount of the gas. The gas storage part 52 retains the predetermined or smaller amount of the gas stored in a first posture therein even if a posture of the liquid chamber 5 is changed from the first posture taken for discharging the liquid from the nozzles along a first direction to a second posture taken by the liquid chamber 5 rotating from the first posture.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a liquid discharge head including a nozzle for discharging a liquid, and a recording apparatus that performs recording on a recording medium using the liquid discharge head.

  2. Description of the Related Art An ink jet recording apparatus that performs recording by discharging a liquid (ink) containing a color material onto a recording medium uses a liquid discharge head in which a plurality of nozzles that discharge liquid are arranged at high density. A common liquid chamber for supplying liquid to each nozzle is formed in the liquid discharge head, and liquid is supplied to the liquid chamber from a liquid storage tank that is a liquid supply source. In such a liquid discharge head, fine bubbles generated when the liquid is discharged, gas dissolved in the liquid in the liquid discharge head, bubbles mixed in the liquid supplied from the liquid storage tank to the liquid chamber, etc. May accumulate in the liquid chamber. In the liquid ejection head, after the liquid is ejected from the nozzle, the same amount of liquid as the ejected liquid flows into the nozzle, thereby enabling the next ejection operation. However, when a large amount of gas is accumulated in the liquid chamber, the gas may hinder the supply of ink from the liquid chamber to the nozzles. In this case, ejection failure such as non-ejection occurs in the nozzle.

  In Patent Document 1, gas is periodically discharged from a liquid discharge head, and the amount of gas accumulated in the liquid discharge head is kept below a predetermined amount, thereby affecting the effect of the gas accumulated in the liquid discharge head. A recording apparatus is disclosed which reduces the above.

JP 2007-168421 A

  Currently, liquid discharge heads are used in recording apparatuses having various structures, forms, and applications. For this reason, the liquid ejection head is required to have a structure corresponding to the recording apparatus to which the liquid ejection head is applied. However, the current liquid discharge head is assumed to be in a posture during a recording operation, and sufficient measures are not taken for a recording apparatus in which the posture of the liquid discharge head changes. That is, even if the amount of gas in the liquid chamber is suppressed to a predetermined amount or less in Patent Document 1, if the posture of the liquid discharge head changes, the remaining gas moves to the nozzle side and remains as the posture changes. In some cases, the supply of ink to the nozzles may be hindered.

  For example, in the conventional liquid discharge head 60 that assumes that the recording operation is performed in an upright posture as shown in FIG. 8A, during the recording operation, the liquid chamber 63 is located above the nozzle 61 located at the lower end. The gas 62 mixed in the liquid chamber 63 is held above the liquid chamber 63. However, when the posture of the liquid discharge head 60 changes as shown in FIG. 8B, the liquid moves below the nozzle 61, and the gas is interposed between the liquid in the liquid chamber 63 and the nozzle 61. It becomes. Thereafter, when the liquid ejection head 60 is returned to the original upright posture in order to start the recording operation, gas may remain in the vicinity of the nozzle, and the remaining gas prevents the supply of ink to the nozzle. Sometimes. Such a change in the posture of the liquid discharge head is caused when the liquid discharge head is taken out for replenishment or replacement of a recording medium (for example, a roll sheet) accommodated below the liquid discharge head, or for maintenance work of the internal mechanism. This often occurs. In particular, in a recording apparatus in which a liquid discharge head is attached to the inner surface of the cover body that covers the internal mechanism and the liquid discharge head is taken out as the cover body is opened, the posture of the liquid discharge head changes every time the cover body is opened. As a result, the possibility of gas adhering to the nozzle increases.

  The present invention relates to a liquid ejection head capable of stably performing liquid ejection without causing gas stored in the liquid ejection head to move to the nozzle in response to a change in posture of the liquid ejection head, and a recording apparatus including the liquid ejection head The purpose is to provide a device.

  The present invention comprises a nozzle having a discharge port for discharging a liquid, and a liquid chamber for storing a liquid to be supplied to the nozzle, wherein the liquid chamber is in communication with the nozzle; A gas storage section that communicates with the liquid storage section and can store a predetermined amount or less of gas, and the gas storage section is configured such that the posture of the liquid chamber is such that the liquid is discharged from the discharge port along the first direction. Even when the first posture for discharging is changed to the second posture obtained by rotating the first posture, the gas stored in the first posture is held below the predetermined amount. It is characterized by that.

  According to the present invention, the gas stored in the liquid discharge head does not move to the nozzle with respect to the change in the posture of the liquid discharge head, and the liquid discharge can be performed stably.

FIG. 3 is an internal perspective view of the recording apparatus on which the liquid ejection head according to the embodiment is mounted. FIG. 6 is a perspective view illustrating a state where an upper cover body of the recording apparatus is opened. It is a perspective view of the liquid discharge head in an embodiment. FIG. 4 is a longitudinal front view of the liquid ejection head shown in FIG. 3. FIG. 4 is a longitudinal side view of the liquid ejection head shown in FIG. 3 in an upright posture. FIG. 6 is a longitudinal side view of the liquid ejection head shown in FIG. 5 in a retracted posture. It is a schematic diagram which shows the flow path connected to a liquid discharge head. It is a vertical side view which shows the conventional liquid discharge head.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an external appearance of a liquid ejection apparatus (hereinafter also simply referred to as a recording apparatus) in the present embodiment. The liquid ejected by the liquid ejecting apparatus includes a recording liquid that adheres to the recording medium to form an image, a fixing processing liquid for improving the quality of an image formed by the recording liquid applied to the recording medium, and the like. Contains liquid.

  As shown in FIG. 1, the recording apparatus 1 has an outer shell composed of a housing 10 composed of a lower cover body 1A and an upper cover body 1B. The recording apparatus 1 accommodates a mechanism for performing a recording operation, for example, a liquid discharge head 2 described later, a liquid tank 11, a roll sheet RS as a recording medium, and a conveying unit that conveys the recording medium. The upper cover body (opening / closing plate) 1B is connected to be rotatable by a hinge 1C provided on the back side. The opening of the lower cover body 1A can be closed or opened by the rotational movement of the upper cover body 1B.

  Various mechanisms other than the liquid discharge head 2 are accommodated and held in the lower cover body 1A, and a roll sheet RS as a recording medium is detachably accommodated. When the roll sheet RS is mounted and taken out or maintenance of the internal mechanism is performed, the upper cover body 1B is rotated around the hinge 1C as shown in FIG. In the present embodiment, the upper cover body 1B can be displaced by a predetermined angle from a closed state in which the opening of the lower cover body 1A is closed. In the present embodiment, the lower cover body 1A can be rotated about 90 degrees.

  A liquid discharge head 2 is attached to the inner surface of the upper cover body (support member) 1B. When the upper cover body 1B is closed, the nozzle of the liquid discharge head faces the sheet S fed out from the roll sheet RS through a predetermined interval, and a recording operation by the liquid discharge head becomes possible. Further, when the upper cover body 1B is opened, the liquid discharge head 2 moves together with the upper cover body 1B. Therefore, the posture when the upper cover body 1B is rotated by 90 degrees changes from the posture when the upper cover body 1B is closed to the rotation direction of 90 degrees. Thus, since the liquid discharge head 2 moves together with the cover body 1B, the liquid discharge head 2 is retracted from above the roll sheet RS, so that the user can contact the roll sheet that is a recording medium in the recording apparatus. The roll sheet RS can be easily replaced and mounted. In this posture, the tank for storing the liquid can be replaced. As described above, the recording apparatus of the present embodiment is a so-called crumb in which the upper cover body 1B constituting the housing 10 is configured to be openable and closable in order to facilitate the replacement of the recording medium and the tank and the maintenance of the internal mechanism. It is a shell type recording device.

  3 to 5 are views showing the liquid ejection head 2 in the present embodiment, FIG. 3 is an external perspective view, FIG. 4 is a longitudinal front view of what is shown in FIG. 3, and FIG. 4 is what is shown in FIG. It is a vertical side view. The liquid discharge head 2 has a plurality of nozzles that discharge liquid. In the liquid ejection head according to the present embodiment, nozzles 3 that eject liquid are arranged at a predetermined density along a direction that intersects the conveyance direction Y of the sheet S (a direction orthogonal to the conveyance direction (X direction)). The line head provided with 30 is comprised. The width in which the nozzles are arranged (the length of the nozzle row) is equal to or larger than the maximum recording width of the recording medium P to be used.

  When the recording apparatus 1 performs recording, the liquid discharge head 2 is held at a predetermined position facing the recording medium P, and the discharge energy generating means provided in each nozzle 3 of the liquid discharge head 2 is driven to drive the liquid from the nozzle. Is recorded on the sheet S in units of one line. As described above, the recording apparatus according to the present embodiment is a full-line type recording apparatus that performs recording in units of one line using the liquid discharge head. In addition, as the discharge energy generating means, the liquid is heated to generate bubbles, and an electrothermal conversion element (heater) that discharges the liquid by the pressure when the bubbles are generated, or the electric energy is converted into mechanical energy. An electromechanical transducer (piezo) or the like is used.

  Further, as shown in FIGS. 4 and 5, a liquid chamber 5 communicating with the plurality of nozzles 3 is provided inside the liquid discharge head 2. A liquid reservoir 51 communicating with the nozzle 3 and a gas reservoir 52 capable of storing gas mixed in the liquid reservoir 51 are formed in the wall surface of the liquid chamber 5. Further, as shown in FIG. 6, the liquid discharge head 2 is provided with a connecting portion 2 a that can be connected to the liquid tank 11 and a liquid supply channel 53. In a state where the liquid discharge head 2 and the liquid tank 11 are connected, the liquid tank 11 and the liquid chamber 5 of the liquid discharge head 2 communicate with each other via the liquid supply channel 53. Thereby, the liquid in the liquid tank 11 can be supplied to the liquid chamber 5.

  FIG. 7 is a schematic diagram showing the liquid discharge head 2 and the flow path connected to the liquid discharge head 2. Liquid L is stored in the liquid tank 11, and the liquid tank 11 is always maintained at a pressure (negative pressure) lower than the atmospheric pressure by a predetermined pressure by a negative pressure generating means (not shown). The liquid L in the liquid tank 11 is supplied to the liquid chamber 5 of the liquid discharge head 2 via the liquid supply flow path 53 and then supplied to the plurality of nozzles 3 constituting the nozzle row 30. Thereby, the liquid can be discharged from the nozzle 3.

  A gas reservoir 52 is formed on the liquid reservoir 51 formed in the liquid chamber 5. The gas storage unit 52 is connected to a buffer 7 provided outside, and the buffer 7 is connected to a pump 8. By driving the pump 8, the pressure inside the buffer 7 can be changed as necessary, and the amount of liquid supplied into the liquid chamber 5 can be adjusted accordingly.

  Further, since the liquid discharge head 2 performs stable liquid discharge, the cleaning operation is performed at a predetermined timing. In the cleaning operation, after the cap 4 is pressed against the liquid ejection head 2, a desired negative pressure is applied to suck out foreign liquids such as old liquid that has become unsuitable for ejection in the nozzle, dust and bubbles that have entered the nozzle. The sucked out foreign matter passes through the buffer 7 and the pump 8 and is collected in the waste liquid tank 9.

  Next, the configuration of the liquid ejection head 2 in this embodiment and the behavior of the internal liquid and air accompanying the change in the posture of the liquid ejection head 2 will be described.

  During the recording operation, the upper cover body 1B is in a closed state, so that the liquid ejection head takes a posture as shown in FIG. In other words, the liquid ejection head 2 has a posture in which the nozzle opening (ejection port) faces the sheet S and recording on the sheet S is possible. This posture of the liquid discharge head 2 is referred to as an upright posture (first posture) in the following description. 4 and 5, the direction indicated by the arrow E represents the liquid discharge direction, and the arrow Z represents the vertical direction.

  When the liquid ejection head 2 is in the upright posture, the gas storage unit 52 is positioned above the communication port 14 that is a boundary portion between the liquid storage unit 51 and the gas storage unit 52, as shown in FIGS. To do. Therefore, the gas mixed in the liquid ejection head by the recording operation is collected and stored in the gas storage unit 52 located above the liquid storage unit 51. However, since the gas reservoir 52 communicates with the liquid reservoir 51 at the communication port 14, the liquid also enters the gas reservoir 52, and an interface between the liquid and the gas is formed in the gas reservoir 52. It becomes a state.

  Here, when exchanging, replenishing, or maintaining the sheet S in the recording apparatus 1, as shown in FIG. 2, the upper cover body 1 </ b> A is in the open state rotated about 90 degrees in the direction of arrow C. The liquid discharge head 2 takes the posture shown in FIGS. 2 and 6 as the upper cover body 1A moves. At this time, the ejection port in the liquid ejection head 2 is retracted from the position facing the recording head, and the liquid ejection direction (E direction) is orthogonal to the vertical direction (Z direction). Hereinafter, the posture of the liquid ejection head 2 shown in FIGS. 1 and 6 is referred to as a retracted posture (second posture).

  The gas storage unit 52 is configured to be always positioned above the horizontal plane that passes through the upper end portion 14a of the communication port 14 until the liquid ejection head 2 changes from the upright posture to the retracted posture. That is, the gas storage unit 52 stores the gas unless the interface between the gas and the liquid in the gas storage unit 52 falls below the lower end portion of the shielding member 14b constituting the gas movement prevention unit, that is, the upper end portion 14a of the communication port 14. The air in the part 52 is configured not to enter the liquid storage part 51. Further, the internal volume of the gas storage unit 52 (the gas storage capacity) changes while the liquid ejection head 2 moves from the upright posture to the retracted posture. For this reason, the gas storage unit 52 is set such that the minimum volume among the internal volumes that change while the liquid ejection head 2 is in the upright position to the retracted position is larger than the predetermined volume. Here, the predetermined volume refers to the volume of gas expected to be generated in the liquid ejection head 2 within a predetermined period. Note that the internal volume (gas storable volume) of the gas reservoir 52 when the liquid ejection head 2 is in the upright state is set to a volume larger than the minimum volume.

  When the liquid ejection head 2 moves from the upright posture to the retracted posture, the gas in the gas storage section 52 moves from the position shown in FIG. 5 to the position shown in FIG. At this time, unless the volume of gas generated in the liquid discharge head 2 exceeds the minimum volume of gas in the gas storage section 52, the interface (liquid level) between the gas and the liquid in the gas storage section 52 is the communication port 14. The upper end portion 14a of the gas does not fall below the gas, and the gas does not move into the liquid storage portion 51. That is, the gas is held in the gas storage part 52, and the liquid storage part 51 maintains the state filled with the liquid. For this reason, even when the liquid ejection head 2 returns to the upright position to perform the recording operation, no gas remains in the liquid inlet of the nozzle and the liquid is reliably supplied to the nozzle. become. Therefore, it is possible to suppress the occurrence of ejection failure due to the liquid supply being blocked.

  In addition, when the usage period of the liquid ejection head 2 elapses a predetermined period, a gas having a volume exceeding the minimum volume of the liquid ejection head 2 may be accumulated in the gas storage unit 52. In this case, when the posture of the liquid ejection head 2 changes, the liquid level in the gas storage unit 52 moves below the upper end portion 14a of the communication port 14, and moves to the nozzle 3 side using the liquid storage unit 51 as a movement path. There is a possibility that the liquid adheres to the nozzle and the supply of the liquid to the nozzle 3 is hindered. Therefore, in the present embodiment, the gas amount detecting means for detecting the volume of the gas stored in the gas storing portion 52, and the gas storage amount when the volume of the gas detected by the gas amount detecting means exceeds a predetermined amount. And an exhaust means for discharging the air in the section 52 to the outside.

  When the liquid chamber 5 of the liquid ejection head 2 is in the first or second posture, the gas amount detection means detects a liquid level that is an interface between the gas and the liquid in the gas storage unit 52, and sets the position of the liquid level. Based on this, the amount of gas stored in the gas storage unit 52 is detected. The liquid level detecting means 15 for detecting the liquid level includes electrodes 15a and 15b protruding into the gas reservoir 52, voltage applying means for applying a predetermined voltage between the electrodes 15a and 15b, and electrodes 15a and 15b. Current detecting means for detecting whether or not the gap is conducted. This liquid level detection means 15 detects whether the liquid in the gas storage part 52 exists between the electrodes 15a and 15b. The electrodes 15a and 15b are arranged so that the lower ends of the electrodes 15a and 15b are separated from the liquid surface when the liquid ejection head 2 is in an upright state and the amount of gas in the gas reservoir 52 reaches the minimum volume. ing. Therefore, it is possible to detect whether or not the air in the gas reservoir 52 has reached the same volume as the aforementioned minimum volume when both the electrodes 15a and 15b become non-conductive. This liquid level detection is performed when the liquid ejection head 2 is in an upright posture.

  When the liquid discharge head 2 takes an upright posture as shown in FIG. 5 and the liquid level detection means 15a, 15b detects that the interface between air and liquid is below the liquid level detection means 15a, 15b, the discharge is performed. The pump 18 as a means applies a desired negative pressure to the gas reservoir 52. As a result, the air in the gas reservoir 52 is discharged from the liquid discharge head 2, and the liquid corresponding to the volume of the discharged air is introduced from the liquid tank 11 to the liquid discharge head 2. When the liquid is introduced into the liquid discharge head 2, the interface (liquid level) between the liquid and air located in the gas storage section 52 rises. Then, the application of negative pressure by the pump 8 is stopped when the liquid level reaches the lower end of the liquid level detection means 15a, 15b. As a result, the amount of gas in the gas storage section 52 of the liquid discharge head 2 can always be kept below the minimum volume, and the air in the gas storage section 52 moves to the nozzle 3 due to a change in the posture of the liquid discharge head 2. You wo n’t have to.

  As described above, in the present embodiment, even when the upper unit 13 to which the liquid ejection head 2 is attached is opened about 90 degrees in the direction of the arrow C in accordance with replacement, replenishment, or maintenance of the recording medium. Gas does not move to the nozzle. Therefore, the liquid can be properly supplied to the nozzle 3 after returning to the upright posture, and stable liquid discharge can be continuously performed. For this reason, it is not necessary to frequently perform the recovery operation for extracting air from the nozzle, and the consumption of liquid can be reduced.

(Other embodiments)
In the above embodiment, an example in which the liquid discharge head is attached to the upper cover body of the clamshell type recording apparatus has been described. However, the present invention is not limited to this and is widely applied to recording apparatuses using the liquid discharge head. Is possible. In a recording apparatus provided with a liquid discharge head, bubbles included in the liquid in the liquid discharge head may adhere to the nozzle when the recording apparatus is tilted during transportation or the like. Therefore, by mounting the liquid discharge head as in the present invention, it is possible to realize proper discharge even when a situation occurs in which the posture of the liquid discharge head is inclined.

  In addition, the present invention is not limited to a full-line type recording apparatus, but can also be applied to a serial type recording apparatus that performs recording while moving a liquid ejection head in a direction that intersects the conveyance direction of the recording medium.

DESCRIPTION OF SYMBOLS 1 Recording device 2 Liquid discharge head 3 Nozzle 5 Liquid chamber 51 Liquid storage part 52 Gas storage part

Claims (12)

A nozzle having a discharge port for discharging liquid;
A liquid chamber that stores liquid to be supplied to the nozzle and is displaceable between a first posture for discharging the liquid from the discharge port and a second posture rotated by a predetermined angle from the first posture. When,
A gas movement preventing unit that prevents gas inside the liquid chamber from moving to the nozzle when the liquid chamber is displaced from the first posture to the second posture;
A liquid discharge head comprising:   The liquid discharge head according to claim 1, wherein the first posture is a posture in which the liquid is discharged from the nozzle in a vertical direction.   The liquid ejection head according to claim 1, wherein the second posture is a posture in which the liquid chamber is rotated 90 degrees from the first posture.   The gas movement prevention unit is provided on a wall surface of the liquid chamber in the second posture, and has a shielding member that shields a gas movement path to the nozzle together with the liquid stored in the liquid chamber. The liquid discharge head according to any one of claims 1 to 3. A recording apparatus that performs recording by using a liquid discharge head that discharges liquid and applying the liquid discharged from the liquid discharge head to a recording medium,
The liquid discharge head is
A nozzle having a discharge port for discharging liquid;
A liquid chamber that stores liquid to be supplied to the nozzle and is displaceable between a first posture for discharging the liquid from the discharge port and a second posture rotated by a predetermined angle from the first posture. When,
A gas movement preventing unit that prevents gas inside the liquid chamber from moving to the nozzle when the liquid chamber is displaced from the first posture to the second posture;
A recording apparatus comprising: A gas amount detecting means for detecting a volume of gas stored in the liquid chamber;
The recording apparatus according to claim 5, further comprising an exhaust unit that discharges the gas inside the liquid chamber to the outside based on the gas amount detected by the gas amount detection unit.   The gas amount detecting means includes a liquid level detecting means for detecting a liquid level in the liquid chamber, and an amount of gas stored in the liquid chamber based on a position of the liquid level detected by the liquid level detecting means. The recording apparatus according to claim 6, wherein the recording apparatus is detected. The liquid discharge head is attached to a support member capable of rotating,
The support member is rotatable to a first position where the discharge port of the liquid discharge head can face the recording medium, and a second position where the discharge port does not face the recording medium.
When the support member is in the first position, the liquid chamber takes the first posture,
The recording apparatus according to claim 5, wherein the liquid chamber takes the second posture when the support member is in the second position.   The recording apparatus according to claim 8, wherein the support member includes an upper cover body that closes and opens an opening of a lower cover body that covers the recording head.   The recording apparatus according to claim 9, wherein a user can contact a recording medium in the recording apparatus by the support member taking the second posture.   The recording apparatus according to claim 9, wherein the liquid ejection head can be replaced by a user when the support member takes the second posture.   The recording apparatus according to claim 9, wherein the support member is in the second posture, so that a user can exchange a tank for storing a recording liquid.

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