JP5863580B2 - Inkjet head maintenance apparatus and inkjet recording apparatus - Google Patents

Description

  The present invention relates to an inkjet head maintenance apparatus and an inkjet recording apparatus, and more particularly to a maintenance technique for preventing nozzle drying during storage of the head.

  In the ink jet recording apparatus, it is necessary to prevent the ink in the nozzles from drying. For this reason, at the time of standby (during storage), the head is covered with a cap in which moisturizing liquid is stored, and the humidity near the nozzle is maintained within a desired range by the transpiration of the moisturizing liquid. .

  Further, in the case of a long head composed of a plurality of head modules, when module replacement is assumed, there is a gap in the connecting portion between the modules. For this reason, a sealed space cannot be created by a method in which the cap is brought into contact with the head. Therefore, when the device is stored for a long period of time, the moisture content inside the cap is reduced due to the evaporation of the moisturizing liquid. Thus, when the moisture content inside the cap decreases, the distance between the head and the moisturizing liquid surface increases.

  The humidity near the nozzle is dominated by the distance between the head and the moisturizing liquid surface. Therefore, when the distance between the head and the moisturizing liquid surface increases, the humidity in the vicinity of the nozzle cannot be maintained in a desired range, and the ink in the nozzle dries, resulting in a deterioration in the quality of the head. There was a point.

  On the other hand, in Patent Document 1, a detection unit for detecting the amount of water such as a sensor is provided in the cap unit, and water is replenished according to the detection result, or water is replenished in the cap using ink. An ink jet recording apparatus provided with a supply means is disclosed.

  According to this technique, the inappropriate amount of moisture in the cap due to use conditions and use environment conditions can be eliminated, and problems such as poor emission can be solved.

JP 2003-182098 A

  However, the technique described in Patent Document 1 has a drawback in that the apparatus is complicated and large because it is necessary to incorporate a sensor, a substrate, a power source, and the like for detecting the amount of moisture in the apparatus.

  In addition, there is also a problem that the run cost increases because it is necessary to always start a power source different from the power source of the main body even while the power source of the apparatus is shut off.

  Further, Patent Document 1 does not mention the sealing degree of the cap and the distance between the head and the liquid surface.

  The present invention has been made in view of such circumstances, and maintains the quality of the head in the storage state with a simple and inexpensive configuration by a mechanism that keeps the liquid level of the moisturizing liquid constant without detecting the amount of moisture. An object of the present invention is to provide an inkjet head maintenance device and an inkjet recording apparatus.

In order to achieve the above object, one aspect of the maintenance device for an inkjet head includes a moisturizing cap for storing a moisturizing liquid for moisturizing the nozzle formed on the nozzle surface of the inkjet head, and a storage amount of the moisturizing liquid. Elevating means for raising and lowering the moisturizing cap and maintaining the liquid level of the moisturizing liquid at a certain height, and head holding means for holding the nozzle surface of the inkjet head facing the liquid surface of the moisturizing liquid stored in the moisturizing cap The elevating means includes a displacing means that is displaced according to the mass of the moisturizing liquid stored in the moisturizing cap.
In order to achieve the above object, one aspect of the maintenance device for an inkjet head includes a moisturizing cap for storing a moisturizing liquid for moisturizing the nozzle formed on the nozzle surface of the inkjet head, and a storage amount of the moisturizing liquid. Elevating means for raising and lowering the moisturizing cap and maintaining the liquid level of the moisturizing liquid at a certain height, and head holding means for holding the nozzle surface of the inkjet head facing the liquid surface of the moisturizing liquid stored in the moisturizing cap And with.

  According to this aspect, since the moisturizing cap is moved up and down according to the amount of moisturizing liquid stored to maintain the liquid level of the moisturizing liquid at a certain height, the liquid level of the moisturizing liquid, the nozzle surface of the inkjet head, Can be kept constant, and the quality of the head during storage can be maintained with a simple and inexpensive configuration.

  It is preferable that the lifting / lowering means includes a displacing means that is displaced according to the mass of the moisturizing liquid stored in the moisturizing cap. Thereby, a moisture retention cap can be raised / lowered appropriately according to the storage amount of a moisture retention liquid.

  The displacement means is preferably an elastic body. Thereby, the liquid level of the moisturizing liquid can be appropriately maintained at a constant height.

  The spring constant k of the elastic body is preferably expressed by k = A × ρ × g, where A is the surface area of the moisturizing liquid, ρ is the density of the moisturizing liquid, and g is the acceleration of gravity. Thereby, the liquid level of the moisturizing liquid can be appropriately maintained at a constant height.

  The head holding means includes a slide guide that holds the inkjet head with a predetermined angle between the nozzle surface and the horizontal plane, and that allows the moisture retention cap to slide in a direction perpendicular to the predetermined angle. The moisturizing cap may be moved up and down by being displaced in the vertical direction with respect to a predetermined angle. As a result, in an inkjet recording apparatus that transports a recording medium in a drum, even if the inkjet head is held along the circumferential surface of the drum with the nozzle surface having a predetermined angle from the horizontal plane, the nozzle is appropriately Can be moisturized.

When the predetermined angle is θ, the surface area of the moisturizing liquid is A, the density of the moisturizing liquid is ρ, and the acceleration of gravity is g, the spring constant k ′ of the elastic body is k ′ = A × ρ × g × It is preferably represented by cos ² θ. Thereby, the liquid level of the moisturizing liquid can be appropriately maintained at a constant height.

  The lifting and lowering means may be a seesaw means that holds a moisturizing cap at one end and a balance load member at the other end. Thereby, the liquid level of the moisturizing liquid can be appropriately maintained at a constant height.

  The opening of the moisturizing cap is larger than the nozzle surface. Thereby, the collision with a moisture retention cap and the nozzle surface of an inkjet head can be prevented.

  Moisturizing liquid supply means for supplying the moisturizing liquid to the moisturizing cap may be provided. Thereby, the nozzle can be appropriately moisturized without cutting the moisturizing liquid.

  In order to achieve the above object, one aspect of an ink jet recording apparatus includes: an ink jet head having a nozzle surface on which nozzles for ejecting ink are formed; a moving unit that relatively moves the ink jet head and the recording medium; Control means for forming an image on the recording surface of the recording medium by ejecting ink from the nozzle while relatively moving the inkjet head and the recording medium, and the maintenance device for the inkjet head described above are provided.

  According to this aspect, since the moisturizing cap is moved up and down according to the amount of moisturizing liquid stored to maintain the liquid level of the moisturizing liquid at a certain height, the liquid level of the moisturizing liquid, the nozzle surface of the inkjet head, Can be kept constant, and the quality of the head during storage can be maintained with a simple and inexpensive configuration.

  The ink-jet head may be an ink-jet head configured as one head by arranging a plurality of head modules in which nozzles for ejecting ink are formed and incorporating them into a fixing member. According to this aspect, even if a gap is generated between the head modules, the nozzle can be appropriately moisturized.

  According to the present invention, the moisturizing cap is moved up and down according to the amount of moisturizing liquid stored so as to maintain the liquid level of the moisturizing liquid at a constant height. Can be kept constant, and the quality of the head during storage can be maintained with a simple and inexpensive configuration.

  According to the present invention, since the position of the liquid surface of the moisturizing liquid in the moisturizing cap can be kept constant, the distance between the liquid surface of the moisturizing liquid and the head is kept constant, and the humidity near the nozzle is kept in a desired range. The quality of the storage state of the head can be maintained.

Schematic diagram of inkjet head maintenance device Diagram for comparing the size of the bottom surface of the inkjet head and the size of the opening surface of the moisture retention cap Graph showing the relationship between the distance from the liquid level at normal temperature and the humidity at that position The figure which shows the maintenance apparatus whose one side of a moisture retention cap is below the one side of the bottom face of an inkjet head Front view showing the configuration of the main part of the inkjet recording apparatus A plan view showing a configuration of a main part of an ink jet recording apparatus Side view showing the configuration of the main part of the inkjet recording apparatus Head perspective view Top view of nozzle surface Side view of maintenance device Front view showing a configuration of a main part of a modified example of the ink jet recording apparatus Side view of a modified maintenance device Schematic diagram of inkjet head maintenance device Front view showing the configuration of the main part of the inkjet recording apparatus A plan view showing a configuration of a main part of an ink jet recording apparatus Side view showing the configuration of the main part of the inkjet recording apparatus Diagram for explaining the angle formed by the nozzle surface and the horizontal plane Side view showing the configuration of the main part of the maintenance device Diagram showing a maintenance device

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
[Maintenance device configuration]
FIG. 1A is a diagram schematically showing an inkjet head maintenance apparatus 100 according to the present embodiment. As shown in the figure, the maintenance device 100 includes a head holding unit 104, a moisturizing liquid 106, a moisturizing cap 108, an elastic member 110, and the like.

  The inkjet head 102 forms an image on the recording surface of the recording medium by ejecting ink droplets from a plurality of nozzles arranged on the nozzle surface 102a based on a command from a control unit (not shown). The head holding unit 104 holds the inkjet head 102 facing downward so that the nozzle surface 102a of the inkjet head 102 is parallel to the horizontal plane.

  The moisturizing liquid 106 is a liquid containing the same solvent as the solvent of the ink ejected from the nozzles of the inkjet head 102, and is a liquid mainly composed of water, for example.

A moisturizing liquid 106 is stored in the moisturizing cap 108. FIG. 2 is a diagram for comparing the size of the bottom surface of the inkjet head 102 with the size of the opening surface of the moisture retention cap 108. As shown in the figure, when the size of the bottom surface of the inkjet head 102 is horizontal x _h and vertical y _h , and the size of the opening surface of the moisture retaining cap 108 is horizontal x _c and vertical y _c , x _h <x _c And y _h <y _c is satisfied.

  As described above, the moisture retaining cap 108 is configured such that the opening surface thereof is larger than the bottom surface of the inkjet head 102, and the bottom surface (surface having the nozzle surface 102a) of the inkjet head 102 can be accommodated from the opening surface. ing.

  Returning to the description of FIG. 1A, the moisturizing cap 108 is held by the elastic member 110 on the bottom surface thereof. The elastic member 110 is an elastic body (an example of a displacement means) that is displaced according to the mass of the moisturizing liquid 106 stored inside the moisturizing cap 108, and presses and holds the moisturizing cap 108 upward.

Here, the opening area of the moisturizing cap 108 (the area of the gas-liquid interface of the moisturizing liquid 106 stored inside the moisturizing cap 108) is A (here, x _c × y _c ) [m ² ], and the moisturizing liquid 106 When the density is ρ [kg / m ³ ] and the gravitational acceleration is g [N / m], the spring constant k of the elastic member 110 is
k = A × ρ × g (Formula 1)
Is set to

  As the elastic member 110, a sponge, an air spring, etc. other than a general compression coil spring can be used.

[Operation of maintenance equipment]
As shown in FIG. 1A, the head holding unit 104 is configured such that the nozzle surface 102a of the inkjet head 102 and the liquid surface of the moisturizing liquid 106 in the moisturizing cap 108 face each other in parallel, and a distance therebetween is set. The inkjet head 102 is fixed and held at a position where s is obtained.

  The inkjet head 102 is fixed and held with the nozzle surface 102a of the inkjet head 102 facing the position where the distance from the liquid surface of the moisturizing liquid 106 in the moisture retention cap 108 is s.

  Due to the transpiration of the moisturizing liquid 106 stored in the moisturizing cap 108, the humidity of the nozzle surface 102a (humidity near the nozzle) is maintained in a desired range (for example, 80%).

  FIG. 3 is a graph showing the relationship between the distance from the liquid surface at normal temperature and the humidity at that position. As can be seen from this graph, the humidity in the vicinity of the nozzle is determined by the dominant factor of the distance between the ink jet head 102 and the liquid surface of the moisturizing liquid 106.

  In this embodiment, since the inkjet head 102 and the moisturizing cap 108 are not brought into contact with each other, the moisturizing liquid 106 inside the moisturizing cap 108 decreases due to evaporation.

Here, as shown in FIG. 1B, it is assumed that the liquid level of the moisturizing liquid 106 inside the moisturizing cap 108 is lowered by h due to the decrease in the moisturizing liquid 106. At this time, since the weight of the reduced moisturizing liquid 106 is ρ × A × h [kg], the displacement amount x of the elastic member 110 is
x = F / k = (ρ × A × h × g) / (A × ρ × g) = h
It becomes. Thus, the amount of descent of the liquid surface of the moisturizing liquid 106 inside the moisturizing cap 108 is equal to the amount of displacement of the elastic member 110. As a result, the moisturizing liquid 106 inside the moisturizing cap 108 evaporates and decreases, and the liquid level is lowered, so that the moisturizing cap 108 is raised by the elastic member 110, and the liquid of the moisturizing liquid 106 viewed from the outside of the moisturizing cap 108. The height of the surface is kept constant.

  That is, regardless of the amount of decrease in the moisturizing liquid 106, the distance between the nozzle surface 102a and the liquid surface of the moisturizing liquid 106 is constant at the initial set distance s. Therefore, the humidity of the nozzle surface 102a can be maintained at an appropriate humidity regardless of the amount of reduction (evaporation amount) of the moisturizing liquid 106.

  Thus, according to the present embodiment, the liquid level of the moisturizing liquid can be maintained at a constant height without detecting the amount of the moisturizing liquid, so that the nozzle surface of the inkjet head and the liquid level of the moisturizing liquid The distance can be made constant. Thereby, the humidity of the nozzle surface of the inkjet head in a storage state can be maintained at an appropriate humidity with a simple and inexpensive configuration, and the quality of the inkjet head can be maintained.

  Moreover, according to this embodiment, even if a moisture retention cap raises, a moisture retention cap and an inkjet head do not collide.

For example, FIG. 4A shows a maintenance apparatus in which one side of the moisture retaining cap 108 ′ is equal to or less than one side of the bottom surface of the inkjet head 102 (that is, x _h ≧ x _c or y _h ≧ y _c holds in the example of FIG. 2). It is a figure which shows 100 '. In the maintenance device 100 ′, the distance between the upper end of the moisture retention cap 108 ′ and the bottom surface of the inkjet head 102 is c.

  The moisturizing liquid 106 in the moisturizing cap 108 ′ is reduced by evaporation, and the elastic member 110 raises the moisturizing cap 108 ′. As shown in FIG. 4B, when the amount of increase exceeds c, the bottom surface of the inkjet head 102 collides with the upper end of the moisture retention cap 108 '.

  On the other hand, in this embodiment, the opening surface of the moisture retention cap is made larger than the bottom surface of the inkjet head, thereby avoiding collision between the moisture retention cap and the inkjet head when the moisture retention cap is raised.

  In order to avoid this collision, the inkjet head is held such that the bottom surface of the inkjet head is higher than the upper end position of the moisture retention cap when the moisture retention liquid in the moisture retention cap becomes empty. Embodiments are possible.

  In this embodiment, the density of the moisturizing liquid is assumed to be constant. However, when the density changes due to the evaporation of moisture from the moisturizing liquid, the moisturizing cap is held by combining a plurality of elastic members having different spring constants k. By doing so, the liquid surface of the moisturizing liquid can be maintained at a certain height.

<Second Embodiment>
[Configuration of inkjet recording apparatus]
Next, an ink jet recording apparatus according to the second embodiment will be described. 5, FIG. 6, and FIG. 7 are a front view, a plan view, and a side view, respectively, showing the configuration of the main part of the ink jet recording apparatus.

  As shown in FIG. 1, the inkjet recording apparatus 10 is a single-pass line printer, and mainly includes a sheet conveying mechanism 20 that conveys a sheet (sheet) P that is a recording medium, and a sheet conveying mechanism 20. Maintenance of the head unit 30 that ejects cyan (C), magenta (M), yellow (Y), and black (K) ink droplets toward the transported paper P, and each head mounted on the head unit 30 It is comprised with the maintenance apparatus 40 which performs.

  The paper transport mechanism 20 is configured by a belt transport mechanism, and adsorbs the paper P to the traveling belt 22 and transports the paper P horizontally in the Y direction.

  The head unit 30 mainly includes a head 32C that ejects cyan ink droplets, a head 32M that ejects magenta ink droplets, a head 32Y that ejects yellow ink droplets, and a head 32K that ejects black ink droplets. The head support frame 38 to which the heads 32C, 32M, 32Y, and 32K are attached, and a head support frame moving mechanism (not shown) that moves the head support frame 38 are configured.

  The heads (inkjet heads) 32C, 32M, 32Y, and 32K are constituted by line heads corresponding to the maximum paper width of the paper P to be printed (width in the X direction orthogonal to the Y direction). Since the configurations of the heads 32C, 32M, 32Y, and 32K are the same, in the following, they are described as the heads 32 unless otherwise distinguished.

  The head 32 (32C, 32M, 32Y, 32K) is formed in a rectangular block shape, and a nozzle surface 33 (33C, 33M, 33Y, 33K) is formed on the bottom thereof.

  FIG. 8 is a perspective view of the head 32. The figure shows a state where the nozzle surface 33 is looked up from below the head 32 (obliquely downward direction). The head 32 has a plurality of head modules 34 arranged in the width direction of the paper P and fixed to the housing 36 so as to be elongated. Here, an example in which the 17 head modules 34 are connected is shown, but the configuration of the modules, the number of modules, and the arrangement form are not limited to the illustrated examples.

  Although the number of nozzles 50 formed on the nozzle surface 33 of the head module 34 and the arrangement form thereof are not particularly limited, FIG. 9 shows an example thereof.

  FIG. 9 is a plan view of the nozzle surface 33 (viewed from the discharge side), and shows one head module 34 here. Here, although the number of nozzles is omitted, for example, 32 × 64 nozzles 50 are two-dimensionally arranged on the nozzle surface 33 of one head module 34.

  This head module 34 has an end surface on the long side along the v direction having an inclination of angle γ with respect to the X direction, and an end surface on the short side along the w direction having an inclination of angle α with respect to the Y direction. The plane shape of a parallelogram having As shown in FIG. 8, by connecting a plurality of head modules 34 configured in this manner in the X direction, a nozzle row that covers the entire drawing range for the width of the paper P is formed, and one drawing scan is performed. A full-line head capable of recording an image with a predetermined recording resolution (for example, 1200 dpi) is configured.

  Further, the head 32 of the present embodiment ejects ink droplets from the nozzles 50 by a so-called piezo method. Each nozzle 50 communicates with a pressure chamber, and ink droplets are ejected from the nozzle 50 by vibrating the wall surface of the pressure chamber with a piezoelectric element. The ink ejection method is not limited to this, and a thermal ejection method may be employed.

  Returning to the description of FIGS. 5 to 6, the head support frame 38 (corresponding to the head holding means) includes a head attachment portion (not shown) for attaching each head 32. Each head 32 is detachably attached to the head attachment portion.

  Each head 32 attached to the head support frame 38 is disposed orthogonal to the transport direction (Y direction) of the paper P. Further, the paper P is arranged in a predetermined order at a constant interval along the conveyance direction of the paper P (in this example, the paper P is arranged in the order of cyan, magenta, yellow, and black).

  The head mounting portion is provided on the head support frame 38 so as to be movable up and down, and is moved up and down by a lifting mechanism (not shown). Each head 32 attached to the head attaching portion is raised and lowered vertically with respect to the transport surface of the paper P by this lifting mechanism.

  The head support frame moving mechanism slides the head support frame 38 horizontally in the X direction at a position above the paper transport mechanism 20.

  The head support frame moving mechanism includes, for example, a ceiling frame that is horizontally installed across the paper transport mechanism 20, a guide rail laid on the ceiling frame, a traveling body that slides on the guide rail, and its traveling It is comprised by the drive means (for example, feed screw mechanism etc.) which moves a body along a guide rail. The head support frame 38 is attached to the traveling body and slides horizontally.

  The head support frame 38 is driven by the head support frame moving mechanism, and is provided so as to be movable between a predetermined “image recording position” and “maintenance position”.

  The head support frame 38 is disposed above the paper transport mechanism 20 when positioned at the image recording position. Accordingly, it is possible to record an image by ejecting ink of each color onto the recording surface of the paper P conveyed by the paper conveyance mechanism 20.

  On the other hand, when it is located at the maintenance position, it is arranged at the installation position of the maintenance device 40.

[Configuration and operation of maintenance equipment]
As shown in FIG. 6, the maintenance device 40 includes four moisturizing caps 42C, 42M, 42Y, and 42K that can moisturize the four heads 32C, 32M, 32Y, and 32K, respectively.

The moisturizing caps 42C, 42M, 42Y, and 42K are filled with moisturizing liquid by a moisturizing liquid supply mechanism (not shown). The moisturizing caps 42C, 42M, 42Y, and 42K are held by elastic members 44C, 44M, 44Y, and 44K on the bottom surface. The opening area of the moisturizing cap 42 (the area of the gas-liquid interface of the moisturizing liquid stored inside the moisturizing cap 42) is A [m ² ], the density of the moisturizing liquid is ρ [kg / m ³ ], and the gravitational acceleration is g [ N / m], the elastic member 44 has its spring constant k set to the value of (Equation 1), and holds the moisturizing cap 42 in the upward direction.

  FIG. 10 is a side view of the maintenance device 40. In the maintenance position, the heads 32C, 32M, 32Y, and 32K are moved up and down perpendicularly to the surface of the moisturizing liquid in the moisturizing caps 42C, 42M, 42Y, and 42K by an elevating mechanism (not shown). The elevating mechanism is located at a position where the distance between the nozzle surfaces 33C, 33M, 33Y, 33K of the heads 32C, 32M, 32Y, 32K and the liquid surface of the moisturizing liquid in the moisturizing caps 42C, 42M, 42Y, 42K is s. The head support frame 38 is fixed and held.

  Therefore, the humidity of the nozzle surfaces 33C, 33M, 33Y, and 33K (humidity near the nozzle) is set to a desired range (for example, 80%) by the transpiration of the moisturizing liquid stored in the moisturizing caps 42C, 42M, 42Y, and 42K. ) Can be maintained.

  In each head 32, a gap may be formed at a joint portion of the head module 34, and a sealed space cannot be formed by each head 32 and each of the moisturizing caps 42 </ b> C, 42 </ b> M, 42 </ b> Y, 42 </ b> K. Therefore, the moisturizing liquid inside the moisturizing caps 42C, 42M, 42Y, 42K is reduced by evaporation.

  However, as in the first embodiment, the spring constants k of the elastic members 44C, 44M, 44Y, and 44K are set to the values of (Equation 1), respectively, so that the liquid of the moisturizing liquid inside the moisturizing cap 42C. The amount of descent of the surface and the amount of displacement of the elastic member 44C, the amount of descent of the surface of the moisturizing liquid inside the moisturizing cap 42M and the amount of displacement of the elastic member 44M, the amount of descent of the surface of moisturizing liquid inside the moisturizing cap 42Y and the elasticity. The amount of displacement of the member 44Y, the amount of descent of the surface of the moisturizing liquid inside the moisturizing cap 42K, and the amount of displacement of the elastic member 44K become equal.

  Accordingly, the moisturizing caps 42C, 42M, 42Y, and 42K are raised by the displacement of the elastic members 44C, 44M, 44Y, and 44K by the amount that the moisturizing liquid inside the moisturizing caps 42C, 42M, 42Y, and 42K is decreased and the liquid level is lowered. In addition, the liquid level of the moisturizing liquid viewed from the outside of the moisturizing caps 42C, 42M, 42Y, and 42K is kept constant.

  That is, regardless of the amount of decrease in the moisturizing liquid, the distance between the nozzle surface 33C and the liquid surface of the moisturizing liquid in the moisturizing cap 42C, the distance between the nozzle surface 33M and the liquid surface of the moisturizing liquid in the moisturizing cap 42M, the nozzle surface 33Y. The distance between the surface of the moisturizing liquid in the moisturizing cap 42Y and the distance between the nozzle surface 33K and the liquid surface of the moisturizing liquid in the moisturizing cap 42K are constant at s. Thereby, the humidity of the nozzle surfaces 33C, 33M, 33Y, and 33K can be maintained at an appropriate humidity regardless of the amount of reduction (evaporation amount) of the moisturizing liquid.

  In this embodiment, the four heads 32C, 32M, 32Y, and 32K are each provided with four moisturizing caps 42C, 42M, 42Y, and 42K that can moisturize, but as shown in FIGS. 11 and 12, the four heads are provided. A moisturizing cap 42 'having a size capable of moisturizing 32C, 32M, 32Y, 32K at the same time may be provided.

In this case, the opening area of the moisturizing cap 42 ′ (the area of the gas-liquid interface of the moisturizing liquid stored inside the moisturizing cap 42 ′) is A [m ² ], and the density of the moisturizing liquid is ρ [kg / m ³ ]. If the gravitational acceleration is g [N / m], the moisturizing cap 42 ′ may be pressed and held upward by the elastic member 44 ′ with the spring constant k set to the value of (Equation 1).

  11 and 12 is a moisturizing liquid supply section (corresponding to the moisturizing liquid supply means), and can supply the moisturizing liquid from the moisturizing liquid supply section 46 to the inside of the moisturizing cap 42 '. It has become. Thereby, the nozzle surface 33 of the head 32 can always be moisturized without emptying the moisturizing liquid in the moisturizing cap 42 '.

  Thus, according to the present embodiment, the liquid level of the moisturizing liquid can be maintained at a constant height without detecting the amount of the moisturizing liquid, so that the nozzle surface of the inkjet head and the liquid level of the moisturizing liquid The distance can be made constant. Thereby, the humidity of the nozzle surface of the inkjet head in a storage state can be maintained at an appropriate humidity with a simple and inexpensive configuration, and the quality of the inkjet head can be maintained.

  Moreover, since the opening surface of the moisture retention cap is made larger than the bottom surface of the head, the risk of collision between the moisture retention cap and the head when the moisture retention cap is raised can be reduced.

<Third Embodiment>
[Maintenance device configuration]
FIG. 13A is a diagram schematically showing a maintenance device 120 for an inkjet head according to the present embodiment. As shown in the figure, the maintenance device 120 includes a slide guide 122, a head holding unit 124, a moisturizing liquid 126, a moisturizing cap 128, an elastic member 130, and the like.

  As in the first embodiment, the inkjet head 102 has a nozzle surface 102a on which a plurality of nozzles that eject ink droplets are arranged. The head holding unit 124 holds the inkjet head 102 by inclining the nozzle surface 102 a of the inkjet head 102 by an angle θ [°] with respect to the horizontal plane.

  Similar to the moisture retention cap 108 of the first embodiment, the moisture retention cap 128 is configured such that the opening surface thereof is larger than the bottom surface of the inkjet head 102, and the bottom surface (surface having the nozzle surface 102 a) of the inkjet head 102 is opened. It can be accommodated from the surface.

  Similar to the moisturizing liquid 106 of the first embodiment, the moisturizing liquid 126 is a liquid containing, for example, water as a main component. A moisturizing liquid 126 is stored in the moisturizing cap 128.

  The moisturizing cap 128 is held on the bottom surface by the elastic member 130 and is placed at an angle θ with respect to the horizontal plane by the slide guide 122. The slide guide 122 is a guide member that contacts the moisturizing cap 128 and guides the sliding movement of the moisturizing cap 128. The elastic member 130 presses and holds the moisturizing cap 128 in a direction inclined by an angle θ from the vertical direction, and the moisturizing cap 128 in a direction inclined by an angle θ with respect to the vertical direction along the slide guide 122. It is movable.

Here, the area of the gas-liquid interface of the moisturizing liquid 126 stored in the moisturizing cap 128 is A ′ [m ² ], the density of the moisturizing liquid 126 is ρ [kg / m ³ ], and the gravitational acceleration is g [N / m], the spring constant k ′ of the elastic member 130 is
k ′ = A ′ × ρ × g × cos ² θ (Formula 2)
Is set to

  As the elastic member 130, a sponge, an air spring, or the like can be used in addition to a general compression coil spring.

[Operation of maintenance equipment]
As shown in FIG. 13A, the head holding unit 124 is arranged so that the nozzle surface 102a of the inkjet head 102 and the liquid surface of the moisturizing liquid 126 in the moisturizing cap 128 are opposed to each other with an angle θ. The inkjet head 102 is fixed and held at a position where the distance between the center of the surface 102a and the liquid level is s.

  As described with reference to FIG. 3, the humidity between the nozzle head and the liquid surface of the moisturizing liquid 126 is dominant in the humidity near the nozzle. According to the maintenance device 120, the humidity of the nozzle surface 102a (humidity near the nozzle) is maintained in a desired range (for example, 80%) by the transpiration of the moisturizing liquid 126 stored in the moisturizing cap 128. .

  Further, as in the first embodiment, the moisturizing liquid 126 inside the moisturizing cap 128 decreases due to evaporation.

Here, as shown in FIG. 13B, it is assumed that the liquid level of the moisturizing liquid 126 in the moisturizing cap 128 is lowered by h due to the decrease in the moisturizing liquid 126. At this time, since the weight of the reduced moisturizing liquid 126 is ρ × A ′ × h [kg], the displacement amount x of the elastic member 130 is
x = F / k = (ρ × A ′ × h × g × cos θ) / (A ′ × ρ × g × cos ² θ)
= H / cos θ
It becomes. Since the elastic member 130 holds the moisturizing cap 128 in a direction inclined by an angle θ from the vertical direction, the vertical component of the displacement amount of the elastic member 130 is h.

  Thus, the amount of descent of the liquid level of the moisturizing liquid 126 inside the moisturizing cap 128 is equal to the vertical component of the amount of displacement of the elastic member 130. As a result, the moisturizing liquid 126 inside the moisturizing cap 128 evaporates and decreases, and the liquid level is lowered, so that the moisturizing cap 128 is raised by the elastic member 130, and the liquid of the moisturizing liquid 126 seen from the outside of the moisturizing cap 128 The surface is kept constant.

  That is, regardless of the amount of decrease in the moisturizing liquid 126, the distance between the central portion of the nozzle surface 102a and the liquid surface of the moisturizing liquid 126 is constant at the initial set distance s. Therefore, the humidity of the nozzle surface 102a can be maintained at an appropriate humidity regardless of the decrease amount (evaporation amount) of the moisturizing liquid 126.

  Thus, even when the nozzle surface of the head is inclined at a predetermined angle from the horizontal plane, the liquid level of the moisturizing liquid can be maintained at a constant height without detecting the amount of the moisturizing liquid. The distance between the nozzle surface of the inkjet head and the liquid surface of the moisturizing liquid can be made constant. Thereby, the humidity of the nozzle surface of the inkjet head in a storage state can be maintained at an appropriate humidity with a simple and inexpensive configuration, and the quality of the inkjet head can be maintained.

  Moreover, since the opening surface of the moisture retention cap is made larger than the bottom surface of the head, the risk of collision between the moisture retention cap and the head when the moisture retention cap is raised can be reduced.

<Fourth Embodiment>
[Configuration of inkjet recording apparatus]
Next, an ink jet recording apparatus according to the fourth embodiment will be described. 14, 15, and 16 are a front view, a plan view, and a side view, respectively, showing the configuration of the main part of the ink jet recording apparatus.

  As shown in the figure, the ink jet recording apparatus 70 is a single-pass type line printer, and mainly includes a paper transport mechanism 72 that transports a paper (sheet) P that is a recording medium, and a paper transport mechanism 72. Maintenance of the head unit 80 that discharges ink droplets of each color of cyan (C), magenta (M), yellow (Y), and black (K) toward the conveyed paper P, and each head mounted on the head unit 80 And a maintenance device 90 for performing

  The paper transport mechanism 72 has a transport drum 74 that rotates by being driven by a motor (not shown). A gripper (not shown) is provided on the outer peripheral surface of the transport drum 74, and the paper P is transported while the leading end is gripped by the gripper. A large number of suction ports (not shown) are formed on the outer peripheral surface of the transport drum 74, and air is sucked inward from the suction holes. The paper P is conveyed while being sucked and held in the suction holes.

  The head unit 80 includes heads 82C, 82M, 82Y, and 82K that discharge cyan, magenta, yellow, and black ink droplets, a head support frame 88 to which the heads 82C, 82M, 82Y, and 82K are attached, and a head support frame. And a head support frame moving mechanism (not shown) for moving 88.

  The heads 82C, 82M, 82Y, and 82K are configured with line heads corresponding to the maximum sheet width (width in the X direction orthogonal to the Y direction) of the sheet P to be printed. Since the configurations of the heads 82C, 82M, 82Y, and 82K are the same, in the following, they are described as the heads 82 unless otherwise distinguished.

  The heads 82C, 82M, 82Y, and 82K are formed in a rectangular block shape like the heads 32C, 32M, 32Y, and 32K in the second embodiment, and the nozzle surfaces 83C, 83M, 83Y, and 83K are formed at the bottoms thereof. Is formed. Further, the number of nozzles formed on the nozzle surfaces 83C, 83M, 83Y, and 83K and the arrangement form thereof are not particularly limited. The head 82 ejects ink from the nozzles by a piezo method or a thermal method.

  The head support frame 88 includes a head attachment portion (not shown) for attaching each head 82. Each head 82 is detachably attached to the head attachment portion.

  Each head 82 attached to the head support frame 88 is arranged orthogonal to the transport direction (Y direction) of the paper P. Further, the paper P is arranged in a predetermined order at a constant interval along the conveyance direction of the paper P (in this example, the paper P is arranged in the order of cyan, magenta, yellow, and black).

The heads 82C, 82M, 82Y, and 82K are attached to the head support frame 88 so that the nozzle surfaces 83C, 83M, 83Y, and 83K are parallel to the circumferential surface of the conveying drum 74 that faces the heads. As shown in FIG. 17, the angles formed by the nozzle surfaces 83C, 83M, 83Y, and 83K and the horizontal plane are θ _C , θ _M , θ _Y , and θ _K , respectively.

  The head mounting portion is provided on the head support frame 88 so as to be lifted and lowered by a lifting mechanism (not shown). The heads 82 attached to the head attaching part are moved up and down perpendicular to the horizontal plane by the lifting mechanism.

  The head support frame moving mechanism slides the head support frame 88 horizontally in the X direction above the paper transport mechanism 72.

  Similar to the second embodiment, the head support frame moving mechanism is slidably moved on the ceiling frame horizontally installed across the paper transport mechanism 72, the guide rail laid on the ceiling frame, and the guide rail. And a driving means (for example, a feed screw mechanism) for moving the traveling body along the guide rail. The head support frame 88 is attached to the traveling body and slides horizontally.

  The head support frame 88 is driven by the head support frame moving mechanism, and is provided so as to be movable between a predetermined “image recording position” and “maintenance position”.

  The head support frame 88 is disposed above the paper transport mechanism 72 when positioned at the image recording position. Accordingly, it is possible to record an image by ejecting ink of each color onto the recording surface of the sheet P conveyed by the sheet conveying mechanism 72.

  On the other hand, when it is located at the maintenance position, it is placed at the installation position of the maintenance device 90.

[Configuration and operation of maintenance equipment]
FIG. 18 is a side view illustrating a configuration of a main part of the maintenance device 90. As shown in the figure, the maintenance device 90 includes four moisturizing caps 92C, 92M, 92Y, and 92K that can moisturize the four heads 82C, 82M, 82Y, and 82K, respectively.

  The moisturizing caps 92C, 92M, 92Y, and 92K are filled with moisturizing liquid by a moisturizing liquid supply mechanism (not shown).

The moisturizing caps 92C, 92M, 92Y, and 92K are held by elastic members 94C, 94M, 94Y, and 94K on the bottom surfaces thereof, respectively, and at angles θ _C and H with respect to the horizontal plane by the slide guides 96C, 96M, 96Y, and 96K, respectively. Mounted by tilting by θ _M , θ _Y , and θ _K.

The elastic members 94C, 94M, 94Y, and 94K hold the moisturizing caps 92C, 92M, 92Y, and 92K by pressing them in the directions inclined by the angles θ _C , θ _M , θ _Y , and θ _K from the vertical direction. The caps 92C, 92M, 92Y, and 92K are movable along the slide guides 96C, 96M, 96Y, and 96K in a direction inclined by angles θ _C , θ _M , θ _Y , and θ _K from the vertical direction.

The area of the gas-liquid interface of the moisturizing liquid stored in the moisturizing cap 92 is A ′ [m ² ], the density of the moisturizing liquid is ρ [kg / m ³ ], the acceleration of gravity is g [N / m], and the vertical direction Assuming that the inclination with respect to is θ, the spring constant k ′ of the elastic members 94C, 94M, 94Y, and 94K is set to the value of (Expression 2).

  In the maintenance position, the heads 82C, 82M, 82Y, and 82K are moved up and down perpendicularly to the surface of the moisturizing liquid in the moisturizing caps 92C, 92M, 92Y, and 92K by an elevating mechanism (not shown). The elevating mechanism is located at a position where the distance between the nozzle surfaces 83C, 83M, 83Y and 83K of the heads 82C, 82M, 82Y and 82K and the liquid surface of the moisturizing liquid in the moisturizing caps 92C, 92M, 92Y and 92K is s. The head support frame 88 is fixed and held (see FIG. 18).

  Therefore, the humidity of the nozzle surfaces 83C, 83M, 83Y, 83K (humidity near the nozzle) is set to a desired range (for example, 80%) by the transpiration of the moisturizing liquid stored in the moisturizing caps 92C, 92M, 92Y, 92K. ) Can be maintained.

  Further, the moisturizing liquid inside the moisturizing caps 92C, 92M, 92Y, 92K is reduced by evaporation. As in the second embodiment, the spring constants k of the elastic members 94C, 94M, 94Y, and 94K are set to the values of (Equation 2), respectively, so that the liquid level of the moisturizing liquid inside the moisturizing cap 92C The amount of descent and the amount of displacement of the elastic member 94C, the amount of descent of the liquid level of the moisturizing liquid inside the moisturizing cap 92M and the amount of displacement of the elastic member 94M, the amount of descent of the liquid level of moisturizing liquid inside the moisturizing cap 92Y and the elastic member 94Y , The descent amount of the moisturizing liquid level inside the moisturizing cap 92K and the displacement amount of the elastic member 94K are equal to each other. Accordingly, the moisturizing caps 92C, 92M, 92Y, and 92K are raised by the displacement of the elastic members 94C, 94M, 94Y, and 94K by the amount that the moisturizing liquid inside the moisturizing caps 92C, 92M, 92Y, and 92K is decreased and the liquid level is lowered. And the liquid level of the moisturizing liquid seen from the outside of the moisturizing caps 92C, 92M, 92Y, 92K is kept constant.

  That is, regardless of the amount of moisturizing liquid decreased, the distance between the nozzle surface 93C and the moisturizing liquid surface in the moisturizing cap 92C, the distance between the nozzle surface 93M and the moisturizing liquid surface in the moisturizing cap 92M, and the nozzle surface 93Y. The distance between the surface of the moisturizing liquid in the moisturizing cap 92Y and the distance between the nozzle surface 93K and the liquid surface of the moisturizing liquid in the moisturizing cap 92K are constant at s. Thereby, the humidity of the nozzle surfaces 93C, 93M, 93Y, and 93K can be maintained at an appropriate humidity regardless of the decrease amount (evaporation amount) of the moisturizing liquid.

  Thus, when applied to an ink jet recording apparatus in which the nozzle surface of the head is inclined at a predetermined angle from the horizontal plane, the liquid level of the moisturizing liquid is maintained at a constant height without detecting the amount of the moisturizing liquid. Therefore, the distance between the nozzle surface and the liquid surface of the moisturizing liquid can be made constant while the nozzle surface of the head is inclined. Thereby, the humidity of the nozzle surface of the inkjet head in a storage state can be maintained at an appropriate humidity with a simple and inexpensive configuration, and the quality of the inkjet head can be maintained.

  Moreover, since the opening surface of the moisture retention cap is made larger than the bottom surface of the head, the risk of collision between the moisture retention cap and the head when the moisture retention cap is raised can be reduced.

<Fifth Embodiment>
[Maintenance device configuration]
FIG. 19A is a diagram schematically illustrating an inkjet head maintenance apparatus 140 according to the fifth embodiment. As shown in the figure, the maintenance device 140 includes a head holding portion 142, a moisture retention cap 144, a seesaw member 146, a fulcrum 148, a balance load member 150, and the like.

  The inkjet head 102 has a nozzle surface 102a on which a plurality of nozzles that eject ink droplets are arranged. The head holding unit 142 holds the inkjet head 102 facing downward so that the nozzle surface 102a of the inkjet head 102 is parallel to the horizontal plane.

  The moisturizing cap 144 is configured such that the opening surface thereof is larger than the bottom surface of the inkjet head 102, and the bottom surface of the inkjet head 102 can be accommodated from the opening surface. The moisturizing cap 144 stores a moisturizing liquid 126 for moisturizing the nozzle surface 102a.

  The moisturizing cap 144 is held by one end of the seesaw member 146 on the bottom surface. The balance load member 150 is held at the other end of the seesaw member 146.

  The seesaw member 146 is configured such that both ends thereof can move up and down around the fulcrum 148, and is displaced according to the mass of the moisturizing liquid 106 stored inside the moisturizing cap 108 (an example of a displacement means).

[Operation of maintenance equipment]
As shown in FIG. 19A, the seesaw member 146 is stable in a state where the left and right are balanced around the fulcrum 148. The head holding unit 142 is configured such that the nozzle surface 102a of the inkjet head 102 and the liquid surface of the moisturizing liquid in the moisturizing cap 144 face each other in parallel, and the distance between the center of the nozzle surface 102a and the liquid surface is s. The inkjet head 102 is fixed and held at the position.

  As described with reference to FIG. 3, the humidity near the nozzle is dominated by the distance between the inkjet head 102 and the surface of the moisturizing liquid. According to the maintenance device 140, the humidity of the nozzle surface 102a (humidity near the nozzle) is maintained in a desired range (for example, 80%) by the transpiration of the moisturizing liquid stored in the moisturizing cap 144.

  In addition, the moisturizing liquid 126 inside the moisturizing cap 128 decreases due to evaporation.

  Here, as shown in FIG. 19B, it is assumed that the liquid level of the moisturizing liquid in the moisturizing cap 144 is lowered by h due to the decrease in the moisturizing liquid. At this time, the right and left weight balance of the seesaw member 146 is lost, and the moisture retention cap 144 is raised by h.

  In this way, the moisturizing cap 144 is raised by the seesaw member 146 by the amount that the moisturizing liquid inside the moisturizing cap 144 is evaporated and decreased, and the liquid level is lowered, and the liquid level of the moisturizing liquid as viewed from the outside of the moisturizing cap 144 Is kept constant.

  That is, the distance between the nozzle surface 102a and the moisturizing liquid surface is constant at the initial set distance s, regardless of the amount of moisturizing liquid decreased. Therefore, the humidity of the nozzle surface 102a can be maintained at an appropriate humidity regardless of the amount of reduction (evaporation amount) of the moisturizing liquid.

  In this way, by using a seesaw-like configuration, the liquid level of the moisturizing liquid can be maintained at a constant height without detecting the amount of the moisturizing liquid. The distance from the surface can be made constant. Thereby, the humidity of the nozzle surface of the inkjet head in a storage state can be maintained at an appropriate humidity with a simple and inexpensive configuration, and the quality of the inkjet head can be maintained.

  The technical scope of the present invention is not limited to the scope described in the above embodiment. The configurations and the like in the embodiments can be appropriately combined between the embodiments without departing from the gist of the present invention.

  DESCRIPTION OF SYMBOLS 10,70 ... Inkjet recording apparatus, 32 ... Head, 33, 102a ... Nozzle surface, 34 ... Head module, 42, 42 ', 92, 108, 128, 144 ... Moisturizing cap, 44, 44', 94, 110, 130 ... elastic member, 50 ... nozzle, 90, 100, 120 ... maintenance device, 96, 122 ... slide guide, 102 ... inkjet head, 104, 124, 142 ... head holding part, 106, 126 ... moisturizing liquid, 146 ... seesaw member

Claims (10)

A moisturizing cap for storing a moisturizing liquid for moisturizing the nozzle formed on the nozzle surface of the inkjet head;
Elevating means for raising and lowering the moisturizing cap according to the amount of the moisturizing liquid stored and maintaining the liquid level of the moisturizing liquid at a constant height;
Head holding means for holding the nozzle surface of the inkjet head facing the liquid surface of the moisturizing liquid stored in the moisturizing cap;
Equipped with a,
The inkjet head maintenance apparatus , wherein the elevating means includes a displacement means that is displaced according to a mass of the moisturizing liquid stored in the moisturizing cap . The inkjet head maintenance apparatus according to claim 1 , wherein the displacement unit is an elastic body. When the surface area of the moisturizing liquid is A, the density of the moisturizing liquid is ρ, and the gravitational acceleration is g, the spring constant k of the elastic body is
k = A × ρ × g
The maintenance apparatus of the inkjet head of Claim 2 represented by these. The head holding means holds the inkjet head with a predetermined angle between the nozzle surface and a horizontal plane,
A slide guide that allows the moisturizing cap to slide in a direction perpendicular to the predetermined angle;
The inkjet head maintenance apparatus according to claim 2 , wherein the elastic body is displaced in a direction perpendicular to the predetermined angle to raise and lower the moisture retention cap. When the predetermined angle is θ, the liquid surface area of the moisturizing liquid is A, the density of the moisturizing liquid is ρ, and the gravitational acceleration is g, the spring constant k ′ of the elastic body is
k ′ = A × ρ × g × cos ² θ
The maintenance apparatus of the inkjet head of Claim 4 represented by these. The inkjet head maintenance device according to claim 1 , wherein the displacement means is a seesaw means that holds a moisture retention cap at one end and a balance load member at the other end. The opening of the moisturizing cap maintenance device of the ink jet head according to any one of the claims 1 greater than the nozzle surface 6. The inkjet head maintenance apparatus according to any one of claims 1 to 7 , further comprising a moisturizing liquid supply unit configured to supply the moisturizing liquid to the moisturizing cap. An inkjet head having a nozzle surface on which nozzles for discharging ink are formed;
Moving means for relatively moving the inkjet head and the recording medium;
Control means for forming an image on a recording surface of the recording medium by ejecting ink from the nozzles while relatively moving the inkjet head and the recording medium;
A maintenance device for an inkjet head according to any one of claims 1 to 8 ,
An ink jet recording apparatus comprising: The ink jet recording apparatus according to claim 9 , wherein the ink jet head is an ink jet head configured as one head by arranging a plurality of head modules formed with nozzles for ejecting ink and arranging the head modules in a fixing member.

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