JP2008120040A - Recording head, method of manufacturing recording head, inkjet recording apparatus, ink jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to form high quality images by suppressing the misalignment of strike positions for main droplets and auxiliary droplets even when in rapid recording in a recording head ejecting a different kind of inks from each of a plurality of ejecting hole groups. <P>SOLUTION: The plurality of ejecting hole groups 41, 42 composed of a plurality of ejecting holes 4a which eject a liquid are formed on an ejecting element 11 of the recording head. The plurality of ejecting hole groups 41, 42 are formed on ejecting hole planes F1, F2 positioned on at least two planes intersecting by different angles θ1, θ2 to a standard plane F orthogonal to an axial line L1 of a nozzle 4 having the ejecting holes 4a at its front end. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a recording head capable of discharging a plurality of types of liquids, a manufacturing method thereof, and an ink jet recording apparatus and an ink jet recording method for recording an image using the recording head.

  An ink jet recording apparatus that performs recording by attaching droplets of fine ink or the like to a recording medium has low running cost and excellent quietness during recording. Further, this type of recording apparatus has an advantage that it is possible to record in color relatively easily by using a plurality of colors of ink. In addition, the so-called bubble jet method using a bubble generating element as a pressure generating element for discharging a droplet is relatively easy to arrange the elements at a high density, which is advantageous for high-resolution printing. It is a simple method.

  In an ink jet recording apparatus, a recording head capable of discharging a liquid such as ink using an electrothermal transducer (heater), a piezoelectric element, or the like is used. In the case of the recording head H using the electrothermal transducer 101 as shown in FIG. 11A, the liquid in the flow path 102 is caused to foam by the heat generated by the electrothermal transducer 101 (FIG. 11B, (See (c)). The liquid in the flow path is discharged from the discharge port 103 by the foaming energy of the bubbles B generated at this time. Thereafter, the bubbles B are defoamed as shown in FIGS. 11 (d) and 11 (e). Further, the recording head H shown here is provided with a movable valve 104 in the flow path 102 in order to effectively cause the foaming energy of the bubbles B to act in the direction of the discharge port 103. The ink jet recording apparatus records an image on a recording medium by adhering the liquid ejected from the ejection port 103 of the recording head H onto the recording medium. In such an ink jet recording apparatus, an improvement in recording speed as well as an improvement in image quality is an important development issue, and various proposals for implementing high speed recording have been made and implemented at present.

  However, with the recent increase in recording operation speed, new problems have become apparent in the recording head H. That is, as shown in FIG. 11D, when the liquid column pushed out from the discharge port 103 is divided to form a droplet (main droplet), the main droplet is usually used as shown in FIG. Along with Dm, a sub-droplet Ds called satellite is formed. Then, as shown in FIGS. 12B and 12C, the main droplet Dm and the sub-droplet Ds are displaced on the recording medium and land, thereby causing a problem that the image quality is deteriorated.

  As shown in the velocity vector of FIG. 12A, the discharge speed Vs of the sub-drop Ds is lower than the discharge speed Vm of the main drop Dm. For this reason, as the relative moving speed Vf between the recording head H and the recording medium W increases, the landing position deviation d between the main droplet Dm and the sub-droplet Ds increases. In FIGS. 12A, 12B, and 12C, the recording medium W is represented as moving relative to the recording head H. In the figure, D1 is a dot formed on the recording medium W by the main droplet Dm, and D2 is a dot formed on the recording medium W by the sub droplet Ds.

  Conventionally, in order to suppress such a deviation in the landing positions of the main droplet and the sub-droplet, the surface between the surface on which the ejection port of the recording head H is formed (hereinafter referred to as the ejection port surface) and the recording medium are conventionally used. The distance h (see FIG. 12) is shortened or the liquid discharge speed is increased.

  On the other hand, Patent Document 1 describes a configuration for matching the ejection directions of the main droplet and the sub droplet of ink. In the configuration of Patent Document 1, the forming material of the nozzle including the discharge port and the flow path is partially different, and the main droplet and the satellite are discharged in the discharge direction due to the difference in surface energy between the materials, that is, the difference in wettability with respect to ink. It was made paying attention to slipping. That is, the discharge port surface is inclined so that the flow channel portion on the side where the material having a small surface energy is located is shorter than the flow channel portion on the side where the material having a large surface energy is positioned, thereby The discharge direction is made to coincide.

JP 2000-263788 A

  As described above, even if an attempt is made to shorten the distance h between the ejection port surface of the recording head and the recording medium in order to suppress the deviation of the landing positions of the main droplet and the sub-droplet, there is a limit to shortening the distance h. is there. That is, if the distance h is too short, there is a possibility that the recording medium on which cockling has occurred due to the application of liquid (ink) will come into contact with the ejection port surface of the recording head. In addition, the liquid bounced off the surface of the recording medium or the mist-like liquid may adhere to the discharge port surface, resulting in liquid discharge failure. Accordingly, the distance h needs to be maintained at a certain interval.

  As described above, in order to cope with further increase in recording speed, the method of shortening the distance h between the ejection port surface of the recording head and the recording medium can sufficiently prevent the landing positions of the main droplet and the secondary droplet from shifting. It is difficult to suppress.

  On the other hand, Patent Document 1 describes a configuration for simply matching the ejection directions of the main droplet and the sub-droplet as shown in FIG. However, with such a configuration, it is possible to suppress the problem accompanying the further increase in the recording speed as shown in FIGS. 12B and 12C, that is, the increase in the deviation of the landing positions of the main droplet and the sub-droplet. Can not.

  As described above, conventionally, it is not possible to sufficiently suppress the deviation of the landing positions of the main droplets and the sub-drops that increase as the recording speed increases. In particular, it is difficult to meet the demands required for industrial inkjet recording apparatuses, that is, higher recording speed and higher image quality.

  On the other hand, it has been proposed to use a single recording head in order to avoid an increase in the size of the recording apparatus when configuring a recording apparatus capable of realizing multicoloring and spot colorization. In this single recording head, a plurality of common liquid chambers for discharging different types of ink are divided and formed therein, and a plurality of discharge chambers are formed on the discharge port surface, which is the surface facing the recording medium. A plurality of types of nozzle port groups corresponding to the common liquid chamber are formed. Then, different ink is ejected from each nozzle port group. This recording head can be reduced in size as compared with a case where a plurality of separate recording heads that discharge different inks are arranged in parallel, and the recording apparatus using the recording head can also be reduced in size. Have.

  However, since liquids have different compositions depending on the type, physical properties such as viscosity and surface tension are different, and accordingly, the flying speed of the droplets is also different. For this reason, depending on the type of liquid used for recording, there are cases where the liquid droplets accurately land on the planned landing positions on the recording medium and cases where the liquid droplets land on positions shifted from the planned landing positions. Therefore, in multi-color or spot color recording using a plurality of types of liquids, there will be a mixture of the part where the landing position is not misaligned and the part where it is generated. It is causing a decline.

  The object of the present invention is to enable the formation of a high-quality image by suppressing the deviation of the landing positions of the main droplet and the sub-droplet even in high-speed recording in a recording head that discharges different types of ink from each of a plurality of ejection port groups The purpose is to.

  In order to achieve the above object, the present invention has the following configuration.

  The first aspect of the present invention is different from a reference plane orthogonal to an axis of a nozzle having the discharge port at a tip in a recording head in which a plurality of discharge port groups each including a plurality of discharge ports for discharging a liquid are formed. A recording head, wherein the plurality of discharge port groups are formed on discharge port surfaces located on two or more planes that intersect at an angle.

  According to a second aspect of the present invention, there is provided a recording head manufacturing method including a plurality of discharge port groups each including a plurality of discharge ports for discharging a liquid, wherein the discharge port forming unit is formed by forming the plurality of discharge port groups. A plurality of different flat surfaces are formed in the discharge port forming portion by sliding a planar polishing member at least at a part thereof at an angle not orthogonal to the axis of the nozzle communicating with the discharge port.

  According to a third aspect of the present invention, there is provided a moving unit that relatively moves the recording head and the recording medium, and a control unit that discharges liquid from the recording head while relatively moving the recording head and the recording medium. It is characterized by providing.

  According to a fourth aspect of the present invention, there is provided a discharge port forming portion for forming a plurality of discharge ports for discharging liquid, and a plurality of types of discharge port groups for discharging different inks are formed in the discharge port forming portion. In an ink jet recording method for recording an image using a recording head, the recording head is positioned on two or more planes that intersect at different angles with respect to a reference plane orthogonal to an axis of a nozzle having the discharge port at the tip. The plurality of ejection port groups are formed on the ejection port surface, and the recording medium is ejected from the plurality of ejection port groups while relatively moving the recording medium and the recording head positioned on the reference plane. It is characterized by recording on the top.

  According to the present invention, since the plurality of discharge port groups are formed on the plurality of discharge port surfaces intersecting the reference plane orthogonal to the nozzle axis, the direction in which the main droplet is discharged from each discharge port, The direction in which the droplets are ejected can be actively changed. For this reason, it is possible to suppress the deviation of the landing positions of the main droplet and the sub droplet on the recording medium. In addition, in the present invention, since the angles formed by the plurality of ejection port surfaces and the reference plane are different, different types of ink are ejected from different ejection port surfaces, so that the landing of the main droplet and the sub-droplet depends on the type of ink. It is possible to further suppress the positional deviation. As a result, it is possible to achieve high image quality while increasing the recording speed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a perspective view showing an inkjet recording head H (hereinafter simply referred to as a recording head) to which the present invention is applied.
In FIG. 1, reference numeral 10 denotes a ceramic plate that forms the bottom of the recording head H. Disposed on the ceramic plate 10 are an ejection element 11 that ejects ink droplets, and a flow path forming member 12 that covers the left and right side surfaces and the upper surface of the ejection element 11. In the ejection element 11, a plurality of nozzles that eject ink are arranged at a predetermined density. In the present specification and claims, a nozzle refers to an ink discharge port, which will be described later, a liquid path communicating therewith, and an electricity as a discharge energy generating element that generates discharge energy for discharging ink. It shall include a thermal conversion element.

  In addition, a plurality of common liquid chambers communicating with each nozzle are formed in the recording head H, and a plurality of types of ink supplied from an ink tank (not shown) are formed in the common liquid chamber. The ink is supplied through the ink supply port 3 a provided in the member 12.

FIG. 2 is a partially cutaway perspective view of the vicinity of the nozzles in the recording head 10.
The heater board 1 is provided with a plurality of heaters (electrothermal converters) 2 for heating and foaming ink. As the heater 2, a resistor such as tantalum nitride is used. For example, the thickness is 0.01 to 0.5 μm, and the sheet resistance is 10 to 300Ω per unit square. The heater 2 is connected to an electrode (not shown) such as aluminum for energization. One of the electrodes is connected to a switching transistor (not shown) for controlling energization to the heater 2. The switching transistor is driven and controlled by an IC including a circuit such as a control gate element, and controls the heater 2 in accordance with a signal from the recording apparatus.

  The heater 2 is formed in each of the plurality of flow paths 3. One end of each flow path 3 communicates with the corresponding discharge port 4 a, and the other end of each flow path 3 communicates with the common liquid chamber 5. The flow path 3 is surrounded by the heater board 1, the nozzle wall 6, the nozzle bank 7 having a thickness of about 5 to 10 μm, and the top plate nozzle 8 having a thickness of about 2 μm to form a tubular shape. In this example, the nozzle wall 6, the nozzle bank 7, and the top plate nozzle 8 are made of a photosensitive epoxy resin.

  A movable valve 9 is provided in the flow path 3. The free end 9A of the movable valve 9 is located on the discharge port 4a side, and the base end is located on the common liquid chamber 5 side. The base end side of the movable valve 9 is attached to the heater board 1 by a valve seat 10 (see FIG. 3). The top nozzle 8 is attached to a flow path forming member 12 formed of Si or the like. In the flow path forming member 12, an ink supply port 3a (see FIG. 1) is formed by anisotropic etching or the like. Liquid ink is supplied from the outside into the common liquid chamber 5 through the ink supply port 3 a, and the ink supplied into the common liquid chamber 5 is supplied into the respective flow paths 3.

  The liquid supplied from the common liquid chamber 5 to the nozzle 4 is heated by the heater 2 disposed at a predetermined position in the nozzle 4 to be foamed. Along with this foaming, the movement of the liquid in the nozzle 4 is started and the movable valve 9 is displaced to restrict the flow of the liquid to the common liquid chamber side. As a result, the foaming energy is efficiently converted into a liquid flow toward the discharge port 4a and discharged from the discharge port 4a. Further, as can be seen from the cross section of the flow path forming member 12 in FIG. 2, the discharge port surface F, which is a plane including the discharge port 4a, has an inclination of an angle θ.

  As shown in FIGS. 3 to 5, the discharge port surface F is not orthogonal to the axis 3 of the flow path 3 (the axis of the nozzle 4) L1, and the normal L2 and the axis L1 of the discharge port surface F are at an angle θ. Tilt with. The ejection port surface F is inclined so as to face the direction (arrow Y2 direction) opposite to the conveyance direction Y1 of the recording medium W, that is, the relative movement direction of the recording head H with respect to the recording medium W. Accordingly, the ejection port surface F is also a surface that is inclined by an angle θ with respect to a plane (reference plane) F0 perpendicular to the axis L1 in the relative movement direction (arrow Y2 direction) of the recording head H. The size of the angle θ is set in consideration of the relative moving speed of the recording medium W and the recording head H, as will be described later.

FIG. 3 is an explanatory diagram of the discharge process of ink droplets from the discharge port 4a.
FIG. 3A shows a state before the heater 2 is not energized and the ink in the flow path 3 is heated. The ink in the vicinity of the discharge port 4a forms a concave arcuate meniscus M.
FIG. 3B and FIG. 3C show a state in which the heater 2 is energized and the ink is heated by the heat generation, thereby causing the foam B to occur with ink film boiling. At this time, the propagation direction of the pressure based on the generation of the bubbles B is guided in the ink ejection direction when the movable valve 9 is displaced with the valve pedestal 11 side as a fulcrum. The ink in the flow path 3 is pushed out from the discharge port 4a by the pressure generated by the foaming, and forms a liquid column as shown in FIG.

  FIG. 3D and FIG. 3E show a state where the heating of the ink by the heater 2 is completed and the bubble B is in the contraction process. In this state, the ink near the ejection port 4 a is drawn into the flow path 3 as the bubbles B contract. Since the inertia force in the ejection direction acts on the tip of the liquid column, the liquid column is separated from the ink in the flow path 3. The separated liquid column forms a main droplet Dm and a sub-droplet (satellite) Ds by the surface tension of the ink, and flies toward the recording medium.

The discharge directions of the main droplet Dm and the sub droplet Ds are different as follows because the discharge port surface F has a predetermined angle θ.
That is, as shown in FIGS. 3B and 3C, the meniscus starts to advance in the discharge direction with the propagation of the pressure generated by the foaming. Then, the ink in the vicinity of the ejection port 4a is pushed out from the ejection port 4a while maintaining an equal contact angle α with respect to the nozzle bank 7 and the top plate nozzle 8 on the ejection port surface F as shown in FIG. . At this time, the angle formed between the direction A1 in which the ink is pushed out and the axis L1 of the flow path 3 is the inclination angle θ of the ejection port surface F as shown in FIG. That is, the ink in the vicinity of the discharge port 4a is pushed out in the direction of the arrow A1 along the normal line L2 orthogonal to the discharge port surface F as shown in FIGS. 3B, 3C, and 4B. become. On the other hand, as shown in FIGS. 3C and 3D, the ink positioned in the vicinity of the heater 2 is pushed out in the direction of the arrow A <b> 2 along the direction of the axis L <b> 1 of the flow path 3.

  Thereafter, when the bubble B enters the contraction process as shown in FIG. 3D, the ink in the vicinity of the ejection port 4 is drawn into the flow path 3, and the main droplet Dm and the sub-droplet Ds as shown in FIG. Is formed. The main droplet Dm and the sub-drop Ds are different in the direction of extrusion by foaming. For this reason, as shown in FIG. 3E, the main droplet Dm flies in the direction of the arrow A1 that forms an angle θ with the axis L1, and the subdrop Ds moves in the nozzle axial direction due to the influence of the liquid drawn into the flow path 3. Flies in a direction with a slight angle (arrow A2 direction). In FIG. 3 (e), an angle that can be discriminated is shown for the sake of explanation. However, since it is a very small angle in actual ejection, it can be considered that it flies almost in the direction of the nozzle axis L1.

  The angle θ of the ejection port surface F, that is, the ejection angle θ of the main droplet Dm is basically desirably set according to the configuration and control conditions of the recording apparatus 120 on which the recording head 110 is mounted. Below, an example of the basic setting method of angle (theta) is demonstrated based on FIG.

Now, the ejection speed of the main droplet Dm is Vm, the ejection speed of the sub-droplet Ds is Vs, the moving speed of the recording head W is Vf, and the distance between the ejection port 4 and the recording medium W is h. At this time, as shown in FIG. 11 and FIG. 12, the displacement d as shown in Equation 1 is present at the landing positions of the main droplets Dm and the sub-drops Ds discharged from the conventional recording head H in which the discharge port surface is not inclined. appear.
d = (1 / Vs−1 / Vm) × h × Vf (Formula 1)

  As described above, in the conventional recording head shown in FIGS. 11 and 12, the landing positions of the main droplets Dm and the sub-droplets Ds are shifted according to the ink ejection speeds Vm, Vs, the distance h, and the transport speed Vf. Therefore, there is a possibility that the image quality is deteriorated.

On the other hand, in the recording head H of this example shown in FIG. 5, the angle θ is set so as to satisfy the condition of the following formula 2, and the angle of the discharge port surface F is set based on this θ.
{(1 / Vs) −1 / (Vm · cos θ)} × h × Vf = h · tan θ
Here, when the above equation is arranged, the following equation is obtained.
1 / Vs−1 / (Vm · cos θ) = tan θ / Vf Equation 2

  By setting the angle θ so as to satisfy Expression 2, the landing positions of the main droplet Dm and the sub droplet Ds on the recording medium W can be substantially matched, and a high-quality image can be formed.

  However, in the configuration in which a plurality of colors of ink can be ejected from a single recording head as in this embodiment, the physical characteristics (viscosity and surface tension) of the ink may be different. In this case, a difference occurs in the flying speed Vm of the droplet, and due to the difference in the flying speed, the landing position deviation amount d between the main droplet Dm and the secondary Ds is as shown in FIG. There is a difference. In other words, the deviation d of the landing position (position indicated by black in FIG. 6A) between the main droplet Dm and the sub-drop Ds of the ink having a relatively slow flying speed is the main droplet of the ink having a relatively slow flying speed. This is larger than the shift amount d between the landing positions of Dm and the sub-drops Ds (positions indicated by hatching in FIG. 6A).

  As described above, the angle θ of the ejection port surface suitable for matching the landing positions of the main droplet Dm and the sub-droplet Ds varies depending on the ejection speed due to physical characteristics such as ink viscosity. For this reason, when only one type of ink is assumed and the angle θ of the ejection port surface of the recording head is set uniformly, as shown in FIG. 6B, a deviation of the landing position occurs on the recording medium. There is a possibility that the part that does not occur and the part that occurs are mixed, leading to a decrease in image quality.

  Therefore, in the present embodiment, as shown in FIG. 7A, an angle corresponding to the ink ejection speed Vm is set for each ejection port surface including ejection port groups that eject different types of ink. . FIG. 7A shows a case where there are two types of ink droplet ejection speeds Vm. The discharge port surface F1 is a discharge port surface including a discharge port group including discharge ports that discharge ink having a relatively high discharge speed. As shown in FIG. 7B, the discharge port surface F1 is formed so as to form a relatively small angle θ1 with respect to the surface parallel to the recording medium W. Further, the discharge port surface F2 is a discharge port surface including a discharge port group composed of discharge ports having a relatively low discharge speed, and the discharge port surface F2 is connected to the recording medium W as shown in FIG. It is formed so as to make a relatively large angle θ2 with respect to the parallel plane (reference plane) F0. The angles θ1 and θ2 of the ejection port surfaces F1 and F2 are angles determined by applying the ejection speed of the ink ejected from each ejection port group to Equation 2 above.

  As described above, the angles of the ejection port surfaces F1 and F2 forming each ejection port group are set according to the ejection speed of the ink ejected from each ejection port group. Accordingly, in any ink, as shown in FIG. 6C, the landing positions of the main droplet Dm and the sub-drop Ds can be matched, and a high-quality image can be formed.

Next, an outline of a processing method for forming the discharge port surfaces F1 and F2 at different angles (for example, θ1 and θ2 in FIG. 6) on the single recording head H will be described with reference to FIG.
In the manufacturing process of the discharge element 11, there is a step of polishing for the purpose of removing minute chips and small scratches on the discharge port surface F and improving flatness. In this case, an abrasive sheet (abrasive member) S having abrasive grains fixed thereon is brought into contact with and sliding on the discharge port surface F. The polishing sheet S is configured to reciprocate in the direction of the arrow along a flat surface by the rotation of the rollers R1 and R2. In this polishing step, the flat surface portion P of the polishing sheet S is slid in contact with the discharge port surface at a desired angle and polished, whereby the discharge port surface 50 can be formed at a desired inclination angle. Further, the width of the polishing sheet S is matched to the width of the ejection port group that ejects ink of each color, and the contact angle between the polishing sheet S and the ejection port surface is made different for each ejection port group. Thereby, the discharge port surface of each discharge port group can be formed with a different inclination angle.

  Note that the recording head 110 in the first embodiment described above is a so-called edge shooter type, and the ink ejection direction and the ink supply direction into the nozzles substantially coincide. However, the present invention can also be applied to a so-called side shooter type recording head. In the side shooter type recording head, the ink ejection direction and the ink supply direction into the nozzles are different.

  Therefore, similarly to the above-described embodiment, the landing positions of the main droplet Dm and the sub droplet Ds on the recording medium W can be matched to record a high-quality image.

(Other embodiments)
The present invention can be applied not only to a recording head that discharges ink but also to a recording head (liquid discharging head) that can discharge various liquids that are used directly or indirectly for image recording. Further, the liquid discharge method in the recording head may be a method using a piezo element or the like in addition to a method using an electrothermal transducer (heater). In the edge shooter type recording head as in the first embodiment described above, the movable valve 10 is not necessarily provided.

  In the above-described embodiment, the nozzle wall 6, the nozzle bank 7, and the top plate nozzle 8 that form the peripheral surface of the discharge port are made of the same material, and their physical characteristics are made the same. However, among these peripheral surfaces, at least the top plate nozzle 8 on the arrow Y1 direction side and the nozzle bank 7 on the arrow Y2 direction side may be formed of the same material. These physical characteristics can include at least one of wettability to liquid or surface roughness, and if the physical characteristics are the same, different materials can be used for the peripheral portion of the discharge port. Good. In addition, an orifice plate in which a discharge port is formed may be attached to the opening of the liquid channel. Further, the material forming the peripheral edge of the discharge port may have different physical characteristics (including wettability with respect to the liquid), and in that case, the main droplet and the liquid droplet caused by those physical characteristics. In consideration of the difference in the discharge direction, the inclination angle of the discharge port can be set optimally.

(Embodiment of inkjet recording apparatus)
Next, an embodiment of a recording apparatus using the ink jet recording head described in the above embodiment will be described with reference to FIGS.
FIG. 9 is a perspective view schematically showing the external configuration of the recording apparatus 20 in the present embodiment. The recording apparatus 20 shown here transports the recording medium P in a certain direction (Y direction) and performs recording while reciprocating the recording head H along the direction (X direction) intersecting the transport direction of the recording medium P. A so-called serial scan type recording apparatus is configured. In the figure, reference numeral 21 denotes a carriage on which the recording head H shown in the above embodiment and an ink tank 22 for storing ink to be supplied are mounted. The carriage 21 is in a direction orthogonal to the conveyance direction Y of the recording medium P ( Reciprocate along the X direction). Various transport mechanisms for transporting the recording medium can be applied. Here, a transport roller that rotates by a driving force such as a motor and a pinch roller (both illustrated) provided opposite to the transport roller. (Omitted).

  FIG. 10 is a block diagram illustrating a schematic configuration of a control device 200 that controls driving of the recording apparatus. The control device 200 includes an image controller 201 that processes print data sent from the host computer 300. Further, the control device 200 includes an engine controller 202 that controls conveyance of the recording medium and movement of the carriage 21, a recording head controller 203 that controls ejection of ink droplets, and the like.

  The engine controller 202 includes a data rasterization unit 205, an ejection pulse generator 206, a transport control unit 207, a motor control unit 208, and the like. Among these, the data rasterization unit 205 performs rasterization processing for assigning serial print data sent from the image controller 101 to each nozzle. Further, the ejection pulse generator 206 sends ejection pulses representing the drive timing of the print head to the print head controller 203. The recording head controller 203 drives each nozzle (heater) of the recording head based on the pulse from the ejection pulse generator 205 and the image data sent from the data rasterizing unit 205.

  The conveyance control unit 207 controls the driving of the conveyance motor, and controls the rotation of the conveyance roller that is rotated by the driving force of the conveyance motor. The carriage motor control unit 107 detects the movement position of the carriage 22 based on a signal from the carriage scale encoder 204 and controls the carriage motor 210 to control the carriage drive, stop and acceleration, constant speed movement, deceleration, and the like. Do.

  In the recording apparatus configured as described above, the recording medium P is intermittently transported in the Y direction while being sandwiched between a transport roller that is rotated by the transport motor 105 and a pinch roller provided opposite to the transport roller. The The carriage 21 on which the recording head H is mounted moves during the stop period of the recording medium P, and performs recording within the nozzle arrangement range by discharging ink from the recording head H during the movement. By repeating this recording operation and the intermittent conveyance operation of the recording medium P, a predetermined image is formed on the recording medium P.

The present invention can also be applied to a full-line type inkjet recording apparatus in addition to the serial scan type inkjet recording apparatus as shown in FIG. In this case, a plurality of ejection port arrays (ejection port groups) in which ejection ports are arranged over a width equal to or larger than the maximum width of the recording medium to be used are arranged in parallel in a single recording head. Different inks are ejected. Furthermore, for each ejection port group, according to the physical characteristics of the ink ejected from the ejection port group, a reference plane orthogonal to the axis of each ejection port, and the ejection port surface on which each ejection port group is formed, Is defined (excluding θ = 0 °). This may be determined using the above-described equation 2 based on the relative movement direction of the recording head and the recording medium and the ejection speed of each ink. That is, in any ink, by preventing the axis (L1) of each nozzle and the normal (L2) of the discharge port surface (orifice surface F) where the discharge port is located, It is possible to match the landing positions with the secondary.
As described above, the liquid discharge head according to the present invention has a configuration having regions having different discharge port surface angles in the discharge element according to the ink to be discharged. Thereby, even in a recording head capable of discharging a plurality of liquids having different conditions, it is possible to prevent the landing position deviation between the main droplet and the satellite on the recording medium.

1 is a perspective view showing a recording head to which the present invention is applied. FIG. 2 is a partially cutaway perspective view of a portion near a nozzle of the recording head illustrated in FIG. 1. FIG. 2 is an explanatory diagram illustrating a discharge process of droplets at a discharge port of the recording head illustrated in FIG. 1. FIG. 2 is an explanatory diagram of a liquid ejection direction in the recording head illustrated in FIG. 1. FIG. 2 is an explanatory diagram illustrating landing positions of droplets ejected from the recording head illustrated in FIG. 1. It is explanatory drawing which shows the landing position of the main droplet and subdrop which were discharged from the recording head. 2A and 2B are diagrams illustrating discharge elements in the recording head illustrated in FIG. 1, in which FIG. 1A is a perspective view, FIG. 2B is a cross-sectional view taken along line B-B in FIG. 1A, and FIG. FIG. It is a perspective view which shows notionally the manufacturing apparatus of each discharge outlet surface of the discharge element shown in FIG. 1 is a perspective view showing a serial scan type inkjet recording apparatus in an embodiment of the present invention. 1 is a block diagram illustrating a schematic configuration of a control system of an ink jet recording apparatus according to an embodiment of the present invention. It is explanatory drawing which shows the discharge process of the droplet in the discharge outlet of the conventional recording head. It is explanatory drawing which shows the landing position of the droplet in the conventional recording head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heater board 2 Heater 3 Flow path 4 Discharge port 11 Discharge element F1, F2 Discharge port surface (theta) Angle L1 Axis line L2 Normal line F0 Reference plane Dm Main droplet Ds Sub droplet B Bubble Y1 Recording medium conveyance direction Y2 Relative movement of recording head direction

Claims (15)

In a recording head in which a plurality of ejection port groups each composed of a plurality of ejection ports that eject liquid are formed.
The plurality of discharge port groups are formed on discharge port surfaces located on two or more planes intersecting at different angles with respect to a reference plane perpendicular to the axis of the nozzle having the discharge port at the tip. Recording head.   An angle formed between each discharge port surface and a reference plane is determined according to the type of liquid discharged from each discharge port group located on each discharge port surface.   3. The recording head according to claim 1, wherein a step is formed at a connection portion of the ejection port surfaces having different angles with respect to the reference plane. Each of the discharge ports discharges a main droplet and a sub-drop with less liquid volume than the main droplet in one liquid discharge operation,
The discharge direction of the main droplet changes according to an angle formed by the region where the discharge port for discharging the main droplet is formed and the reference plane,
4. The recording according to claim 1, wherein the discharge direction of the sub-droplet changes according to an angle formed by an axis of the nozzle that discharges the sub-droplet and the reference plane. 5. head.   The recording head is held so as to be relatively movable along a linear direction on a plane parallel to the surface of the recording medium with respect to a recording medium existing at a position parallel to the reference plane. The recording head according to claim 4. When the discharge speed of the main droplet is Vm, the discharge speed of the sub-droplet is Vs, the relative movement speed between the recording head and the recording medium is Vf, and the distance from the nozzle to the recording medium is h,
The angle θ between the region and the reference plane is
1 / Vs−1 / (Vm · cos θ) = tan θ / Vf
The recording head according to claim 5, wherein the following condition is satisfied.   The recording head according to claim 1, wherein an ejection port surface on which the ejection port is located is inclined with respect to the reference plane toward a relative movement direction of the recording head.   The recording head according to claim 1, wherein the nozzle includes an electrothermal converter that generates thermal energy for discharging a liquid.   The recording head according to claim 9, wherein the nozzle includes a movable plate that is displaced according to foaming of the liquid generated by the thermal energy. A method for manufacturing a recording head comprising a plurality of ejection port groups each composed of a plurality of ejection ports for ejecting liquid,
Forming the discharge port by sliding a planar polishing member at least at an angle not perpendicular to the axis of the nozzle communicating with the discharge port on at least a part of the discharge port forming portion formed by forming the plurality of discharge port groups. A method of manufacturing a recording head, wherein a plurality of different planes are formed in a portion.   The method of manufacturing a recording head according to claim 11, wherein the polishing member is configured by a belt-like polishing member that can travel along a planar movement path. A moving means for relatively moving the recording head according to any one of claims 1 to 12 and the recording medium;
Control means for ejecting liquid from the recording head while relatively moving the recording head and the recording medium;
An ink jet recording apparatus comprising:   The moving means includes a moving mechanism for moving the recording head in a main scanning direction, and a conveying mechanism for conveying the recording medium in a sub-scanning direction intersecting the main scanning direction. 2. An ink jet recording apparatus according to 1. A plurality of the nozzles in the recording head are provided so as to be aligned along a predetermined nozzle row direction,
The inkjet recording apparatus according to claim 14, wherein the moving unit includes a transport mechanism that transports the recording medium in a direction intersecting the nozzle row. An ejection port forming unit that forms a plurality of ejection ports for ejecting liquid is used, and an image is recorded using a recording head in which a plurality of types of ejection port groups that eject different inks are formed in the ejection port forming unit. In the inkjet recording method to be performed,
The recording head has the plurality of discharge port groups formed on discharge port surfaces located on two or more planes intersecting at different angles with respect to a reference plane perpendicular to the axis of the nozzle having the discharge port at the tip,
An ink jet recording method, wherein recording is performed on a recording medium by ejecting different inks from the plurality of ejection port groups while relatively moving a recording medium positioned on the reference plane and the recording head.

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