JP4137164B2 - Inkjet recording head - Google Patents

Description

  The present invention relates to a liquid discharge head for performing recording on a recording medium by discharging droplets such as ink droplets, and more particularly to a liquid discharge head for performing ink jet recording.

  The ink jet recording method is one of so-called non-impact recording methods.

  This ink-jet recording method has a noise that can be ignored during recording and can be recorded at high speed. In addition, the ink jet recording method can record on various recording media, and the ink can be fixed without requiring special processing even for so-called plain paper, and a high-definition image can be obtained at a low price. It is done. Due to such advantages, the ink jet recording system has been rapidly spread in recent years as a recording means for copying machines, facsimiles, word processors and the like as well as printers as peripheral devices for computers.

  Ink-jet recording method ink discharge methods that are generally used include a method that uses an electrothermal conversion element such as a heater as a discharge energy generating element used to discharge ink droplets, and a method that uses a piezoelectric element or the like. There is a method using a piezoelectric element, and any method can control ejection of ink droplets by an electric signal. The principle of the ink ejection method using an electrothermal conversion element is that a voltage is applied to the electrothermal conversion element to instantaneously boil the ink in the vicinity of the electrothermal conversion element, and the rapid change caused by the phase change of the ink at the time of boiling. Ink droplets are ejected at high speed by the foaming pressure. On the other hand, the principle of the ink ejection method using a piezoelectric element is that a voltage is applied to the piezoelectric element, whereby the piezoelectric element is displaced and ink droplets are ejected by the pressure generated at the time of the displacement.

  The ink discharge method using the electrothermal conversion element does not require a large space for disposing the discharge energy generating element, has the advantage that the structure of the recording head is simple and the nozzles are easily integrated. There is. On the other hand, problems inherent to this ink ejection method are caused by fluctuations in the volume of flying ink droplets or defoaming due to the heat generated by the electrothermal conversion element being stored in the recording head. The cavitation has an adverse effect on the electrothermal conversion element, and the air dissolved in the ink becomes residual bubbles in the recording head, thereby adversely affecting the ink droplet ejection characteristics and image quality.

  As a method for solving these problems, there are an ink jet recording method and a recording head described in Patent Literature 1, Patent Literature 2, Patent Literature 3, and Patent Literature 4. In other words, the ink jet recording method described in the above-described literature is configured to allow air bubbles generated by driving an electrothermal conversion element by a recording signal to be vented to the outside air. By adopting this inkjet recording method, the volume of flying ink droplets can be stabilized, and a small amount of ink droplets can be ejected at high speed, eliminating cavitation that occurs when bubbles are removed. It is possible to improve the durability of the heater and the like, and a further high-definition image can be easily obtained. In the above-mentioned publication, as a configuration for communicating bubbles with the outside air, the shortest distance between the electrothermal conversion element that generates bubbles in the ink and the discharge port that is an opening through which the ink is discharged is compared with the conventional one. Therefore, a configuration that greatly shortens is mentioned.

  The configuration of this type of recording head will be described below. An element substrate provided with an electrothermal conversion element that discharges ink and a flow path configuration substrate (also referred to as an orifice substrate) that is bonded to the element substrate and forms an ink flow path are provided. The flow path constituting substrate has a plurality of nozzles through which ink flows, a supply chamber that supplies ink to each of these nozzles, and a plurality of discharge ports that are nozzle tip openings that discharge ink droplets. The nozzle includes a foaming chamber in which bubbles are generated by the electrothermal conversion element, and a supply path for supplying ink to the foaming chamber. On the element substrate, an electrothermal conversion element is disposed in the foam chamber. The element substrate is provided with a supply port for supplying ink to the supply chamber from the back surface opposite to the main surface in contact with the flow path constituting substrate. The flow path constituting substrate is provided with a discharge port at a position facing the electrothermal conversion element on the element substrate.

  Further, in the recording head configured as described above, the ink supplied from the supply port to the supply chamber is supplied along each nozzle and filled in the foaming chamber. The ink filled in the foaming chamber is ejected in the direction substantially perpendicular to the main surface of the element substrate by bubbles generated by film boiling by the electrothermal conversion element and ejected as ink droplets from the ejection port.

JP 54-161935 A JP-A 61-185455 JP 61-249768 A JP-A-4-10941

  By the way, in the recording head described above, when ink droplets are ejected, the ink filled in the foaming chamber is divided into the ejection port side and the supply path side by the bubbles that grow in the foaming chamber. Pressure due to foam escapes to the supply channel side, or pressure loss occurs due to friction with the inner wall of the discharge port. This phenomenon is a phenomenon that adversely affects ejection, and tends to become more prominent as small droplet ejection occurs. That is, by reducing the diameter of the discharge port in order to make a small droplet, the resistance of the discharge port portion becomes extremely large, the flow rate in the discharge port direction decreases, and the flow rate in the flow channel direction increases. The discharge speed is reduced. Therefore, by providing the second discharge port portion whose cross-sectional area perpendicular to the flow is larger than that of the discharge port, the overall flow resistance in the discharge port direction is reduced, and foaming causes a pressure loss in the discharge port direction. Since the growth is small, it is possible to suppress the flow rate that escapes in the direction of the flow path, and to prevent the ink droplet ejection speed from decreasing.

  By the way, when the second discharge port portion is provided as described above and the flow path resistance on the downstream side (discharge port side) of the heating element is reduced, the first discharge port portion and the second discharge port portion are separated at the first. It was found that a state in which refilling is delayed occurs as compared with the case where the two discharge ports are not provided.

  Of course, if the volume of the second discharge port portion is reduced, the refill state changes in the direction of improvement, but the effect of reducing the flow path resistance on the downstream side (discharge port side) of the heating element is drastically reduced. . Therefore, the present inventor has reached the present invention by earnestly studying the configuration of the second discharge port portion that secures the volume of the second discharge port portion as much as possible and reduces the decrease in refill.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an ink jet recording head having a nozzle shape that can prevent a decrease in refill speed while reducing flow resistance in the ejection direction in view of the above-described problems in the actual situation.

  Another object of the present invention is to provide a nozzle-shaped ink jet recording head capable of suppressing the variation in ejection volume due to the heat accumulation of ink as described above.

In order to achieve the above object, the present invention provides:
A plurality of nozzles through which the liquid flows, a supply chamber that supplies the liquid to the plurality of nozzles, and a plurality of discharge ports that are front end openings of the nozzles that discharge liquid droplets,
A foaming chamber having an energy generating element for generating thermal energy for discharging droplets; a discharge port portion including the discharge port and communicating between the discharge port and the foaming chamber; and the foaming chamber a flow path forming substrate comprising a supply passage for supplying the liquid, said nozzle consisting in,
An element substrate on which the energy generating element is provided and the flow path configuration substrate is bonded to a main surface;
The discharge port portion includes a first discharge port portion including the discharge port,
A second discharge port portion that is continuous to the first discharge port portion with a step and is parallel to the main surface of the element substrate and communicated with the foaming chamber with a cross section larger than the cross section of the first discharge port portion; An ink jet recording head comprising:
A distance in the liquid supply direction of the supply path in a cross section parallel to the main surface of the element substrate of the second discharge port portion is smaller than a distance in a direction orthogonal to the supply direction.

  According to the above-described invention, there is very little pressure loss in the flow of the liquid to the discharge port, and the liquid is discharged well toward the discharge port. By doing this, even if the discharge port at the tip of the nozzle is further reduced and the flow resistance in the discharge port direction at the first discharge port portion is increased, the decrease in the flow rate in the discharge port direction during discharge is suppressed. Further, it is possible to prevent a drop in the ink droplet ejection speed. Furthermore, the ink inflow position (especially the maximum flow velocity position) into the second ejection opening is shifted to the ink supply side, and as a result, the ink flow distance during refill is shortened and the refill frequency is improved. When the second discharge port is totally displaced to the ink supply side, the step between the first discharge port and the second discharge port located far from the ink supply chamber is reduced, and meniscus clipping during refilling is also reduced. It also has the effect of improving the refill frequency. This is a problem in that the ink meniscus is caught during the refill at the step portion between the first discharge port portion and the second discharge port portion on the side far from the ink supply chamber, and the refill time becomes long. This is because the refill frequency is improved.

  At this time, the second discharge port portion is symmetric with respect to a perpendicular passing through the discharge ports and intersecting the array direction of the discharge ports, and has a balanced shape, so that it is substantially orthogonal to the main surface of the element substrate. In this direction, it is possible to stably discharge the droplets.

  Further, with respect to the cross section of the second discharge port portion in the direction substantially parallel to the element substrate, that is, the spatial volume, the direction parallel to the arrangement direction of the discharge ports (the direction perpendicular to the longitudinal direction of the supply path) is Since the length is longer than the length in the direction perpendicular to the arrangement direction (the direction parallel to the longitudinal direction of the supply path), the shape of the second discharge port portion is not largely limited to the position of the side wall where the supply path of the foaming chamber comes into contact. Moreover, in order to reduce the flow resistance in the direction of the discharge port, the height of the supply channel immediately upstream of the foaming chamber is increased by changing the shape so that the longitudinal direction of the supply channel of the second discharge port is not increased. In other words, there is no concern that the pressure due to the foaming of the liquid escapes to the supply channel side and lowers the discharge efficiency.

  Further, in the main part of the ink jet recording head, the opening surface on the first discharge port side of the second discharge port that intersects the discharge axis is the opening surface on the bubbling chamber side of the second discharge port. Since the cross-sectional shape is similar and has a smaller area than the opening surface on the foaming chamber side, the step portion between the first discharge port portion and the second discharge port portion can be made smaller. When the ink is ejected in a small amount, the stagnation region of the minute ink having almost no flow velocity is reduced in the flow in the direction of the ejection port after foaming. As a result, it is possible to prevent ink from being stored during the continuous ejection operation by the electrothermal conversion element, and to reduce the variation in the volume of the ejected droplets.

  Furthermore, if the opening surface on the first discharge port side of the second discharge port portion intersecting the discharge axis and the opening surface on the foaming chamber side of the second discharge port portion are elliptical or oval, Compared with the case where the opening surface on the discharge port portion side of the two discharge port portions is substantially rectangular, the area of the four corners is reduced and the ink stagnation region is also reduced, so that the variation in the volume of the discharged droplets is further reduced. Furthermore, in the planar perspective view seen from the direction perpendicular to the main surface of the element substrate, the opening surface on the first discharge port side of the second discharge port is inscribed in two points with the discharge port. Then, the ink stagnation region is further reduced, and the variation in the volume of the ejected droplets is further reduced.

  Further, in the main part of the ink jet recording head, the opening surface on the foaming chamber side of the second discharge port that intersects the discharge axis is an ellipse or an ellipse, and the first discharge port side of the second discharge port The opening surface of the first discharge port portion is circular and the inside of an ellipse or an ellipse that is the opening surface of the second discharge port portion on the foaming chamber side, thereby providing a stepped portion between the first discharge port portion and the second discharge port portion. In addition, since the step portion is point-symmetric with respect to the center of the ejection port, the ink stagnation region is not biased. Therefore, it is possible to eliminate unstable ejection due to the deviation of the stagnation region.

  Further, in the main part of the ink jet recording head, the opening surface on the first discharge port side of the second discharge port that intersects the discharge axis is defined as the opening surface on the foaming chamber side of the first discharge port. By making the concentric circles, there is almost no stepped portion between the first discharge port portion and the second discharge port portion. Therefore, a minute ink stagnation region having almost no flow velocity in the flow toward the discharge port after foaming. Does not occur. As a result, the ink is not stored during the high-frequency continuous ejection operation by the electrothermal transducer, and the variation in the volume of the ejected droplets is extremely reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The ink jet recording head of the present invention includes a means for generating thermal energy as energy used for ejecting liquid ink, among ink jet recording methods, and a method for causing a change in the state of the ink by the heat energy. The recording head adopted. By using this method, higher density and higher definition of recorded characters and images are achieved. In particular, in the present embodiment, an electrothermal conversion element is used as a means for generating thermal energy, and the ink is ejected by using pressure caused by bubbles generated when the ink is heated by the electrothermal conversion element to boil the film. ing.

  First, the overall configuration of the ink jet recording head of this embodiment will be described.

  FIG. 1 is a perspective view in which an embodiment of an ink jet recording head suitable for the present invention is partially cut away.

  In the ink jet recording head of the form shown in FIG. 1, a plurality of heaters 2 that are electrothermal conversion elements are provided in each heater 2, and an isolation wall for individually forming nozzles 5 that are ink flow paths has a discharge wall. The configuration extends from the outlet 4 to the vicinity of the supply chamber 6.

  This ink jet recording head has a plurality of heaters 2 and a plurality of nozzles 5, and the first nozzle row 7 in which the longitudinal directions of the nozzles 5 are arranged in parallel and the first nozzle row 7 across the supply chamber 6. And a second nozzle row 8 in which the longitudinal directions of the nozzles 5 are arranged in parallel to each other.

  In the first and second nozzle rows 7 and 8, the interval between adjacent nozzles is formed at a pitch of 600 dpi. Further, the nozzles 5 of the second nozzle row 8 are arranged so that the pitch between adjacent nozzles is shifted from the nozzles 5 of the first nozzle row 7 by ½ pitch.

  Such a recording head has an ink discharge means to which the ink jet recording method disclosed in Japanese Patent Application Laid-Open Nos. 4-10940 and 4-10941 is applied, and bubbles generated during ink discharge are generated. It communicates with the outside air through the discharge port.

  Hereinafter, the nozzle structure of the ink jet recording head, which is the main part of the present invention, will be described with various embodiments.

(First embodiment)
FIG. 2 shows the nozzle structure of the ink jet recording head according to the first embodiment of the present invention. FIG. 4A is a plan perspective view of one of the plurality of nozzles of the ink jet recording head viewed from a direction perpendicular to the substrate, and FIG. 4B is a cross-sectional view taken along line AA in FIG. (C) is sectional drawing along the BB line of (a).

  As shown in FIG. 1, the recording head having the nozzle structure of the present embodiment is bonded to an element substrate 2 provided with a plurality of heaters 1 that are electrothermal conversion elements and laminated on the main surface of the element substrate 2. And a flow path constituting substrate 3 constituting a plurality of ink flow paths.

  The element substrate 2 is made of, for example, glass, ceramics, resin, metal or the like, and is generally made of Si. On the main surface of the element substrate 2, for each ink flow path, a heater 1, an electrode (not shown) for applying a voltage to the heater 1, and wiring (not shown) connected to the electrode are provided. Are provided in a predetermined wiring pattern. In addition, an insulating film (not shown) for improving the heat dissipation property is provided on the main surface of the element substrate 2 so as to cover the heater 1. In addition, a protective film (not shown) is provided on the main surface of the element substrate 2 so as to cover the insulating film to protect against cavitation that occurs when bubbles are eliminated.

  As shown in FIG. 1, the flow path constituting substrate 3 includes a plurality of nozzles 5 through which ink flows, a supply chamber 6 that supplies ink to each nozzle 5, and a front end opening of the nozzle 5 that discharges ink droplets. A plurality of discharge ports 4 are provided. The discharge port 4 is formed at a position facing the heater 1 on the element substrate 2. As shown in FIG. 2, the nozzle 5 includes a discharge port 4, a first discharge port portion having a substantially constant diameter, and a second discharge port portion for reducing flow resistance on the discharge port side of the heater. 10, a foaming chamber 11, and a supply path 9 (shaded portion in the figure). The foaming chamber 11 is formed on the heater 1 so that the bottom surface facing the opening surface of the discharge port 4 has a substantially rectangular shape. The supply path 9 has one end communicating with the foaming chamber 11 and the other end communicated with the supply chamber 6, and the supply path 9 is formed in a straight shape having substantially the same width from the supply chamber 6 to the foaming chamber 8. ing. The second discharge port 10 is continuously formed on the foaming chamber 11. Further, the nozzle 5 is formed such that the ejection direction in which the ink droplets fly from the ejection port 4 and the flow direction of the ink liquid flowing in the supply path 9 are orthogonal to each other.

  The nozzle 5 shown in FIG. 1, which includes the first discharge port portion including the discharge port 4, the second discharge port portion 10, the foaming chamber 11, and the supply path 9, faces the main surface of the element substrate 2. The inner wall surfaces are formed in parallel to the main surface of the element substrate 2 from the supply chamber 6 to the foaming chamber 11.

  2A, the opening surface on the foaming chamber 11 side of the second discharge port portion 10 has a length in a direction parallel to the arrangement direction of the discharge ports 4 and the arrangement of the discharge ports 4. The opening surface on the first discharge port side is also a cross-sectional shape congruent with the opening surface on the foaming chamber 11 side. However, in FIG. 2A, the cross section of the second discharge port portion 10 cut in a direction substantially parallel to the formation surface of the heater 1 is described in a substantially rectangular shape.

  Further, in order to stably discharge droplets in a direction substantially orthogonal to the formation surface of the heater 1 (main surface of the element substrate 2), the second discharge port portion 10 passes through the discharge port 4 and discharge ports. Symmetrical shape with respect to the perpendicular line intersecting the direction of the arrangement, and a balanced shape. Note that, in any cross section that passes through the center of the discharge port 4 and is perpendicular to the main surface of the element substrate, the side wall of the second discharge port portion 10 is represented by a straight line, and the first discharge port portion 10 has a first side. The opening surface on the discharge port side, the opening surface on the foaming chamber 11 side, and the main surface of the element substrate are parallel.

  Further, the section (space volume) of the second ejection port portion 10 in a direction substantially parallel to the element substrate, that is, the direction parallel to the arrangement direction of the ejection ports 4 farthest from the ink supply direction (liquid supply direction) (supply) Ink supply to the foaming chamber 11 is achieved by making the direction perpendicular to the longitudinal direction of the passage 9 longer than the length perpendicular to the arrangement direction of the ejection ports 4 (the direction parallel to the longitudinal direction of the supply passage 9). The shape of the second discharge port portion 10 is not largely limited to the position of the side wall where the passage 9 comes into contact. Moreover, in order to reduce the flow resistance in the discharge port direction, the longitudinal direction of the supply passage 9 of the second discharge port portion 10 is changed so as not to increase, so that the supply passage 9 immediately upstream of the foaming chamber 11 The height does not increase, and there is no fear that the pressure due to the foaming of the liquid escapes to the supply channel side and the discharge efficiency is lowered.

  Furthermore, by increasing the length in the direction parallel to the arrangement direction of the ejection ports 4 farthest from the ink supply direction (the direction perpendicular to the longitudinal direction of the supply path 9), the ink filling speed to the ejection port portion is increased. The refill speed can be improved while the flow path resistance on the discharge port side is reduced.

  Next, an operation for ejecting ink droplets from the ejection port 4 by the recording head configured as described above will be described with reference to FIGS. 1 and 2.

  First, the ink supplied into the supply chamber 6 is supplied to the respective nozzles 5 of the first nozzle row 7 and the second nozzle row 8. The ink supplied to each nozzle 5 flows along the supply path 9 and fills the foaming chamber 11. The ink filled in the foaming chamber 11 is ejected in a direction substantially perpendicular to the main surface of the element substrate 2 by the growth pressure of bubbles generated by film boiling by the heater 1, and ink droplets are ejected from the ejection ports 4. Are discharged. Further, when the ink filled in the foaming chamber 11 is ejected, a part of the ink in the foaming chamber 11 flows toward the supply path 9 due to the pressure of bubbles generated in the foaming chamber 11. Here, if the state from the foaming of the nozzle to the discharge is locally observed, the pressure of the bubbles generated in the foaming chamber 11 is immediately transmitted also to the second discharge port portion 10, and the foam chamber 11 and the second discharge port portion. The ink filled in 10 moves in the second ejection port portion 10.

  At this time, compared with the recording head of FIG. 8 in which the second discharge port portion 10 in the nozzle is cylindrical, in the first embodiment, the cross section of the second discharge port portion 10 parallel to the main surface of the element substrate 2. That is, since the space volume is large, pressure loss is very small, and the liquid is discharged well toward the discharge port 4. In this way, even if the discharge port at the nozzle tip is further reduced and the flow resistance in the discharge port direction at the discharge port portion is increased, the decrease in the flow rate in the discharge port direction during discharge is suppressed, and the ink A drop in the droplet discharge speed can be prevented.

(Second Embodiment)
In the present embodiment, when the cross-sectional area perpendicular to the flow of the second discharge port is increased, the ink stagnation region also increases, and the heat from the electrothermal conversion element is stored in the head during continuous discharge. The nozzle structure that takes into account the problem is shown. In addition, here, differences from the first embodiment will be mainly described based on FIG.

  FIG. 3 shows the nozzle structure of an ink jet recording head according to the second embodiment of the present invention. FIG. 4A is a plan perspective view of one of the plurality of nozzles of the ink jet recording head viewed from a direction perpendicular to the substrate, and FIG. 4B is a cross-sectional view taken along line AA in FIG. (C) is sectional drawing along the BB line of (a).

  As shown in the plan perspective view of FIG. 3A, the opening surface on the foaming chamber 11 side of the second discharge port portion 10 has a length in a direction parallel to the array direction of the discharge ports 4. The opening surface on the first discharge port side is similar to the opening surface on the foaming chamber 11 side and has an area larger than the opening surface on the foaming chamber 11 side. Small cross-sectional shape. However, in FIG. 2A, the cross section of the second discharge port portion 10 cut in a direction substantially parallel to the formation surface of the heater 1 is described in a substantially rectangular shape.

  Further, in order to stably discharge droplets in a direction substantially orthogonal to the formation surface of the heater 1 (main surface of the element substrate 2), the second discharge port portion 10 passes through the discharge port 4 and discharge ports. Symmetrical shape with respect to the perpendicular line intersecting the direction of the arrangement, and a balanced shape. Note that, in any cross section that passes through the center of the discharge port 4 and is perpendicular to the main surface of the element substrate, the side wall of the second discharge port portion 10 is represented by a straight line, and the first discharge port portion 10 has a first side. The opening surface on the discharge port side, the opening surface on the foaming chamber 11 side, and the main surface of the element substrate are parallel.

  Further, the cross section of the second ejection port portion 10 in the direction substantially parallel to the element substrate, that is, the space volume, is parallel to the arrangement direction of the ejection ports 4 farthest from the ink supply direction (the longitudinal direction of the supply path 9). The direction perpendicular to the arrangement direction of the ejection ports 4 is made longer than the length in the direction perpendicular to the arrangement direction of the discharge ports 4 (the direction parallel to the longitudinal direction of the supply path 9). The shape of the second discharge port portion 10 is not greatly limited to the position of the side wall. Moreover, in order to reduce the flow resistance in the discharge port direction, the longitudinal direction of the supply passage 9 of the second discharge port portion 10 is changed so as not to increase, so that the supply passage 9 immediately upstream of the foaming chamber 11 The height does not increase, and there is no fear that the pressure due to the foaming of the liquid escapes to the supply channel side and the discharge efficiency is lowered.

  Next, an operation of ejecting ink droplets from the ejection port 4 by the recording head configured as described above will be described with reference to FIGS.

  First, the ink supplied into the supply chamber 6 is supplied to the respective nozzles 5 of the first nozzle row 7 and the second nozzle row 8. The ink supplied to each nozzle 5 flows along the supply path 9 and fills the foaming chamber 11. The ink filled in the foaming chamber 11 is ejected in a direction substantially perpendicular to the main surface of the element substrate 2 by the growth pressure of bubbles generated by film boiling by the heater 1, and ink droplets are ejected from the ejection ports 4. Are discharged. Further, when the ink filled in the foaming chamber 11 is ejected, a part of the ink in the foaming chamber 11 flows toward the supply path 9 due to the pressure of bubbles generated in the foaming chamber 11. Here, if the state from the foaming of the nozzle to the discharge is locally observed, the pressure of the bubbles generated in the foaming chamber 11 is immediately transmitted also to the second discharge port portion 10, and the foam chamber 11 and the second discharge port portion. The ink filled in 10 moves in the second ejection port portion 10.

  At this time, compared to the recording head of FIG. 8 in which the second discharge port portion 10 in the nozzle is cylindrical, in the second embodiment, the cross section of the second discharge port portion 10 parallel to the main surface of the element substrate 2. That is, since the space volume is large, pressure loss is very small, and the liquid is discharged well toward the discharge port 4. By doing this, even if the discharge port at the tip of the nozzle is further reduced and the flow resistance in the discharge port direction at the first discharge port portion is increased, the decrease in the flow rate in the discharge port direction during discharge is suppressed. Further, it is possible to prevent a drop in the ink droplet ejection speed.

  Here, it should be noted that the cross section parallel to the main surface of the element substrate 2 of the second discharge port portion 10 becomes smaller toward the discharge port 4 as compared with the first embodiment. This is because the flow resistance of the entire outlet portion 10 may be large. However, since the step portion between the first discharge port portion and the second discharge port portion 10 is actually a stagnation portion where fluid does not flow, as a result, the same flow resistance is maintained as compared with the first embodiment. Is done.

  Further, when the discharge is continuously performed at a high frequency, the step portion between the first discharge port portion and the second discharge port portion 10 is smaller than that in the first embodiment. In the flow in the direction, the stagnation region of minute ink having almost no flow velocity is also reduced. As a result, it is possible to prevent ink from being stored during the continuous ejection operation by the electrothermal conversion element, and to reduce the variation in the volume of the ejected droplets. Note that when ink is continuously ejected at a high frequency, the mechanism in which the ink stagnation in the nozzle causes the volume variation of the ejected droplets is as described in the section “Problems to be solved by the invention”. .

(Third embodiment)
The third embodiment is also intended to reduce the ink stagnation region so that the variation in the ejection volume is reduced.

  Here, the difference between the third embodiment and the first embodiment will be mainly described based on FIG.

  FIG. 4 shows the nozzle structure of an ink jet recording head according to the third embodiment of the present invention. FIG. 4A is a plan perspective view of one of the plurality of nozzles of the ink jet recording head viewed from a direction perpendicular to the substrate, and FIG. 4B is a cross-sectional view taken along line AA in FIG. (C) is sectional drawing along the BB line of (a).

  4A, the opening surface on the foaming chamber 11 side of the second discharge port portion 10 has a diameter in a direction parallel to the arrangement direction of the discharge ports 4, and the arrangement direction of the discharge ports 4. The opening surface on the first discharge port side is similar to the opening surface on the foaming chamber 11 side and more than the opening surface on the foaming chamber 11 side. Is also a cross-sectional shape with a small area. Thus, by making the cross section of the second discharge port portion 10 cut in a direction substantially parallel to the surface on which the heater 1 is formed into an ellipse or an ellipse, the stagnation regions at the four corners that can be formed when the cross section is substantially rectangular are obtained. It can be omitted.

  Further, in order to stably discharge droplets in a direction substantially orthogonal to the formation surface of the heater 1 (main surface of the element substrate 2), the second discharge port portion 10 passes through the discharge port 4 and discharge ports. Symmetrical shape with respect to the perpendicular line intersecting the direction of the arrangement, and a balanced shape. Note that, in any cross section that passes through the center of the discharge port 4 and is perpendicular to the main surface of the element substrate, the side wall of the second discharge port portion 10 is represented by a straight line, and the first discharge port portion 10 has a first side. The opening surface on the discharge port side, the opening surface on the foaming chamber 11 side, and the main surface of the element substrate are parallel.

  Further, the cross section of the second ejection port portion 10 in the direction substantially parallel to the element substrate, that is, the space volume, is parallel to the arrangement direction of the ejection ports 4 farthest from the ink supply direction (the longitudinal direction of the supply path 9). The direction perpendicular to the arrangement direction of the ejection ports 4 is made longer than the length in the direction perpendicular to the arrangement direction of the discharge ports 4 (the direction parallel to the longitudinal direction of the supply path 9). The shape of the second discharge port portion 10 is not greatly limited to the position of the side wall. Moreover, in order to reduce the flow resistance in the discharge port direction, the longitudinal direction of the supply passage 9 of the second discharge port portion 10 is changed so as not to increase, so that the supply passage 9 immediately upstream of the foaming chamber 11 The height does not increase, and there is no fear that the pressure due to the foaming of the liquid escapes to the supply channel side and the discharge efficiency is lowered.

  Next, an operation of ejecting ink droplets from the ejection port 4 by the recording head configured as described above will be described with reference to FIGS.

  First, the ink supplied into the supply chamber 6 is supplied to the respective nozzles 5 of the first nozzle row 7 and the second nozzle row 8. The ink supplied to each nozzle 5 flows along the supply path 9 and fills the foaming chamber 11. The ink filled in the foaming chamber 11 is ejected in a direction substantially perpendicular to the main surface of the element substrate 2 by the growth pressure of bubbles generated by film boiling by the heater 1, and ink droplets are ejected from the ejection ports 4. Are discharged. Further, when the ink filled in the foaming chamber 11 is ejected, a part of the ink in the foaming chamber 11 flows toward the supply path 9 due to the pressure of bubbles generated in the foaming chamber 11. Here, if the state from the foaming of the nozzle to the discharge is locally observed, the pressure of the bubbles generated in the foaming chamber 11 is immediately transmitted also to the second discharge port portion 10, and the foam chamber 11 and the second discharge port portion. The ink filled in 10 moves in the second ejection port portion 10.

  At this time, compared with the recording head of FIG. 8 in which the resistance relaxing portion 10 in the nozzle is cylindrical, in the third embodiment, the cross section or space of the second discharge port portion 10 parallel to the main surface of the element substrate 2 is obtained. Since the volume is large, there is very little pressure loss and the ink is discharged well toward the discharge port 4. By doing this, even if the discharge port at the tip of the nozzle is further reduced and the flow resistance in the discharge port direction at the first discharge port portion is increased, the decrease in the flow rate in the discharge port direction during discharge is suppressed. Further, it is possible to prevent a drop in the ink droplet ejection speed.

  Here, it should be noted that the cross section parallel to the main surface of the element substrate 2 of the second discharge port portion 10 is made ellipse or oval so that the area of the four corners is smaller than in the second embodiment. Thus, there is a possibility that the flow resistance of the entire second discharge port portion 10 may increase. However, since the area of the four corners is actually a stagnation part where the fluid does not flow, as a result, compared with the second embodiment, the same flow resistance is maintained.

  In addition, when the discharge is continuously performed at a high frequency, the area of the four corners of the cross section parallel to the main surface of the element substrate 2 of the second discharge port portion 10 is smaller than that of the second embodiment, and the ink Since the stagnation region is also reduced, the volume variation of the ejected droplets is further reduced.

(Fourth embodiment)
The fourth embodiment is also intended to reduce the ink stagnation region so that the variation in the ejection volume is reduced.

  Here, the difference between the fourth embodiment and the first embodiment will be mainly described based on FIG.

  FIG. 5 shows a nozzle structure of an ink jet recording head according to the fourth embodiment of the present invention. FIG. 4A is a plan perspective view of one of the plurality of nozzles of the ink jet recording head viewed from a direction perpendicular to the substrate, and FIG. 4B is a cross-sectional view taken along line AA in FIG. (C) is sectional drawing along the BB line of (a).

  As shown in the plan perspective view of FIG. 5A, the opening surface on the foaming chamber 11 side of the second discharge port portion 10 has a diameter in a direction parallel to the array direction of the discharge ports 4. The opening surface on the first discharge port side is similar to the opening surface on the foaming chamber 11 side, and has two points inside the discharge port portion. Touch. In such a shape, the step portion between the first discharge port portion and the second discharge port portion 10 becomes smaller than in the third embodiment, and the ink stagnation region decreases.

  Further, in order to stably discharge droplets in a direction substantially orthogonal to the formation surface of the heater 1 (main surface of the element substrate 2), the second discharge port portion 10 passes through the discharge port 4 and discharge ports. Symmetrical shape with respect to the perpendicular line intersecting the direction of the arrangement, and a balanced shape. Note that, in any cross section that passes through the center of the discharge port 4 and is perpendicular to the main surface of the element substrate, the side wall of the second discharge port portion 10 is represented by a straight line, and the first discharge port portion 10 has a first side. The opening surface on the discharge port side, the opening surface on the foaming chamber 11 side, and the main surface of the element substrate are parallel.

  Further, the cross section of the second ejection port portion 10 in the direction substantially parallel to the element substrate, that is, the space volume, is parallel to the arrangement direction of the ejection ports 4 farthest from the ink supply direction (the longitudinal direction of the supply path 9). The direction perpendicular to the arrangement direction of the ejection ports 4 is made longer than the length in the direction perpendicular to the arrangement direction of the discharge ports 4 (the direction parallel to the longitudinal direction of the supply path 9). The shape of the second discharge port portion 10 is not greatly limited to the position of the side wall. Moreover, in order to reduce the flow resistance in the discharge port direction, the longitudinal direction of the supply passage 9 of the second discharge port portion 10 is changed so as not to increase, so that the supply passage 9 immediately upstream of the foaming chamber 11 The height does not increase, and there is no fear that the pressure due to the foaming of the liquid escapes to the supply channel side and the discharge efficiency is lowered.

  Next, an operation of ejecting ink droplets from the ejection port 4 by the recording head configured as described above will be described with reference to FIGS.

  First, the ink supplied into the supply chamber 6 is supplied to the respective nozzles 5 of the first nozzle row 7 and the second nozzle row 8. The ink supplied to each nozzle 5 flows along the supply path 9 and fills the foaming chamber 11. The ink filled in the foaming chamber 11 is ejected in a direction substantially perpendicular to the main surface of the element substrate 2 by the growth pressure of bubbles generated by film boiling by the heater 1, and ink droplets are ejected from the ejection ports 4. Are discharged. Further, when the ink filled in the foaming chamber 11 is ejected, a part of the ink in the foaming chamber 11 flows toward the supply path 9 due to the pressure of bubbles generated in the foaming chamber 11. Here, if the state from the foaming of the nozzle to the discharge is locally observed, the pressure of the bubbles generated in the foaming chamber 11 is immediately transmitted also to the second discharge port portion 10, and the foam chamber 11 and the second discharge port portion. The ink filled in 10 moves in the second ejection port portion 10.

  At this time, compared with the recording head of FIG. 8 in which the second discharge port portion 10 in the nozzle is cylindrical, in the fourth embodiment, the cross section of the second discharge port portion 10 parallel to the main surface of the element substrate 2. That is, since the space volume is large, pressure loss is very small, and the liquid is discharged well toward the discharge port 4. By doing this, even if the discharge port at the tip of the nozzle is further reduced and the flow resistance in the discharge port direction at the first discharge port portion is increased, the decrease in the flow rate in the discharge port direction during discharge is suppressed. Further, it is possible to prevent a drop in the ink droplet ejection speed.

  Here, it should be noted that the cross section of the second discharge port portion 10 parallel to the main surface of the element substrate 2 is smaller than that of the third embodiment. It can be big. However, since the step portion between the first discharge port portion and the second discharge port portion 10 is actually a stagnation portion where fluid does not flow, as a result, the same flow resistance is maintained as compared with the third embodiment. Is done.

  Further, when the discharge is continuously performed at a high frequency, the stepped portion between the discharge port portion and the second discharge port portion 10 becomes smaller and the ink stagnation region is reduced as compared with the third embodiment. There is less variation in the volume of the ejected droplets.

(Fifth embodiment)
The fifth embodiment is also intended to reduce the ink stagnation region so that the variation in the ejection volume is reduced. In the fifth embodiment, the step portion between the second discharge port portion and the first discharge port portion is formed to be point-symmetric (in a donut shape), and the stagnation region formed in the step portion is formed. The purpose is also to eliminate unstable discharge due to bias.

  Here, the difference of the fifth embodiment from the first embodiment will be mainly described based on FIG.

  FIG. 6 shows a nozzle structure of an ink jet recording head according to the fifth embodiment of the present invention. FIG. 4A is a plan perspective view of one of the plurality of nozzles of the ink jet recording head viewed from a direction perpendicular to the substrate, and FIG. 4B is a cross-sectional view taken along line AA in FIG. (C) is sectional drawing along the BB line of (a).

  6A, the opening surface on the foaming chamber 11 side of the second discharge port portion 10 has a diameter in a direction parallel to the direction in which the discharge ports 4 are arranged, and the direction in which the discharge ports 4 are arranged. The opening surface on the first discharge port side is circular and inside the opening surface on the foaming chamber 11 side. In such a shape, the step portion between the second discharge port portion 10 and the first discharge port portion is formed so as to be point-symmetric with respect to a perpendicular line extending from the center of the discharge port 4 to the main surface of the element substrate. Therefore, there is no possibility of causing unstable ejection due to deviation of the ink stagnation region.

  Further, in order to stably discharge droplets in a direction substantially orthogonal to the formation surface of the heater 1 (main surface of the element substrate 2), the second discharge port portion 10 passes through the discharge port 4 and discharge ports. Symmetrical shape with respect to the perpendicular line intersecting the direction of the arrangement, and a balanced shape. Note that, in any cross section that passes through the center of the discharge port 4 and is perpendicular to the main surface of the element substrate, the side wall of the second discharge port portion 10 is represented by a straight line, and the first discharge port portion 10 has a first side. The opening surface on the discharge port side, the opening surface on the foaming chamber 11 side, and the main surface of the element substrate are parallel.

  Further, the cross section of the second ejection port portion 10 in the direction substantially parallel to the element substrate, that is, the space volume, is parallel to the arrangement direction of the ejection ports 4 farthest from the ink supply direction (the longitudinal direction of the supply path 9). The direction perpendicular to the arrangement direction of the ejection ports 4 is made longer than the length in the direction perpendicular to the arrangement direction of the discharge ports 4 (the direction parallel to the longitudinal direction of the supply path 9). The shape of the second discharge port portion 10 is not greatly limited to the position of the side wall. Moreover, in order to reduce the flow resistance in the discharge port direction, the longitudinal direction of the supply passage 9 of the second discharge port portion 10 is changed so as not to increase, so that the supply passage 9 immediately upstream of the foaming chamber 11 The height does not increase, and there is no fear that the pressure due to the foaming of the liquid escapes to the supply channel side and the discharge efficiency is lowered.

  Next, an operation of ejecting ink droplets from the ejection ports 4 by the recording head configured as described above will be described with reference to FIGS. 1 and 6.

  First, the ink supplied into the supply chamber 6 is supplied to the respective nozzles 5 of the first nozzle row 7 and the second nozzle row 8. The ink supplied to each nozzle 5 flows along the supply path 9 and fills the foaming chamber 11. The ink filled in the foaming chamber 11 is ejected in a direction substantially perpendicular to the main surface of the element substrate 2 by the growth pressure of bubbles generated by film boiling by the heater 1, and ink droplets are ejected from the ejection ports 4. Are discharged. Further, when the ink filled in the foaming chamber 11 is ejected, a part of the ink in the foaming chamber 11 flows toward the supply path 9 due to the pressure of bubbles generated in the foaming chamber 11. Here, if the state from the foaming of the nozzle to the discharge is locally observed, the pressure of the bubbles generated in the foaming chamber 11 is immediately transmitted also to the second discharge port portion 10, and the foam chamber 11 and the second discharge port portion. The ink filled in 10 moves in the second ejection port portion 10.

  At this time, compared with the recording head of FIG. 8 in which the resistance relaxing portion 10 in the nozzle is cylindrical, in the fifth embodiment, the cross section of the second discharge port portion 10 parallel to the main surface of the element substrate 2, that is, Since the space volume is large, there is very little pressure loss and the ink is discharged well toward the discharge port 4. By doing this, even if the discharge port at the tip of the nozzle is further reduced and the flow resistance in the discharge port direction at the first discharge port portion is increased, the decrease in the flow rate in the discharge port direction during discharge is suppressed. Further, it is possible to prevent a drop in the ink droplet ejection speed.

  Here, it should be noted that since the cross section of the second discharge port portion parallel to the main surface of the element substrate is smaller than in the first embodiment, the total resistance of the second discharge port portion may be increased. Is that there is. However, since the step portion between the first discharge port portion and the second discharge port portion is actually a stagnation portion where fluid does not flow, as a result, compared with the first embodiment, it is maintained with the same flow resistance. The

  Furthermore, compared to the above-described embodiments, the step portion between the second discharge port portion 10 and the first discharge port portion is formed point-symmetrically, so that the ink stagnation portion is biased in the entire step portion. As a result, the ejection characteristics are stable.

(Sixth embodiment)
The sixth embodiment is also intended to reduce the ink stagnation region so that the variation in the volume of the ejected droplets is reduced. Another object of the sixth embodiment is to eliminate unstable discharge due to deviation of the stagnation region by substantially eliminating the step portion between the second discharge port portion and the first discharge port portion.

  Here, the difference between the sixth embodiment and the first embodiment will be mainly described based on FIG.

  FIG. 7 shows the nozzle structure of an ink jet recording head according to a sixth embodiment of the present invention. FIG. 4A is a plan perspective view of one of the plurality of nozzles of the ink jet recording head viewed from a direction perpendicular to the substrate, and FIG. 4B is a cross-sectional view taken along line AA in FIG. (C) is sectional drawing along the BB line of (a).

  As shown in the plan perspective view of FIG. 7A, the opening surface on the foaming chamber 11 side of the second discharge port portion 10 has a diameter in a direction parallel to the alignment direction of the discharge ports 4. An ellipse that is longer than the diameter in the direction perpendicular to the direction or an ellipse, the opening surface on the first discharge port side is circular, and a circle that is congruent with the opening surface on the second discharge port 10 side of the discharge port It becomes. In such a shape, there is almost no step portion between the second ejection port portion 10 and the first ejection port portion, so an ink stagnation region occurs between the second ejection port portion and the first ejection port portion. Absent.

  Further, in order to stably discharge droplets in a direction substantially orthogonal to the formation surface of the heater 1 (main surface of the element substrate 2), the second discharge port portion 10 passes through the discharge port 4 and discharge ports. Symmetrical shape with respect to the perpendicular line intersecting the direction of the arrangement, and a balanced shape. Note that, in any cross section that passes through the center of the discharge port 4 and is perpendicular to the main surface of the element substrate, the side wall of the second discharge port portion 10 is represented by a straight line, and the first discharge port portion 10 has a first side. The opening surface on the discharge port side, the opening surface on the foaming chamber 11 side, and the main surface of the element substrate are parallel.

  Further, the cross section of the second ejection port portion 10 in the direction substantially parallel to the element substrate, that is, the space volume, is parallel to the arrangement direction of the ejection ports 4 farthest from the ink supply direction (the longitudinal direction of the supply path 9). The direction perpendicular to the arrangement direction of the ejection ports 4 is made longer than the length in the direction perpendicular to the arrangement direction of the discharge ports 4 (the direction parallel to the longitudinal direction of the supply path 9). The shape of the second discharge port portion 10 is not greatly limited to the position of the side wall. Moreover, in order to reduce the flow resistance in the discharge port direction, the longitudinal direction of the supply passage 9 of the second discharge port portion 10 is changed so as not to increase, so that the supply passage 9 immediately upstream of the foaming chamber 11 The height does not increase, and there is no fear that the pressure due to the foaming of the liquid escapes to the supply channel side and the discharge efficiency is lowered.

  Next, an operation for ejecting ink droplets from the ejection port 4 by the recording head configured as described above will be described with reference to FIGS. 1 and 7.

  First, the ink supplied into the supply chamber 6 is supplied to the respective nozzles 5 of the first nozzle row 7 and the second nozzle row 8. The ink supplied to each nozzle 5 flows along the supply path 9 and fills the foaming chamber 11. The ink filled in the foaming chamber 11 is ejected in a direction substantially perpendicular to the main surface of the element substrate 2 by the growth pressure of bubbles generated by film boiling by the heater 1, and ink droplets are ejected from the ejection ports 4. Are discharged. Further, when the ink filled in the foaming chamber 11 is ejected, a part of the ink in the foaming chamber 11 flows toward the supply path 9 due to the pressure of bubbles generated in the foaming chamber 11. Here, if the state from the foaming of the nozzle to the discharge is locally observed, the pressure of the bubbles generated in the foaming chamber 11 is immediately transmitted also to the second discharge port portion 10, and the foam chamber 11 and the second discharge port portion. The ink filled in 10 moves in the second ejection port portion 10.

  At this time, compared with the recording head of FIG. 8 in which the second discharge port portion 10 in the nozzle is cylindrical, in the fourth embodiment, the cross section of the second discharge port portion 10 parallel to the main surface of the element substrate 2. That is, since the space volume is large, pressure loss is very small, and the liquid is discharged well toward the discharge port 4. In this way, even if the discharge port at the nozzle tip is further reduced and the flow resistance in the discharge port direction at the discharge port portion is increased, the decrease in the flow rate in the discharge port direction during discharge is suppressed, and the ink A drop in the droplet discharge speed can be prevented.

(Seventh embodiment)
9 to 12 show the nozzle structure of an ink jet recording head according to a seventh embodiment of the present invention. FIG. 4A is a plan perspective view of one of the plurality of nozzles of the ink jet recording head viewed from a direction perpendicular to the substrate, and FIG. 4B is a cross-sectional view taken along line AA in FIG. It is.

  As shown in FIG. 8, the recording head having the nozzle structure of the present embodiment has a plurality of inks stacked on and bonded to the element substrate 2 provided with the electrothermal conversion element 1 on the main surface of the element substrate 2. And a flow path configuration substrate 3 constituting the flow path.

  The element substrate 2 is made of, for example, glass, ceramics, resin, metal or the like, and is generally made of Si. On the main surface of the element substrate 2, for each ink flow path, a heater 1, an electrode (not shown) for applying a voltage to the heater 1, and wiring (not shown) connected to the electrode are provided. Are provided in a predetermined wiring pattern. In addition, an insulating film (not shown) that improves heat dissipation is provided on the main surface of the element substrate 2 so as to cover the electrothermal conversion element 1. In addition, a protective film (not shown) is provided on the main surface of the element substrate 2 so as to cover the insulating film to protect against cavitation that occurs when bubbles are eliminated.

  As shown in FIG. 8, the flow path constituting substrate 3 has a plurality of nozzles 24 through which ink flows. Each of these nozzles 24 boiles the ink by boiling the supply chamber 6 and the supply path 20 for supplying the ink. It has a foaming chamber 11 to be generated and a discharge port portion 20 that is a tip opening of a nozzle 24 that discharges ink droplets. The discharge port portion 20 is formed at a position facing the electrothermal conversion element 1 on the element substrate 2.

  The nozzle shape passes through the center of gravity of the upper end surface 21 of the discharge port and passes through the center of gravity of the lower end surface 13 of the discharge port with respect to an axis perpendicular to the main surface of the element substrate 2 (hereinafter referred to as the first axis 12 of the discharge port). An axis perpendicular to the main surface of the substrate (hereinafter referred to as a second outlet port axis 14) is shifted toward the ink supply chamber in a plan perspective view viewed from the direction perpendicular to the main surface of the element substrate. And an axis (hereinafter referred to as a heater shaft 15) passing through the center of gravity of the electrothermal transducer 1 and perpendicular to the main surface of the element substrate is aligned with the discharge port portion first axis 12. Yes.

  By disposing the discharge port portion first shaft 12 and the discharge port portion second shaft 14 as described above and arranging the discharge port portion first shaft 12 and the heater shaft 15 so as to coincide with each other, there are the following advantages. By matching the discharge port portion first shaft 12 and the heater shaft 15, the foaming pressure generated in the electrothermal conversion element 1 and the ink flow generated by the foaming pressure are made uniform with respect to the discharge port portion first shaft 12. This has the effect of preventing the ink droplets discharged and the satellite droplets from being twisted and improving the landing accuracy. Further, by bringing the ejection port portion second axis closer to the ink supply chamber than the ejection port portion first axis, there is an effect of shortening the ink flow distance and improving the refill frequency. Further, when the ejection port portion 20 is formed of the first ejection port portion 16 and the second ejection port portion 10, the ink flow position is the ink supply chamber of the first ejection port portion 16 and the second ejection port portion 10. 6 The refill frequency is improved by moving away from the step 18 on the opposite side to reduce clipping of ink during refilling at the step 18.

  Hereinafter, the seventh embodiment in which the discharge port second shaft 14 is displaced toward the ink supply chamber with respect to the discharge port first shaft 12 and the discharge port first shaft 12 and the heater shaft 15 coincide with each other will be described. Some specific examples will be given while referring to the effect of the difference in the shape of the discharge port portion 20.

“Specific Example 7-1”
In the nozzle shape shown in FIG. 9, the discharge port portion 20 is formed by the first discharge port portion 16 and the second discharge port portion 10 from the side close to the discharge port 11, and is perpendicular to the main surface of the element substrate 2. The cross-sectional area in the plan perspective view seen from above forms the second discharge port portion 10 larger than the first discharge port portion 16.

  By adopting such a shape, the flow resistance of the discharge port portion 20 can be reduced, and the print quality can be improved without decreasing the discharge speed even if the discharge droplets are reduced. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

"Specific Example 7-2"
The nozzle shape shown in FIG. 10 is one of variations of “Specific Example 1”. In the nozzle shape illustrated in FIG. 10, the first discharge port portion 16 has a cylindrical shape, and the second discharge port portion 10 has a truncated cone shape. By making the second discharge port portion 10 into a truncated cone shape, it is possible to further reduce the flow resistance as compared with the “specific example 1”. Further, since the step portion 18 between the first discharge port portion 16 and the second discharge port portion 10 is reduced, the stagnation area of the ink stagnating in the step portion 18 is reduced, the discharge amount and the discharge speed are stabilized, and the printing is performed. The quality is increased. This is because the ink stagnating in the step portion 18 has a higher temperature than the surrounding ink due to the effect of being warmed by the electrothermal conversion element, and changes the viscosity resistance of the ink to be ejected, thereby adversely affecting the ejection characteristics. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

"Specific Example 7-3"
In the nozzle shape shown in FIG. 11, the first discharge port portion 16 and the second discharge port portion 10 are both cylindrical and have the same combination as the specific example of FIG. 9, but perpendicular to the main surface of the element substrate 2. In the plan perspective view seen from the direction, the first discharge port portion 16 on the side opposite to the ink supply chamber 6 and the step portion 18 of the second discharge port portion 10 are formed so as not to occur. Thus, as compared with “Specific Example 1”, there is an effect of improving the refill frequency by reducing ink clipping in the stepped portion 18. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

"Specific Example 7-4"
The nozzle shape shown in FIG. 12 is a plane in which the first discharge port portion 16 has a cylindrical shape, the second discharge port portion 10 has a truncated cone shape, and is viewed from a direction perpendicular to the main surface of the element substrate 2. In the perspective view, the first discharge port portion 16 on the side opposite to the ink supply chamber 6 and the step portion 18 of the second discharge port portion 10 are formed so as not to occur. As described in “Specific Example 2”, when the second discharge port 10 has a truncated cone shape, the ink stagnation area is smaller than that of the cylindrical shape, and the discharge amount varies due to the temperature rise of the ink in the stagnation area. Printing defects can be suppressed. Further, by designing so as to eliminate the stepped portion 18, the meniscus clipping at the time of refilling is alleviated, and the refill frequency is increased. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

(Eighth embodiment)
13 to 16 show the nozzle shape of the ink jet recording head according to the eighth embodiment of the present invention. FIG. 4A is a plan perspective view of one of the plurality of nozzles of the ink jet recording head viewed from a direction perpendicular to the substrate, and FIG. 4B is a cross-sectional view taken along line AA in FIG. It is.

  The element substrate 2 and the flow path constituting substrate 3 of the ink jet recording head of this embodiment are the same as those of the first embodiment, and the nozzle shape is such that the discharge port portion second shaft 14 is in relation to the discharge port portion first shaft 12. In the plane perspective view seen from the direction perpendicular to the main surface of the element substrate, the heater shaft 15 and the discharge port portion second axis 14 are coincident with each other. It is formed to do. Hereinafter, embodiments will be described focusing on the nozzle shape.

  Disposing the discharge port portion first shaft 12 and the discharge port portion second shaft 14 as described above and arranging the discharge port portion second shaft 14 and the heater shaft 15 so as to coincide with each other has the following advantages. The matching of the discharge port portion second shaft 14 and the heater shaft 15 has the advantage that the foaming pressure generated in the electrothermal conversion element 1 is evenly transmitted to the second discharge port and the foaming power can be taken in sufficiently. Further, since the heater shaft 15 is also closer to the ink supply chamber 6 than in the first embodiment, the maximum foaming position is also shifted to the ink supply chamber 6 side, and the ejection port portion 20 and the foaming chamber are moved from the ink supply chamber 6. 11 has an effect that the ink flow distance at the time of refilling to 11 is further shortened and the refill frequency is increased.

  Hereinafter, an eighth embodiment in which the discharge port second shaft 14 is displaced toward the ink supply chamber 6 with respect to the discharge port first shaft 12 and the discharge port second shaft 14 and the heater shaft 15 coincide with each other. Specific examples will be given while referring to the effect of the difference in the shape of the discharge port portion 20.

"Specific Example 8-1"
In the nozzle shape shown in FIG. 13, the discharge port portion 20 is formed by the first discharge port portion 16 and the second discharge port portion 10 from the side close to the discharge port 11, and is perpendicular to the main surface of the element substrate 2. The cross-sectional area in the plan perspective view seen from above forms the second discharge port portion 10 larger than the first discharge port portion 16.

  By adopting such a shape, the flow resistance of the discharge port portion 20 can be reduced, and the print quality can be improved without decreasing the discharge speed even if the discharge droplets are reduced. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

"Specific Example 8-2"
The nozzle shape shown in FIG. 14 is one of variations of (Example 8-1). In the nozzle shape illustrated in FIG. 14, the first discharge port portion 16 has a cylindrical shape, and the second discharge port portion 10 has a truncated cone shape. By making the 2nd discharge outlet part 10 into a truncated cone shape, flow resistance can further be reduced compared with (Example 8-1). Further, since the step portion 18 between the first discharge port portion 16 and the second discharge port portion 10 is reduced, the stagnation area of the ink stagnating in the step portion 18 is reduced, the discharge amount and the discharge speed are stabilized, and the printing is performed. The quality rises. This is because the ink stagnating in the step portion 18 has a higher temperature than the surrounding ink due to the effect of being warmed by the electrothermal conversion element, and changes the viscosity resistance of the ink to be ejected, thereby adversely affecting the ejection characteristics. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

"Specific Example 8-3"
In the nozzle shape shown in FIG. 15, the first discharge port portion 16 and the second discharge port portion 10 are both cylindrical and have the same combination as the specific example of FIG. 13, but perpendicular to the main surface of the element substrate 2. In the plan perspective view seen from the direction, the first discharge port portion 16 on the side opposite to the ink supply chamber 6 and the step portion 18 of the second discharge port portion 10 are formed so as not to occur. Thus, as compared with “Specific Example 8-1”, there is an effect of improving the refill frequency by reducing the ink clipping at the stepped portion 18. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

"Specific Example 8-4"
The nozzle shape shown in FIG. 16 is a plane in which the first discharge port portion 16 has a cylindrical shape, the second discharge port portion 10 has a truncated cone shape, and is viewed from a direction perpendicular to the main surface of the element substrate 2. In the perspective view, the first discharge port portion 16 on the side opposite to the ink supply chamber 6 and the step portion 18 of the second discharge port portion 10 are formed so as not to occur. As described in “Specific Example 8-2”, when the second discharge port portion 10 has a truncated cone shape, the ink stagnation area is smaller than that of the cylindrical shape, and the discharge amount varies due to the temperature rise of the ink in the stagnation area. Thus, printing defects can be suppressed. Further, by designing so as to eliminate the stepped portion 18, the meniscus clipping at the time of refilling is alleviated, and the refill frequency is increased. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

(Ninth embodiment)
17 to 20 show the nozzle shape of the ink jet recording head according to the ninth embodiment of the present invention. FIG. 4A is a plan perspective view of one of the plurality of nozzles of the ink jet recording head viewed from a direction perpendicular to the substrate, and FIG. 4B is a cross-sectional view taken along line AA in FIG. It is.

  The element substrate 2 and the flow path constituting substrate 3 of the ink jet recording head of this embodiment are the same as those of the first embodiment, and the nozzle shape is such that the discharge port portion second shaft 14 is in relation to the discharge port portion first shaft 12. In the plan perspective view seen from the direction perpendicular to the main surface of the element substrate, it is formed so as to be shifted to the ink supply chamber side, and the discharge port portion second axis 14 is the discharge port portion first axis 12. And the heater shaft 15.

  In view of the relationship between these three axes, the present embodiment is located between the seventh and eighth embodiments. In the seventh embodiment, since the discharge port portion first shaft 12 and the heater shaft 15 coincide with each other, the foaming pressure to the first discharge port portion 16 is made uniform and the discharge is stabilized. On the other hand, in the eighth embodiment, since the discharge port portion second shaft 14 and the heater shaft 15 coincide with each other, the foaming pressure generated in the electrothermal conversion element 1 is evenly transmitted to the second discharge port 17 and the foam power Can be fully captured. Further, there is an advantage that the maximum foaming position is shifted to the ink supply chamber 6 side to further increase the refill frequency. The present embodiment is a shape that captures the advantages of these two embodiments.

  Hereinafter, the discharge port second shaft 14 is displaced toward the ink supply chamber 6 with respect to the discharge port first shaft 12, and the heater shaft 15 is positioned between the discharge port first shaft 12 and the discharge port second shaft 14. Specific examples of the third embodiment will be described with reference to the effect of the difference in the shape of the discharge port portion 20.

"Specific Example 9-1"
In the nozzle shape shown in FIG. 17, the discharge port portion 20 is formed by the first discharge port portion 16 and the second discharge port portion 10 from the side closer to the discharge port 11, and is perpendicular to the main surface of the element substrate 2. The cross-sectional area in the plan perspective view seen from above forms the second discharge port portion 10 larger than the first discharge port portion 16.

  By adopting such a shape, the flow resistance of the discharge port portion 20 can be reduced, and the print quality can be improved without decreasing the discharge speed even if the discharge droplets are reduced. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

"Specific Example 9-2"
The nozzle shape shown in FIG. 18 is one of variations of “Specific Example 9-1”. In the nozzle shape illustrated in FIG. 18, the first discharge port portion 16 has a cylindrical shape, and the second discharge port portion 10 has a truncated cone shape. By making the second discharge port portion 10 into a truncated cone shape, the flow resistance can be further reduced as compared with “Specific example 9-1”. Further, since the step portion 18 between the first discharge port portion 16 and the second discharge port portion 10 is reduced, the stagnation area of the ink stagnating in the step portion 18 is reduced, the discharge amount and the discharge speed are stabilized, and the printing is performed. The quality rises. This is because the ink stagnating in the step portion 18 has a higher temperature than the surrounding ink due to the effect of being warmed by the electrothermal conversion element, and changes the viscosity resistance of the ink to be ejected, thereby adversely affecting the ejection characteristics. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

"Specific Example 9-3"
In the nozzle shape shown in FIG. 19, the first discharge port portion 16 and the second discharge port portion 10 are both cylindrical and have the same combination as the specific example of FIG. 17, but perpendicular to the main surface of the element substrate 2. In the plan perspective view seen from the direction, the first discharge port portion 16 on the side opposite to the ink supply chamber 6 and the step portion 18 of the second discharge port portion 10 are formed so as not to occur. Thus, as compared with “Specific Example 9-1”, there is an effect of improving the refill frequency by reducing the ink clipping at the stepped portion 18. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

"Specific Example 9-4"
The nozzle shape shown in FIG. 20 is a plane in which the first discharge port portion 16 has a cylindrical shape, the second discharge port portion 10 has a truncated cone shape, and is viewed from a direction perpendicular to the main surface of the element substrate 2. In the perspective view, the first discharge port portion 16 on the side opposite to the ink supply chamber 6 and the step portion 18 of the second discharge port portion 10 are formed so as not to occur. As described in “Specific Example 9-2”, when the second discharge port portion 10 has a truncated cone shape, the ink stagnation area is smaller than that of the cylindrical shape, and the discharge amount varies due to the temperature rise of the ink in the stagnation area. Thus, printing defects can be suppressed. Further, by designing so as to eliminate the stepped portion 18, the meniscus clipping at the time of refilling is alleviated, and the refill frequency is increased. Here, the cross section perpendicular to the flow of the first discharge port portion 16 and the second discharge port portion 10 is not limited to a circle, but is a circle surrounded by a circle, an ellipse, a polygon, and a curve, and a figure close to a circle. If you are doing.

1 is a perspective view of an embodiment of an ink jet recording head suitable for the present invention, partially cut away. FIG. 3 is a diagram for explaining a nozzle structure of the ink jet recording head according to the first embodiment of the present invention. It is a figure for demonstrating the nozzle structure of the inkjet recording head by the 2nd Embodiment of this invention. It is a figure for demonstrating the nozzle structure of the inkjet recording head by the 3rd Embodiment of this invention. It is a figure for demonstrating the nozzle structure of the inkjet recording head by the 4th Embodiment of this invention. It is a figure for demonstrating the nozzle structure of the inkjet recording head by the 5th Embodiment of this invention. It is a figure for demonstrating the nozzle structure of the inkjet recording head by the 6th Embodiment of this invention. It is the perspective view which cut and looked at 7th Embodiment of the inkjet recording head suitable for this invention. It is a schematic diagram of the specific example 1 of the nozzle structure of the ink jet recording head according to the seventh embodiment of the present invention. It is a schematic diagram of Example 2 of the nozzle structure of the ink jet recording head according to the seventh embodiment of the present invention. It is a schematic diagram of specific example 3 of the nozzle structure of the ink jet recording head according to the seventh embodiment of the present invention. It is a schematic diagram of the specific example 4 of the nozzle structure of the ink jet recording head according to the seventh embodiment of the present invention. It is the schematic diagram of the specific example 1 of the nozzle structure of the inkjet recording head by the 8th Embodiment of this invention. It is a schematic diagram of Example 2 of the nozzle structure of the ink jet recording head according to the eighth embodiment of the present invention. It is a schematic diagram of specific example 3 of the nozzle structure of the ink jet recording head according to the eighth embodiment of the present invention. It is a schematic diagram of Example 4 of the nozzle structure of the ink jet recording head according to the eighth embodiment of the present invention. It is the schematic diagram of the specific example 1 of the nozzle structure of the inkjet recording head by the 9th Embodiment of this invention. It is the schematic diagram of the specific example 2 of the nozzle structure of the inkjet recording head by the 9th Embodiment of this invention. It is a schematic diagram of specific example 3 of the nozzle structure of the ink jet recording head according to the ninth embodiment of the present invention. It is the schematic diagram of the specific example 4 of the nozzle structure of the inkjet recording head by the 9th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heater 2 Element board | substrate 3 Flow path structure board | substrate 4 Discharge port 5 Nozzle 6 Supply chamber 7 1st nozzle row 8 2nd nozzle row 9 Supply path 10 2nd discharge port part 11 Foaming chamber 12 1st axis | shaft 13 Below discharge port part End surface 14 Second shaft 15 Heater shaft 16 First discharge port portion 18 Stepped portion 20 Discharge port portion 21 Discharge port upper end surface 24 Nozzle

Claims (5)

A plurality of nozzles through which the liquid flows, a supply chamber that supplies the liquid to the plurality of nozzles, and a plurality of discharge ports that are front end openings of the nozzles that discharge liquid droplets,
A foaming chamber having an energy generating element for generating thermal energy for discharging droplets; a discharge port portion including the discharge port and communicating between the discharge port and the foaming chamber; and the foaming chamber a flow path forming substrate comprising a supply passage for supplying the liquid, said nozzle consisting in,
An element substrate on which the energy generating element is provided and the flow path configuration substrate is bonded to a main surface;
The discharge port portion includes a first discharge port portion including the discharge port,
A second discharge port portion that is continuous to the first discharge port portion with a step and is parallel to the main surface of the element substrate and communicated with the foaming chamber with a cross section larger than the cross section of the first discharge port portion; An ink jet recording head comprising:
An ink jet recording head, wherein a distance in the liquid supply direction of the supply path in a cross section parallel to the main surface of the element substrate of the second discharge port portion is smaller than a distance in a direction orthogonal to the supply direction.   2. The ink jet recording head according to claim 1, wherein a cross section of the second discharge port portion parallel to the main surface of the element substrate gradually decreases toward the first discharge port portion. A plurality of nozzles through which the liquid flows, a supply chamber that supplies the liquid to the plurality of nozzles, and a plurality of discharge ports that are front end openings of the nozzles that discharge liquid droplets,
A foaming chamber having an energy generating element for generating thermal energy for discharging droplets; a discharge port portion including the discharge port and communicating between the discharge port and the foaming chamber; and the foaming chamber a flow path forming substrate comprising a supply passage for supplying the liquid, said nozzle consisting in,
An element substrate on which the energy generating element is provided and the flow path configuration substrate is bonded to a main surface;
The discharge port portion includes a first discharge port portion including the discharge port,
A second discharge port portion that is continuous to the first discharge port portion with a step and is parallel to the main surface of the element substrate and communicated with the foaming chamber with a cross section larger than the cross section of the first discharge port portion; An ink jet recording head comprising:
The center of gravity of the discharge port side end surface of the first discharge port portion in the cross section parallel to the element substrate is the center of gravity of the end surface of the second discharge port portion in the cross section of the second discharge port portion parallel to the element substrate. An ink jet recording head, wherein the ink jet recording head is shifted downstream from the center of gravity with respect to a liquid supply direction of the supply path.   The center of gravity of the energy generating element and the center of gravity of the discharge port side end surface in a cross section parallel to the element substrate of the first discharge port are aligned with the liquid supply direction of the supply path. The ink jet recording head according to claim 3.   The center of gravity of the energy generating element and the center of gravity of the end surface on the first discharge port side in the cross section parallel to the element substrate of the second discharge port coincide with the liquid supply direction of the supply path. The ink jet recording head according to claim 3, wherein the ink jet recording head is provided.

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