JPH0427550A - Ink jet recording method and apparatus - Google Patents

Abstract

PURPOSE:To correct an angle of jetting of ink by discharging the ink when the ink is jetted out of a plurality of printing nozzles to such an extent that the ink is kept from flying at a hole adjacent to a printing nozzle hole positioned at an end of the printing nozzle holes. CONSTITUTION:Bubble outflow holes 5a of a bubble outflow path 5 and end printing nozzle holes 61a are arranged at a pitch interval equal to printing nozzle holes 6a of a group of printing nozzles 6. Then, when ink is jetted from the printing nozzles 6, a piezo-electric element 81 of the bubble outflow path 5 is vibrated finely at a timing the same as that of the printing nozzle 6 to such an extent that ink particles are kept from flying. Thus, an ink wall i1 in the perimeter of the nozzle holes 61a at both ends of the group of the printing nozzles 6 can be kept as even as that in the perimeter of other printing nozzle holes 6a, thereby enabling the correction of an angle of jetting of the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording method and apparatus for performing recording by ejecting ink used for blinking or the like in response to an input signal.

[Prior Art 1] An ink ejection head used in a conventional inkjet recording apparatus is shown in FIG. 4(a) and Section 5. Ink channels and nozzles are formed by welding a substrate 1 formed with grooves corresponding to the channels and a substrate 2 made of the same material. Ink is supplied from an ink tank not shown in the drawings through the ink supply port 3 and filled into the ink supply preparation chamber 4. The ink supply preparation chamber 4 is connected to the supply ports of each nozzle, and has branched flow paths. The nozzle includes a printing nozzle 6 used for actual printing and a bubble outlet path 5 used for discharging bubbles.
The bubble outlet path 5 is located above and below a series of printing nozzles 6.

There is a pressure chamber 7 in the middle of the flow path of the printing nozzle 6, and a piezoelectric element 8 constituting a driving means is bonded onto the pressure chamber 7. When an electric signal is applied to the pressure element 8, pressure is applied to the ink in the pressure chamber 7 through the substrate 2, and ink droplets are ejected from the tip of the printing nozzle.

When a signal is applied to the piezoelectric element 8 and an ink droplet is ejected from the printing nozzle hole 6a, the printing nozzle hole 6a on the nozzle surface
The ink spreads around the area to form an ink wall. The wall of ink created during this ink jetting has a large effect on the jetting angle of the jetted ink droplets. Specifically, the 6th
As shown in the figure, when a non-uniform ink pool 11 is formed around the printing nozzle hole 6a, the ejected ink droplets 12 are pushed toward the smaller ink pool and fly as the ink pool becomes a jetting wall. This phenomenon occurs especially when adjacent printing nozzles are driven at the same time, and as shown in FIG.
2 flies outward.

[Problems to be Solved by the Invention] As explained above, when ink is ejected from the printing nozzle, an ink wall is formed around the nozzle hole. At this time, if adjacent nozzles eject ink at the same time, the ink pools will come into contact with each other and the ink will attract each other, making the ink pool around a single nozzle hole uneven and changing the jetting angle of the ink droplets. There was a problem.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the inkjet recording method of the present invention provides a method for ejecting ink from a plurality of printing nozzles, when ejecting ink from a plurality of printing nozzle holes. It is characterized by ejecting ink from a hole adjacent to a nozzle hole to the extent that it does not fly.

Further, the inkjet recording device of the present invention includes a plurality of printing nozzles, a pressure chamber that communicates with each of the plurality of printing nozzles, and driving the ink in the pressure chamber to direct the ink from the printing nozzle toward the recording medium. In the inkjet recording apparatus, the inkjet recording apparatus includes a hole adjacent to the printing nozzle hole located at the end of the plurality of printing nozzle holes, an auxiliary pressure chamber communicating with the hole, and an auxiliary pressure chamber in the auxiliary pressure chamber. The present invention is characterized in that it includes an auxiliary drive means that drives a certain ink in synchronization with the drive means to eject the ink from the holes to the extent that it does not fly.

[Function] When the printing nozzle ejects ink, the ink is ejected from the bubble discharge hole to such an extent that it does not fly, and the ink pool ejected from the bubble discharge hole connects with the ink pool in the print nozzle hole, causing the ink to flow through the printing nozzle group. Wetting by ink around the nozzle hole becomes uniform. Therefore, the ejection angle of the ink is corrected, and the ink is ejected in a direction perpendicular to the nozzle surface.

[Embodiment] FIG. 1 is a diagram showing an embodiment of the inkjet recording method and apparatus of the present invention, and is a diagram simultaneously showing a front view, a side view, and a partially enlarged sectional view of an inkjet head. In this embodiment, a hole adjacent to the printing nozzle hole 61a located at the end of the plurality of printing nozzle holes 6a is formed as a bubble outflow hole 5a. An auxiliary pressure chamber 71 is provided in the middle of the bubble outflow path 5 in communication with the bubble outflow hole 5a, similar to the printing nozzle 6, and a piezoelectric element 81 is stacked on the auxiliary pressure chamber 71 as an auxiliary driving means. Air bubble outflow hole 5 of air bubble outflow path 5
The printing nozzle holes 61a at the ends a and 61a are arranged at the same pitch spacing as the printing nozzle holes 6a of the printing nozzle group. and,
When the printing nozzle 6 jets ink, the air bubble outflow path 5
At the same timing as the printing nozzle 6, the piezoelectric element 81 of the bubble outflow channel 5 is slightly vibrated to such an extent that ink droplets do not fly. As a result, the ink pools 11 around the nozzle holes 61a at both ends of the printing nozzle group can be kept uniform like the surroundings of the other printing nozzle holes 6a, and as shown in FIG. 4(b), the ink pools 11 can be kept uniform. The ejection angle can be corrected.

FIG. 2 is an explanatory view of a driving means that changes the shape of the piezoelectric element 81 of the bubble outflow path 5 to apply a slight vibration to the extent that ink droplets are not ejected from the bubble outflow hole 5a. Specifically, compared to the piezoelectric element 8 on the pressure chamber 7 of the printing nozzle 6 used for printing, the auxiliary pressure chamber 71
The area (axb) of the upper piezoelectric element 81 is reduced. Alternatively, the thickness t of the piezoelectric element 81 is increased. As a result, the piezoelectric elements 8 of the printing nozzle group and the piezoelectric elements 81 of the bubble outflow path 5
Furthermore, when a driving voltage suitable for printing is applied, the energy applied to the ink by the piezoelectric element 81 of the bubble outlet path 5 is smaller than that of the printing nozzle group. Therefore, the ink cannot fly out from the bubble outflow hole 5a, and the ink bleeds around the bubble outflow hole 5a. As a result, the ink pools around the nozzle holes 61a at the ends of the printing nozzle group are connected with the ink ejected from the bubble outflow holes 5a, so that the ink pools around the nozzle holes 61a at both ends of the printing nozzle group become uniform. .

FIG. 2 also shows a driving method in which the shape of the auxiliary pressure chamber 71 of the bubble outflow path 5 is changed to drive the ink in the bubble outflow path 5 to such an extent that ink droplets are not ejected from the bubble outflow hole 5a. It also shows the means. Compared to the pressure chambers 7 of a series of printing nozzle groups, the auxiliary pressure chamber 7 of the bubble outlet path 5
1 or the pressure projected area of the surface on which the piezoelectric elements 81 are stacked. Specifically, the width W of the auxiliary pressure chamber 71
Or make the length i smaller. Alternatively, the depth d of the auxiliary pressure chamber 71 is increased. This prevents the ink from jumping out from the bubble outflow holes 5a, causing the ink to smear around the bubble outflow holes 5a, and making the ink pools around the printing nozzle holes of the printing nozzle group uniform.

Furthermore, by increasing the water head loss in the bubble outflow path 5 compared to the printing nozzle group, it is possible to provide a slight vibration to the extent that ink droplets do not fly from the bubble outflow hole 5a. When ink flows into the bubble outflow path 5, the ink flows through the air bubble outflow path 5.
A head loss attributable to the shape of is generated. Specifically, when the cross section is circular, the diameter is made smaller or the flow path length is made longer than that of the printing nozzle 6. When the cross section is rectangular, head loss increases by making the channel width narrower (or the channel depth shallower, or the channel length longer) than that of the printing nozzle 6. For details on head loss, refer to "Mechanical Engineering Handbook Hydraulics and Fluid Mechanics JP8-1 (Japan Society of Mechanical Engineers Line)" When the energy necessary for ejecting ink is applied to the piezoelectric element 8.81 of the bubble outflow path 5, the ink cannot fly from the bubble outflow hole 5a, and the same effect as in the case described above cannot be obtained. can.

FIGS. 3(a) to 3(d) show the piezoelectric element 81 of the bubble outflow path 5.
FIG. 6 is an explanatory diagram of a driving method in which micro vibrations are applied to such an extent that ink droplets do not fly from the air bubble outlet hole 5a by changing the driving conditions of the piezoelectric element 8 of the printing nozzle 6 to the driving conditions of the piezoelectric element 8 of the printing nozzle 6. FIG. 3(a) shows the driving waveform of the piezoelectric element 8 of the printing nozzle group. VH is the drive voltage applied to the piezoelectric element 8, Pwb is the time during which the charge is discharged from the piezoelectric element 8, and Pwc
is the time required for the piezoelectric element 8 to be charged,
The discharge curve (1) and the charge curve (2) are based on the piezoelectric element 8.
This curve is caused by the capacitance and discharge, charging resistance, and drive voltage applied to the piezoelectric element 8. Section A is in a standby state, and a voltage is applied to the piezoelectric element in such a way that it contracts, causing the piezoelectric element to bend. The voltage applied to the piezoelectric element in section B is released. Then, since the piezoelectric element no longer bends, the pressure inside the pressure chamber 7 is reduced, ink flows in from the ink near the nozzle and the ink supply path, and air is drawn into the nozzle hole. In section C, voltage is applied to the piezoelectric element again. Therefore, the piezoelectric element contracts, pressure is applied to the ink, and the ink is ejected from the nozzle hole. Due to the surface tension in the nozzle in this section, the ink becomes stable in the nozzle hole and becomes in a standby state. Figure 3 (b
The driving methods shown in ) to (d) reduce the energy applied to the piezoelectric element 81 of the bubble outflow path 5 by changing the driving conditions, compared to the piezoelectric element 8 of the printing nozzle, and This applies slight vibration to the piezoelectric element 81 to the extent that ink droplets do not fly. Specifically, the electric signal applied to the piezoelectric element 81 of the bubble outflow path 5 is
Change it as shown in (c) below.

(a) Shorten the discharge time Pwb'.

(b) See figure (b) Reduce the drive voltage VH' applied to the piezoelectric element 81. (c) See figure (c) Increase discharge resistance.

(d) See figure As described above, when simultaneously injecting from two or more adjacent nozzle holes on the same substrate, an electric signal is sent to the piezoelectric element 81 of the bubble outflow path 5 at the same timing as the piezoelectric element 8 of the printing nozzle 6. Even if the ink is driven, the ink cannot fly from the bubble outflow hole 5a, and the same effect as described above can be obtained.

In addition, in the case of a recording medium liquid ejection recording method in which an electrothermal transducer is provided in the flow path instead of a piezoelectric element and the ink in the nozzle is ejected using thermal energy, bubbles are similarly generated in the flow path. The electrothermal converter having a lower conversion efficiency than the printing nozzle may be provided, or the thermal energy generated in the bubble outflow path 5 may be smaller than the energy generated from the heat generating part in the flow path of the printing nozzle. The same effects as in the embodiments described above can be obtained by reducing the drive current and voltage application time, or by coating the energy generating portion with a cutting material.

[Effects of the Invention] The present invention makes it possible to equalize the ink pool around the printing nozzle hole and suppress variations in the ink jetting direction by ejecting ink from the hole adjacent to the printing nozzle hole to the extent that it does not fly. There is an effect like this.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the inkjet recording method and apparatus of the present invention, showing a front view, a side view, and a partially enlarged sectional view of an inkjet head, and FIG. 2 is a front view and a partially enlarged sectional view of an inkjet head. 3(a) to 3(d) are explanatory diagrams of the piezoelectric element driving method, and FIG. 4(a) and (b) are the conventional example and the present implementation. FIG. 5 is a perspective view of the conventional example, and FIGS. 6(a) and 6(b) are action explanatory diagrams of the conventional example. l ・ 2 ・ ・ 5 a ・ 6 ・ ・ 7 ・ ・First substrate, second substrate, bubble outflow path, bubble outflow hole, printing nozzle pressure chamber, auxiliary pressure chamber, piezoelectric element, auxiliary drive means and above

Claims (4)

[Claims] (1) In an inkjet recording method in which recording is performed by ejecting ink from a plurality of printing nozzle holes toward a recording medium, when ink is ejected from the plurality of printing nozzle holes, one of the plurality of printing nozzle holes An inkjet recording method characterized by ejecting ink from a hole adjacent to a printing nozzle hole located at an end to the extent that it does not fly. (2) A plurality of printing nozzle holes, a plurality of printing nozzles communicating with the plurality of printing nozzle holes, a pressure chamber communicating with each of the plurality of printing nozzles, and ink in the pressure chamber being driven. In an inkjet recording device comprising a driving means for ejecting ink from a printing nozzle hole toward a recording medium, a hole adjacent to a printing nozzle hole located at an end of the plurality of printing nozzle holes communicates with this hole. An auxiliary pressure chamber, and an auxiliary drive means for driving the ink in the auxiliary pressure chamber in synchronization with the drive means to eject the ink from a hole adjacent to the printing nozzle hole at the end to the extent that the ink does not fly away. An inkjet recording device characterized by: (3) The inkjet recording method according to claim 1, wherein the hole adjacent to the printing nozzle hole at the end is a bubble outflow hole. (4) The inkjet recording apparatus according to claim 2, wherein the hole adjacent to the printing nozzle hole at the end is a bubble outflow hole.