JPH0444855A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To enhance not only image quality but also execution drive frequency by a method wherein interference correcting drive parts made independently drivable in a divided state are driven corresponding to the emitting droplet forming drive parts arranged to the parallel flow paths of liquid droplet injection communicating with a common liquid chamber part in the timing corresponding to the driving of the emitting droplet forming drive parts. CONSTITUTION:When emitting droplet forming driving parts 11a are driven in order to emit liquid droplets from nozzles 6a, the interference correcting drive parts 12a in a common liquid chamber 4a are simultaneously driven to pressurize the common liquid chamber 4a. The liquid in the common liquid chamber 4a enters respective flow paths 3a to generate fluidal mutual interference. The direction of this interference acts in the positive direction with respect to the emission of liquid droplets, that is, in the same direction as that enhancing the pressure in the respective flow paths by the volumetric reduction of the flow paths 3a due to the driving of the emitting droplet forming drive parts 11a. Mechanical mutual interference is corrected so as to be set off by forcibly imparting the fluidal mutual interference.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording device, and more particularly to a head portion of an inkjet recording device.

Historical Technical Rights Publicly known documents describing the prior art related to the present invention include the following. In Japanese Patent Application Laid-open No. 60-90770,
A head made of a rigid member is disclosed in which a piezoelectric element is provided on a diaphragm and held rigidly, and instead of deformation by a piezoelectric strain constant perpendicular to the polarization direction, deformation by a piezoelectric strain constant that is the same as the polarization direction is used. This allows pressurized chambers to be arranged in high density.

It facilitates electrical connection.

FIG. 5 is a diagram showing the above conventional example, in which 21 is a pressurizing chamber, 22 is a pressurizing chamber plate, 23 is a diaphragm, 24° and 26 are electrodes,
25 is a piezoelectric body, 27 is a substrate, and 28 is a groove. By applying a voltage to the two electrodes 24 and 26, the piezoelectric body 25 divided by the groove 28 is displaced into the pressurizing chamber 21 formed on the pressurizing chamber plate 22 via the vibration plate 23, and the volume at this time is Droplets are ejected from a nozzle communicating with a pressurized chamber due to pressure changes.

FIG. 6 is a diagram for explaining mutual interference between adjacent nozzles due to the configuration shown in FIG. 5, where H is the thickness of the pressurizing chamber plate, and S
L is the length of the substrate support part, SG is the length of the groove forming part, ■ ~ ■
is a convex portion of the piezoelectric body.

Focusing on the convex part ■ of the piezoelectric body, change in volume △v2 of the pressurizing chamber 21 when voltage is applied only to the convex part ■ of the piezoelectric body, and change in volume Δv2 when voltage is applied to the convex part ■■■■ of the piezoelectric body The ratio of the volume change △VT of the pressurizing chamber 21 at the time is 1.0 in the absence of mutual interference, but since the pressurizing chamber plate 22 is deformed as shown by the dotted line in the figure, the ratio is less than 1°O. becomes. This is because the pressurizing chamber plate 22 has a length SL of the substrate support portion with respect to the substrate, which is equivalent to deformation of a beam having a length SG of the groove forming portion. That is, the amount of deformation (deflection) of the beam is proportional to the cube of SG and inversely proportional to the cube of the thickness H. When the length SG of the groove forming part is constant, as the length SL of the support part is increased, the amount of deformation becomes smaller and the mutual interference becomes smaller, but if the length SG of the groove forming part reaches a certain value. If it exceeds this, even if the length SL of the support portion is increased, the amount of deformation hardly decreases and becomes saturated. Therefore, if the length SG of the groove forming part is increased (increasing the number of nozzles) while the length SL of the support part is constant, this deformation gradually becomes larger. Therefore, depending on the groove width, the amount of displacement of the piezoelectric body, the length SL of the support part, the materials of the substrate and pressurizing chamber plate, and the allowable mutual interference (△■2/△VT), the length SL of the support part, the groove forming part The length SG of is determined.

In addition, when one actuator moves, it affects the actuator that is in contact with it, and the adjacent actuator is connected via the diaphragm, and the flow path is also connected to the diaphragm, so the adjacent actuator This has the disadvantage that the influence on the actuator cannot be avoided. For this reason, when the number of nozzles is increased and the length is increased, special measures are required to prevent such mutual interference.

In addition, in the previously proposed patent application No. 1-138503, there is a filler between the slits, so when one of the slits is driven through this filler, the filler also moves with the slit, causing the bonded flow to flow. There was an inconvenience that the road plates also moved together.

In this way, due to the drawbacks seen in the conventional method, when several adjacent pixels are activated at the same time, uniform ejection cannot be obtained because each of them influences each other, resulting in differences in the diameter of adjacent pixels and poor 5-pixel position accuracy. , which caused the image quality to deteriorate. Moreover, if this is driven at a distance that is not affected in order to improve this, the actual printing frequency will be slowed down, and the printing speed will be reduced.

In order to solve these problems, a head section as shown in FIG. 7 has been proposed. In the figure, 31 is a substrate, 32 is a piezoelectric element (
PZT), 33 is a channel plate, 33a is an ink channel, 34
34a is a common liquid chamber component, 35 is an ink supply pipe, 36 is a nozzle plate, 36a is a nozzle,
37 is a copper medium, 38 is a rieet wire, 39 is a grounding lead wire, 41.42 is a protection plate, and 41b and 42b are electrodes.

Among the pair of electrodes 41b and 42b of the piezoelectric element 32, one electrode (here, the hot side: 42b) is.

The other electrode (
Here on the ground side: 41. b) is arranged only in the part corresponding to the ink flow path 33a,
In this conventional example, the piezoelectric element is driven only in the flow path section by driving the ejected droplet forming drive section.

However, at present, even with this configuration, the above-mentioned problems have not been sufficiently solved.

Purpose The present invention was made in view of the above-mentioned circumstances.
Improving image quality by being able to drive without affecting adjacent actuators.

The purpose of this invention is to provide an inkjet recording apparatus that is designed to improve the effective driving frequency.

In order to achieve the above object, the present invention provides (1) a large number of parallel flow channels spaced apart from each other in the longitudinal direction of the flow channels;
Each nozzle is connected to each of the parallel flow paths for ejecting droplets, and a supply means for supplying liquid to the parallel flow paths through a common liquid chamber, and the actuation of a certain flow path is selected. When the selected parallel flow path is moved, at least one wall surface of the selected parallel flow path is deformed by driving a piezoelectric element that is an ejection droplet formation drive unit that causes displacement perpendicular to the longitudinal direction, and the nozzle corresponding to the flow path is In an inkjet recording device that ejects droplets from a common liquid chamber that communicates with each of the parallel flow paths, there is an interference that can be divided and driven independently, corresponding to the ejection droplet formation drive unit disposed in the flow path. (2) a correction drive unit is provided, and an interference correction drive unit corresponding to the ejection droplet formation drive unit disposed in the flow path is driven at a timing corresponding to driving of the ejection droplet formation drive unit; a plurality of parallel channels spaced apart from each other in the longitudinal direction of the channels; each nozzle connected to each parallel channel for ejecting droplets; and a common liquid chamber connected to the parallel channels. and a supply means for supplying liquid,
When one of the seven sections of a certain channel is selected, at least one wall surface of the selected parallel channel is shaped into a bite shape by driving a piezoelectric element, which is an ejection droplet formation drive unit, that causes displacement perpendicular to the longitudinal direction. In an inkjet recording device that ejects droplets from nozzles corresponding to the flow paths, a common liquid chamber communicating with each of the parallel flow paths is integrated with an ejection droplet formation drive unit disposed in the flow paths. The present invention is characterized in that an interference correction drive unit is provided, and the interference correction drive unit is driven at the same time as the ejection droplet formation drive unit disposed in the flow path is driven. Hereinafter, based on the examples of the present invention, A
I will explain.

FIGS. 1 and 2 are configuration diagrams for explaining an embodiment of an inkjet recording apparatus according to the present invention, and FIG.
The cross-sectional view, FIG. 2, is a perspective view.

In the figure, 1 is a substrate, 2 is a piezoelectric element (PZT), 3 is a channel plate, 3a is an ink channel, 4 is a common liquid chamber component, 4a is a common liquid chamber, 5 is an ink supply pipe, and 6 is a nozzle. plate,
6a is a nozzle, 7 is a copper wire, 8 is a lead wire, 9a is an electrode,
9b and 10 are grounding lead wires, 10a is a wiring plate,
11.12 is a protection plate, 11a is a discharge droplet formation drive unit, 12
a is an interference correction drive unit, and llb and 12b are electrodes.

A channel plate 3 and a substrate 1 are disposed to sandwich a piezoelectric element 2, and a nozzle plate 6 and a liquid chamber 4a are provided in the longitudinal direction.

In the present invention, the interference correction drive section 12a is disposed within the common liquid chamber 48 in correspondence with the drive of the ejection droplet formation drive section 11a that causes displacement on at least one wall surface of the flow path 3a.
This is to force fluid mutual interference by creating a degree of pressure, correct the mechanical mutual interference mentioned above, and equalize the ejection characteristics of the droplets. A part of the piezoelectric element 2 is arranged to extend into the common liquid chamber 4a, and serves as an interference correction drive section 12a.

Therefore, when the ejection droplet forming drive section 11a is driven to eject a droplet from the nozzle 6a, the interference correction piece moving section 12a in the common liquid chamber 4a is also driven at the same time to pressurize the inside of the common liquid chamber 4a. As a result, the liquid in the common liquid chamber 4a goes around to each flow path 3a.

Mutual fluid interference occurs, and the direction of this interference is in the positive direction with respect to droplet ejection, that is, by driving the ejection droplet formation drive 11a, the volume of the flow path 3a is reduced and the pressure inside the flow path is reduced. It works in the same direction as increasing. By the way, as mentioned above, the mechanical mutual interference that occurs between the flow path parts is caused by the plow in the negative direction with respect to the ejection of droplets. , are compensated by forcibly applying fluidic mutual interference according to the present invention. The magnitude of mutual fluid interference is determined by the size and drive voltage of each interference correction drive section 12a, the shape of the common liquid chamber 4a, etc. Therefore, mutual interference can be corrected by appropriately combining these. As described above, mechanical interference is particularly large in driving adjacent piezoelectric elements 2, but fluid interference has a similar tendency. Therefore, the ejection droplet formation drive unit 11a is driven in any combination.

Even when ejecting ink droplets, each ejected droplet forming drive unit 1
Since the interference correction drive unit 12a corresponding to 1a is driven, interference correction is performed in each flow path.

FIG. 3 is an enlarged view of a part of FIG. 2, in which 13a is a filler, 13 is an ink, 14 is an electrode, and other parts having the same function as those in FIGS. 1 and 2 have the same references. It is numbered. The piezoelectric element (PZT) 2 is grooved so that it can be driven independently, and the convex portion formed by the groove as the ejection droplet forming driving portion 11a is displaced in thickness, thereby forming a correspondingly provided channel plate. The volume of the flow path 3a in the nozzle 3 changes, and the ink 13 is ejected from the nozzle. Further, the groove portion is filled with a filler 13a so as not to affect the driving of adjacent piezoelectric elements. In the examples shown in FIGS. 2 and 3, a laminated type piezoelectric element is shown, but a single layer structure is also applicable.

FIGS. 4(a) to 4(c) show an example of the deformation of the flow path during driving when a filler is used.

First, from the initial state shown in FIG.
Figure (b) shows a case in which only one of the two parts is driven.

The partition walls (S, S, , S4) deform in the direction of decreasing volume, but the partition wall (S2) deforms in the direction of expansion, and the actual discharge amount ΔSA1 is as follows.

Δ5A1=(S+S,+54)−S2 Next, FIG. 5(c) shows the case where the ejection droplet formation drive units A, B, and C are driven from the initial state shown in FIG. 12(a).

The partition walls (83, S,) related to the ejected droplet formation drive section A are deformed in the direction of decreasing the volume as in the case of single drive, but
The partition walls (S, , S,) related to the ejected droplet formation drive section B are deformed so as to be attracted to the ejection droplet formation drive section A. Each effective discharge amount ΔSA2. Δ5B is as follows.

8SA, = (sx+S, +84)-82ΔSB, =
(S, +S,)-(S, +S,), and the magnitude relationship in each case is as follows.

ΔSA〉ΔSA,＞ΔSB.

All of these result from variations in the pixel diameter and pixel position accuracy.

This is because the ejected droplet formation drive unit is filled with filler (the same applies to the diaphragm).
This phenomenon occurs because the channel plate is lifted up through the

Another embodiment of the present invention includes a discharge/f5 disposed in the flow path.
? There is an example (not shown) in which the interference correction drive section corresponding to the il formation drive section is driven independently of the drive of the ejection droplet formation drive section.

Here, in the same way as the piezoelectric element being grooved and filled with a filler, the ejection droplet formation drive section can be driven independently between each channel, the ejection droplet formation drive section, Grooves are also formed between the interference correction drive parts, and by filling with filler, etc., independent drive is made possible.

Therefore, since it can be obtained by processing an integrated piezoelectric element by the same means, it can be easily manufactured and an increase in cost can be suppressed.

In this case, a time difference can be set between the drive of the ejection droplet formation drive section and the drive of the interference correction drive section.

Further, drive waveforms can also be set separately.

By appropriately selecting these, it is possible to further improve the effect of interference correction.

Kazuki HiroAs is clear from the above description, the present invention has the following effects.

(1) Mechanical interference (acting in the negative direction).

By adding fluidic interference (acting in the positive direction), it is possible to cancel out the droplet formation, and at the same time drive the ejection droplet formation drive units between adjacent ones to obtain the same ejection amount as when driving alone, improving image quality. Does not decrease.

Furthermore, since adjacent parts can be driven at the same time, there is no need for thinning-out driving, and the effective frequency does not decrease.

(2) As an effect corresponding to claim 1, it is possible to set a time difference between the drive between the ejection droplet formation drive section and the interference correction drive section, and the drive waveforms can also be set separately, so that the effect of interference correction can be increased. can.

(3) ￥f! As an effect corresponding to claim 2, there is no need to add any new parts, and interference correction can be performed with almost the same configuration as the conventional one.

[Brief explanation of the drawing]

1 and 2 are configuration diagrams for explaining one embodiment of an inkjet recording apparatus according to the present invention, FIG. 3 is a partially enlarged view of FIG. 2, and FIG. 4 is a flow path during driving. Figure 5 is a diagram showing a conventional head part, Figure 6 is a diagram showing a modification of
FIG. 7, a diagram showing a conventional head section for explaining mutual interference, is a cross-sectional view of the conventional head section. 1... Substrate, 2... Piezoelectric element (PZT), 3...
Channel plate, 3a... Ink channel, 4... Common liquid chamber component, 4a... Common liquid chamber, 5... Ink supply pipe, 6... Nozzle plate, 6a... Nozzle ,7...
・Copper wire, 8... Lead wire, 9a... Electrode, 9b, 1
0... Grounding lead wire, 10a... Wiring plate,
11.12... Protective plate, 11a... Discharge droplet formation drive unit, 12a... Interference correction drive unit, llb, 12b...
·electrode. Diagram! Figure Figure Figure (0) Initial state tb) A drive Figure Figure

Claims (1)

[Claims] 1. A large number of parallel flow channels spaced apart from each other in the longitudinal direction of the flow channels, each nozzle connected to each of the parallel flow channels for ejecting droplets, and a common liquid chamber. supply means for supplying liquid to the parallel flow path through a section, and when actuation of a certain flow path is selected, at least one wall surface of the selected parallel flow path is perpendicular to the longitudinal direction. In an inkjet recording device that is deformed by the drive of a piezoelectric element that is a discharge droplet formation drive unit that causes displacement and discharges droplets from nozzles corresponding to the flow channels, a common liquid chamber section that communicates with each of the parallel flow channels is provided. , an interference correction drive section corresponding to the ejection droplet formation drive section disposed in the flow path and capable of being divided and driven independently is provided, an interference correction drive section corresponding to the ejection droplet formation drive section disposed in the flow path; is driven at a timing corresponding to the drive of the ejection droplet forming drive section. 2. A large number of parallel flow channels spaced apart from each other in the longitudinal direction of the flow channels, each nozzle connected to each of the parallel flow channels for ejecting droplets, and a supply means for supplying liquid to a flow path, and when an actuation of a certain flow path is selected, at least one wall surface of the selected parallel flow path is displaced perpendicular to the longitudinal direction. Deformed by the drive of the piezoelectric element that is the droplet formation drive unit,
In an inkjet recording device that ejects droplets from nozzles corresponding to the flow paths, a common liquid chamber communicating with each of the parallel flow paths is integrated with an ejected droplet formation drive unit disposed in the flow paths. An inkjet recording apparatus characterized in that an interference correction drive section is provided, and the interference correction drive section is driven at the same time as the ejection droplet formation drive section disposed in the flow path is driven.