JPH03290257A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To improve the picture quality and effective drive frequency by providing an interference correction hole through which a liquid is movable at least one spot between passages individually and independently separated, for an ink jet recording device. CONSTITUTION:At a part of a barrier 17 separating respective passages 16 of a passage plate 15 individually for an ink jet recording device, an interference correction hole 18 is provided. By doing this, mechanical mutual interference is corrected, and discharge characteristics of liquid drops are unified. For example, even when a large number of actuations are simultaneously performed, the effective discharge quantity for each nozzle is unified. Therefore, The size of a picture element diameter or unevenness of picture element positional precision can be greatly reduced. since adjacent ink jet heads can be driven simultaneously, thinning drive is unnecessary, and the effective frequency is not reduced.

Description

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

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 the pressurized chambers to be arranged in high density and facilitates electrical connection.

FIG. 6 is a diagram showing the above-mentioned 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. 7 is a diagram for explaining the mutual interference between adjacent nozzles 1-1 due to the configuration shown in FIG. 6, where H is the thickness of the pressurizing chamber plate, S is the length of the substrate support part, and So is the length of the groove forming portion, and ■ to ■ are the convex portions of the piezoelectric body.

Focusing on the convex part ■ of the piezoelectric body, we calculate the volume change Δ■2 of the pressurizing chamber 21 when voltage is applied only to the convex part ■ of the piezoelectric body, and the change in volume Δ■2 of the pressurized chamber 21 when voltage is applied only to the convex part ■■■■ of the piezoelectric body. The ratio to the volume change Δ■7 of the pressurizing chamber 21 when the pressurizing chamber plate 22 is deformed as shown by the dotted line in the figure is 1.0, but if there is no mutual interference, the ratio is 1.0. It becomes 0 or less. This is because the pressurizing chamber plate 22 has a length Sr of the substrate support portion with respect to the substrate, which is equivalent to deformation of a beam having a length Sa of the groove forming portion. In other words, the amount of deformation (deflection) of the beam is S. It is proportional to the cube of the thickness H and inversely proportional to the cube of the thickness H. When the length Sa of the groove forming part is constant, as the length S of the supporting part is increased, the amount of deformation becomes smaller and the mutual interference becomes smaller, but the length Sa of the groove forming part becomes a certain value. If it exceeds, even if the length SL of the support portion is increased, the amount of deformation hardly decreases and becomes saturated. Therefore, if the length Sa of the groove forming part is increased (increasing the number of nozzles) while the length S of the support part is constant, this deformation gradually becomes larger. Therefore, the groove width, the displacement amount of the piezoelectric body, the length Sl of the support part, the material of the substrate and the pressure chamber plate, and the allowable mutual interference (ΔV, /ΔVT)
The length SL of the support portion and the length Sa of the groove forming portion are determined by.

In addition, when one actuator moves, it affects the adjacent actuators, and the adjacent actuators are connected via the diaphragm, and the flow path is also connected to the diaphragm. 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.

As described above, due to the drawbacks seen in the conventional art, when several adjacent pixels are driven at the same time, each of them influences each other, making it impossible to obtain uniform ejection. This resulted in poor positioning accuracy and reduced image quality. 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.

The present invention was made in view of the above-mentioned circumstances, and
The purpose of this invention is to provide an inkjet recording apparatus that can be driven without affecting adjacent actuators, thereby improving image quality and effective drive frequency.

In order to achieve the above object, the present invention has a plurality of parallel channels spaced apart from each other in the longitudinal direction of the channels, and a plurality of parallel channels connected to each parallel channel for droplet jetting. and a supply means for supplying liquid to the parallel flow path, and when actuation of a certain flow path is selected, at least one wall surface of the selected parallel flow path extends in the longitudinal direction. In an inkjet recording device that is deformed by driving a piezoelectric element that causes vertical displacement and ejects droplets from a nozzle corresponding to the flow path, movement of liquid to at least one location between each individually separated flow path. This feature is characterized by the provision of an interference correction hole that allows for. Hereinafter, the present invention will be explained based on examples.

FIG. 2 is a configuration diagram of the head section of the inkjet recording apparatus according to the present invention, in which 1 is a substrate, 2 is a piezoelectric element (PZ
T), 3 is a channel plate, 4 is a liquid chamber, 5 is an ink supply pipe,
6 is a nozzle plate, 7 is a copper wire, 8 is a lead wire, 9 is an electrode, 1o is a grounding lead wire, and 11 is a wiring plate.

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 4 are provided in the longitudinal direction.

Figure 3 is an enlarged view of part ■ in Figure 2. In the figure, 3a is an ink flow path, 12 is a filler, 13 is ink, 14 is an electrode, and other parts that have the same function as in Figure 2 are the same. Reference numbers are attached. The piezoelectric element (PZZT) 2 is grooved so that it can be driven independently, and the thickness of the convex part formed by the groove changes, thereby creating a flow path in the corresponding flow path plate 3. 3a changes in volume and ejects ink 13 from the nozzle. Further, the groove portion is filled with a filler 12 so as not to affect adjacent actuators. 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, Figure (b) shows the case where only the piezoelectric element A is driven from the initial state of Figure (a).

The partition walls (Sl, S3.S,) 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.

ΔSAd” (S1+s, 10S4) 82 Next, piezoelectric element A is shown in FIG.

Figure (c) shows the case where B and C are driven.

The partition wall (83, S,) related to piezoelectric element A deforms in the direction of decreasing the volume as in the case of single drive, but piezoelectric element B
The partition wall (S7.ss) associated with the piezoelectric element A is deformed so as to be attracted to the piezoelectric element A. Each effective discharge amount ΔSA2 at this time
+ΔSB2 is as follows.

ΔSA, I=(S1+83+84)−82ΔSB□=
(S5+87)-(SG+Ss), and the magnitude relationship in each case is as follows.

△SA□>△SA□>△SB2, all of which result from variations in the pixel diameter and pixel position accuracy.

This phenomenon occurs because the actuator (PZT) lifts the channel plate via the filler (the same applies to the diaphragm).

FIG. 1 is a perspective view of a channel plate for explaining one embodiment of an inkjet recording apparatus according to the present invention, in which 15 is a channel plate, 16 is a channel, 17 is a partition, and 18 is an interference correction It is a hole. By providing an interference correction hole 18 in a part of the partition wall 17 that separates each flow path 16 of the flow path plate 15, the above-mentioned mutual mechanical interference is corrected and the droplet ejection characteristics are made uniform. 7- It is something that can be done.

For comparison with the embodiment of the present invention, a perspective view of a conventional channel plate is shown in FIG. Reference numbers in the figure are the same as in FIG.

In the embodiment of the present invention, when only A is driven from the initial state, the discharge amount ΔSA: is ΔSAt": ΔsA1
(LOSSAB+LOSSAC), at this time Lo
ss is a fluid loss due to the effect of volume change escaping from the interference correction hole to the adjacent flow path. Here, LOSSAB is A
The loss from the flow path to the B flow path, LossA, is the loss from the A flow path to the C flow path.
This is a loss to the flow path.

Furthermore, when driving ABC, the actual discharge amount △SAz is ΔsAz = ΔSAZ (LOS SAll + LO
S SAC)+LOSSsA+LOSSCA Cape ΔSA□. Here, LOSSBA is the loss from the B channel to the A channel, and LOSSCA is the loss from the C channel to the A channel. This is because the aforementioned losses are canceled out by driving the adjacent channels B and C. Therefore, if this loss is appropriately selected to balance the mechanical deformation mentioned above, ΔSAx = ΔSA2, and considering the entire head as a total,
For example, even when a large number of actuations are performed at the same time, the actual discharge amount from each nozzle is made more uniform than in the past. Therefore, variations in pixel diameter and pixel position accuracy can be significantly reduced compared to conventional ones. The positions and numbers of interference correction holes are shown in Figures 1(a) to (
There is no particular limitation as in c), and the shape may be selected in consideration of providing an appropriate loss. Further, dummy channels may be provided at both ends of the flow channels in order to equalize the loss.

As is clear from the above explanation, the present invention has the following effects.

(1) By providing the interference correction hole, it is possible to mechanically cancel interference by using fluid loss.

(2) By configuring the piezoelectric body and its corresponding flow path in a non-contact state, even if adjacent actuators are driven at the same time, each actuator will not affect each other, resulting in a uniform discharge amount and reduced image quality. I won't lower it.

(3) Since adjacent parts can be driven simultaneously, there is no need for thinning-out driving and there is no reduction in the effective frequency.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a flow path plate for explaining one embodiment of an inkjet recording apparatus according to the present invention, FIG. 2 is a diagram showing the configuration of a head section of the inkjet recording apparatus according to the present invention, and FIG. is an enlarged view of part ■ in Figure 2, Figure 4 (,)
-(c) are diagrams showing the deformation of the flow path during driving using a filler as an example. Figures (,) are in the initial state, Figure (b) is A drive, Figure (c) is A, FIG. 5 is a perspective view of a conventional flow path plate for comparison with FIG. 1, FIG. 6 is a diagram showing a conventional head section, and FIG. FIG. 2 is a configuration diagram of a conventional head section for explaining mutual interference. 15... Channel plate, 16... Channel, 17... Partition wall,
18...Interference correction hole.

Claims (1)

[Claims] 1. A large number of parallel channels spaced apart from each other in the longitudinal direction of the channels, each nozzle connected to each parallel channel for droplet ejection, and a supply for supplying liquid to the parallel channels. when actuation of a certain flow path is selected, at least one wall surface of the selected parallel flow path is deformed by driving a piezoelectric element that causes displacement perpendicular to the longitudinal direction; An inkjet recording device that ejects liquid droplets from nozzles corresponding to the flow channels, characterized in that an interference correction hole through which liquid can move is provided at at least one location between each of the individually separated flow channels. Inkjet recording device.