JPS59162061A - On-demand type printing-head - Google Patents

Abstract

PURPOSE:To obtain stable injection of ink grains of uniform velocity and grain diameter by providing a concavity in a fixed part between a diaphragms and by suspending a deformation of the fixed part due to the deformation of diaphragm at the concavity for preventing generation of bubbles. CONSTITUTION:In a fixed part 11 between diaphragm 8 a V-shaped concavity 12 is provided from the opposite side of a substrate 2 whose depth d is loarger than a thickness t of the diaphragm and whose length L is longer than an electrostrictive element 10. Under this condition, when the electrostrictive element 10-1 is driven, a deformation of the fixed part 11 due to deformation of diaphragm 8-1 can be suspended and an undesirable deformation of adjacent diaphragm 8-2 can be controlled to a value pronouncedly smaller than its usual value. Consequently, a typing-head can be made compact and lightweight by improving an actual tightness of ink passage and further, by prevention of generation of bubbles in the ink passage, long durable stable typing becomes available and further, uniform velocity and diameter of ink grains injected from a nozzle 4 can be maintained and thus, better typing quantity can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an on-demand print head that is used in an on-demand inkjet printer and generates stable ink droplets.

The prior art will be explained using FIGS. 1 and 2.

For example, by providing a groove in the diaphragm 1 made of silicon and bonding it to a substrate 2 made of glass, for example, the ink flow in the ink chamber 3, nozzle 4, outlet passage 5, common ink chamber 6, and ink introduction hole 7 can be achieved. form a road. A thin plate portion covering the ink chamber 3 is a diaphragm 8, and an electrostrictive element 10 is bonded to the upper portion of the diaphragm 8 with an adhesive 9. Although the diaphragm 1 and the substrate 2 are in close contact with each other except for the groove portion of the ink flow path, the portion between the diamonds 72 and 8 is particularly referred to as a fixed portion 11.

In the print head having the above structure, the plurality of ink chambers 2- are filled with ink via the ink introduction hole 7 and the common ink chamber 6. Now, when a driving voltage is applied to the electrostrictive element 10 by a means not shown so as to cause it to contract in the direction of the arrow shown in FIG. The ink pressure generated at this time, which causes the volume to decrease rapidly, is amplified in the outlet channel 5 and causes the ink particles 20 to be ejected from the nozzle 4.

However, when a voltage is applied to the electrostrictive element 10-1 to cause the diaphragm 8-1 to deform downward in a convex manner, the fixed portion 11
Since it is not a completely rigid body, strain propagates to the fixed part 11, causing the diaphragm 8-2 to deform in an upwardly convex manner.For example, in FIG. 2, T=03, t=0.15 t.
In the case of m, b = 0.5 ax, the amount of deformation of diaphragm 8-2 is 1 of the amount of deformation of diaphragm 8-1.
Reach 0chi or more. Similarly, when a voltage is applied to the electrostrictive element 10-3, the diaphragm 8-2 undergoes an upwardly convex deformation. When electrostrictive elements 10-1 and 10-3 on both sides are driven simultaneously, although electrostrictive element 10-2 is not driven,
The amount of deformation (convex upward) of the diaphragm 8-2 reaches 20 inches or more of the diaphragm 8-1 or 8-3.

For this reason, the inside of the ink chamber 3 suddenly becomes negative pressure, and bubbles are likely to be generated in the ink flow path. The bubbles generated in the ink chamber 3 cause problems such as inhibiting the normal ejection of ink particles 20.

Furthermore, when the electrostrictive elements 10-1, 10-2 and 10-3 are driven simultaneously, the amount of deformation of the downward convexity of the diaphragm 8-2 (the amount of deformation of the ink droplet 20 from the ejecting reservoir) is the same as that of the diaphragms on both sides. Due to the influence of deformation of elements 8-1 and 8-3, the amount of deformation does not reach 80 degrees, which is the amount when the electrostrictive element 10-2 is driven alone. Therefore, the nozzle 4 leading to the diaphragm 8-2
As the velocity of the ink droplets 20 ejected from the ink droplet increases, the diameter thereof also decreases, and sometimes no ink droplets are ejected.

If the speed or particle size of the ink particles 20 fluctuates, this will cause a disadvantage that the print quality will be significantly degraded. One way to eliminate these disadvantages is to increase the rigidity of the fixing part 11 by increasing the width of the fixing part 11, that is, the 5th dimension, but this reduces the mounting density of the ink flow paths in a multi-nozzle print head. , which is not a preferred method because it increases the size of the print head.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, suppress the generation of bubbles, and stably eject ink particles having a uniform velocity and particle size.

The present invention is devised so that by providing a recess in the fixing part between the diaphragms, the distortion of the fixing part due to the deformation of the diaphragm is blocked at four parts, thereby suppressing undesirable deformation of the adjacent diaphragms.

An embodiment of the present invention will be described with reference to FIGS. 3 and 4. A V-shaped recess whose depth d is larger than the thickness t of the diaphragm 8 and whose length L is larger than the length of the electrostrictive element 10 is formed in the fixed part 11 between the diaphragms 8 from the opposite side of the substrate 2. 12 will be provided. By applying such pressure, for example, when the electrostrictive element 10-1 is driven, distortion of the fixing part 11 due to deformation of the diaphragm 8-1 is cut off, and the adjacent diaphragm 8
The amount of undesirable deformation of -2 can be suppressed to a much smaller amount than in the past.

In the above embodiment, the recess 12 has a V-shape, but it may have any shape as long as it can block the propagation of strain in the fixing part 11. In addition, the length L and depth d of the four parts 12 are assumed to be larger than the length of the electrostrictive element 10 and the thickness t of the diaphragm 8, respectively, but for mounting reasons, even if they are small, is it possible? You can expect great results. Note that the depth d may reach the substrate 2. Furthermore, the recess 12 may be filled with a vibration-proofing material so that the recess does not have to be formed in terms of appearance. It should be noted that although grooves are provided in the diaphragm 1 to provide ink channels such as the ink chambers 3, grooves may be provided in the substrate 2 to form ink channels.

According to the present invention, the following effects are achieved by providing four parts in the fixing part between the diaphragms.

(1) By increasing the mounting density of the ink channels, the print head can be made smaller and lighter.

(2) By suppressing the generation of bubbles in the ink flow path, stable printing is possible for a long time, improving reliability.

(3) The speed and particle size of the ink particles ejected from the nozzle 4 can be kept uniform, and good printing quality can be obtained.

[Brief explanation of the drawing]

FIGS. 1 and 2 are a bottom view and a sectional view taken along the line ■--■ showing an example of a conventional print head. FIGS. 3 and 4 are a plan view and a sectional view taken along the line IV--IV of an embodiment of the print head of the present invention, as seen from the electrostrictive element side. In the figure, 1 is a diaphragm, 2 is a substrate, 3 is an inlet chamber, and 4 is a diaphragm.
5 is a nozzle, 5 is 4 outlet passages, 6 is a common ink chamber, 7 is an ink introduction hole, 8 is a diaphragm, 9 is an adhesive, 10 is an electrostrictive confectionery, 11 is a fixed part, 12 is a recessed part, 20 is an ink particle be. talent figure

Claims (1)

[Claims] 1. In an on-demand multi-nozzle print head in which a diaphragm plate and a substrate are bonded together to form a plurality of ink channels such as ink chambers and nozzles, a fixed portion between diaphragms that covers an ink chamber. The on-demand print head is characterized in that it is provided with four parts that block the propagation of rock fishing machine strain. 2. A bill-on-demand print head, characterized in that the recessed portion is longer than the length of the ink chamber.