JPH05169650A - Ink jet head and ink jet head driving method - Google Patents

Abstract

PURPOSE:To achieve reduction of a number of driving circuits per nozzle while a characteristic capable of discharging by a number of high frequencies is being maintained by a method wherein one common pressure chamber and a plurality of pressure chambers interconnected therewith are provided. CONSTITUTION:A first PZT 6 is arranged at a position corresponding to a first pressure chamber 9. A plurality of second pressure chambers 8 separated with partition walls 10 are interconnected with the first pressure chamber 9. A second PZT 5 is arranged respectively to a position corresponding to the second pressure chamber 8. A nozzle 2 is formed so that its sectional form narrows in a tapered manner from the second pressure chamber 8. A feed opening performs a role wherein a flow of ink toward an ink tank generated by variation in volume between the first pressure chamber 9 and the second pressure chamber 8 is restrained. A pipe 11 is connected to a tube 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet type recording apparatus for ejecting ink droplets to form an ink image on a medium such as recording paper, and more particularly to an on-demand ink jet head and a driving method thereof.

[0002]

2. Description of the Related Art A conventional ink jet head has one ink pressurizing chamber for one nozzle and ejects ink by pressurizing the ink pressurizing chamber. However, in today's demand for higher recording speed, there is a limit to the ink ejection repetition frequency in the head configuration. Therefore, two pressure chambers and pressure means are provided for one nozzle to enable high-speed response.
JP-A-3-43253 and JP-A-2-303845 are disclosed. Specifically, (Prior Art Example 1) Japanese Patent Laid-Open No. 2-162048 discloses a first pressure chamber 2 in which pressure chambers 200 communicate with each other as shown in FIG.
01 and the second pressure chamber 202. By driving the piezoelectric elements 203 and 204 of these two pressure chambers 201 and 202 with a delay time, the ink supply capability is enhanced, the retraction of the meniscus is suppressed, and ink droplets can be ejected at a higher frequency. Is.

(Prior art example 2) Japanese Patent Laid-Open No. 3-43253 discloses
As shown in FIG. 16, two pressure chambers 206 and 207 capable of individually pressurizing one nozzle 205.
Have. By pressurizing these two pressure chambers with a time lag, it is possible to drive at a low voltage and increase the limit repetition frequency of ink droplet ejection.

(Prior Art 3) In Japanese Patent Laid-Open No. 2-303845, as shown in FIG. 17, a first energy generating means 209 for pressurizing the pressure chamber 208 and a nozzle 210 without passing through the pressure chamber 208 are communicated. Sub flow path 211 and sub flow path 211
Second energy generating means 21 for pressurizing the interior of the
Have two. Therefore, the meniscus returns quickly to the initial position after the ink droplets are ejected, which enables high-speed recording with better frequency characteristics.

[0005]

In the above-mentioned conventional ink jet head, since one nozzle has two pressure generating means, it is necessary to provide a drive circuit for each pressure generating means, and wiring and drive circuit are required. Has a problem that it becomes complicated. In addition, since each nozzle has two pressure chambers, the area and volume occupied by each nozzle are large. Therefore, when a plurality of nozzles are arranged to form a multi-nozzle inkjet head, it is difficult to arrange the nozzles at a high density.

The present invention has been made in view of the above circumstances, and an object thereof is to maintain the characteristic of ejecting ink droplets at a high frequency, which is obtained by having two pressure chambers. It is still possible to reduce the number of drive circuits per nozzle and realize an inexpensive inkjet head. Another object of the present invention is to provide an ink jet head that enables high-density nozzle arrangement and realizes high print quality.

[0007]

An ink jet head according to the present invention comprises a first pressure chamber communicating with a reservoir and a plurality of second pressure chambers having one end communicating with the first pressure chamber and the other end having a nozzle opening. And a pressure chamber of.

Further, in the ink jet head driving method of the present invention, the first pressure means for deforming the first pressure chamber communicating with the reservoir, and the nozzle opening at the other end communicating with the first pressure chamber. A first step of providing second pressure means for deforming the plurality of second pressure chambers, and driving the first and second pressure generating means to expand and deform the first and second pressure chambers. And a second step of driving the first and second pressure generating means to reduce and deform the first and second pressure chambers, thereby ejecting ink droplets.

Further, another ink jet head driving method of the present invention comprises a first step of driving the first pressure generating means to expand and deform the first pressure chamber, and the first and second steps. And a second stroke for reducing and deforming the first and second pressure chambers by simultaneously driving the pressure generating means of
It is characterized by ejecting ink droplets.

Further, when ink droplets are not ejected, the first pressure generating means is driven to expand and deform the first pressure chamber, and at the same time, the second pressure generating means is driven to drive the second pressure generating means. Vibration of the meniscus is also suppressed by a first step of reducing and deforming the pressure chamber and a second step of driving the first pressure generating means to reduce and deform the first pressure chamber. ..

[0011]

According to the structure of the present invention, the volume of the second pressure chamber 8 is controlled in accordance with the expansion or contraction deformation of the first pressure chamber 9 to change the ink flow in the pressure chamber. Ink ejection control is performed.

[0012]

1 is a perspective view of a first embodiment of an ink jet head of the present invention. This inkjet head has a plurality of nozzles 2 (five in FIG. 1). The head shown in FIG. 1 is formed by an etching technique, a method of laminating a plurality of thin plates, or a base 1 provided with an uneven surface serving as an ink flow path by plastic injection molding and a pressure plate 3 are laminated and bonded to each other. It forms a flow path. A common electrode 4 is formed on one surface of the pressure plate 3 by plating or sputtering. On the upper surface of the common electrode 4, one first piezoelectric element (hereinafter referred to as PZT) 6 and a plurality of second PZTs 5 corresponding to each nozzle are adhered so as to have electrical conductivity. Electrodes are provided on both surfaces of the first PZT 6 and the second PZT 5, and are connected to a drive circuit (not shown) by a signal line (not shown). The first pressure generating means is composed of the first PZT 6 and the pressure plate 3, and the second pressure generating means is the second PZT 5 and the pressure plate 3.
It is composed of and. The ink is supplied from an ink tank (not shown) through the tube 7 and fills the inside of the ink flow path from the ink tank to the nozzle 2.

FIG. 2 is a plan view of the ink jet head of FIG. 1, and FIG. 3 is a sectional view taken along the line AA '. Figure 2 below
The ink flow path structure will be described with reference to FIG.

Reference numeral 9 denotes a first pressure chamber common to all nozzles, and a first PZ is provided at a position corresponding to the first pressure chamber 9.
T6 is provided. A partition wall 10 is provided in the first pressure chamber 9.
A plurality of second pressure chambers 8 that are separated from each other communicate with each other. The second PZTs 5 are arranged at the positions corresponding to the second pressure chambers 8, respectively. The nozzle 2 has a second pressure chamber 8
Is tapered so that the cross-sectional shape is narrowed. Reference numeral 14 is a supply port, which plays a role of suppressing the flow of ink toward the ink tank, which is generated by the volume change of the first pressure chamber 9 and the second pressure chamber 8. Reference numeral 11 denotes a pipe, which is joined to the tube 7. An introduction path 12 is formed inside the pipe 11 and serves to guide the ink from the ink tank to the inside of the inkjet head. Here, the acoustic impedance of the ink flow path from the ink tank to the introduction path 12, that is, the flow path resistance and inertance is set as small as possible so as not to affect the ejection characteristics of the ink droplets. Also, the pressure plate 3 and the first P
The ZT6 and the second PZT5 are selected and used in combination so that the amplitude of deformation is large and the combined compliance is large. Although PZT is used as the pressure generating means in this embodiment, it is also possible to use the expansion movement of the voice coil or the air bubble as another embodiment. Figure 4
5A to 5C are drive waveform diagrams for explaining the driving method of the first embodiment of the inkjet head of the present invention, FIGS. 5A to 5C are diagrams for explaining the ejection operation, and FIGS. It is a figure explaining discharge operation.

In FIG. 4, V1 represents a drive waveform applied to the first PZT6, and V2 represents a drive waveform applied to the second PZT5. Further, a time t1 to a time t4 are drive waveforms when ejecting ink droplets,
Times t5 to t8 are drive waveforms used in the case of non-ejection. The ejection and non-ejection operations of the first embodiment will be described below.

(Discharging operation in the first embodiment) In the initial state before t1, the voltages 15 and 16 are applied to the first PZT 6 and the second PZT 5, respectively. At this time, the first
PZT6 and second PZT5 are deformed to the reduced state. Therefore, the pressure plate 3 is
The pressure chamber 9 and the second pressure chamber 8 are slid and deformed in a direction in which the volumes of the pressure chamber 9 and the second pressure chamber 8 are reduced, and are stationary.

However, in the process from time t1 to time t2 shown in FIG. 5A, the applied voltage to the first and second PZTs gradually decreases, so that the first PZT 6 moves in the direction of arrow 22. , And the second PZT 5 is deformed in the direction of arrow 21. That is, the first pressure chamber 9 and the second pressure chamber 8 are expanded and deformed. Due to this deformation, a flow occurs in the ink inside the first pressure chamber 9 and the second pressure chamber 8. Supply port 14
In the first pressure chamber 9, the ink flows in the directions of arrows 26 and 25, and in the nozzle 2 and the second pressure chamber 8, the arrow 2
Ink flow occurs in the 3rd and 24th directions. Especially nozzle 2
At, a greatly drawn meniscus 36 is formed.

In the process from time t2 to time t3 shown in FIG. 5 (b), the voltage applied to the first PZT6 and the second PZT5 is zero, and the movement of the PZT is stopped. However, the ink inside the supply port 14, the first pressure chamber 9, and the second pressure chamber 8 flows in the directions of arrows 27 to 30 due to inertia. Due to this flow, the meniscus in the nozzle 2 is 37
To reduce. The reason why the flow in the directions of the arrows 27 to 30 occurs is that the meniscus 36 is drawn in from the time t1 to the time t2, and as a result, the arrow 23,
This is because the kinetic energy of the ink in the 24 directions becomes smaller than the kinetic energy of the ink in the directions of the arrows 25 and 26.

In the process from time t3 to t4 shown in FIG. 5 (c), the application of the voltage to the first PZT6 and the second PZT5 is started again. Along with that, the first PZT 6 and the second P
The ZT5 starts slanting deformation in the directions of the arrows 32 and 31. That is, the first pressure chamber 9 and the second pressure chamber 8 are contracted and deformed. As a result, in the first pressure chamber 9 and the second pressure chamber 8, flows in the directions of arrows 33, 34, and 35, which are added to the flows in the directions of arrows 27 to 30 due to the inertia, are generated. In particular, since the flow of the arrow 33 is high speed, the ink is extruded from the nozzle into the ink column 38 and finally ejected as an ink droplet. In addition, an arrow 35 directed to the supply port 14
Is sufficiently smaller than the flow of arrow 33.

(Non-ejection operation in the first embodiment) In the state before t5, the first pressure chamber 9 and the second pressure chamber 8 are in the first PZT 6 and the second PZ as in the initial state of the ejection operation.
It is still stationary after being deformed in a direction of decreasing the volume by T5.

In the process from time t5 to time t6 shown in FIG. 6A, the applied voltage to the first PZT6 gradually decreases, so that the first PZT6 is deformed in the direction of arrow 39,
The volume of the first pressure chamber 9 is increased. However, the second PZ
Since there is no change in the applied voltage at T5, no change in volume occurs. Only the volume of the first pressure chamber 9 is expanded and deformed, so that the ink inside the first pressure chamber 9 and the second pressure chamber 8 is smaller than the flows of arrows 23 to 26 in FIG. 5A. Flow in the directions of arrows 40 and 41 occurs. Further, the meniscus in the nozzle 2 is drawn in like 46.

In the process from time t6 to time t7 shown in FIG. 6 (b), the applied voltage to the first PZT6 becomes zero,
The movement of the first PZT6 is stopped. However, the supply port 14
The ink in the first pressure chamber 9 and the second pressure chamber 8 flows in the direction of arrow 42 due to inertia. This arrow 42
The flow in the direction is also smaller than the flow in the directions of arrows 27 to 30 in FIG. The meniscus of the nozzle 2 returns to the original position 47 by the flow in the direction of the arrow 42.

In the process from time t7 to time t8 shown in FIG. 6 (c), the application of voltage to the first PZT 6 is started again. Along with that, the first PZT 6 starts sluggish deformation in the direction of arrow 43, and the volume of the first pressure chamber is reduced and deformed. As a result, a flow in the direction of the arrow 44 is generated inside the second pressure chamber 8. In addition, an ink flow in the direction of arrow 45 is generated inside the first pressure chamber 9 and the supply passage 14. But,
Since the flow velocity of the ink in the direction of the arrow 44 is low, the ink can only project from the nozzles 2 to the extent shown by 48, and does not overcome the surface tension of the ink and fly as an ink droplet.

As described above, the periodic drive waveform such as the drive waveform V1 is applied to the first PZT 6 regardless of whether ink is ejected or not. On the other hand, the second PZT 5 is configured to be driven in synchronization with the drive timing of the drive waveform V1 only when ink droplets are desired to be ejected.

Although the drive waveforms V1 and V2 are shown in FIG. 4 to start changing at the times t1, t2, t3, and t4 at the same time, they do not necessarily have to match completely. Further, although a trapezoidal wave is used as the drive waveform, a rectangular wave, a sine wave, an exponential function wave, or a combination of these waveforms can be used.

FIG. 7 shows the displacement amount (volume) of the meniscus when the ink jet head is driven by the first driving method.
It is a graph showing the time change of. Here, W1 represents the temporal change of the meniscus during the ejection operation and W2 during the non-ejection operation. Times t1, t2, t3, t4 in FIG. 7 are times t1, t2, t3, t4 or t5, t in FIG.
It corresponds to 6, t7, and t8, respectively. Although overlapping with the above description of the operation, W1 will be described first.

The meniscus is pulled in from time t1 to time t2. The maximum retraction amount 50 of the meniscus is
It represents the maximum volume of the meniscus 36. The meniscus 37 continues to shrink from time t2 to time t3. The reason why the reduction speed is gradually decreased is that the flow velocity resistance acts and the flow velocity is attenuated. Ink columns are formed from time t3 to time t4. At time t4, there is a discontinuous point of the meniscus displacement amount. This indicates that the ink column has separated from the nozzle 2 and started flying as an ink droplet. Reference numeral 49 represents the volume of the ink droplet. After time t4, the meniscus settles in its original position while slightly vibrating. The ink jet head of this embodiment has time t
The time from 4 to settling is short and the frequency response is good.

Next, W2 will be described. The meniscus is pulled in from time t1 to time t2. Time t2
From time t3 to time t3, the movement of the first pressure plate 6 is stopped, but the ink flow occurs in the direction in which the meniscus contracts due to the inertial force of the ink. However, the reduction speed of this meniscus is lower than the reduction speed of the meniscus shown in W1. The reason is that the amount of meniscus 46 drawn at time t2 is smaller than the amount of meniscus 36 drawn, and thus the amount of inertance reduction in nozzle 2 is smaller in W2. That is, because the difference between the kinetic energy of the flow in the direction of the arrow 41 and the kinetic energy of the flow in the direction of the arrow 40 is small, the flow of the arrow 42 is small. Therefore, at time t3, the meniscus is not completely returned. From time t3 to time t4, the meniscus is pushed out of the nozzle 2, but due to the effect of the surface tension of the ink, the meniscus is not ejected as an ink droplet and the vibration is gradually attenuated after time t4 and settles.

FIG. 8 is a drive waveform diagram for explaining the drive method of the second embodiment of the ink jet head of the present invention, and FIG.
(A)-(c) is a figure explaining discharge operation, FIG.10 (a).
11C are diagrams for explaining one of the non-ejection operations, FIG.
(A)-(c) is a figure explaining another non-ejection operation.

In FIG. 8, V3 is a drive waveform applied to the first PZT6. The waveform V4 is a drive waveform applied to the second PZT 5 during the ejection operation. Waveform V5
Is a drive waveform applied to the second PZT 5 during non-ejection operation, and the waveform V6 is the second PZT during another non-ejection operation.
It is a drive waveform applied to T5. The ejection and non-ejection operations of the second embodiment will be described below.

(Discharging operation in the second embodiment) In the initial state before t1, the voltage 52 is applied to the first PZT 6. At this time, the first PZT 6 is deformed to the contracted state. Therefore, the pressure plate 3 is slid and deformed in the direction in which the volume of the first pressure chamber 9 is reduced by the action of bending stress, and is stationary.

However, in the process from time t1 to time t2 shown in FIG. 9A, the applied voltage to the first PZT 6 gradually decreases, so that the first PZT 6 deforms in the direction of arrow 55. That is, the first pressure chamber 9 is expanded and deformed. However, the second PZT 5 is not deformed because the applied voltage does not change. Due to the volume change of the first pressure chamber 9,
In the ink inside the first pressure chamber 9 and the second pressure chamber 8,
Flow in the directions of arrows 56 to 59 occurs. At the same time, the meniscus 69 is drawn into the nozzle 2.

In the process from time t2 to time t3 shown in FIG. 9B, the applied voltage to the first PZT6 becomes zero,
The movement of the first PZT6 is stopped. However, the supply port 14
The flow of the ink in the first pressure chamber 9 and the ink in the second pressure chamber 8 flows in the directions of arrows 60 to 63 due to the inertia. Due to this flow, the meniscus in the nozzle 2 is reduced like 70.

In the process from time t3 to time t4 shown in FIG. 9 (c), application of voltage to the first PZT6 and the second PZT5 is started. Along with that, the first PZT 6 and the second P
The ZT 5 starts to deform in the directions of the arrows 65 and 64, and the volumes of the first pressure chamber 9 and the second pressure chamber 8 are reduced and deformed.
As a result, inside the first pressure chamber 9 and the second pressure chamber 8,
Flows in the directions of arrows 66, 67 and 68 are added to the flows in the directions of arrows 60 to 63 due to the inertia.
In particular, since the flow of the arrow 66 is high speed, the ink is extruded from the nozzle as the ink column 71 and finally becomes an ink droplet and flies. The flow of the arrow 68 toward the supply port 14 is sufficiently smaller than the flow of the arrow 66.

(Non-ejection operation in the second embodiment) The non-ejection operation process of the second embodiment will be described with reference to the waveforms V3 and V5 of FIG.

The drive waveforms from time t1 to time t3 are the same as in the ejection operation, and the ink flow is as shown in FIGS. 9 (a) and 9 (b).
It is similar to that shown in. Figure 10 (a) again,
It is shown in (b).

Time t3 to time t4 shown in FIG.
In the process of 1, the voltage application to the first PZT 6 is started. Along with that, the first PZT 6 starts the radial deformation in the direction of the arrow 74, and reduces and deforms the volume of the first pressure chamber.
However, since no voltage is applied to the second PZT 5, the volume of the second pressure chamber does not change. As a result, in the first pressure chamber 9 and the second pressure chamber 8, a flow in the direction of arrow 72 and a flow in the direction of arrow 60 generated by inertia are added. The velocity of this flow is
Is not large enough to fly as an ink drop.

(Another non-ejection operation in the second embodiment) Another non-ejection operation process will be described with reference to waveforms V3 and V6 of FIG.

In the initial state before t1, the voltage 52 is applied to the first PZT 6 and the voltage is not applied to the second PZT 5, so that the volume of the first pressure chamber is reduced to the second state. The volume of the pressure chamber is transformed into an expanded state and is stationary.

Time t1 to time t2 shown in FIG.
In the process of, the voltage applied to the first PZT 6 gradually decreases, and conversely, the voltage is applied to the second PZT 5. Therefore, the first pressure chamber 9 is expanded and deformed from the contracted state, and the second pressure chamber 8 is contracted and deformed from the expanded state. Therefore, the flow of the generated ink is only the flow in the direction of the arrows 77 and 78 inside the first pressure chamber 9. However, when it is not required to eject ink droplets from all of the plurality of nozzles 2, the flow in the directions of the arrows 77 and 78 described above does not occur.

Time t2 to time t3 shown in FIG. 11 (b).
In the process (1), the first PZT 6 is stationary with the applied voltage being zero, and the second PZT 5 is stationary with the applied voltage 54. At this time, the flow in the directions of arrows 79 and 80 is generated by inertia. Therefore, the meniscus 87 is
To the outside of. However, since the ink flow speed is low, the meniscus 87 does not fly as an ink droplet.

Time t3 to time t4 shown in FIG. 11 (c).
In the process of, the voltage applied to the first PZT 6 gradually increases, and conversely, the voltage applied to the second PZT 5 decreases. Therefore, the first PZT 6 is displaced in the direction of the arrow 82 to reduce and deform the first pressure chamber 9. Also, the second P
The ZT 5 is displaced in the direction of the arrow 81 to expand and deform the second pressure chamber 8. As a result, ink flows are generated in the directions of the arrows 83, 84, and 85, and the meniscus 8 is generated by the respective flows and the volume changes of the first pressure chamber 9 and the second pressure chamber 8.
8 hardly vibrates.

As described above, the periodic voltage such as the drive waveform V3 is applied to the first PZT 6 regardless of whether ink is ejected or not. When ejecting ink droplets, the second PZT 5 is driven by the drive waveform V4 in synchronization with the drive timing of the drive waveform V3. On the other hand, when ink droplets are not ejected, the drive waveform V5 or V6 is used to drive the second PZT5.
To use.

Although a trapezoidal wave is used as the driving waveform, a rectangular wave, a sine wave, an exponential function wave, or a waveform obtained by combining these waveforms can be used.

FIG. 12 is a graph showing the change over time of the displacement amount (volume) of the meniscus when the method of driving the ink jet head according to the embodiment of the present invention is used. Here, W3 is the case of the ejection operation when the drive waveforms V3 and V4 are used. W4 is the non-ejection operation when the drive waveforms V3 and V5 are used, and W5 is the non-ejection operation when the drive waveforms V3 and V6 are used. Time t in FIG.
1, t2, t3, t4, t9, and t10 correspond to times t1, t2, t3, t4, t9, and t10 in FIG. 4, respectively. First, W3
Will be described. The meniscus 69 is pulled in from time t1 to time t2. The maximum drawing amount 90 of the meniscus 69 represents the maximum volume of the meniscus 69. The meniscus 70 continues to shrink from time t2 to time t3. The reason why the contraction speed is gradually decreasing is that the resistance in the flow channel is acting. Time t3 to time t4
Ink columns are formed. At time t4, the ink droplet separates from the nozzle 2 and starts flying as an ink droplet. 89 indicates the volume of the ink droplet in this case. After time t4, the meniscus settles in its original position while slightly vibrating. The inkjet head of this embodiment is
The time from the time t4 to settling is short and the frequency response is good.

Next, W4 will be described. The meniscus 69 is pulled in from the time t1 to the time t2. From time t2 to time t3, the movement of the first pressure plate 6 is stopped, but ink flow occurs in the direction in which the meniscus 70 contracts due to the inertial force of the ink. This meniscus 7
The reduction speed of 0 is equivalent to the reduction speed of the meniscus 70 shown in W3. From time t3 to time t4, the meniscus 73 is pushed out of the nozzle 2, but is not ejected as an ink droplet due to the action of the surface tension of the ink. The vibration of the meniscus 73 is gradually attenuated after time t4, and then settles. Next, W5 will be described. The meniscus 86 does not vibrate from the time t1 to the time t2. The reason for this is that the first pressure chamber 9 expands and deforms at the same time as the second pressure chamber 9
This is because the pressure chamber 8 is contracted and deformed. The meniscus 87 is pushed out of the nozzle 2 from time t2 to time t3. However, it does not have enough kinetic energy to overcome the surface tension of the ink and fly as an ink droplet. From the time t3 to the time t4, the meniscus 88 becomes almost stationary.

FIG. 13 is a perspective view showing another embodiment of the ink jet head of the present invention. Reference numeral 101 denotes a nozzle, which is linearly arranged on the nozzle plate 100.
The inkjet head includes a nozzle plate 100, a first frame 103, a film 104, and a second frame 10.
It is configured by stacking 5 and joining. 10
An ink supply pipe 2 supplies ink from an ink tank (not shown) to the inkjet head.
Reference numeral 106 denotes an FPC, which is a PZ from a circuit board (not shown)
It serves to transmit a drive signal for driving T108.

FIG. 14 is a sectional view of the ink jet head described with reference to FIG. The nozzle plate 100 has
A nozzle 101 having a horn shape is formed. 11
Reference numeral 5 is a vibrator and a pressure generating means. Oscillator 115
Is formed by stacking the PZT 108 and the elastic plate 109. Further, the vibrator 115 has a cantilever structure in which one end is a fixed end and the other end is a free end. Fixed end is spacer 1
It is held between the nozzle plate 100 and the first frame 103 via 07 and the FPC 106. The free end of the nozzle 10 is separated from the nozzle plate 100 by a minute gap 114.
It is configured to face 1. When a voltage is applied to the PZT 108, the vibrator 115 vibrates in a slanting manner. This vibration is vibration in which the free end of the vibrator 115 is deformed in the direction of the nozzle 101. Further, the vibrator 115 is configured to correspond to the nozzle 101 in a one-to-one relationship. The laminated PZT 110 is also a pressure generating means, one end of which is fixed to the second frame 105 and the other end of which is the film 104.
Is joined to. When a voltage from a circuit board (not shown) is applied to the electrodes 111 and 112, the laminated PZT 110 becomes
Elongate and deform. This deformation causes a volume change of the pressure chamber 113 via the film 104. Although it is possible to form a plurality of laminated PZTs 110 for one inkjet head, in the present embodiment, one laminated PZT 11 is formed.
Only 0 is used. The minute gap 114 and the nozzle 101 are filled with ink.

The ink jet head of this embodiment is characterized in that the laminated PZT110 is used, so that the generated pressure of 5 atm or more can be obtained. Further, since the vibrator 115 that vibrates in a slidable manner is used as the second pressure generating means, the absolute displacement amount on the nozzle 101 is large (for example, 10 μm).
m) can be taken. Therefore, since the acoustic impedance of the nozzle 2 can be largely controlled by the amplitude of the vibrator 115,
It is characterized in that good ink droplets can be ejected even when the pressure generated in the laminated PZT 110 is large.

Comparing this embodiment with the embodiment shown in FIG. 1, the pressure chamber 113 corresponds to the first pressure chamber 9 and the minute gap 114 corresponds to the second pressure chamber 8. Also, the laminated P
The ZT110 corresponds to the first PZT6, and the vibrator 115 corresponds to the second PZT5. Therefore, the driving method can be performed by the method shown in FIGS.

[0051]

Since the ink jet head of the present invention has a structure having one common pressure chamber and a plurality of pressure chambers communicating with the common pressure chamber, a drive circuit per nozzle while maintaining the characteristic that ink droplets can be ejected at a high frequency. The number can be reduced. In addition, only one supply port 14 that requires precise dimension control is required, and management and manufacturing are simpler and cheaper than conventional inkjet heads that require multiple conventional supply ports, and an inexpensive inkjet head Can be realized.

Further, in the ink jet head of the present embodiment, the second pressure chamber 8 can be made small and a high density nozzle arrangement can be realized, and the second PZT 5 occupying most of the drive circuit can be provided. It can be driven at a low voltage.

[Brief description of drawings]

FIG. 1 is a perspective view of an inkjet head that is a first embodiment of the present invention.

FIG. 2 is a plan view for explaining the shape of the ink flow path on the base of the inkjet head that is the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of an inkjet head that is a first embodiment of the present invention.

FIG. 4 is a diagram showing drive waveforms for explaining the first embodiment of the inkjet head drive method of the present invention.

5 (a) to 5 (c) are diagrams showing the flow of ink inside the inkjet head that occurs during the ejection operation in the first embodiment of the inkjet head driving method of the present invention.

FIGS. 6A to 6C are diagrams showing the flow of ink inside an inkjet head that occurs during a non-ejection operation in the first embodiment of the inkjet head driving method of the present invention.

FIG. 7 is a first method for driving an inkjet head according to the present invention.
6 is a graph showing the time displacement of the nozzle meniscus in the example.

FIG. 8 is a diagram showing drive waveforms for explaining a second embodiment of the inkjet head drive method of the present invention.

9A to 9C are diagrams showing the flow of ink inside an inkjet head that occurs during a non-ejection operation in a second embodiment of the inkjet head driving method of the present invention.

10A to 10C are diagrams showing the flow of ink inside the inkjet head that occurs during a non-ejection operation in the second embodiment of the inkjet head driving method of the present invention.

11 (a) to 11 (c) are diagrams showing the flow of ink inside an inkjet head that occurs during another non-ejection operation in the second embodiment of the inkjet head driving method of the present invention.

FIG. 12 is a graph showing the time displacement of the nozzle meniscus in the second embodiment of the inkjet head driving method of the present invention.

FIG. 13 is a perspective view of an inkjet head that is a second embodiment of the present invention.

FIG. 14 is a sectional view of an inkjet head that is a second embodiment of the present invention.

FIG. 15 is a cross-sectional view of an inkjet head of Conventional Example 1.

16 is a plan view showing an ink flow path of an inkjet head of Conventional Example 2. FIG.

FIG. 17 is a cross-sectional view of an inkjet head of Conventional Example 3.

[Explanation of symbols]

 1 Base 2 Nozzle 3 Pressure Plate 5 Second PZT 6 First PZT 8 Second Pressure Chamber 9 First Pressure Chamber

Claims (4)

[Claims] 1. A first pressure chamber communicating with a reservoir, and a plurality of second pressure chambers having one end communicating with the first pressure chamber and the other end having a nozzle opening. Inkjet head to do. 2. The ink jet head according to claim 1, further comprising first pressure generating means for deforming the first pressure chamber and second pressure generating means for deforming the second pressure chamber. First driving for driving the first and second pressure generating means to expand and deform the first and second pressure chambers
And the second step of driving the first and second pressure generating means to reduce and deform the first and second pressure chambers, an ink droplet is ejected. Driving method. 3. The ink jet head according to claim 1, further comprising a first pressure generating unit that deforms the first pressure chamber and a second pressure generating unit that deforms the second pressure chamber. A first step of driving the first pressure generating means to expand and deform the first pressure chamber, and simultaneously driving the first and second pressure generating means to drive the first and second pressure chambers. A method for driving an inkjet head, characterized in that ink droplets are ejected by a second step of reducing and deforming. 4. The first pressure generating means is driven to expand and deform the first pressure chamber, and at the same time, the second pressure generating means is driven to reduce and deform the second pressure chamber. The first step and the second step of driving the first pressure generating means to reduce and deform the first pressure chamber,
The ink jet head driving method according to claim 3, wherein vibration of the meniscus during non-ejection is suppressed.