JPH0331140B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF INDUSTRIAL APPLICATION This invention relates to non-impact recording devices, and more particularly to so-called ink jet recording devices of the type in which droplets of ink are ejected from an orifice in a printing head. [Prior Art] Conventional non-impact recording devices use various devices that create information patterns (letters, numbers, symbols, figures, etc.), including electrostatic,
It is well known as an electrolytic type, a discharge type, a thermal type, etc. recording device. However, all of these methods not only require specially treated recording media, but also require complex processes and special printing processing media. Therefore, ink jet recording devices have been developed to improve the drawbacks of these devices. This method prints by depositing small droplets of ink onto an untreated recording medium (hereinafter referred to as recording paper) in a predetermined information pattern, and features high-speed printing, low noise, and low running costs due to the use of plain paper. It has the characteristics of
In recent years, it has attracted attention as a promising recording device. However, in order for an ink jet recording apparatus to accurately record a wide range of information patterns at high speed and with low noise, the ink jet action itself must be adapted to meet these objectives. To this end, the flight characteristics of the ink droplets must be calculated for all ink droplets in order to maintain the accuracy of the information pattern.
It must be stable under all conditions of use. Since a large number of droplets are ejected at high speed, it is desirable to avoid wasting ink. In order to achieve high speed and smooth relative movement between the recording paper and the ink ejecting head, it is desirable to make the ink ejecting head as light and compact as possible. Furthermore, since it is intended for long-term use, it is of course important to maintain high reliability as an apparatus, and in particular, the structure of the ink ejecting head must be carefully designed to prevent failures and for maintenance and inspection. ,
It is desired that the structure be as simple and reliable as possible. Naturally, it is desired that it be of low cost. These conditions are desirable as basic conditions for device design. However, all currently known ink jet recording devices do not necessarily satisfy these basic conditions. Among conventional ink jet recording devices, the first method is as described in Japanese Patent Publication No. 42-8350, Japanese Patent Publication No. 42-4381, and Japanese Patent Publication No. 44-4517. High pressure is applied to make the ink flow out continuously from the nozzle tip. ◎The nozzle vibrator mechanically vibrates to ensure the formation of ink droplets. ◎Next, the ink is placed in front of the nozzle A charged electrode is used to charge each ejected ink droplet according to the information pattern, and a deflection electrode plate that generates a high voltage electric field is installed in the flight space of the ink droplet to In this method, ink droplets passing through a constant high-voltage electric field are deflected according to the amount of charge on each droplet, thereby forming a predetermined information pattern on recording paper. However, this method has the following drawbacks. (a) A special pressurizing device is required to apply high continuous pressure to the ink. (b) Since the nozzle is mechanically vibrated at high speed using a magnetostrictive vibrator or a piezoelectric vibrator, the nozzle structure becomes extremely complicated. (c) When the ink column ejected from the nozzle at high pressure is turned into ink droplets by a vibrator, the ink droplets must be made at regular time intervals and of uniform size, which makes it difficult to actually commercialize the product. In some cases, complex equipment and electrical circuits are required. (d) Since a high voltage is required for the charging electrode and the charging of the ink droplets needs to be controlled according to the information pattern, precision is required for the control and the device is expensive. . (e) The formation of ink droplets by the vibrator and the charging time of the droplets must be precisely synchronized, making the synchronization means complicated. (f) It is also necessary to apply a high voltage of several thousand volts to the deflection electrodes. (g) Since charging electrodes and biasing electrodes are easily contaminated by dust and ink, their performance is likely to be hindered by these substances. Therefore, countermeasures are required. (h) In addition, the application of high voltages between the nozzle and the electrode causes electrolysis of the ink, which produces corrosive by-products on the nozzle and the electrode. Since this causes significant deterioration, preventive measures are required. (i) Continuous ejection of ink droplets from the nozzle ejects a large number of droplets that do not participate in the formation of the information pattern, so there is no need to collect these unnecessary ink for reuse or disposal. Requires extra equipment. etc. In order to overcome these shortcomings and create a highly reliable ink jet recording device based on the above basic conditions, there are still many technical problems to be solved, including the need for precise and complex equipment and electrical equipment. This requires circuitry and makes the product expensive. The second method, as shown in Japanese Patent Publication No. 36-13768, is to form an information pattern by deflecting continuously flying ink droplets from a reference trajectory using a deflection moving pole. The method is the same as the first method, but
However, this method differs from the first method only in that ink droplets are formed and the flying direction of the ink droplets is deflected by changing the intensity of the deflection electric field. That is, ◎First, an acceleration electrode and a deflection electrode are respectively installed in the space of the nozzle. ◎Next, pressure is applied to the ink so that the ink becomes a convex meniscus state at the tip of the nozzle, and ◎By applying a constant high voltage between the accelerating electrode and the ink in the nozzle, the ink is sucked out from the nozzle by the action of this strong electrostatic field, and the flow of the sucked ink is , broken into successive ink droplets of essentially constant volume and charge. ◎ Furthermore, the deflection electrode provided outside the accelerating electrode is controlled according to the input signal to deflect the ink droplets through which the electric field passes, thereby forming a predetermined information pattern on the recording paper. It is. However, this method also has drawbacks comparable to those of the first method. In other words, the timing of ink droplet formation and the high-voltage pulse application time are synchronized, dirt and ink tend to adhere to each electrode, deterioration of the nozzle and electrodes due to high voltage, and when information patterns are created by ink droplets. Regarding the issue of unnecessary ink droplets,
Both have the same drawbacks as the first method, but
Furthermore, (a) since the electrostatic suction effect of the nozzle is used, there is a limit to the droplet formation speed, making high-speed printing impossible. (b) The equipment becomes expensive because it is necessary to apply a high voltage of several thousand volts between the accelerating electrode and the nozzle. (c) Furthermore, it is necessary to apply a high electric current of several thousand volts to the bias electrode, and this must be changed for each ink droplet according to the information pattern, so its control is difficult. accompanied by difficulty. etc. In order to overcome these shortcomings and complete a highly reliable ink jet recording device based on the above basic conditions, there are still many technical problems to be solved, and it is necessary to use a precise and complicated device and a highly reliable ink jet recording device. Requires electrical circuit. Furthermore, compared to the first method, there is a fundamental drawback in that high-speed printing cannot be performed. Although this is a very special example, another method is also known. It is shown in US Pat. No. 2,512,743. According to this disclosure, an ultrasonic shock wave is continuously generated at a mechanical resonance frequency in a horn-shaped nozzle filled with ink, and the shock wave moves from a large diameter part to a small diameter part along the internal slope of the nozzle. During this process, the strength of the shock wave increases, and the bubble action of cavitation generated in the ink by this ultrasonic shock wave causes a spray of ink to be ejected from the end of the nozzle. However, this method has the following drawbacks. (a) The device operates at a constant speed determined by mechanical resonance. (b) The ejection system cannot form a single ink droplet in response to a single electrical signal because it does not return to an equilibrium state after ejecting a single drop. The combined resonant effects of multiple signals are required for ink jetting. (c) Since the ink is ejected in the form of a spray, it is difficult to control it to obtain a highly accurate information pattern. For this reason, this system cannot be used as it is for general-purpose ink jet recording, and improvements are desired. Therefore, at this stage, this method cannot be considered as a method used for special purposes, and in addition, it can be said that it does not meet most of the basic conditions mentioned above. [Object of the Invention] An object of the present invention is to obtain an ink jet recording device with improved printing quality and speed. [Configuration of the Invention] The configuration of the present invention includes an ink reservoir that accommodates recording ink and applies static pressure to the ink, and a constant opening that maintains the ink in an equilibrium state during non-recording using the static pressure and the surface tension of the ink. an orifice having a diameter; a pressure chamber communicating with the ink reservoir; an inlet passage connecting the pressure chamber and the ink reservoir so that the pressure chamber communicates with the ink reservoir and supplying ink to the pressure chamber; a planar electromechanical transducer disposed above the chamber, which rapidly reduces the volume of the pressure chamber in response to a single electrical pulse and causes a portion of the ink to be ejected as an ink droplet from the orifice toward the recording medium; an outlet passage provided opposite to the inlet passage across the pressure chamber and communicating the pressure chamber and the orifice, and the inlet passage and the outlet passage are connected to the plate-shaped machine. It has a plurality of flat print heads formed parallel to the conversion element and extending in the plane direction of the flat electromechanical conversion element, and the plurality of print heads are arranged perpendicular to the plane direction of the flat electromechanical conversion element. This is an ink jet recording device characterized by being laminated in a direction. [Embodiments] Hereinafter, the ink jet recording apparatus equipped with a print head according to the present invention will be described based on illustrated embodiments. 1, 2, and 3 are schematic diagrams of embodiments for explaining the principle of an ink jet recording apparatus to which the present invention is applied. FIG. 1 is a schematic diagram showing an apparatus 11 configured to record information patterns on recording paper 12. As shown in FIG. Recording paper 12 is shown moving relative to apparatus 11 from a supply roller 13 to a take-up roller 14. However, it is clear that the relative movement between the device 11 and the recording paper 12 can be effected in any suitable manner such that either or both of the device 11 and the recording paper 12 can actually be moved. . The device 11 includes a suitable reservoir 16 for storing the particular ink to be used. This ink reservoir 16 is connected to a device for ejecting ink droplets through a communication pipe 17, that is, a printing head (ink ejection head).
It leads to 18. Electronic pulse generator 19 sends pulse voltages to the printhead through suitable transmission means 21, such as wires. At this time, print head 18 receives a single pulse of voltage from generator 19 and ejects a single discrete droplet 22 of ink from orifice 24. That is, each pulse voltage creates one ink droplet,
The amount of liquid is controlled by the energy of the applied pulse voltage. In the embodiment shown in FIG. 1, groups of ink droplets ejected as recording paper 12 passes printhead 18 form lines 23 on the recording paper. In order to form an accurate record of the information pattern on the recording paper, the ink droplets must travel in a substantially straight trajectory from the orifice 24 of the print head 18 to the recording paper 12. The precise relative positioning of device 11 and recording paper 12 also allows the ink droplets to collide to form a predetermined information pattern based on pulse signals from electronic pulse generator 19. I can do it. Additionally, the ink droplets must be of precise shape and volume for optimal recording of the information pattern. That is, this means that the ink droplets are uniform in size from droplet to droplet and that the ink droplets are ejected at intervals of the electronic signals from the pulse generator 19. 2 and 3 illustrate a preferred droplet ejector,
That is, they are a plan view and a sectional view showing the detailed structure of the print head 18. However, in the sectional view of FIG. 3, for convenience of structural explanation, the print head 18 is shown in a state in which the power is not turned on (a state in which no current is applied to the pressure plate 41, which will be described later). Print head 18 consists of a housing 36 forming part of a pressure chamber 37. A communication tube 17 conveys ink from the ink reservoir 16 to an inlet passage 38 of the pressure chamber. Pressure chamber 37 includes an outlet passage 39 .
The upper wall of the pressure chamber is formed by a pressure plate (flexible plate) 41. Pressure plate 41 is preferably made of piezoelectric material. In the embodiment shown, the pressure plate 41 consists of two laterally expanding piezoelectric plates 42, 43, each in the form of a laminar disk, which are secured to each other by a conductive membrane 44. has been done. The outer surfaces of the plates 42, 43 are coated with conductive coatings 46, 4.
7 is attached, which is electrically connected to the faces of both plates and led to the outside by wires 48, 49. Therefore, by applying a voltage to the two surfaces, the plates 42, 43
voltage can be applied to. In this case, when a suitable positive voltage is applied to the plates 42 and 43, one plate 42 contracts and the other plate 43 expands, causing the pressure plate 41 to open in the pressure chamber as shown in FIGS. 6 and 7. 37, and conversely, when a suitable negative voltage is applied to both plates 42 and 43, the former plate 42 expands and the latter plate 43 contracts, as shown in FIGS. As shown in FIG. 8, the pressure plate 41 is bent outward of the pressure chamber 37. In this way, the pressure plate 41 has an integral structure by joining two piezoelectric plates 42 and 43 (hereinafter referred to as a bimorph), and a pressure plate with only one electric plate (hereinafter referred to as a unimorph). )
Since the deformation is approximately twice as large for a predetermined pulse as compared to the above, the volume change efficiency of the pressure chamber 37 is high. A bimorph can be achieved with a smaller pulse voltage peak value than a unimorph. In either case of the above-mentioned bimorph or unimorph, if the shape is made into a disk shape, the deformation efficiency with respect to the applied voltage is good, so it is also effective in deforming the volume of the pressure chamber 37. However, when a positive voltage is applied, the pressure plate 41 closes to the pressure chamber 37.
, the volume of the pressure chamber decreases and pressure is applied to the ink within the pressure chamber, forcing some of the ink towards the exit passage 39 and ejecting it towards the recording paper 12, while the remaining The ink is returned to the ink reservoir 16 through the communication pipe 17 against the hydrostatic pressure of the ink reservoir. The exit passageway 39 terminates in a precision diameter orifice 52 which precisely controls the diameter of the ink droplets ejected from the printhead 18. The size of the ink droplet is
It is a function of the voltage across plates 42 and 43 and its pulse width as well as the diameter of orifice 52. Pressure plate 41 is secured within printhead housing 36, as shown in FIG. 3, by suitable attachment means such as epoxy resin adhesive. still,
A piezoelectric transducer suitable as pressure plate 41 is commercially available under the trade name "Bimorph" by Clevite Corporation of Ohio, USA. Now, when the power (not shown) is turned on to the print head 18 and no pressure pulse is sent yet, a negative voltage is applied from the pulse generator 19 to the pressure plate 41 as shown in FIG. 4A. Pressure plate 41
is held in an outwardly bent state as shown in FIG. 5 prior to the printing operation. In this case, the ink will create a slight meniscus extending from the orifice 52. This meniscus is ink reservoir 16
This is because the static pressure from is applied to the ink in the pressure chamber 37. The surface tension of the ink prevents the ink from dripping out of the orifice. During printing, a positive pulse voltage from the pulse generator 19 is applied to the pressure plate 41 in this state, thereby ejecting ink droplets. That is, the conductor 4
When an electric pulse signal having a selected amplitude and pulse width is applied from the pulse generator 19 to the pressure plate 41 via the pulse generator 8 and 49, the pressure plate 41 changes from the state shown in FIG. There is a sudden transition to the state shown in the figure, the volume within the pressure chamber is reduced, and a rapid pressure pulse is applied to the ink within the pressure chamber 37. The pressure pulse causes the ink within the pressure chamber to proceed through the outlet passageway 39 to the orifice 52 and is ejected from the orifice 52 in discrete droplets in response to the pulse, as shown in the schematic diagram of FIG.
This droplet 22 impinges on the recording paper 12, and the relative movement between the print head and the recording paper will define a line or other shape depending on the direction and magnitude of the relative movement. As described above, the pressure plate 41 has a negative voltage applied to it before injection and has an upwardly convex shape, and is deformed upward into a concave shape by applying a positive voltage during injection. The amount of change in volume is approximately twice that in the case where a positive or negative voltage is applied from a no-load voltage, and the volume change efficiency of the pressure chamber 37 is high. Further, the same volume change can be obtained by making the peak voltage value of the applied pulse voltage smaller. After injection, a negative voltage is again applied to the pressure plate 41 to return it to its upwardly convex shape and wait for the next signal. The sizes of the inlet and outlet passages 38, 39 are regulated to a certain size depending on the viscosity of the ink used. Larger tubes may be necessary for more viscous inks. When the pressure pulse by the pressure plate 41 ejects the ink droplet 22 from the orifice 52, that pressure also acts to cause the ink to flow back from the inlet passageway 38 into the ink sump against the hydrostatic pressure of the ink applied from the ink sump 16. . In this case, the amount of backflow is limited by adjusting the length and diameter of the inlet passageway 38, and the anti-friction forces of the ink limit the amount of backflow that occurs during ejection of ink droplets. In addition, the flow of layered liquid flows through a pipe of length L,
It has been found that the friction inhibiting force F when flowing at a velocity V is given by the following formula. F=8πηLV where η is the viscosity coefficient of the liquid. Thus, the hydrostatic pressure applied to the ink reservoir 16 prevents the ink within the pressure chamber from returning into the inlet passageway 38.
The droplet acts to exit from the orifice 52.
Two inches of hydrostatic pressure is sufficient for most purposes. If reverse flow through the inlet passageway 38 is not restricted, the pressure pulse from the pressure plate 41 will spend most of its energy pushing the bulk of the ink droplet 22 in the opposite direction through the inlet passageway 38.
It becomes impossible to sufficiently increase the pressure within the pressure chamber necessary for injecting from the orifice 52. The length and diameter of the outlet passage 39 should also be selected to result in lower friction losses compared to those caused by the hydrostatic water and the inlet passage 38 and the communicating tube 17. The permissible hydrostatic pressure applied through the ink reservoir 16 is represented by Pmax=4S/D. where D is the diameter of the orifice S is the constant of the surface tension of the ink. However, in order to stabilize the meniscus at the orifice 52, the ink must not wet the front surface of the housing 36 of the print head 18. That is, the natural contact angle between the ink and the front surface of the housing 36 needs to be 90° or more. In this state, water-based ink is used to coat the front surface 57 of the housing 36 with Teflon (trade name of DuPont, USA).
It will be satisfied if it is covered with. Although it is preferred to coat surface 57 with Teflon, there are many other ink and solid combinations with contact angles greater than 90 degrees that are suitable for the purposes of this invention. Figures 4A and B show the pressure plate 41 as a function of time.
3 is a diagram schematically showing the correlation between the input voltage to the pressure chamber 37 and the pressure applied to the liquid in the pressure chamber 37. FIG. In the injection system, a positive input voltage pulse 62 is applied to the pressure plate 4.
1 _{, the positive voltage applied at t 1 causes} the pressure plate 41 to deflect to the state shown in FIG. Increase the pressure applied to the ink until it reaches about 10 times the value in the state shown in Figure 5. The maximum pressure on the ink (point 64) can be set within the range of 1 to 20 psi (pounds per square inch). In particular, around 5 psi is preferable. In this case, due to the reaction time of the pressure plate 41 and the inertia of the ink, the pressure of the ink does not rise immediately even though the application of the voltage pulse at time _t1 is rapid. That is, as shown in FIG. 4, the ink pressure, which was maintained at a predetermined static value until time _t1 , rises to its maximum value at point 64 at time _t2 . This point 64
The higher pressure we want to increase in the orifice 52
Since the column of ink in the outlet passage 39 acts as a driving force on the ink in the orifice 52
flows out and reaches high velocities. This high velocity overcomes the surface tension of the ink in the orifice 52 and causes the column of ink to protrude from the orifice 52. Therefore, from a predetermined time, i.e., t ₂ in FIG.
After a time up to t ₃ has elapsed and the voltage from the pulse generator 19 is switched back to the negative initial voltage, the pressure in the pressure chamber 37 rapidly increases to the value indicated at point 66 at time t ₄ . and finally returns to its resting state 67 at time _t5 . At this time, the particularly protruding ink column is caused by the droplet 22 due to the relationship between the above-mentioned ejection speed and this pressure reduction effect.
Then, it separates from the orifice 52 and flies along a substantially natural straight trajectory to the recording paper, where it forms a small dot in the line 28. This process is described in detail in the series of Figures 5-8. FIG. 5 is a sectional view of the print head in a state before time _t1 , that is, in a state in which the power is turned on and a negative voltage from the pulse generator 19 is applied to the pressure plate 41. In this state, when a positive voltage pulse for printing is applied from the pulse generator 19, the pressure plate 41, which had been bent upward, passes through a flat state and bends inward, shifting to the state shown in FIG. FIG. 6 shows the state of the pressure chamber when only the inward deflection of the pressure plate 41 is at its maximum, that is, at time _t3 . In this case, the application of a positive voltage to the pressure plate 41 causes one plate 42 to contract and the other plate 43 to expand, thereby deflecting the pressure plate 41 inward and reducing the volume of the pressure chamber 37. , which acts to move a certain amount of ink. At this time, the ink pool 16 hanging over the inlet passage 38
Depending on the hydrostatic pressure at , the viscosity of the ink, the length of the inlet passageway 38, and the diameter of the inlet passageway, as well as the aforementioned considerations, some of the displaced ink will flow back through the inlet passageway 38 into the communicating tube. . However, the movement of ink within the pressure chamber 37 caused by the pressure plate 41 primarily serves to push the ink column 101 out of the orifice 52. FIG. 7 shows that although the pressure plate 41 is still at its maximum deflection, the voltage supply reaches t ₄ as indicated by point 66 in FIG.
This shows the state after the temperature has decreased. In other words, this shows a state in which the voltage application to the pressure plate 41, which had been deflected inward to the maximum extent, is reversed and the pressure plate 41 begins to return to the state shown in FIG. 5. In this case, the ink pressure in the pressure chamber 37 is
As shown in Figure B, the ink column 1 decreases the most.
01 acceleration turns into deceleration. However, ink column 1
Since a portion of 01 (the tip) has already reached its ejection velocity, it separates from the slowing ink column and forms an ink droplet 102. The remainder of the ink column is then still in communication with the ink in the pressure chamber 37. FIG. 8 shows the state of the injection system at time _t5 in FIG. That is, the pressure plate 41 is
Figure 6 shows the return to its ready position at time _t5 (the state before the positive voltage pulse was applied) at the position shown at point 67; In this case, the effect of reducing the ink pressure from point 66 to point 67 shown in FIG.
1 into the outlet passage 39. During this time, the surface tension of the ink droplet 102 ejected from the orifice acts to make the droplet spherical in shape. After each pulse creates a droplet, the ejection system returns to equilibrium as shown in FIG. Note that the amount of ink to be ejected depends on the width and voltage value of the output pulse from time t ₁ to t ₃ , that is, the applied energy, so if you change the length of this time, it will vary from 4 mils to 25 mils. Ink droplets can be made with diameters between. The next pulse 68 thus applied will eject another droplet. Therefore, the frequency of droplets is controlled by the frequency of the voltage pulses when the pulses are applied. In order to rapidly release high quality ink droplets,
Examples of specific parameters when using the apparatus described in Figure 3 are as follows.

[Table] FIG. 9 is a schematic diagram of the same apparatus as shown in FIG. 1, except that patterns such as letters and numbers are printed depending on the composition of the ink. It has a series of printing heads 111-120 which can be individually controlled by electronic pulse generators 19. Print heads 111-120 are stack 1
Since they are vertically grouped into 10 ink droplets, 1-10 ink droplets can be ejected at the same time.
Assume that the invention prints the letter "T". FIG. 11 shows a method for constructing the letter "T" from rows and columns of ink dots having nine locations on the X-axis and ten locations on the Y-axis. The letter "T" is formed by the apparatus shown in FIG. 9 by first locating stack 110 at position 1 on the X-axis as follows. That is, the top printing head 111 is driven so that an ink point is marked at position 10 on the Y axis. Next, move the stack 110 to position 2 on the X-axis and print head 1.
11 is driven again to mark another ink dot at position 10 on the Y axis. This process
continues until X-axis position 5 is located, at which time all ten print heads are driven so that an ink droplet is ejected from each of print heads 111-120. This runs from 1 to 10 on the Y axis to create the vertical component of the letter “T”.
Mark a small drop at the position up to. Then stack 110
As the dot moves from position 6 to position 9 on the X axis, print head 111 is driven so as to print a dot at position 10 on the Y axis, respectively. Although FIG. 9 shows ten print heads, numbered 111 to 120, it is known that legible characters can be created with at least five vertical positions. However, it is preferred that the printing head have 7 to 10 vertical positions to produce characters with a legible configuration. Stack 110 is mounted on a threaded support 121 that cooperates with a lead screw 122. The lead screw is rotatably journaled at its ends 123, 124 and is driven by a step motor 126. The number of threads per inch on lead screw 122 is determined by the number of threads per inch for each unit rotation of step motor 126 between two adjacent print heads on the X axis in FIG.
is selected to move horizontally between two columns. By this method, the step motor 12
Each unit rotation of 6 advances the print head from a previous position to a next position along the X-axis of FIG. FIG. 10 shows a plurality of print heads 1 arranged side by side instead of stacked as shown in FIG.
31-140. Recording paper 12
moves perpendicularly to the head to print characters and other shapes. It will be appreciated that the series of print heads may be oriented either vertically or horizontally as desired. Each nozzle in the stack may thus be supplied with ink, for example from a vertically arranged piezoelectric plate. Similarly, the relative movement between the paper and the head can be either vertical or horizontal. As described above, according to the present invention, since the ink jet recording device is constructed by stacking individual print heads, high print quality and high print speed can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a recording device incorporating a droplet jetting recording device equipped with a printing head according to the present invention, and FIG. 2 is a plan view of an embodiment of the droplet jetting device shown in FIG. FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 2, FIG. 4A is a diagram showing voltage pulses applied to the droplet ejector, and FIG. Diagrams showing the variation of liquid pressure in the pressure chamber as a function; FIG. 5 is a cross-sectional view of the liquid injection device showing the state just before a voltage pulse is applied to the piezoelectric plate; FIG. FIG. 7 is a cross-sectional view of the device in a state where the piezoelectric plate is returning to its original position; FIG. 8 is a cross-sectional view of the device in a state where the piezoelectric plate is returning to its original position. FIG. 9 is a schematic diagram of an apparatus capable of ejecting a plurality of droplets onto recording paper; FIG. A schematic representation of another apparatus, FIG. 11, shows characters formed by the recording apparatus shown diagrammatically in FIGS. 9 and 10. 11... Recording device, 12... Recording medium (recording paper), 16... Ink reservoir, 18... Printing head,
19...electronic pulse generator, 22...ink droplet, 24...orifice, 37...pressure chamber, 38
...Inlet passage, 39...Outlet passage, 41...Pressure plate (flexible plate), 42, 43...Piezoelectric plate, 52...Orifice, 56...Meniscus.

Claims (1)

[Scope of Claims] 1. An ink reservoir that accommodates recording ink and applies static pressure to the ink, and an orifice having a constant opening diameter that maintains the ink in an equilibrium state during non-recording using the static pressure and the surface tension of the ink. , a pressure chamber communicating with the ink reservoir; an inlet passage connecting the pressure chamber and the ink reservoir so that the pressure chamber communicates with the ink reservoir and supplying ink to the pressure chamber; a flat plate-shaped electromechanical transducer that is provided and rapidly reduces the volume of the pressure chamber in response to one electric pulse, and causes a portion of the ink to be ejected as an ink droplet from the orifice toward the recording medium; an outlet passage provided opposite the inlet passage across a chamber and communicating the pressure chamber and the orifice, the inlet passage and the outlet passage being parallel to the flat mechanical transducer element. and has a plurality of flat print heads extending in the plane direction of the flat electromechanical transducer, and the plurality of print heads are stacked in a direction perpendicular to the plane direction of the flat electromechanical transducer. An ink jet recording device characterized by: