JP3529226B2 - Inkjet printer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer in which ink ejected in the form of droplets is adhered to a recording paper to perform recording in dot units, and more specifically, an ink ejection printer for ejecting ink from ejection ports. The present invention relates to an ink jet printer including an ink jet head having a driving means and a jetting control means which is operated in response to a recording input signal.

[0002]

2. Description of the Related Art Heretofore, there have been proposed some methods for producing a halftone by controlling the ejection amount of ink in an ink jet printer or the like. For example, Japanese Patent Publication No. 61-5991,
Many of the disclosed devices control the ejection means (for example, the energy applied to the heating element in the bubble jet).

Further, the one disclosed in Japanese Patent Laid-Open No. 58-102774 has a structure in which a nozzle is pressurized by a piezoelectric element such as a piezo element as means for controlling the ejection amount by newly adding a component. This is a proposal of a microvalve system provided with a microvalve for preventing backflow of ink. Most of these methods are used when ejecting ink.
It is designed to stop the path to the nozzle that ejects ink, or to limit the amount of ink that is put into the liquid chamber. For example, the one disclosed in Japanese Patent Laid-Open No. 2-158348 reaches an ink ejection port. A valve for opening and closing the path is provided in the path, and the opening of this valve is adjusted based on the image signal included in the input signal.

As typified by the above-mentioned microvalve system, when the ejecting means provided in the liquid chamber is operated to eject the ink, the energy ejected from the nozzle is effectively used without being released to the common liquid chamber. Many are designed to close the flow path. In such a configuration, in order to produce a halftone, many eject the inkjet means by controlling the ink pressurization amount when operating the ejection means. The initial energy at the time of ejection changes. That is, when the piezoelectric element (PZT) is used, the applied energy to the piezoelectric element, for example, the applied voltage, the application time (pulse width, the number of pulses, etc.) are controlled, so that the initial energy at the time of ink ejection is likely to change. . Especially, when such initial energy fluctuates, the initial velocity of the ink when ejected changes, so the size of the ink droplet changes and the time to reach the paper also changes, so that stable ejection cannot be obtained at present. is there.

A specific ink jetting operation of an example of a conventional ink jet printer will be described below with reference to FIG. FIG. 1 is a configuration diagram of an inkjet printer to which the present invention is applied. The characteristic portions of the present invention are an outflow passage control unit 2 and an outflow passage 3, and the other portions are constituent elements according to the related art. Can be shown as In FIG. 1, 1 is a jet outlet, 2 is outflow control means, 3
Is an outflow passage, 4 is a liquid chamber, 5 is a common liquid chamber, 6 is an ejection driving unit, 7 is an inflow unit control unit, 8 is an ink supply unit, and 9 is an ejection control unit.

First, like the bubble system and the electrostrictor system,
By operating the ejection means 6, the size of the liquid chamber 4 is changed and the inside of the liquid chamber 4 is filled with ink. When the ink is full, the ejection drive means 6 is operated to change the liquid chamber 4 in a direction opposite to the movement of the previous ink full movement. At this time, acoustic vibration and a change in the liquid chamber occur in the liquid chamber 4, and the ink tends to eject from the ejection port 1. At this time, the liquid does not escape on the common liquid chamber 5 side of the liquid chamber 4 because the inflow portion control means 7 is closed. The meniscus of the ink ejected from the ejection port 1 changes depending on the displacement state of the ejection unit 6, and this eventually becomes an ink droplet and ejects as an inkjet. When the ink jet is ejected, the inflow section control means 7 is opened to return to the initial state.

The above is the normal operation, and the microvalve system operates similarly. With this configuration, when the ink jet is ejected, the energy generated by the ejection driving means does not escape to the common liquid chamber side, and the efficient use can be achieved. Such a mechanism is the same in the microvalve system. However, in the microvalve system, when the ejection drive means is operated to enlarge the liquid chamber in order to produce a halftone, the amount of change in the liquid chamber is controlled to change the amount of ink in the liquid chamber. By this, the size of the ink jet when ejecting the ink is changed. By doing so, the size of the inkjet changes, but the injection energy due to the operation of the injection drive means also changes in the initial state of the injection, so stable inkjet ejection is not always performed.

Further, in the ordinary ink jet system, it is difficult to stably perform the ink supply / discharge operation to / from the liquid chamber in the cycle of ink jet flight and ink supply to the liquid chamber, and the ink flow to the liquid chamber is difficult. We are trying to secure a stable ink jet flight condition by providing fluid resistance at the inlet. In particular, this fluid resistance has a great influence on the flight response speed, so that the degree of difficulty in design was high.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in an ink jet system which has been carried out with a conventional jetting structure, the jetting energy in the vicinity of the jetting port can be rapidly increased at the time of jetting. By making it have a jetting amount control function that changes the jetting amount of ink by this, it is simple and highly reliable,
It is a problem to be solved to provide an inkjet printer capable of expressing halftone.

[0010]

According to a first aspect of the present invention, there is provided a jet port, a jet driving unit for jetting ink from the jet port, a liquid chamber in which the ink is stored, and an ink for the liquid chamber. An ink jet printer having a head section including a liquid inlet, and an ink supply section for supplying ink to the head section, and an ejection control section for operating the ejection drive means in response to an input signal, Ink liquid from the liquid chamber
The ink liquid outlet that allows the ink to flow out and the ink ejection operation are opened.
After the start, the ink liquid outlet is opened according to the input signal.
By controlling the discharge timing,
It which was characterized by having a control means output stream that controls the size of the ink droplets which issued to keep the injection energy of the jet initially constant, the injection initial condition by the same, a drop of ink jet Even if the size of the ink jet is changed, the jetting stability of the inkjet can be ensured.

[0011]

[0012] According to a second aspect of the invention, in the invention of claim 1 Symbol mounting, characterized in that the provided the ink flow outlet and said outlet control means in the vicinity the spout, the ink ejection cycle In the above, since the ink flow can be controlled when the ink is about to be ejected, it is an efficient and fast responsive inkjet printer.

According to a third aspect of the present invention, in the invention according to the first or second aspect, a plurality of head portions are provided, and the ejection driving means provided in each of the head portions is integrally formed. Therefore, the outflow control means can be arranged without worrying about the space of the nozzle portion.

According to a fourth aspect of the present invention, the ink liquid inlet according to any one of the first to third aspects is provided by providing the outflow control means in the ink liquid inlet or a liquid flow path connected to the ink liquid inlet. Is made to function as the ink liquid outlet, the ink inlet can be made large, and there is no need to consider the fluid resistance of the inlet portion, and the inkjet generation cycle can be shortened. It was made possible to be converted.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION In order to achieve a halftone expression, the present invention makes the ejection energy constant in the same state at the beginning of ejection in the ejection cycle of ink, and ejects the droplets during ejection. It is intended to control the size of the ink jet, and to ensure the jetting stability of the ink jet even if the size of the jetted ink jet droplet changes. This is because the ejection energy from the nozzle is released by opening the liquid chamber after the ejection of ink droplets is started, and at this point the ink outside the ink nozzle (ejection port) is made into droplets. The size is controlled. By doing so, the relationship between the meniscus at the ejection port and the fluid resistance of the ink supply path, which has been conventionally designed in the ink jet, is significantly eased,
There is also an advantage that the design area is expanded. For example, as shown in FIG. 1, in the configuration according to the present invention including the outflow control means 2 and the outflow passage 3, the ejection drive means is the same as that of the conventional method, but the outflow control means 2 is opened during the ink ejection. By doing so, the ejection energy is allowed to escape from the outflow passage 3 to the common liquid chamber 5, and thereby the size of the inkjet that is about to come out from the ejection port 1 is controlled.

The appearance of the ink jet will be described below with reference to FIG. FIG. 2 is a diagram for explaining an ink flight model of an inkjet printer according to the present invention, in which a flight model according to the present invention is shown in (A) and a flight model according to a conventional technique for comparison is shown in (B). . In the figure, 10 is an inkjet, 11 is an ejection port (ink nozzle), and 12 is an outflow control means. As shown in FIG. 2 (B), in the conventional ejecting aspect of an ink jet, when the ink droplets fly as an ink jet, the ink droplets become large as the ejection energy becomes large. According to the present invention, as shown in FIG. 2 (A), when the ink droplet is becoming large, the outflow control means of the outflow path is opened according to the print information, and a part of the ejection energy is released to this outflow path. Escape to. That is, the ink that has started to eject from the ejection port has a constant ejection energy, but the ink in the liquid chamber escapes to the outflow passage, so the ink is cut near the ejection port and ejected to the outside from the ejection port. The ink that forms is flying as an ink jet.

Next, an embodiment of a PZT (piezoelectric element) type and bubble type ink jet printer to which the present invention is applied will be described with reference to FIGS. Figure 3
FIG. 1 is a sectional view of a head portion for explaining an embodiment of a PZT type inkjet printer to which the present invention is applied. In the figure, 21 is a nozzle, 22 is a valve, 23 is an outflow passage, 24 is a liquid chamber, 25 Is a common liquid chamber, 26 is PZT, 27
Is a piezo element, 28 is a nozzle plate, and 29 is a diaphragm. FIG. 4 is a sectional view of a head portion for explaining an embodiment of a bubble type inkjet printer to which the present invention is applied. In the figure, 31 is a nozzle, 32 is a dielectric cantilever, 33 is an outflow passage, and 34 is Liquid chamber, 35 is a common liquid chamber,
Reference numeral 36 is a heating element, 37 is an electrode, and 38 is a nozzle plate.

In each of the configurations shown in FIGS. 3 and 4, after the ink ejection operation is started, the outflow passage may be opened by the operation of the outflow control means in accordance with the input image information. The member for opening and closing the outflow path provided in the outflow control means is the valve 22 operated by the piezo element 27 in the PZT system of FIG. 3, and the dielectric operated by the electrode 37 in the bubble system of FIG. The body cantilever 32. The operation of these outlet control means is
The relationship between the opening timing of the ejection port and the size of the ejected ink droplet may be grasped in advance, and the ejected droplet may be controlled by creating a calculation formula or a table.

In recent years, the head of an ink jet printer is often manufactured by using a micromachine technology in consideration of its manufacturability, cost reduction and the like. However, a member provided in the outflow control means (for example, the PZT method is shown above). Valve) has the possibility to be manufactured in many forms by micromachine technology. The configuration of the outflow control means may be selected in consideration of the optimality as a product. Further, the present invention can be applied to all ink jets having a liquid chamber nozzle on demand such as a PZT system, a bubble system, an electrostatic system, and a system configured by IC technology. In addition to the configuration examples shown in FIGS. Can also support various methods. In such various inkjet heads, a portion that is greatly affected by the vibration and movement of the liquid when ejecting ink by the operation of the ejection drive unit (for example, a position facing the diaphragm 29 in the PZT method shown in FIG. 3). By providing the outflow passage and the outflow control means in (1), it is possible to efficiently stop the movement of the ink in the liquid chamber after the start of the ink ejection, and to speed up the response.

Next, FIGS. 5 and 6 show an embodiment of an ink jet printer in which the outflow passage and the outflow control means according to the present invention are arranged near the nozzle. FIG. 5 is a cross-sectional view of a head portion for explaining another embodiment of a PZT type inkjet printer to which the present invention is applied, and portions having the same functions as those in FIG. 3 are designated by the same reference numerals as those in FIG. There is. Figure 6
4 is a cross-sectional view of a head portion for explaining another embodiment of a bubble type inkjet printer to which the present invention is applied, and portions having the same functions as those in FIG. 4 are denoted by the same reference numerals as those in FIG. As shown in FIGS. 5 and 6, by providing the outflow passage and the outflow control means in the vicinity of the nozzle, it is possible to control the ink flow when the ink is about to eject in the ink ejection cycle. It is possible to form various inkjets, and the responsiveness can be increased.

Next, an embodiment of an ink jet printer having a multi-nozzle head to which the present invention is applied and in which ejection driving means is integrally formed will be described. In the method according to the present invention, since the size of the ink droplet is controlled when the ink is ejected, if the outflow control means is arranged for each individual nozzle of the multi-nozzle,
Even if the ejection driving means is integrated, ejection of ink droplets from each nozzle can be controlled by individual outflow control means, and an ink jet can be formed according to an image signal. This is, for example, JP-A-2-2745.
As proposed in Japanese Patent No. 50, it does not have a structure for opening and closing the nozzle, so that the outflow control means can be arranged without worrying about the space of the nozzle portion, which is practical. Is.

Next, an embodiment of an ink jet printer to which the present invention is applied, in which the liquid inlet is made to function as a liquid outlet, will be described. In this embodiment, in order to control the outflow or flight vibration of the ink in the liquid chamber, a separate outflow passage is not provided separately, and the conventional inflow port is used as the outflow port. With this configuration, the outflow control means may be provided at the inflow port of the conventional head configuration. This is a configuration simplified from the one disclosed in Japanese Patent Laid-Open No. 2-274550, but the operation method is different from the method according to the present invention. That is, according to the present invention, when the ink jet is flown, the operation of opening the outflow passage is performed, but the one disclosed in Japanese Patent Laid-Open No. 274550/1990 has a motion of blocking the flow. It will be.

With regard to the design of the ink inlet size and the fluid resistance as described in the prior art, according to the present invention, the outflow passage is opened by the operation of the outflow control means when the ink flows into the liquid chamber. Therefore, the ink inflow port (outflow port) can be increased as much as possible, and when the ink is ejected, the outflow passage is sealed until a necessary ink droplet is secured, and the fluid resistance at this time is You don't have to consider. Furthermore, since the outflow path is opened when the required ink droplet size is secured, it is possible to immediately enter the next ink droplet generation step after the inkjet ink droplet is generated. That is, since the inflow port (outflow port) is opened when the ink jet ink droplet is generated, it is possible to immediately perform the ink replenishment to the liquid chamber, which is a step for the next ink generation.

[0024]

According to the first aspect of the present invention, there are provided an ejection port, an ejection driving means for ejecting ink from the ejection port, a liquid chamber in which the ink is stored, and an ink liquid inlet port to the liquid chamber. In an ink jet printer having a head part provided with the ink supply part for supplying ink to the head part, and an ejection control part for operating the ejection drive means in response to an input signal, ink from the liquid chamber is ejected. after the in-<br/> click flow outlet for discharging the liquid, ejection operation of the ink is started, the input
The opening timing of the ink outlet is controlled according to the signal.
Ink droplets ejected from the ejection port by controlling
Of so and a flow exit control means that controls the size, keeping the injection energy of the jet initially constant, by the same injection initial conditions, they change the size of the ink jet droplets, the inkjet Injection stability can be secured. Further, in this case, the relationship between the meniscus at the ejection port and the fluid resistance of the ink supply path, which is conventionally designed by the ink jet, is significantly relaxed, and there is an advantage that the design area is expanded.

[0025]

[0026] according to claim 2 Effect: In the invention of claim 1 Symbol placement. Thus providing the ink flow outlet and said outlet control means in the vicinity the spout, the ink ejection cycle, jump out exactly ink now During that time, the ink flow can be controlled, an efficient inkjet can be formed, and the responsiveness can be increased.

The effect of claim 3 : In the invention of claim 1 or 2 , since a plurality of head portions are provided, and the jetting means provided in each of the head portions is integrally formed, It is practical because the outflow control means can be arranged without worrying about the space.

The effect of claim 4 : In the invention according to any one of claims 1 to 3 , the ink liquid inlet is provided by providing the outflow control means in the ink liquid inlet or a liquid flow path connected to the ink liquid inlet. Since it is made to function as the ink liquid outlet, the outflow amount control means may be arranged at the inlet of the conventional head configuration, the ink inlet can be made large, and the fluid resistance of the inlet portion can be increased. There is no need to consider and the inkjet production cycle can be shortened.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an inkjet printer to which the present invention is applied.

FIG. 2 is a diagram for explaining an ink flight model of an inkjet printer according to the present invention.

FIG. 3 is a cross-sectional view of a head portion for explaining an embodiment of a PZT type inkjet printer to which the present invention is applied.

FIG. 4 is a cross-sectional view of a head portion for explaining an embodiment of a bubble type inkjet printer to which the present invention is applied.

FIG. 5 is a sectional view of a head portion for explaining another embodiment of a PZT type inkjet printer to which the present invention is applied.

FIG. 6 is a cross-sectional view of a head portion for explaining another embodiment of a bubble type inkjet printer to which the present invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Jet outlet, 2 ... Flow path control means, 3 ... Outflow path, 4 ... Liquid chamber, 5 ... Common liquid chamber, 6 ... Jet drive means, 7 ... Inflow part control means, 8 ... Ink supply part, 9 ... Jet Control unit, 10 ... Inkjet, 11 ... Jet port (nozzle), 12 ... Outflow passage control means, 21 ... Nozzle, 22 ... Valve, 23 ... Outflow passage,
24 ... Liquid chamber, 25 ... Common liquid chamber, 26 ... PZT, 27 ... Piezo element, 28 ... Nozzle plate, 29 ... Vibration plate, 31
... Nozzle, 32 ... Dielectric cantilever, 33 ... Outflow path,
34 ... Liquid chamber, 35 ... Common liquid chamber, 36 ... Heating element, 37 ... Electrode, 38 ... Nozzle plate.

Claims (4)

(57) [Claims] 1. A head portion comprising an ejection port, an ejection driving unit for ejecting ink from the ejection port, a liquid chamber in which the ink is stored, and an ink liquid inflow port to the liquid chamber. An ink jet printer having an ink supply unit that supplies ink to the head unit and an ejection control unit that operates the ejection drive unit according to an input signal,
An ink liquid outlet for flowing out the ink liquid from the liquid chamber,
After the ink ejection operation is started,
To control the opening timing of the serial ink flow outlet
Ri, inkjet printers, characterized by a control means output stream that controls <br/> the size of an ink droplet to be ejected from the ejection port. 2. A method according to claim 1 Symbol mounting ink jet printer, characterized in that the provided the ink flow outlet and said outlet control means to said ejection opening neighborhood. 3. has a plurality of said head portion, an ink jet printer according to claim 1 or 2, wherein the jet drive means is characterized by comprising integrally formed, each of said head portion comprises. 4. The ink liquid inflow port or the liquid flow path connected to the ink liquid inflow port is provided with the outflow control means so that the ink liquid inflow port functions as the ink liquid outflow port. Any one of items 1 to 3
The described inkjet printer.