JP2001063047A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mechanism means capable of adjusting a fluid resistance value corresponding to the drive frequency of a head and to ensure the proper supply of ink even when the head is driven by high-frequency waves. SOLUTION: Each of a large number of pressure chambers 5 formed in a head housing 9 parallelly is connected to at least a liquid drop jet flow channel 6 having a liquid drop jet nozzle 8 provided in the leading end part thereof and a fluid resistance flow channel 11 for supplying ink to each of the pressure chambers 5 from a common liquid chamber 12 and a vibration plate 3 is vibrated up and down by a piezoelectric element 2 and an ink drop is emitted from the nozzle 8 by the control of the pressure in each of the pressure chambers 5. When the pressure chamber 5 is pressurized, the fluid resistance flow channel 11 is narrowed at the same time to increase a fluid resistance value and, when pressurization is released, the fluid resistance flow channel is expanded to make it easy to supply ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head, and more particularly, to a means for adjusting a fluid resistance value to a driving frequency of a head in a multi-nozzle type ink jet head using a piezoelectric element as a driving body.
The present invention relates to a head arrangement for realizing this.

[0002]

2. Description of the Related Art In recent years, an ink jet printer has tended to expand a driving frequency band to a higher frequency side in order to respond to a demand for faster printing. The head of an ink-jet printer includes a first step of displacing a diaphragm to pressurize a pressure chamber or growing a bubble in a liquid chamber to pressurize the pressure chamber to eject ink droplets; Based on the second step of supplying ink to the pressure chamber, the ink supply means to the pressure chamber is usually connected to a narrow flow path called a fluid resistance path to the pressure liquid chamber and the common liquid chamber, A mechanism is used in which ink is supplied from the common liquid chamber to the pressure chamber via the fluid resistance path when the pressure in the pressure chamber decreases after ejection. Note that Japanese Patent Application Laid-Open No. 8-17482
Japanese Patent Application Laid-Open No. 4 (1999) -1995 discloses that, in order to prevent the ink from flowing back into the fluid resistance path when the pressure chamber is pressurized, the connecting portion between the fluid resistance path and the pressure chamber is constituted by a tapered part oscillating toward the pressure chamber and a straight part. An example is shown.

[0003]

In the conventional ink jet head as described above, ink can be supplied to the pressure chamber within the driving frequency band even with the configuration in which the shape of the fluid resistance portion is fixed. However, if the drive frequency is further increased to achieve high-speed printing, the supply of ink to the pressure chambers may not be able to keep up, especially in a high-frequency region. If the supply of ink is insufficient, the position of the ink surface (usually referred to as a meniscus surface) in the ejection nozzle tube provided continuously with the pressure chamber is lowered, and normal ejection becomes impossible.

The present invention has been made in view of the above circumstances, and provides a mechanism capable of adjusting a fluid resistance value in accordance with a driving frequency of a head, and is suitable for driving a head at a high frequency. It is intended to ensure the supply of ink.

It is another object of the present invention to provide a mechanism capable of adjusting a fluid resistance value in accordance with the driving of the head so that an appropriate ink supply can be ensured even when the head is driven at a high frequency. is there.

Further, the above object can be achieved even when the internal pressure control of the pressure chamber of the head is complicated in order to reduce the size of the ink droplets and to attenuate the residual vibration of the meniscus after the ejection of the ink droplets. The purpose is to do so.

Another object of the present invention is to provide an ink jet printer capable of performing stable printing even in a wide driving frequency band.

[0008]

According to a first aspect of the present invention, each of a plurality of pressure chambers formed side by side inside a head housing includes:
At least, a droplet ejection flow path having a droplet ejection nozzle at the tip end, and a fluid resistance flow path that supplies ink from the common liquid chamber to the pressure chamber, the bottom surface of the pressure chamber and the diaphragm, The diaphragm and the laminated piezoelectric element are joined, the surface of the piezoelectric element and the surface on the opposite side are joined to a fixed substrate, and the bottom surface of the head housing and the fixed substrate are joined and fixed by a frame, In the ink jet head that moves the diaphragm up and down by the piezoelectric element to control the internal pressure of the pressure chamber to eject ink droplets from the nozzles, the fluid resistance flow path portion provided at a side end of the pressure chamber A bottom surface is joined to the vibrating plate, and the piezoelectric element is joined thereunder.

According to a second aspect of the present invention, each of the plurality of pressure chambers formed side by side in the head housing has at least a liquid droplet ejection flow path having a liquid droplet ejection nozzle at a tip end thereof, and a common liquid chamber. And a fluid resistance flow path for supplying ink to the pressure chamber.The bottom surface of the pressure chamber and the vibration plate, the vibration plate and the laminated piezoelectric element are joined, and the vibration plate joining surface of the piezoelectric element is The opposite surface is joined to a fixed substrate, and the bottom surface of the head housing and the fixed substrate are joined and fixed by a frame,
In an ink jet head that moves the diaphragm up and down by the piezoelectric element to control the internal pressure of the pressure chamber to eject ink droplets from the nozzles, a bottom surface of a fluid resistance flow path provided at a side end of the pressure chamber Is bonded to the diaphragm, and the piezo piezoelectric element is bonded thereunder, and the resistance value of the fluid resistance flow path portion is variably controlled following the driving of the piezo piezoelectric element. is there.

[0010] The invention of claim 3 is characterized in that, in the invention of claim 1 or 2, there is provided variable means for changing the resistance value of the fluid resistance flow path.

According to a fourth aspect of the present invention, each of the plurality of pressure chambers formed side by side inside the head housing has at least a droplet jetting channel having a droplet jetting nozzle at a tip end thereof, and a common liquid chamber. And a fluid resistance flow path for supplying ink to the pressure chamber.The bottom surface of the pressure chamber and the vibration plate, the vibration plate and the laminated piezoelectric element are joined, and the vibration plate joining surface of the piezoelectric element is The opposite surface is joined to a fixed substrate, and the bottom surface of the head housing and the fixed substrate are joined and fixed by a frame,
In an ink jet head that moves the diaphragm up and down by the piezoelectric element to control the internal pressure of the pressure chamber to eject ink droplets from the nozzles, the bottom of the pressure chamber and the bottom of the fluid resistance flow path Each is characterized by having a separate piezoelectric element.

According to a fifth aspect of the present invention, each of the plurality of pressure chambers formed side by side in the interior of the head housing has at least a droplet jetting channel having a droplet jetting nozzle at a tip end thereof, and a common liquid chamber. And a fluid resistance flow path for supplying ink to the pressure chamber.The bottom surface of the pressure chamber and the vibration plate, the vibration plate and the laminated piezoelectric element are joined, and the vibration plate joining surface of the piezoelectric element is The opposite surface is joined to a fixed substrate, and the bottom surface of the head housing and the fixed substrate are joined and fixed by a frame,
In an ink jet head that moves the diaphragm up and down by the piezoelectric element to control the internal pressure of the pressure chamber to eject ink droplets from the nozzles, a pressure chamber bottom portion,
A separated piezoelectric element is joined to each of the bottom surfaces of the fluid resistance paths, and the displacement amount or the phase of the displacement of each piezoelectric element is controlled independently.

According to a sixth aspect of the present invention, each of the plurality of pressure chambers formed side by side in the interior of the head housing includes at least a droplet ejection flow path having a droplet ejection nozzle at a tip end portion, and a common liquid chamber. And a fluid resistance flow path for supplying ink to the pressure chamber.The bottom surface of the pressure chamber and the vibration plate, the vibration plate and the laminated piezoelectric element are joined, and the vibration plate joining surface of the piezoelectric element is The opposite surface is joined to a fixed substrate, and the bottom surface of the head housing and the fixed substrate are joined and fixed by a frame,
In an ink jet head that moves the diaphragm up and down by the piezoelectric element to control the internal pressure of the pressure chamber to eject ink droplets from the nozzles, a bottom part of the pressure chamber and a bottom part of the fluid resistance path part Are separated from each other, and the driving frequency of each piezoelectric element is controlled independently.

According to a seventh aspect of the present invention, an ink jet head according to any one of the first to sixth aspects is mounted.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Claim 1) FIGS. 1 and 2 are cross-sectional views (main scanning direction cross-sectional configuration views) of a main portion for explaining an embodiment of the invention of claim 1. 1 is a substrate, 2 is a piezoelectric element (laminated type), 3 is a SUS diaphragm (however, a diaphragm diaphragm in the example shown in FIG. 1),
4 is a polyimide film, 5 is a pressure chamber, 6 is a droplet ejection flow path, 7 is a nozzle plate, 8 is an ejection nozzle, 9 is a head housing,
10 is a frame supporting and fixing member, 11 is a fluid resistance path, 12
Is a common liquid chamber, and 13 is an electrode layer.
Each of the plurality of pressure chambers 5 juxtaposed in the inside of the nozzle has at least a droplet ejection flow path 6 having a droplet ejection nozzle 8 at a tip end thereof, and a fluid to supply ink from the common liquid chamber 12 to the pressure chamber 5. The bottom surface of the pressure chamber 5 is connected to the vibration plate 3, and the vibration plate 3 and the multilayer piezoelectric element 2 are joined together.
The opposite surface of the piezo piezoelectric element to the diaphragm joining surface is joined to the fixed substrate 1, the bottom surface of the head housing 9 and the fixed substrate 1 are joined and fixed by a frame, and the piezo piezoelectric element 2 vibrates the diaphragm 3 up and down. The present invention relates to an arrangement for enabling variable control of the fluid resistance value of the fluid resistance path 11 in an ink jet head that ejects ink droplets from the nozzles 8 by controlling the internal pressure of the chamber 5. The bottom surface of the fluid resistance path 11 provided at the side end of the diaphragm 3
And a piezo-electric element is joined thereunder.

According to the above arrangement, when the piezoelectric element 2 is driven at a predetermined frequency, the bottom of the fluid resistance portion 11 can be moved up and down following the driving of the piezoelectric element 2. Due to the structural expansion and contraction deformation of the fluid resistance portion 11, the fluid resistance value can be changed according to the drive frequency. That is, when pressurizing the pressure chamber 5,
At the same time, the fluid resistance value is increased by sandwiching the flow path of the fluid resistance path 11 to prevent backflow, and when the pressurization is released, the fluid resistance path 11 is widened to facilitate ink supply. FIG. 10 is a view showing the structure of a conventional ink jet head in comparison with the present invention. In the conventional ink jet head, as shown in FIG. , But not joined to the fluid resistance flow path 11.

Embodiment 1 By reducing the rigidity of the material surrounding the fluid resistance path 11, the rate of change of the fluid resistance value with respect to the driving force of the piezoelectric element can be improved. As an example, the rate of change of the fluid resistance can be improved by selecting a material having relatively low rigidity such as a dry film. More specifically, since the bottom of the fluid resistance path 11 is in contact with the diaphragm, the diaphragm 3 is formed as a diaphragm and a highly rigid metal material represented by SUS or the like is formed in a thin plate shape as shown in FIG. In addition to the plate, as shown in FIG. 2, a thin plate having a two-layer structure in which a polyimide film 4 is bonded thereto can also be used. In this case, by arranging the polyimide film 4 so as to be an upper layer, the stress applied to the joint surface between the diaphragm 3 and the upper structure when the diaphragm 3 is vibrated is absorbed by the polyimide film 4 having low rigidity. In addition, it is possible to prevent the vibration plate 3 from peeling off from the upper structure, and to prevent problems such as ink leakage and pressure loss in the liquid chamber.

When the diaphragm having a two-layer structure shown in FIG. 2 is used, the polyimide film 4 formed opposite to the bottom of the fluid resistance path 11 has a highly rigid SUS plate (diaphragm) joined thereunder. 3, the bottom of the fluid resistance path 11 is actuated vertically by driving the piezoelectric element 2, and the effect of making the fluid resistance variable is not impaired.
Further, in the illustrated embodiment, the common liquid chamber 1 of the fluid resistance portion 11 is provided.
The piezo piezoelectric element 2 is not joined to the portion near the common liquid chamber. However, when the piezo piezoelectric element 2 is joined to the common liquid chamber and set to the pull mode, the diaphragm at the bottom of the common liquid chamber 12 is also pulled down. The internal pressure of the liquid chamber drops, and the pressure chamber 5
And a reduction in the ink supply efficiency due to a decrease in the pressure difference in the common liquid chamber 12.

(Claim 2) According to a second aspect of the present invention, each of the plurality of pressure chambers 5 juxtaposedly formed inside the head housing 9 has a droplet jetting nozzle 8 provided at least at a tip portion. The flow path 6 is connected to a fluid resistance path 11 for supplying ink from the common liquid chamber 12 to the pressure chamber 5. The bottom surface of the pressure chamber 5, the diaphragm 3 (or the polyimide film 4), and the diaphragm are laminated. The piezoelectric element 2 is joined, the surface of the piezoelectric element 2 on the side opposite to the joint surface with the vibration plate 11 is joined to the fixed substrate 1, and the bottom surface of the head housing 9 and the fixed substrate 1 are joined and fixed by the frame 10. In an ink-jet head for ejecting ink droplets from the nozzles 8 by controlling the internal pressure of the pressure chamber 5 by moving the diaphragm 3 up and down by a piezoelectric element, a fluid resistance path provided as ink supply means to the pressure chamber 5 is provided. 11
Means for variably controlling the fluid resistance value of the fluid chamber by joining the bottom surface of the fluid resistance portion provided at the end of the pressure chamber 5 to the diaphragm and joining the piezoelectric element thereunder. Thus, the fluid resistance value is variably controlled following the driving of the piezoelectric element.
By the above means, when the piezoelectric element is driven at a predetermined frequency, the bottom of the fluid resistance part can be moved up and down following the driving of the piezoelectric element, and the structural characteristics of the fluid resistance part accompanying this can be increased. The fluid resistance value can be changed in accordance with the driving frequency by a proper expansion and contraction deformation.

(Embodiment 2) The driving modes of the piezoelectric element include a push mode in which the diaphragm layer 3 (or the polyimide film 4) is lifted and a pull mode in which the diaphragm layer 3 is lowered. The state where the pressure chamber 5 is filled with ink will be described as an initial state. First, as a first step, the pressure chamber is pressurized by the push mode.
At this time, in addition to the conventional effect that the inside of the pressure chamber 5 is pressurized by lifting the diaphragm layer 3 by the piezoelectric element 2, according to the means of the present invention, the opening of the fluid resistance path becomes narrow. Since the resistance value increases, the effect of preventing the backflow of ink from the pressure chamber 5 to the fluid resistance path 11 can be increased as compared with the related art. Thereby, the pressurizing efficiency of the pressure chamber 5 is also improved as compared with the head having the conventional configuration, so that there is an effect that the ink jetting efficiency can be improved. As a second step, the pressure in the pressure chamber 5 is also reduced by the pull mode so that the pressure in the pressure chamber is lower than the internal pressure in the common liquid chamber 12, so that the ink flows from the common liquid chamber 12 to the pressure chamber 5 side. I do. In this pull mode process, the frontage of the fluid resistance portion 11 is widened, so that ink can be supplied to the pressure chamber earlier than in a head having a conventional configuration.

(Embodiment 3) The resistance value of the fluid resistance path 12 is changed corresponding to each frequency by changing the amount of pulling down of the piezoelectric element in the pull mode in the second step in the second step according to the driving frequency of the head. be able to. Generally, as the drive frequency increases, the pressure chamber 5
Ink tends to be unable to keep up. As means for solving this problem, means for decreasing the fluid resistance value in the pull mode in accordance with an increase in the driving frequency can be taken. That is, the driving of the piezoelectric element 2 is controlled in a direction in which the amount of reduction of the piezoelectric element in the pull mode is increased in response to an increase in the driving frequency. The lengths of arrows A and B in FIGS. 3 and 4 schematically represent the amount of reduction. FIG. 3 shows the amount of reduction A in the pull mode during low-frequency driving, and FIG. 4 shows the amount of reduction B in the pull mode during high-frequency driving. Is shown.

According to a third aspect of the present invention, there is provided an ink jet head in which a fluid resistance value is variably controlled in accordance with a driving frequency of the head. The control is performed by changing the drive frequency of the piezoelectric element. The pressure chamber generated when the head proposed in claim 3 variably controls the fluid resistance value in accordance with the driving frequency of the head and drives the head at a high frequency from the description of the invention content of claim 2 described above. It can be understood that it has an unconventional function that can solve the problem of insufficient ink supply to the unit.

(Embodiment 4) FIG. 5 is a schematic diagram showing a main part of a fourth embodiment of the present invention, in which a plurality of pressure chambers 5 are arranged in a head and each pressure chamber is arranged. 5, a flow path 6 communicating with the droplet jetting nozzle 8, a fluid resistance path 11 for filling the pressure chamber 5 with ink, a diaphragm 3 (or a polyimide film 4), a diaphragm driving element (piezo piezoelectric element) 2 Etc. are provided. Each fluid resistance path 11 is connected to a common liquid chamber 12. Each piezoelectric element 2
Can be driven and controlled at independent frequencies. As the piezoelectric element 2 is driven in the vertical direction, the bottom of the fluid resistance path 11 expands and contracts at the opening of the flow path, and the fluid resistance value can be variably controlled by driving the piezoelectric element. In the push mode, the frontage of the fluid resistance path 11 is reduced to increase the fluid resistance value, so that the backflow of ink from the pressure chamber 5 is unlikely to occur, so that the pressurizing effect of the pressure chamber is improved and the ejection of ink droplets is improved. Efficiency is improved. In the pull mode, since the internal pressure of the pressure chamber 5 decreases and becomes lower than the internal pressure of the common liquid chamber 12, ink is supplied from the common liquid chamber 12 to the pressure chamber 5 via the fluid resistance path 11. At this time, the fluid resistance path 11 is connected to the piezoelectric element 2
As a result, the frontage is widened and the fluid resistance value is reduced, so that the pressure chamber can be quickly filled with ink.

Further, when the driving frequency of the piezoelectric element 2 is further increased, the fluid resistance value is further reduced by increasing the amount of pull-down in the pull mode, as described above, so that the fluid resistance in the fluid resistance path 11 is reduced. It is possible to make the ink easier to flow, and to increase the ink filling speed from the common liquid chamber 12 to the pressure chamber 5. As described above, since the fluid resistance value can be changed according to the driving frequency, it is possible to solve the problem that the ink cannot be filled in the pressure chamber 5 in time when the head is driven at a high frequency. Since the fluid resistance value of the conventional head is constant, it is necessary to set a fluid resistance path so that the pressure chamber is properly filled with ink in all the drive frequency bands when the drive frequency band is widened. However, this has been a hindrance to the realization of a high-frequency drive head and the realization of high-speed printing. However, the present invention can solve the above-mentioned hindrance.

(Claim 4) According to a fourth aspect of the present invention, as shown in FIG. 6, the pressure control for the pressure chamber 5 and the fluid resistance 1
In this case, the fluid resistance variable control unit is separated and arranged, and the fluid resistance variable control unit is disposed on the bottom of the pressure chamber 5 via the diaphragm layer 3 (or the polyimide film 4) as shown in the figure. The piezoelectric element is separated from the contact area and the area in contact with the bottom surface of the fluid resistance portion 11 via the diaphragm layer 3. The vibration plate vibrates, and the diaphragm of the fluid resistance portion 11 is vibrated by the piezoelectric element 14. In order to achieve the object of reducing the size of the ink droplet to be ejected by adjusting the pressure applied to the pressure chamber 5 or reducing the residual vibration of the meniscus surface after the ejection of the ink droplet, a piezo piezoelectric element is required. Becomes complicated, and a plurality of pull and push mode drives are performed for one ink droplet ejection.

In the case of performing the complicated discharge control as described above, in the arrangements shown in FIGS. 1 and 2, the piezoelectric element for controlling the pressure of the pressure chamber 5 and the resistance control of the fluid resistance section 11 are performed. Since the piezo-electric element for use is also used by one piezo-electric element, the timing of adjusting the fluid resistance value is synchronized with the timing of the pressure control of the pressure chamber, so that the fluid resistance value is adjusted before the ejection is completed. There is a possibility that the ink will flow down into the pressure chamber due to a decrease and the ink amount in the pressure chamber will exceed an appropriate value. Therefore, in the invention of claim 4, as shown in FIG. 6, the piezoelectric element 2 for controlling the internal pressure of the pressure chamber and the piezoelectric element 14 for controlling the fluid resistance value are provided.
Were separated and arranged. Since each of the separated piezo elements can be operated independently, ink droplets can be reduced by the complicated control of the internal pressure of the pressure chamber as described above, and meniscus vibration can be reduced. In the process in which the ejection is performed, the fluid resistance value is increased, and after the ejection of the ink droplet is completed, the fluid resistance value can be decreased to increase the efficiency of ink supply to the pressure chamber, and the fluid resistance value can be decreased according to the driving frequency, The gist of the present invention that ink supply can be ensured even during high-frequency driving can be satisfied.

In the embodiment shown in FIG. 6, a D33 laminated piezoelectric element is disposed at the bottom of the pressurizing chamber 2, and a D31 laminated piezoelectric element is disposed at the bottom of the fluid resistance portion 11. Although the piezoelectric element 14 is arranged, as shown in FIG. 6, since the area of the fluid resistance portion 11 is narrow, it is difficult to form a D33 laminated piezoelectric element in this area. It is because of that.

(Claim 5) The invention of claim 5 is based on claim 4
In the invention, the displacement amount or the phase of the displacement of the piezoelectric elements 2, 14 which are separately joined to the bottom of the pressure chamber 5 and the bottom of the fluid resistance path 11 are controlled independently. That is, the pressure control for the pressure chamber 5 and the fluid resistance variable control of the fluid resistance path 11 are separately performed. In order to achieve the purpose of reducing the size of the ink droplets to be ejected by adjusting the pressure applied to the pressure chamber 5 or attenuating the residual vibration of the meniscus surface after the ejection of the ink droplets, a piezoelectric element is required. Becomes complicated, and a plurality of pull and push mode drives are performed for one ink droplet ejection. When such complicated discharge control is performed, in the invention of FIGS. 1 and 2, the piezo element for controlling the pressure of the pressure chamber 5 and the fluid resistance path also serve as the piezo element for controlling the resistance value. Therefore, the adjustment timing of the fluid resistance value is synchronized with the pressure control timing of the pressure chamber, so that the fluid resistance value decreases before the ejection is completed, ink flows into the pressure chamber, and the amount of ink in the pressure chamber increases. May exceed the proper value.

According to a fifth aspect of the present invention, the above-mentioned disadvantage is solved by means of separating a piezo element for controlling the internal pressure of the pressure chamber and a piezo piezoelectric element for controlling the fluid resistance value and driving each of them independently. is there. By means of operating each separated piezo element independently, ink droplets can be reduced by complicated control of the internal pressure of the pressure chamber as described above, and meniscus vibration can be attenuated. Is performed, the fluid resistance value is increased, and after the ejection of the ink droplet is completed, the fluid resistance value can be reduced to increase the efficiency of ink supply to the pressure chambers. This is to satisfy the gist of the invention that the ink supply can be ensured even during driving.

(Claim 6) The invention of claim 6 is a proposal of an ink jet head for variably controlling the fluid resistance value according to the driving frequency of the head. FIG. 7 shows a low frequency driving pull mode, and FIG. FIG. 9 is a cross-sectional view of the operation in the high-frequency driving pull mode. FIG. 9 is a cross-sectional view in the direction in which the nozzles are arranged. In order to reduce the size of ink droplets and suppress residual vibration of the meniscus after ink droplet ejection, the internal pressure is controlled by complexly combining the push and pull drive of the piezo element to the pressure chamber in one ejection cycle In such a case, the fluid resistance value is variably controlled in accordance with the drive frequency of the head, thereby eliminating the problem of insufficient ink supply to the pressure chambers, which is a particular problem during high-frequency drive. At the suggestion of Ettoheddo, according to claim 4
It is intended to change the described fluid resistance value according to the driving frequency of the piezoelectric element. From the above description of the fourth and fifth aspects of the present invention, the head proposed in the sixth aspect variably controls the fluid resistance value according to the driving frequency of the head, and is generated when the head is driven at a high frequency. It can be understood that it has an unprecedented function of solving the problem of insufficient ink supply to the pressure chambers.

(Claim 7) The invention of claim 7 is a proposal of an ink jet printer equipped with an ink jet head, characterized by any one of the arrangements or means of the above claims 1 to 6. This printer draws an image or a character by ejecting ink droplets from an ink jet head onto a print medium supplied from a paper supply unit, and the head is arranged in a direction perpendicular to the transport direction of the print medium. The scanning means is provided in the (main scanning direction), and at the completion of one main scanning, the print medium is conveyed and stopped in a direction (sub-scanning direction) perpendicular to the main scanning direction and stopped, and the main scanning of the head is performed again. By repeating the process of ejecting ink droplets and drawing images or characters,
An image or a character is drawn on a print medium.
In the non-printing target area of the head in the main scanning direction, a measure such as a capping of the head and a bubble discharging mechanism is configured to prevent clogging of the head. Alternatively, an ink tank for supplying ink to the head is provided, and ink is periodically supplied to an ink reservoir tank provided in the head.

The printer receives an image or character information to be printed transmitted from an external device such as a personal computer.
By converting such received information into dot information,
An image or a character is drawn on a print medium as an aggregate of dots formed by a large number of ink droplets. For the image information to be drawn, for example, the outline of a character can be smoothly corrected by image processing software, the contrast of the image can be adjusted, and a device can be provided so that the unevenness of the image becomes less noticeable by an error dispersion method.

Although the mechanism configuration and functions of the printer main body are not limited to those described above, the present invention is, as will be apparent from claims 1 to 6,
In particular, the ink jet printer according to the present invention has a mechanism for adjusting the fluid resistance value of the head to a positive value even when driven at a high frequency, thereby quickly filling the liquid chamber of the head with ink. Can be performed, it is possible to correct the disturbance of the ink droplet ejection characteristics due to the lack of ink supply, and thus, it is possible to discharge the ink droplets stably in a wide driving frequency band. Of the landing position is reduced, and the quality of the drawn image is also improved.

[0034]

(Effects of the Inventions of Claims 1 to 3) In order to improve the ink supply problem in an ink jet head compatible with high frequency driving, a fluid resistance path which plays an important role as an ink supply path of a high frequency driving type head is used. The fluid resistance value is arbitrarily adjusted according to the drive frequency.
As a result, an optimum fluid resistance value is provided for each drive frequency, and the ink supply to the liquid chamber of the head can be performed stably, thereby contributing to the improvement of the ejection characteristics of the head. This makes it possible to provide an ink jet head having printing performance with higher image quality than before even during high-speed printing.

(Functions and Effects of the Inventions of Claims 4 to 6) In addition to the functions and effects of the inventions of claims 1 to 3, ink separation is achieved by separating the pressure adjustment mechanism for the liquid chamber and the resistance value adjustment mechanism for the fluid resistance path. It is possible to adjust the fluid resistance value independently of the function of the liquid chamber pressure adjustment mechanism, such as miniaturization of droplets and suppression of meniscus residual vibration. The drive frequency response of the ink supply to the liquid chamber can be improved.

(Effects of the Invention of Claim 7) Compared with the conventional ink jet printer, it is possible to obtain more stable image quality particularly in a wide driving frequency band, and even in high frequency driving. The stability of ink supply is improved, and it is possible to supply a printer with superior performance in response to the need for high-speed printing, which is increasingly important in the future.

[0037]

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part (main scanning direction) for describing an embodiment of an ink jet head according to the present invention.

FIG. 2 is a sectional view of a main part (main scanning direction) for explaining another embodiment of the ink jet head according to the present invention.

FIG. 3 is a cross-sectional configuration diagram showing a pull mode state when the inkjet head shown in FIG. 1 or 2 is driven at a low frequency.

FIG. 4 is a cross-sectional configuration diagram illustrating a pull mode state when the inkjet head illustrated in FIG. 1 or 2 is driven at a high frequency.

FIG. 5 is a sectional configuration diagram of a main part (sub-scanning direction) of the inkjet head shown in FIG. 1 or FIG. 2;

FIG. 6 is a sectional view of a main part (main scanning direction) for describing another embodiment of the ink jet head according to the present invention.

FIG. 7 is a diagram illustrating a state of a pull mode at the time of low-frequency driving of the inkjet head illustrated in FIG. 6;

8 is a diagram illustrating a state of a pull mode during high-frequency driving of the inkjet head illustrated in FIG. 6;

FIG. 9 is a sectional configuration diagram of a main part (sub-scanning direction) of the ink jet head shown in FIG.

FIG. 10 is a sectional configuration diagram of a main part (main scanning direction) of a conventional inkjet head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Piezoelectric element (laminated type), 3 ... SUS diaphragm (or diaphragm diaphragm), 4 ... Polyimide film, 5 ... Pressure chamber, 6 ... Drop ejection path, 7 ... Nozzle plate, 8
... injection nozzle, 9 ... head housing, 10 ... frame (support and fixing member), 11 ... fluid resistance path, 12 ... common liquid chamber, 13
... Electrode layer, 14. Piezoelectric element for controlling fluid resistance.

Claims (7)

[Claims] A plurality of pressure chambers formed side by side inside a head housing are each provided at least with a droplet ejection flow path having a droplet ejection nozzle at a tip portion, and a common liquid chamber to the pressure chamber. The bottom surface of the pressure chamber and the vibration plate, the vibration plate and the laminated piezoelectric element are joined together, and the surface on the side opposite to the diaphragm joining surface of the piezoelectric element is formed. The bottom surface of the head housing and the fixed substrate are joined and fixed by a frame, and the diaphragm is moved up and down by the piezo piezoelectric element to control the internal pressure of the pressure chamber to thereby form ink droplets from the nozzles. A bottom surface of the fluid resistance flow path portion provided at a side end of the pressure chamber is joined to the vibration plate, and the piezoelectric element is joined thereunder. Characterized by Inkjet head. 2. A plurality of pressure chambers formed side by side inside a head housing are each provided at least with a droplet ejection flow path having a droplet ejection nozzle at a distal end portion and a common liquid chamber to the pressure chamber. The bottom surface of the pressure chamber and the vibration plate, the vibration plate and the laminated piezoelectric element are joined together, and the surface on the side opposite to the diaphragm joining surface of the piezoelectric element is formed. The bottom surface of the head housing and the fixed substrate are joined and fixed by a frame, and the diaphragm is moved up and down by the piezo piezoelectric element to control the internal pressure of the pressure chamber to thereby form ink droplets from the nozzles. In the ink jet head for ejecting liquid, the bottom surface of the fluid resistance flow path provided at the side end of the pressure chamber is joined to the vibration plate, and the piezo piezoelectric element is joined thereunder to drive the piezo piezoelectric element. Following the fluid An ink jet head that variably controls a resistance value of a resistance channel section. 3. The ink jet head according to claim 1, further comprising a variable unit that changes a resistance value of the fluid resistance flow path unit. 4. Each of a plurality of pressure chambers formed side by side inside the head housing has at least a droplet ejection flow path provided with a droplet ejection nozzle at a tip end portion, and a common liquid chamber to the pressure chamber. The bottom surface of the pressure chamber and the vibration plate, the vibration plate and the laminated piezoelectric element are joined together, and the surface on the side opposite to the diaphragm joining surface of the piezoelectric element is formed. The bottom surface of the head housing and the fixed substrate are joined and fixed by a frame, and the diaphragm is moved up and down by the piezo piezoelectric element to control the internal pressure of the pressure chamber to thereby form ink droplets from the nozzles. An ink jet head comprising: a piezoelectric element which is separated from each of a bottom surface of the pressure chamber and a bottom surface of the fluid resistance flow path. 5. A plurality of pressure chambers formed side by side inside the head housing are each provided at least with a droplet ejection flow path having a droplet ejection nozzle at a tip portion, and a common liquid chamber to the pressure chamber. The bottom surface of the pressure chamber and the vibration plate, the vibration plate and the laminated piezoelectric element are joined together, and the surface on the side opposite to the diaphragm joining surface of the piezoelectric element is formed. The bottom surface of the head housing and the fixed substrate are joined and fixed by a frame, and the diaphragm is moved up and down by the piezo piezoelectric element to control the internal pressure of the pressure chamber to thereby form ink droplets from the nozzles. In the ink jet head for ejecting, the separated piezoelectric elements are joined to the bottom of the pressure chamber and the bottom of the fluid resistance path, respectively, and the displacement amount or the phase of the displacement of each piezoelectric element is Independently controlled An ink jet head characterized by being made to perform. 6. Each of a plurality of pressure chambers formed side by side inside the head housing includes at least a droplet ejection flow path having a droplet ejection nozzle at a distal end portion and a common liquid chamber to the pressure chamber. The bottom surface of the pressure chamber and the vibration plate, the vibration plate and the laminated piezoelectric element are joined together, and the surface on the side opposite to the diaphragm joining surface of the piezoelectric element is formed. The bottom surface of the head housing and the fixed substrate are joined and fixed by a frame, and the diaphragm is moved up and down by the piezo piezoelectric element to control the internal pressure of the pressure chamber to thereby form ink droplets from the nozzles. In the ink jet head for ejecting, the separated piezoelectric elements are joined to the bottom of the pressure chamber and the bottom of the fluid resistance path, and the driving frequency of each piezoelectric element is independently controlled. To make An ink jet head characterized by the following. 7. An ink jet printer comprising the ink jet head according to claim 1.