JP3102324B2 - INK JET PRINT HEAD, INK JET PRINTER, AND INK JET PRINT HEAD MAINTENANCE METHOD - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-demand type ink jet printer for forming an image on a recording material by ejecting ink from a discharge port, an ink jet print head, and a method of maintaining the ink jet print head. .

[0002]

2. Description of the Related Art Conventionally, as an ink jet printer,
Typical examples include those using a piezoelectric type ink jet print head that mechanically deforms the pressure chamber with a piezoelectric material and ejecting ink from the ink ejection port with the generated pressure, and heaters arranged in the ink flow path. There has been known a printer using a thermal ink jet printhead that energizes the ink to vaporize the ink and ejects the ink from the ink discharge port by the pressure.

In these ink-jet printers, in order to improve image quality and printing speed,
Development is proceeding in the direction of increasing the number of nozzles that eject ink. Increasing the number of nozzles increases the pressure that propagates from the pressure source to the common liquid chamber where multiple nozzles communicate with each other, resulting in instability of the ink ejection state and obstruction of ink supply. This causes problems such as inability to jet.

FIG. 19 is a graph showing an example of pressure fluctuation in a common liquid chamber in a conventional ink jet printer. For example, when printing of a pattern with high coverage is started, a pressure for ejecting ink is generated in all nozzles. Since the pressure in each nozzle propagates to the common liquid chamber, a large pressure is temporarily applied as a whole in the direction from the nozzle to the common liquid chamber. After that, ink is supplied from the common liquid chamber to the nozzles for performing the next printing. At that time, pressure is applied in the direction from the common liquid chamber to the nozzles by the flow of the ink. Thus, the pressure in the common liquid chamber oscillates due to the inertia of the ink as shown in FIG. Under the worst conditions, such pressure fluctuations are 400 mmH ₂
Also reaches O. Due to such a change in pressure, the pressure in the nozzle, the amount of supplied ink, and the like at each print timing change, and the ink ejection state becomes unstable.

FIG. 20 is an explanatory diagram of a printing state when image quality is poor in a conventional ink jet printer. When printing in the unstable ejection state as described above, for example, when a large pressure is applied in the direction from the common liquid chamber to the nozzle,
As shown in FIG. 20A, in addition to the dots formed by regular ink droplets, a phenomenon occurs in which small ink droplets fly at a timing different from the printing timing, and the density partially increases. . In particular, at the moment when the negative pressure in the common liquid chamber reaches a peak, ink supply shortage occurs, ink is not ejected from the nozzles, and white spots occur, for example, as shown in FIG.

In order to solve such a problem, for example, in JP-A-63-128947, a damper chamber having an air layer is provided in an ink supply path. The pressure transmitted to the common liquid chamber advances to the damper chamber, and the pressure transmitted by the air layer in the damper chamber is reduced. Therefore, the pressure fluctuation in the common liquid chamber can be reduced, and the ink ejection state can be stabilized. However, in the structure described in this document, since the opening of the damper chamber faces the position where the flow of ink is strong, ink can easily flow into the damper chamber, so that the air in the damper chamber gradually flows to the liquid chamber. There is a problem that the fluid flows out and the function of the damper chamber is reduced.

[0007] For example, in Japanese Patent Laid-Open No. Hei 6-344558, an air chamber communicating with the common liquid chamber is provided behind the common liquid chamber. Further, in the configuration described in this document, the communicating portion between the common liquid chamber and the air chamber is narrow and the air chamber is wide, so that the outflow of air due to the inflow of ink can be prevented. Therefore, it is possible to maintain the pressure buffering function. However, in the configuration described in this document,
Since the air chamber is provided on the second substrate on which the common liquid chamber is formed, there is a problem in that the print head is enlarged accordingly.

Further, in JP-A-1-308644, a pressure-volume converter is provided in a liquid chamber or adjacent to the liquid chamber. However, there is no description of a specific configuration when the pressure-volume converter is made of gas.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an ink jet printer and an ink jet print head which can always stably eject ink without increasing the size of the print head. It is intended for. It is another object of the present invention to provide a maintenance method for always enabling stable ink ejection in such an ink jet print head.

[0010]

According to a first aspect of the present invention, there is provided an ink jet print head which forms an image by discharging ink from a plurality of nozzles, wherein a plurality of energy generating means for discharging ink from the nozzles are provided. An inkjet head formed with a plurality of ink flow paths arranged individually corresponding to the energy generating means and supplying ink to the energy generating means, and an ink reservoir in which the plurality of ink flow paths are commonly communicated; And an ink supply member provided with an ink supply tube for supplying ink to the ink reservoir of the inkjet head, wherein the ink supply member communicates only with the ink reservoir and holds a gas inside. The gas holding portion is provided, and the gas holding portion has a substantially circular cross section. It is an feature.

According to a second aspect of the present invention, there is provided an ink-jet printhead which forms an image by discharging ink from a plurality of nozzles, wherein a plurality of energy generating means for discharging ink from the nozzles, and A plurality of ink flow paths each individually arranged to supply ink to the energy generating means, an ink jet head having an ink reservoir formed by the plurality of ink flow paths in common communication, and an ink jet head of the ink jet head. An ink supply member provided with an ink supply pipe for supplying ink to the ink reservoir, wherein the ink supply member is provided with a plurality of gas holding portions communicating only with the ink reservoir and holding a gas inside; And the gas holding portions are substantially equally spaced along the arrangement direction of the ink flow paths. And it is characterized in that provided in the.

According to a third aspect of the present invention, there is provided an ink jet print head which forms an image by discharging ink from a plurality of nozzles, wherein a plurality of energy generating means for discharging ink from the nozzles, and A plurality of ink flow paths each individually arranged to supply ink to the energy generating means, an ink jet head having an ink reservoir formed by the plurality of ink flow paths in common communication, and an ink jet head of the ink jet head. An ink supply member provided with an ink supply pipe for supplying ink to the ink reservoir, wherein the ink supply member is provided with a plurality of gas holding portions communicating only with the ink reservoir and holding a gas inside; And the gas holding unit is directly connected to the ink reservoir. Area of the portion is characterized in that less than the cross-sectional area of the surface facing the ink reservoir of the gas holding part.

According to a fourth aspect of the present invention, there is provided an ink jet print head which forms an image by ejecting ink from a nozzle by pressure of a bubble generated by heat, wherein a plurality of heat generating resistors which generate heat to generate the bubble are provided. A first substrate provided with a plurality of channels provided opposite to the first substrate and configured to supply ink on the heating resistor and a common ink reservoir common to the plurality of channels. A substrate, an ink supply path for supplying ink to the common ink reservoir, and an ink supply member provided with a plurality of air chambers holding air therein and communicating only with the common ink reservoir, and the air chamber is , The section of which is substantially circular.

According to a fifth aspect of the present invention, there is provided an ink jet print head which forms an image by ejecting ink from a nozzle by pressure of a bubble generated by heat, wherein a plurality of heat generating resistors which generate heat to generate the bubble are provided. A first substrate provided with a plurality of channels provided opposite to the first substrate and configured to supply ink on the heating resistor and a common ink reservoir common to the plurality of channels. A substrate, an ink supply path for supplying ink to the common ink reservoir, and an ink supply member provided with a plurality of air chambers holding air therein and communicating only with the common ink reservoir, and the air chamber is , Are provided at substantially equal intervals along the direction of arrangement of the ink flow paths.

According to a sixth aspect of the present invention, there is provided an ink jet print head which forms an image by ejecting ink from a nozzle by the pressure of a bubble generated by heat, wherein a plurality of heat generating resistors which generate heat to generate the bubble are provided. A first substrate provided with a plurality of channels provided opposite to the first substrate and configured to supply ink on the heating resistor and a common ink reservoir common to the plurality of channels. A substrate, an ink supply path for supplying ink to the common ink reservoir, and an ink supply member provided with a plurality of air chambers holding air therein and communicating only with the common ink reservoir, and the air chambers are provided. The area of the communicating portion formed by directly joining the ink reservoir is determined by the sectional area of the surface of the air chamber facing the ink reservoir. It is characterized in that the small.

According to a seventh aspect of the present invention, there is provided an ink jet printer including the ink jet print head according to any one of the first to sixth aspects.

According to an eighth aspect of the present invention, a pressure is generated by a pressure generating source, ink is ejected from a discharge port by the pressure to form an image, and pressure vibration propagated from the pressure generating source is generated in an air chamber. In the maintenance method of the inkjet print head to absorb, after filling the initial ink,
Alternatively, the temperature of the ink jet print head is increased after ink replacement or ink suction operation, and ink is sucked from the discharge ports.

[0018]

1 to 5 show an embodiment of an ink jet print head according to the present invention. FIG. 1 is a perspective view, FIG. 2 is a sectional view taken along the line AA ', and FIG. B
-B 'sectional view, FIG. 4 is DD' sectional view, and FIG. 5 is CC '.
It is sectional drawing. In the drawing, 1 is a heater substrate, 2 is a channel substrate, 3 is a nozzle, 4 is a heating element, 5 is an ink flow path, 6 is a common reservoir, 7 is a concave portion, 11 is an ink supply member, 12
Denotes an ink supply path, and 13 denotes a gas holding unit.

In the channel substrate 2, ink channels 5 are formed corresponding to the respective nozzles 3, and a common reservoir 6 provided in common to the plurality of ink channels 5 is formed. The common reservoir 6 is formed so as to penetrate the channel substrate 2. Here, one common reservoir 6 is formed in common to all the ink flow paths 5, but it may be formed by dividing into a plurality of common reservoirs.

On the other hand, each ink flow path 5
2 and 3, recesses 7 are provided from above each of the heating elements 4 so that the ink flow path 5 and the common reservoir 6 communicate with each other. I have. As shown in FIG. 5, the concave portion 7 has a partially constricted shape, and the wall surface on the common reservoir 6 side can be formed in an arc shape. Such a shape makes it difficult to transmit the pressure generated on the heating element 4 to the common reservoir 6.

By bonding the heater substrate 1 and the channel substrate 2 together, an ink flow path from the common reservoir 6 to the ink flow path 5 via the recess 7 is formed. Actually, a large number of the heater substrates 1 and the channel substrates 2 are formed on the respective wafers, and are bonded and then separated by dicing or the like. In the bonded state, the end of the ink flow path 5 and the through-hole of the common reservoir 6 are exposed. At this time, the end of the ink flow path 5 is
Becomes

An ink supply member 11 is attached to the through hole of the common reservoir 6. In the ink supply member 11,
An ink supply path 12 for supplying ink from an ink tank (not shown) to the common reservoir 6 and a gas holding unit 13 for holding gas therein are formed. Gas holding unit 13
Is formed as a substantially circular hole which does not penetrate and communicates only with the common reservoir 6, as shown in FIG. After the ink is filled, the gas remaining in the gas holding unit 13 reduces the pressure fluctuation in the common reservoir 6. As shown in FIG. 4, a plurality of the gas holding units 13 are arranged at substantially equal intervals together with the ink supply path 12.
Since the gas holding portion 13 can be formed together with the ink supply path 12 when the ink supply member 11 is molded, the manufacturing process for forming the gas holding portion 13 does not become complicated.

The ink is guided from an ink tank (not shown) to the common reservoir 6 via an ink supply path 12 in the ink supply member 11. The ink guided to the common reservoir 6 fills the common reservoir 6 and fills each ink flow path 5. At this time, the ink is attracted by the negative pressure generated in the ink tank and the surface tension at the interface of the ink in each ink flow path 5, and the ink does not leak from the nozzles 3 in a state where printing is not performed. Also, when the common reservoir 6 is filled with ink, gas remains in the gas holding unit 13.

Thereafter, the pressure of each part is stabilized by a maintenance operation. The maintenance operation is performed after initial ink filling, after ink replacement, or after ink suction maintenance when trouble occurs. As a specific maintenance operation, for example, after the temperature of the inkjet print head is raised to, for example, about 60 degrees, ink is further sucked from the nozzle 3 side. By doing so, the gas held in the gas holding unit 13 expands due to a rise in temperature. Then, the gas expanded by the temperature rise is released into the common reservoir 6, and the released gas is discharged to the outside by suction of the ink.
After such a maintenance operation, even if the head temperature rises in the actual use state, the gas held in the gas holding unit 13 is not released to the common reservoir 6, and the printing is always stable. By such a maintenance operation, it is possible to maintain the effect of more reliably suppressing the pressure fluctuation.

At the time of printing, the nozzle 3 for discharging ink
Is supplied to the heating element 4 disposed in the ink flow path 5 corresponding to. Thus, the ink is ejected from the nozzles 3 by the pressure of the bubbles generated in the ink, and flies onto the recording medium to perform recording. At that time, the pressure of the bubble is
It also propagates to the rear of the recess 7 and further to the common reservoir 6. The pressure at this time is a force in a direction from the ink flow path 5 to the common reservoir 6. Thereafter, as the bubbles disappear, the ink becomes insufficient on the heating element 4, and a force acts in the direction from the common reservoir 6 toward the ink flow path 5, and the ink is supplied from the common reservoir 6 to the ink flow path 5.

As described above, in the short period from the growth of the bubble to the disappearance of the bubble, opposing forces act in the common reservoir 6.
Therefore, in the conventional inkjet head in which the bubble holding unit 13 does not exist, the pressure fluctuation as shown in FIG. In the present invention, the pressure transmitted to the common reservoir 6 during bubble growth also propagates to the gas holding unit 13 and the gas holding unit 1
The pressure transmitted by compressing the gas in 3 is relieved. Further, when the bubbles disappear, the gas in the gas holding unit 13 expands, so that the increase in the negative pressure due to the sudden lack of ink is reduced. In this manner, the gas holding unit 13 functions to reduce the pressure fluctuation in the common reservoir 6.

The flow of ink during ink supply is in the direction from the ink supply path 12 to the recess 7 corresponding to each ink flow path 5. Therefore, the position where the gas holding unit 13 communicates with the common reservoir 6 is a portion where the flow of ink is small, and it is possible to suppress the outflow of gas in the gas holding unit 13 due to the flow of ink as in the related art, and to stably As a result, pressure fluctuation can be suppressed.

FIG. 6 is a graph showing an example of the pressure fluctuation generated in the common reservoir in one embodiment of the ink jet print head of the present invention. As described above, according to this embodiment, since the pressure fluctuation in the common reservoir 6 is suppressed by the gas holding unit 13, even when printing is performed under the same conditions as those shown in FIG. FIG.
As shown in Fig. 7, no large pressure fluctuation was observed, and printing was performed normally.

7 and 8 show a first modification of the embodiment of the ink jet print head according to the present invention. FIG. 7 is a sectional view taken along the line BB 'in FIG. 1, and FIG. 1 is a sectional view taken along the line DD ′. In this example,
An example in which the cross-sectional area of the gas holding unit 13 is increased is shown.
By increasing the cross-sectional area of the gas holding unit 13 in this manner, the volume of the gas holding unit 13 can be increased, and the amount of gas held inside can be increased. Therefore, the function of suppressing pressure fluctuation can be increased. Further, when the length of the gas holding portion 13 cannot be obtained, the cross-sectional area can be increased as in this example to secure the amount of gas.

9 and 10 show a second modification of the embodiment of the ink jet print head according to the present invention. FIG. 9 is a sectional view taken along the line BB 'in FIG.
FIG. 10 is a sectional view taken along the line DD ′ in FIG. In this example, the position of the gas holding unit 13 is shifted. In this configuration, since the cross-sectional area of the communicating portion between the gas holding unit 13 and the common reservoir 6 is reduced, the inflow of ink and the outflow of gas into the gas holding unit 13 are further suppressed, and the suppression of pressure fluctuation is stabilized. Can do it. Further, in this example, the position of the gas holding unit 13 is shifted to the side opposite to the nozzle 3, so that even in an ink jet printer in which the nozzle 3 is directed downward and ink droplets fly downward, for example, The pressure fluctuation can be satisfactorily suppressed without the gas in 13 flowing out.

FIGS. 11 and 12 show a third modification of the embodiment of the ink jet print head according to the present invention. FIG. 11 is a sectional view taken along line BB 'in FIG. 1, and FIG. 1 is a sectional view taken along the line DD ′. In this example, the gas holding unit 13 is extended obliquely rearward. In this example, since the gas is held from the deepest part of the gas holding unit 13, the gas can be applied even when the ejection direction of the ink droplet is horizontal or when the ink droplet is ejected downward. Can be prevented from being replaced with ink.

FIG. 13 is a sectional view taken along the line BB 'in FIG. 1 showing a fourth modification of the embodiment of the ink jet print head of the present invention. In this example, a groove serving as the gas holding portion 13 is formed on the surface of the ink supply member 11 and attached to the channel substrate 2. In this case, one surface of the gas holding unit 13 becomes the surface of the channel substrate 2. This example is particularly effective when ejecting ink droplets downward. In this example, since the surface of the channel substrate 2 is used as a part of the gas holding portion 13, the length of the portion behind the common reservoir 6 is required, and the airtightness of the attached portion is required. As a further modification of the fourth modification, it is conceivable to form a gas holding portion 13 that bends in the ink supply member 11 if it can be formed.

FIG. 14 is a sectional view taken along the line DD 'in FIG. 1 showing a fifth modification of the embodiment of the ink jet print head of the present invention. In this example, a gas holding portion 13 having a cross-sectional shape along the opening of the common reservoir 6 is formed. By thus increasing the area of the communication portion with the common reservoir 6, the pressure propagated in the common reservoir 6 can be received in a wide range and can be attenuated. Further, since the capacity of the gas holding unit 13 can be increased, the effect of suppressing pressure fluctuation can be enhanced. However, if the width is too large, it is possible that the flow of the ink will be induced and the bubbles in the gas holding unit 13 will flow out into the common reservoir 6, so it is necessary to set the width to an appropriate size.

Various modifications can be made in addition to the modifications described above. For example, the cross-sectional shape of the gas holding unit 13 is a circle or an ellipse in the above-described embodiment and each of the modifications, but may be other than this, for example, a rectangle or a triangle. Various configurations are possible as long as the shape and arrangement of the gas holding unit 13 are along the opening of the common reservoir 6, and a configuration in which some of the above-described embodiments and each of the modifications are combined may be used.

Further, in the above-described embodiment and each of the modifications, the ink jet print head having the flow path structure in which the ink flow path 5 and the common reservoir 6 are communicated with each other through the concave portion 7 has been described. Not limited to the structure, for example, a configuration in which the ink flow path 5 and the common reservoir 6 are directly connected, a configuration in which a concave portion on the heating element 4 and a concave portion in which the ink flow channel 5 and the common reservoir 6 are communicated are provided separately, Various flow channel structures such as a configuration having a common slit can be applied to an inkjet print head having a common reservoir 6.

Further, by mounting the above-described ink jet print head on a printer, an ink jet printer capable of obtaining a high quality printed image without white spots or density unevenness can be constructed.

[0037]

FIG. 15 is an explanatory diagram of a specific experimental example in an embodiment of the ink jet print head of the present invention. 16 to 18 are explanatory diagrams of the position and shape of the gas holding unit provided in the experimental example. As a specific example, an inkjet print head in which 125 nozzles are arranged and the volume of ink droplets ejected from one nozzle is 80 pl is driven at a print frequency of 7 KHz. The maximum ink flow rate during solid printing is 125 lines x 80
pl × 7 KHz = 0.07 cc / sec = 70 mm ³ /
sec. The size of the through-hole of the common reservoir 6 is 0.5 mm in width and 10.4 mm in length. FIG. 15 shows the gas amount per ink ejection amount obtained by dividing the total gas amount in the plurality of gas holding units 13 by the maximum ink flow rate. The head number is a number for identifying the head used in the experiment.

The ink jet print head having the head number 0 is a conventional head having no gas holding section 13. In this case, as described above, density unevenness and white spots as shown in FIG. 20 occurred.

The ink jet print head of head number 1 has a gas holding portion 13 having a diameter of 0.4 mm and a depth of 2 mm.
Are provided. In this ink jet print head, as shown in FIG. 16, two gas holding portions 13 are provided near both ends of the through-hole of the common reservoir 6.
In this case, white spots and density unevenness as seen with the head number 0 were not found, but slight density unevenness occurred near the center of the head where the gas holding portion 13 was not provided.

The ink jet print head of head number 2 has a gas holding portion 13 having a diameter of 0.4 mm × a depth of 2 mm.
This is an example in which eight are provided. In this ink jet print head, as shown in FIG. 17, the gas holding portions 13 were arranged almost uniformly at the through holes of the common reservoir 6. In this case, white spots and density unevenness did not occur, and good image quality could be obtained.

As can be seen by comparing the printing results of the ink jet print heads of head numbers 0 to 2, the provision of the gas holding section 13 can reduce white spots and density unevenness which have conventionally occurred. Also, from the comparison between head number 1 and head number 2, the gas holding unit 13
It can be seen that white spots and density unevenness can be prevented over the entire width of the head and good image quality can be obtained by arranging them almost uniformly in the through holes of the common reservoir 6.

The ink jet print head of head number 3 has a gas holding portion 13 having a diameter of 0.7 mm × a depth of 2 mm.
Are provided. This ink jet print head corresponds to the above-described first modification, and is shown in FIG.
As shown in (2), the gas holding portions 13 having a diameter larger than the width of the common reservoir 6 are arranged almost uniformly at the through holes of the common reservoir 6. Also in this case, white spots and density unevenness do not occur.
Good image quality could be obtained.

The ink jet print head of head number 4 has a gas holding portion 13 having a diameter of 0.5 mm and a depth of 2 mm.
This is an example in which eight are provided at an angle of 30 °. This ink jet print head corresponds to the above-described third modification. Each gas holding part 13 was arranged almost uniformly in the through-hole of the common reservoir 6. Also in this case, white spots and density unevenness did not occur, and good image quality could be obtained.

As described above, according to the above-described various modifications, it is found that white spots and density unevenness can be prevented, and good image quality can be obtained.

The head numbers 5 to 7 are obtained by adjusting the amount of gas remaining in the gas holding unit 13 and examining changes in the ink jet print head of head number 3. In the head No. 5, the head is evacuated and filled with ink, and the total amount of gas remaining in each gas holding unit 13 is 0.415 mm ³ . In the head No. 6, the gas in the head is slightly sucked and filled with ink, and the total amount of gas remaining in each gas holding unit 13 is 2.05 mm ³ . In the head number 7, the ink is filled with a slight suction, and
The total amount of gas remaining inside is 3.39 mm ³ . As a result, a slight density unevenness occurred in head number 5,
With head numbers 6 and 7, white spots and density unevenness did not occur, and good image quality could be obtained. As described above, when almost no gas is present in the gas holding unit 13, the structure is the same as that of the conventional structure without the gas holding unit 13. It can be seen that the density unevenness does not occur if it is held.

The head number 8 is the same as the head numbers 5 to 7 in that the ink is filled in the ink jet print head of the head number 2 by evacuating the inside of the head. Is 0.
0025 mm ³ . As described above, in a state where almost no gas is present in the gas holding unit 13, density unevenness occurs as in a conventional head having a structure in which the gas holding unit 13 is not provided.

From these experimental results, it can be seen that by providing the gas holding unit 13 and holding the gas inside, it is possible to suppress the occurrence of white spots and density unevenness and obtain good image quality. The amount of gas is held in the gas holding part 13, since the ink ejection amount 1 mm ³ / sec per 0.014mm slight density unevenness in ³ per unit time occurs, 0.015 mm ³ or more gas retention If so, good image quality could be obtained.

[0048]

As is apparent from the above description, according to the first to third aspects of the present invention, in an ink jet print head which forms an image by discharging ink from a plurality of nozzles, ink is discharged from the nozzles. A plurality of energy generating means for causing the energy generating means, a plurality of ink flow paths which are arranged individually corresponding to the energy generating means and supply ink to the energy generating means, and a plurality of the ink flow paths are commonly communicated. And an ink supply member provided with an ink supply pipe for supplying ink to the ink reservoir of the inkjet head, wherein the ink supply member is provided only in the ink reservoir. By providing a plurality of gas holding portions for holding the communicating gas inside, a plurality of gas holding portions are provided. By the compression / expansion of the gas held in the holding unit, pressure propagation in the common reservoir during printing can be suppressed, and stable ink ejection is always performed, realizing high image quality without white spots and density unevenness. can do. Further, since the gas holding unit communicates with the portion of the common reservoir where the ink flow is small, the gas in the gas holding unit does not flow off due to the ink flow, and a stable pressure adjustment function can be always realized. Further, since the gas holding portion is formed in the ink supply member, there is an effect that a new component is not required, the head size can be maintained, and the ink supply member can be manufactured without a special process. Furthermore, according to the first aspect of the present invention, the gas holding portion has a substantially circular cross section. Further, by providing the gas holding portions at substantially equal intervals along the arrangement direction of the ink flow paths, as described in claim 2,
White spots and density unevenness can be prevented. Also,
By making the area of the communicating portion smaller than that of the gas holding portion, it is possible to prevent the gas held in the gas holding portion from flowing out, and to stabilize the gas for a long period of time. Image quality can be maintained.

Further, according to the present invention, in an ink jet print head which forms an image by ejecting ink from a nozzle by the pressure of a bubble generated by heat, heat is generated to generate the bubble. A first substrate provided with a plurality of heat generating resistors, a plurality of channels provided to face the first substrate for supplying ink onto the heat generating resistors, and a common ink reservoir common to the plurality of channels. A second substrate provided with an ink supply path for supplying ink to the common ink reservoir, and an ink supply member provided with a plurality of air chambers holding air therein and communicating only with the common ink reservoir. Thus, the compression / expansion of the gas held in the plurality of air chambers suppresses the pressure propagation in the common reservoir caused by printing. Can always perform injection of stable ink, it is possible to realize high image quality without all white spots and density unevenness. Further, since the air chamber communicates with the portion of the common reservoir where the ink flow is small, the gas in the air chamber does not flow off due to the ink flow, and a stable pressure adjustment function can be always realized. Further, since the air chamber is formed in the ink supply member, there is an effect that a new component is not required, the size of the head can be maintained, and the ink supply member can be manufactured without a special process. Further, in the invention described in claim 4, the air chamber is configured to have a substantially circular cross section. Further, by providing the air chambers at substantially equal intervals along the arrangement direction of the ink flow paths, it is possible to prevent white spots and density unevenness over the entire head. Further, by making the area of the communicating portion smaller than that of the air chamber, it is possible to prevent the gas held in the air chamber from flowing out, and to stably maintain the gas for a long period of time. Image quality can be maintained.

Further, as in the invention according to claim 7,
By mounting the above-mentioned inkjet print head on the printer, there is no white spots or uneven density,
An ink jet printer capable of obtaining a high quality printed image can be obtained.

Further, by performing the maintenance of the ink jet print head by the maintenance method according to the eighth aspect, the amount of gas held in the gas holding portion can be made appropriate, for example, by increasing the temperature of the head. It is possible to prevent the gas from being released from the gas holding unit, and to reliably maintain a stable pressure fluctuation adjustment function.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of an ink jet print head of the present invention.

FIG. 2 is an AA ′ cross-sectional view showing one embodiment of the inkjet print head of the present invention.

FIG. 3 is a sectional view taken along the line BB ′ showing an embodiment of the ink jet print head of the present invention.

FIG. 4 is a sectional view taken along the line DD ′ showing an embodiment of the ink jet print head of the present invention.

FIG. 5 is a sectional view taken along the line CC ′ showing an embodiment of the inkjet print head of the present invention.

FIG. 6 is a graph showing an example of a pressure fluctuation generated in a common reservoir in the embodiment of the inkjet print head of the present invention.

7 shows a first modification of the embodiment of the ink jet print head according to the present invention; FIG.
FIG. 14 is a sectional view taken along the line B-B '.

8 shows a first modification of the embodiment of the ink jet print head according to the present invention.
FIG. 4 is a sectional view taken along the line -D '.

FIG. 9 shows a second modification of the embodiment of the inkjet print head according to the present invention;
FIG. 14 is a sectional view taken along the line B-B '.

FIG. 10 is a cross-sectional view taken along the line DD ′ in FIG. 1, illustrating a second modification of the embodiment of the inkjet print head according to the present invention.

FIG. 11 is a sectional view taken along the line BB ′ in FIG. 1 showing a third modification of the embodiment of the inkjet print head according to the present invention.

FIG. 12 is a cross-sectional view taken along the line DD ′ in FIG. 1, illustrating a third modification of the embodiment of the inkjet print head according to the present invention.

FIG. 13 is a sectional view taken along the line BB ′ in FIG. 1 showing a fourth modification of the embodiment of the inkjet print head of the present invention.

FIG. 14 is a cross-sectional view taken along the line DD ′ of FIG. 1, illustrating a fifth modification of the embodiment of the inkjet print head of the present invention.

FIG. 15 is an explanatory diagram of a specific experimental example in one embodiment of the inkjet print head of the present invention.

FIG. 16 is an explanatory diagram of an example of an inkjet print head of head number 1 having a position and a shape of a gas holding unit provided in an experimental example.

FIG. 17 is an explanatory diagram of an example of an inkjet print head of head number 2 having a position and a shape of a gas holding unit provided in an experimental example.

FIG. 18 is an explanatory diagram of an example of an inkjet print head of head number 3 having a position and a shape of a gas holding unit provided in an experimental example.

FIG. 19 is a graph showing an example of pressure fluctuation in a common liquid chamber in a conventional ink jet printer.

FIG. 20 is an explanatory diagram of a printing state when image quality is poor in a conventional inkjet printer.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heater board, 2 ... Channel board, 3 ... Nozzle, 4 ...
Heating element, 5: ink flow path, 6: common reservoir, 7: recess, 11: ink supply member, 12: ink supply path, 13
... Gas holding unit.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ichiro Tomikawa 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd. (56) References JP-A-1-308644 (JP, A) JP-A-6-344558 ( JP, A) JP-A-63-128947 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/05 B41J 2/175 B41J 2/18 B41J 2/185

Claims (8)

(57) [Claims] 1. An ink-jet printhead which forms an image by discharging ink from a plurality of nozzles, wherein a plurality of energy generating means for discharging ink from the nozzles, and the plurality of energy generating means are arranged respectively corresponding to the energy generating means. A plurality of ink flow paths for supplying ink to the energy generating means, an ink jet head having an ink reservoir formed by the plurality of ink flow paths in common communication, and supplying ink to the ink reservoir of the ink jet head. And a plurality of gas holding portions that communicate only with the ink reservoir and hold a gas inside the ink supply member. An ink-jet printhead, wherein the holding section has a substantially circular cross section. . 2. An ink jet print head for ejecting ink from a plurality of nozzles to form an image, wherein a plurality of energy generating means for ejecting ink from said nozzles, and the energy generating means are individually arranged. A plurality of ink flow paths for supplying ink to the energy generating means, an ink jet head having an ink reservoir formed by the plurality of ink flow paths in common communication, and supplying ink to the ink reservoir of the ink jet head. And a plurality of gas holding portions that communicate only with the ink reservoir and hold a gas inside the ink supply member. The holding portions are provided at substantially equal intervals along the arrangement direction of the ink flow paths. Characteristic inkjet print head. 3. An ink-jet printhead which forms an image by discharging ink from a plurality of nozzles, wherein a plurality of energy generating means for discharging ink from said nozzles, and each of said energy generating means is individually arranged. A plurality of ink flow paths for supplying ink to the energy generating means, an ink jet head having an ink reservoir formed by the plurality of ink flow paths in common communication, and supplying ink to the ink reservoir of the ink jet head. And a plurality of gas holding portions that communicate only with the ink reservoir and hold a gas inside the ink supply member. The area of the communicating portion formed by directly holding the holding portion to the ink reservoir is the gas An ink-jet printhead, wherein a cross-sectional area of a surface of the holding portion facing the ink reservoir is smaller than a cross-sectional area thereof. 4. An ink-jet printhead which forms an image by ejecting ink from nozzles by pressure of a bubble generated by heat, a first substrate provided with a plurality of heating resistors for generating heat to generate the bubble. A second substrate provided opposite to the first substrate and provided with a plurality of channels for supplying ink onto the heating resistor and a common ink reservoir common to the plurality of channels; and a common ink reservoir. An ink supply path for supplying ink to the ink supply member and an ink supply member provided with a plurality of air chambers holding air therein and communicating only with the common ink reservoir, and the air chamber has a substantially circular cross section. An ink-jet printhead, characterized in that: 5. An ink jet print head which forms an image by ejecting ink from nozzles by pressure of a bubble generated by heat, a first substrate provided with a plurality of heat generating resistors for generating heat to generate the bubble. A second substrate provided opposite to the first substrate and provided with a plurality of channels for supplying ink onto the heating resistor and a common ink reservoir common to the plurality of channels; and a common ink reservoir. An ink supply path for supplying ink to the ink supply member, and an ink supply member provided with a plurality of air chambers holding air therein and communicating only with the common ink reservoir, and the air chambers are arranged in the ink flow path. An ink jet print head provided at substantially equal intervals along a direction. 6. A first substrate provided with a plurality of heat generating resistors for generating an air bubble in an ink jet print head for forming an image by ejecting ink from a nozzle by pressure of a bubble generated by heat. A second substrate provided opposite to the first substrate and provided with a plurality of channels for supplying ink onto the heating resistor and a common ink reservoir common to the plurality of channels; and a common ink reservoir. An ink supply path for supplying ink to the ink supply member and a plurality of air chambers holding air therein and communicating only with the common ink reservoir, and the air chamber is directly joined to the ink reservoir. The area of the communication part formed is smaller than the cross-sectional area of the surface of the air chamber facing the ink reservoir. Ink jet print head. 7. An ink jet printer comprising the ink jet print head according to claim 1. 8. A maintenance method for an ink jet print head in which a pressure is generated by a pressure generation source, ink is ejected from an ejection port by the pressure to form an image, and a pressure vibration transmitted from the pressure generation source is absorbed in an air chamber. In the method, after initial ink filling or after ink replacement,
Alternatively, after the ink suction operation, the temperature of the ink jet print head is increased, and the ink is suctioned from the discharge port, thereby maintaining the ink jet print head.