JP3229465B2 - Ink jet head and recording device - 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 recording head and a recording apparatus in which the durability of an energy generating element is improved. Here, the record is a cloth, thread, paper,
The recording apparatus includes ink application (printing) to all ink supports that receive ink application such as sheet materials.
The present invention includes all of various information processing apparatuses or a printer as an output device thereof, and the present invention can be used for them.

[0002]

2. Description of the Related Art An ink jet recording apparatus discharges ink as fine droplets from nozzles to record characters, figures, and the like, and has excellent advantages as means for outputting high-definition images and high-speed printing. ing. In particular, a method using a bubble (bubble) pressure generated by an electrothermal transducer (hereinafter referred to as a heater) or the like, a so-called thermal ink jet recording method (Japanese Patent Publication No.
No. 1-59911-4) have features such as easy downsizing of the apparatus and high density of images.

A device of this type is generally disclosed in, for example,
As described in Japanese Patent Application Laid-Open No. 5-100169, a fluid resistance portion is provided on a more upstream side of an electrothermal converter that generates thermal energy in an ink flow path. FIG. 8 shows the structure of such an ink jet head. As shown in the drawing, ink 04 flows from an inflow opening 03 into an ink flow path 02 communicating with a discharge port 01 for discharging ink. In the vicinity of the discharge port 01 of the ink flow path 02, an electrothermal converter 05 for generating thermal energy used for discharging ink by forming bubbles is disposed on a wall surface. A barrier 06 protrudes from a wall surface on which the converter 05 is provided, on the upstream side of the electrothermal converter 05 (on the inflow opening 03 side). In such a head,
When an electric signal is input to the electrothermal converter 05, the ink 0
A bubble is generated in the nozzle 4 and the ink droplet 07 is ejected from the ejection port 01 by this action. At this time, the acting force of the bubble also acts in the anti-discharge direction, but due to the barrier 06 provided in the anti-discharge direction, the fluid resistance in the anti-discharge direction becomes larger than the fluid resistance in the discharge direction. The action force of the bubbles is effectively used for discharging the ink droplet 07. Incidentally, such a barrier 06 is disclosed in
As shown in FIGS. 2 to 7 of Japanese Patent No. 100169, the ink flow path 0
It is provided symmetrically with respect to a plane including the center line of the two.

[0004]

In the above-described ink jet head, there is a problem that the durability of the electrothermal transducer 05 is reduced due to cavitation at the time of defoaming. In the above-described conventional example, the flow rate of ink in the anti-discharge direction is reduced due to an increase in fluid resistance in the anti-discharge direction due to the barrier 18 when firing. The cavitation energy at the time of defoaming is reduced by reducing the ink flow rate to the
This is advantageous for durability performance. However, an inkjet head having sufficient durability performance has not yet been developed.

[0005] In view of such circumstances, an object of the present invention is to provide
An object of the present invention is to provide an ink jet recording head and a recording apparatus in which the durability of an energy conversion element is improved.

[0006]

In order to achieve the above object, an ink jet head according to the present invention comprises a plurality of ejection openings for ejecting recording liquid droplets, and each of the ejection openings communicates with each of the ejection openings. A plurality of liquid paths for supplying the recording liquid, a common liquid chamber communicating with the plurality of liquid paths, and heat energy which is provided corresponding to each of the liquid paths and causes film boiling in the recording liquid. A discharge energy generating element that generates a discharge liquid, wherein an inner surface of the liquid path where the discharge energy generating element is located is different from an inner surface of the liquid path between the central portion of the discharge energy generating element and the common liquid chamber. And a projecting portion projecting to a height exceeding the center line of the liquid path, and displacing a defoaming position of bubbles generated by the film boiling from a central portion of the discharge energy generating element, Liquid path , Characterized in that the asymmetric shape with respect to a plane perpendicular to the surface of contain and the discharge energy generating element centerline of the liquid path. Here, a concave portion may be provided on the inner surface of the liquid passage facing the tip of the protruding portion, and ink may be ejected substantially in a direction along the liquid passage.

[0007] An ink jet recording apparatus of the present invention is an ink jet recording apparatus provided with an ink jet head, wherein the ink jet head is detachable from a main body of the recording apparatus.

[0008]

According to the present invention, a projection is provided on the inner surface different from the inner surface of the liquid passage where the discharge energy generating element is located, and the protrusion protrudes to a height exceeding the center line of the liquid passage. The bubble position is largely displaced from the center of the ejection energy generating element.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

FIG. 1 shows the structure of an ink jet head according to one embodiment. FIG. 1 (A) is a sectional view of a nozzle, FIG. 1 (B) is a front view of a discharge port, and FIG. It is an exploded perspective view. As shown in these figures, an ink 14 flows from an inflow opening 13 into an ink flow path 12 communicating with a discharge port 11 for discharging ink. In the vicinity of the discharge port 11 of the ink flow path 12, an electrothermal converter 15 for generating thermal energy used for forming bubbles and discharging ink is provided. On the upstream side (inflow opening 13 side) from 15,
A fluid resistance part 16 is provided. This fluid resistance part 16
Is to make the fluid resistance in the counter-discharge direction from the center of the electrothermal transducer 15 larger at the time of ink ejection than the fluid resistance in the ejection direction. 13 to electrothermal converter 1
5 is formed so that the fluid resistance in the ejection direction to the central portion of the electrothermal transducer 15 during ejection of ink is smaller than the fluid resistance in the non-ejection direction from the central portion of the electrothermal transducer 15. Further, it is provided at a position on the upstream side of the electrothermal converter 15 at which the bubbles are divided, but the state of the provision is different from the conventional one.
That is, the fluid resistance portion 16 is provided so as to protrude from a surface adjacent to the surface on which the electrothermal converter 15 is provided, and the shape of the ink flow path 12 on the upstream side of the electrothermal converter 15 is formed by this protrusion. , And is asymmetric with respect to a plane including the center line of the ink flow path 12 and perpendicular to the surface of the electrothermal converter 15. In addition, as shown in FIG. 1C, the ink flow path 12 is defined by a substrate 17, a top plate 18, and partition walls 19 provided at predetermined intervals therebetween. A common liquid chamber 2 communicating with the ink flow path 12 through the inflow opening 13 is formed between the substrate 17 and the top plate 18 by a partition wall 19.
0 is defined, and a supply port 21 for supplying the ink 14 to the common liquid chamber 20 is formed in the top plate 18.

FIG. 2 shows how ink is ejected from the nozzles of such an ink jet head. FIG. 2 (A)
This indicates a state in which the ink droplet 22 is ejected by inputting an electric signal to the electrothermal converter 15 and the generated bubble 2
3 shows a state where foaming is maximized. At this time, a part of the bubble 23 is divided by the fluid resistance part 16. FIG. 2 (B)
Indicates a state in which the bubble 23 is contracted, and the bubble 23
Is in the direction along the surface of the electrothermal converter 15, that is, passing through the center of the ink flow path 12 and
Shrink while deforming asymmetrically with respect to a plane perpendicular to the surface of the. This is because the fluid resistance portion 16 is provided asymmetrically in the direction along the surface of the electrothermal converter 15. FIG.
(C) shows a state immediately before the bubble 23 disappears. The ink that is replenished with the ejection of the ink droplets 22 is filled from the fluid resistance passage 24 that is biased to one side (the lower side in the figure) along the surface of the electrothermal converter 15, so that the ink is replenished at the lower side in the figure. The flow of the ink increases, and the bubbles 23 disappear at the position offset toward the upper side in the figure, not at the center on the surface of the electrothermal transducer 15. That is, the defoaming position of the bubble 23 varies in a direction orthogonal to the discharge direction, and may be located on a position other than the electrothermal converter 15. Accordingly, damage to the electrothermal converter 15 due to cavitation is reduced, and the durability of the electrothermal converter 15 is improved.

FIG. 3 shows a cross section of a nozzle of an ink jet head according to another embodiment. In this embodiment, on both sides of a plane passing through the center line of the ink flow path 12 and perpendicular to the surface of the electrothermal converter 15 on the upstream side of the ink flow path 12, the fluid is asymmetrical with respect to the surface. Resistance parts 25A and 2
5B is projected. In this example, the fluid resistance passage 26 serving as a passage for the ink to be filled immediately after the ejection is formed from the top to the bottom in the drawing, and the flow of the ink at the time of filling the ink increases as much as possible on the lower side in the drawing. It is supposed to be. Therefore, in the present embodiment, the dispersion of the defoaming position in the direction orthogonal to the discharge direction further increases, and the probability of defoaming other than on the electrothermal converter 15 further increases.

FIG. 4 shows a cross section of a nozzle of an ink jet head according to still another embodiment. In this embodiment,
A protruding fluid resistance portion 27A protrudes on one side of a surface passing through the center line of the ink flow path 12 on the upstream side of the ink flow path 12 and perpendicular to the surface of the electrothermal converter 15, and has a recess on the other side. A fluid resistance portion 27 </ b> B having a shape is formed, so that the shape of the ink flow path 12 on the upstream side of the electrothermal conversion body 15 can be changed through the center line of the ink flow path 12 and the shape of the electrothermal conversion body 15. It is asymmetrical with respect to a plane perpendicular to the surface. In this example, the flow of the ink from the fluid resistance passage 28, which is the passage of the ink to be filled immediately after the ejection, goes from the top to the bottom in the figure, and therefore, the flow of the ink at the time of ink filling is lower in the figure. It is designed to be increased as much as possible on the side. Thus, in the present embodiment, the variation of the defoaming position in the direction orthogonal to the ejection direction further increases, and the probability of defoaming other than on the electrothermal converter 15 further increases.

FIG. 5 is a perspective view of an ink jet cartridge IJC to which the ink jet head having the above configuration is applied, and FIG. 6 is an exploded perspective view thereof. In these figures, reference numeral 100 denotes a heater in which a plurality of electrothermal transducers arranged on a Si substrate and electric wiring such as Al for supplying power to the electrothermal transducer are formed by a film forming technique. A board 200 is a wiring board for the heater board 100. The wiring board 200 has wiring corresponding to the wiring of the heater board 100 and pads 210 located at ends of the wiring and receiving electric signals from the main unit. Reference numeral 300 denotes a top plate provided with a plurality of ink flow paths and a partition wall for separating each of the common liquid chambers communicating with them, 400 denotes an ink receiving port communicating with the common liquid chamber, and 500 denotes an orifice plate having a plurality of discharge ports. Yes, these are integrally molded with, for example, polysulfone. 600 is the wiring board 20
0 is a support made of, for example, a metal that supports the back surface of the ink jet unit 0 in a plane, and serves as a bottom plate of the ink jet unit. Reference numeral 700 denotes a pressing spring that presses and fixes the top plate 300 and the heater board 100 to the support 600, and the feet of the pressing spring 700 are engaged with holes 610 of the support 600. 80
Reference numeral 0 denotes an ink supply member.
An ink supply pipe 810 having one end pressed against the ink absorber 1100 via a supply port 1020 of an ink tank IT described later, and one end connected to the other end of the ink supply pipe 810 and the other end connected to the ink receiving port. An ink conduit 820 pressed against 400 is formed. Reference numeral 900 denotes a filter provided at an end of the ink supply pipe 810 on the tank side. At a position corresponding to the supply port 1020 of the support 600, a hole 620 through which the ink supply pipe 810 passes is formed.

The ink tank IT for supplying ink to the ink jet unit IJU thus configured includes a cartridge body 1000, an ink absorber 1100 for impregnating the ink, and the ink absorber 1100 mounted on the cartridge body 1000. A lid member 1200 is provided for inserting the ink jet unit IJU from the side opposite to the mounting surface and then sealing it. The cartridge body 1000 includes an ink tank IT.
An air communication port 1010 for supplying air to the inside is formed, and the air communication port 1010 has a lyophobic material 1 for preventing ink from leaking from the air communication port 1010.
300 has been inserted. The cartridge body 10
00, an ink supply port 1020 is formed, and a packing 1400 is provided in the ink supply port 1020. Note that the above-described inkjet unit I
JU is the ink absorber 11 of the cartridge body 1000.
00 is attached by fixing the side support 600 opposite to the insertion side, and is covered with the cover member 1500.

FIG. 7 is a schematic view showing an example of an ink jet recording apparatus in which the ink jet cartridge IJC configured as described above is mounted. This ink jet recording apparatus IJRA has a lead screw 2040 that rotates via driving force transmission gears 2020 and 2030 in conjunction with forward and reverse rotation of a driving motor 2010. Carriage HC on which inkjet cartridge IJC is mounted
Is the carriage shaft 2050 and the lead screw 20
40 and the lead groove 202 of the lead screw 2040.
041 and a pin (not shown) that engages with
With the rotation of the lead screw 2040, arrows a and b
It is reciprocated in the direction. Reference numeral 2060 denotes a paper holding plate, which applies paper P to the platen roller 20 in the carriage movement direction.
Press against 70. Reference numerals 2080 and 2090 denote photocouplers, which confirm the presence of a lever 2100 provided on the carriage HC in this area, and
It operates as a home position detecting means for switching the rotation direction of 0 or the like. Reference numeral 2110 denotes a cap member for capping the front surface of the recording head, which is supported by a support member 2120. Reference numeral 2130 denotes suction means for sucking the inside of the cap, and performs suction recovery of the recording head through the opening in the cap. A cleaning blade 2140 for cleaning the end face of the recording head is provided on a member 2150 so as to be movable in the front-rear direction, and these are supported by a main body support plate 2160. The blade 2140 is not limited to this form, and it goes without saying that a well-known cleaning blade can be applied to this embodiment. Reference numeral 2170 denotes a lever for starting suction for recovery of suction, which is moved in accordance with the movement of the cam 2180 engaged with the carriage HC, whereby the driving force from the driving motor 2010 is switched by clutch switching. The movement is controlled by known transmission means such as.

The capping, cleaning, and suction recovery are configured so that desired operations can be performed at the corresponding positions by the action of the lead screw 2040 when the carriage HC comes to the home position side area. If a desired operation is performed at a well-known timing, any of the embodiments can be applied. Each of the configurations described above is an excellent invention when viewed alone or in combination, and shows preferred configuration examples for the present invention.

(Others) The present invention includes a means (for example, an electrothermal converter, a laser beam, or the like) for generating thermal energy as energy used for discharging ink, particularly in an ink jet recording system. An excellent effect is obtained in a recording head and a recording apparatus of a type in which the state of ink is changed by the thermal energy. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method is a so-called on-demand type,
Although it can be applied to any type of continuous type, in particular, in the case of the on-demand type, it can be applied to a sheet holding liquid (ink) or an electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding the nucleate boiling, heat energy is generated in the electrothermal transducer, and film boiling occurs on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal on a one-to-one basis.
This is effective because air bubbles inside can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

The configuration of the recording head may be a combination of a discharge port, a liquid path, and an electrothermal converter (a linear liquid flow path or a right-angled liquid flow path) as disclosed in the above-mentioned specifications. U.S. Pat. No. 4,558,333 and U.S. Pat. No. 44,558 which disclose a configuration in which a heat acting portion is arranged in a bending region.
A configuration using the specification of Japanese Patent No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Application Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, according to the present invention, recording can be reliably and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full-line type recording head having a length corresponding to the maximum width of a recording medium on which a recording apparatus can record. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads, or a configuration as one integrally formed recording head.

In addition, even in the case of the serial type as described above, a recording head fixed to the apparatus main body or an electric connection with the apparatus main body or ink from the apparatus main body by being attached to the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is provided integrally with the recording head itself is used.

Further, it is preferable to add ejection recovery means for the recording head, preliminary auxiliary means, and the like as the configuration of the recording apparatus of the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, the recording head is heated using capping means, cleaning means, pressurizing or suction means, an electrothermal transducer, another heating element or a combination thereof. Pre-heating means for performing the pre-heating and pre-discharging means for performing the discharging other than the recording can be used.

The type and number of recording heads to be mounted are, for example, not only those provided for one color ink but also a plurality of inks having different recording colors and densities. A plurality may be provided. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, but may be any of integrally forming a printing head or a combination of a plurality of printing heads. The present invention is also very effective for an apparatus provided with at least one of the recording modes of full color by color mixture.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink which solidifies at room temperature or lower and which softens or liquefies at room temperature may be used. In general, the ink jet method generally controls the temperature of the ink itself within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. Sometimes, the ink may be in a liquid state. In addition, in order to positively prevent temperature rise due to thermal energy by using it as energy for changing the state of the ink from a solid state to a liquid state, or to prevent evaporation of the ink, the ink is solidified in a standing state and heated. May be used. In any case, the application of heat energy causes the ink to be liquefied by the application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start solidifying when it reaches the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, the ink
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent Publication No. 1260, it is also possible to adopt a form in which the sheet is opposed to the electrothermal converter in a state where it is held as a liquid or solid substance in the concave portion or through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition, the form of the ink jet recording apparatus of the present invention is not only used as an image output terminal of an information processing apparatus such as a computer, but also for a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmitting / receiving function. It may take a form.

[0027]

As described above, according to the present invention, the inner surface different from the inner surface of the liquid passage where the ejection energy generating element is located is provided.
Damage to the discharge energy generation element due to cavitation by providing a protrusion that protrudes to a height that exceeds the center line of the liquid path, and by displacing the bubble defoaming position from the center of the discharge energy generation element by the protrusion. Can be reliably reduced, and the durability thereof can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of an inkjet head according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state of ejection from nozzles of the inkjet head of FIG. 1 of the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of a nozzle of an inkjet head according to another embodiment of the present invention.

FIG. 4 is a cross-sectional view illustrating a configuration of a nozzle of an inkjet head according to another embodiment of the present invention.

FIG. 5 is a perspective view illustrating an example of an inkjet unit to which the inkjet head of the present invention is applied.

FIG. 6 is an exploded perspective view of the ink jet unit of FIG.

FIG. 7 is a perspective view showing an example of an ink jet recording apparatus to which the ink jet head of the present invention is applied.

FIG. 8 is a cross-sectional view illustrating a nozzle of an inkjet head according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Discharge port 12 Ink flow path 13 Inflow opening 14 Ink 15 Electrothermal converter 16, 25A, 25B, 27A, 27B Fluid resistance part 17 Substrate 18 Top plate 19 Partition wall 20 Common liquid chamber 21 Supply port 22 Ink drop 23 Bubbles 24, 26,28 Fluid resistance passage

Claims (4)

(57) [Claims] A plurality of discharge ports for discharging recording liquid droplets, a plurality of liquid paths communicating with the respective discharge ports and supplying a recording liquid discharged from the discharge ports, and the plurality of liquids. An ink jet head comprising: a common liquid chamber in which the paths communicate with each other; and a discharge energy generating element that is provided corresponding to each of the liquid paths and generates thermal energy that causes film boiling in the recording liquid. On the inner surface different from the inner surface of the liquid path where the energy generating element is located, located between the central part of the discharge energy generating element and the common liquid chamber, and protruding to a height exceeding the center line of the liquid path. A projecting portion for displacing a defoaming position of bubbles generated by the film boiling from a central portion of the discharge energy generating element, wherein the liquid path includes a center line of the liquid path and the discharge energy generating element. Perpendicular to the surface of Ink jet head is characterized in that it has an asymmetrical shape with respect. 2. The ink jet head according to claim 1, wherein a concave portion is provided on an inner surface of the liquid passage facing a tip of the projecting portion. 3. The ink jet head according to claim 1, wherein the ink jet head discharges ink substantially in a direction along the liquid path. 4. An ink jet recording apparatus comprising the ink jet head according to claim 1, wherein said ink jet head is detachable from a main body of the recording apparatus. .