JPH06344566A - Ink jet recording apparatus - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide an inkjet recording apparatus including an inexpensive and highly reliable recovery device even if the inkjet head has many orifices. In an inkjet recording apparatus including an inkjet head having a plurality of orifices for ejecting ink, and a suction cap covering all of the plurality of orifices for sucking and discharging the ink from the plurality of orifices, It has at least one second suction cap provided inside, and a control mechanism that causes suction and discharge by the suction cap after suction and discharge, and then performs suction and discharge by only the second suction cap.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet device for forming flying droplets by ejecting liquid from an orifice and recording using the flying droplets, and more particularly to a recovery device for preventing clogging. The present invention relates to an inkjet recording device.

[0002]

2. Description of the Related Art Ink jet recording method is to eject ink (recording liquid) from an orifice provided in a recording head,
This is a recording method in which recording is performed by adhering this to a recording material such as paper, and noise generation is extremely low, high-speed recording is possible, and there is no need to use a specially configured recording paper. And various types of recording heads have been developed.

In such an ink jet recording method as well, in recent years, higher speed recording has been desired, and it is one of the main points of the present development.

In order to enable high speed recording, one of the measures is to reduce the flow path resistance of ink, increase the ink ejection frequency, and increase the number of orifices for ejecting ink. , Now both of these are done a lot. However, although the recording speed can be increased by increasing the number of orifices, various problems have occurred.

The ink jet recording head has a fine orifice for ejecting ink and has a drawback that the orifice is easily clogged. Therefore, an ink supply system and a recovery device for preventing clogging have been developed. The reason for the clogging is that the water of the water-based ink evaporates from the orifice and the viscosity of the ink near the orifice increases,
It may be that the ink cannot be ejected.

For this reason, an operation of discharging the ink having an increased viscosity from the orifice is performed. Evacuation operations include those called circulatory recovery and suction recovery.

The circulation recovery is to send ink from the ink tank to the common liquid chamber of the head by the pump and return the ink to the ink tank. At this time, the ink pushes out the ink having the increased viscosity from the orifice and enables the ejection of the ink. The ink discharged from the orifice is sent to the discharged ink reservoir through the cap. Since the ink is pressurized, a high pressure difference can be obtained and high reliability can be obtained, but there is a problem that the device becomes large and the cost is high.

The suction recovery is a recovery device in which a negative pressure is applied through a cap by a suction pump and ink is directly discharged from an orifice. Although it has the advantage that the device is small and the cost is low, since recovery operation is performed by using reduced pressure, when the number of orifices increases, the amount of ink flowing out from the orifices increases, and pressure is not applied much to the desired place. There is a problem that the recovery performance differs depending on the position of the orifice.

[0009]

Among the above-mentioned discharge operations, there is a problem that the apparatus for the circulation recovery is large and costly, and the recovery performance for the suction recovery is different depending on the position of the orifice. There is.

In view of the problems, it is an object of the present invention to provide an ink jet recording apparatus having an inexpensive and highly reliable recovery device even in an ink jet head having a large number of orifices.

[0011]

An ink jet recording apparatus of the present invention includes an ink jet head having a plurality of orifices for ejecting ink and a plurality of orifices for sucking and discharging ink from the plurality of orifices. In an inkjet recording apparatus having a covering suction cap, at least one second suction cap is provided inside the suction cap, and at the time of suction discharge, suction is performed by the suction cap and then suction is performed only by the second suction cap. And a control mechanism for performing discharge.

In this case, the suction cap that covers all of the plurality of orifices and at least one second suction cap provided in the cap may be integrally formed.

[0013]

When the recovery operation by suction is performed only with the suction cap covering all of the plurality of orifices, there are orifices that are difficult to recover, and their locations are fixed depending on the position of the ink supply port. Therefore, if a suction system having a large suction capability is formed at this position, a highly reliable recovery operation can be realized.

In the present invention, by providing the second suction cap at a position corresponding to the orifice that is difficult to recover, ink of the orifice that could not be discharged by suction discharge to all of the plurality of orifices is sucked by the second suction cap. Since it is discharged, the recovery operation becomes more reliable.

Further, by forming a suction system having a large suction capacity in the suction cap covering all of the plurality of orifices, the capping operation (the movement of the cap during the recovery operation) and the mechanism can be simplified. Become.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a perspective view showing the structure of a bubble jet type ink jet head used in this embodiment.

The illustrated ink jet head is 400
It has 512 orifices 202 formed with an orifice density of DPI (not shown). The substrate 101 and the glass top plate 205 are bonded together, and the nozzle 201, which is a part of the ink flow path, is formed between them. Nozzle 20
An ink reservoir called a common liquid chamber 204 is formed in the rear of 1 by digging the glass top plate 205. Common liquid chamber 20
Reference numeral 4 has ink supply ports at both ends of the head so that ink can be supplied from both sides to the orifice row.

FIG. 2A is a cross-sectional view showing the structure of the head having the above-mentioned structure and the cap covering the orifice array provided in the head, and FIG. 2B is a side view thereof.

The head 1 has a substrate 2, a top plate 3 and a common liquid chamber 6 which are constructed similarly to those shown in FIG. These are mounted on the base plate 4 and supported by the cap contact member 5.

As shown in the figure, the cap for covering the head 1 constructed as described above is located at a position covering only the suction cap 7 for covering all the orifices 202 and the central portion of the orifice row inside the suction cap 7. A small cap 8 (second suction cap) is provided. A pipe 11 is connected to the cap 8, which is connected to a suction pump (not shown). The small cap 8 and the large cap 7 are configured so that there is no leak through the O-ring 9, and a spring coil 10 that constitutes a control mechanism is provided between the large cap 7 and the pipe 11, and a space between them is provided. The position is adjusted.

Next, the operation of this embodiment will be described.

When the suction operation is started, the head 1 moves so as to face each other at the position where the cap is provided. A motor (not shown) causes the cap to move upwards in the drawing to the pipe 11
Is pushed up. Then, the large cap 7 contacts the head 1, and the suction pump reduces the pressure. At this time, the ink with increased viscosity is discharged from the orifice. But,
Since ink is supplied from both sides of the orifice array, bubbles may easily remain in the central portion of the orifice array in this state, and there may be a case where the ink cannot be properly recovered.

The pipe 11 then slowly rises,
Push up on the small cap 8. When the small cap 8 comes into contact with the orifice row, the decompression ability of the suction pump concentrates on the central portion of the orifice row, and the remaining bubbles and the like are sucked up by the small cap 8. In this embodiment, a cylinder and a piston are used for the pump, and when the large cap 7 comes into contact with the head 1, the cylinder starts to move, and when the small cap 8 starts to come into contact, suction is started again (the pump itself 2 cycles).

According to the present embodiment, a good printing condition was exhibited without any bubbles remaining during the initial filling of the ink into the head and during the recovery operation.

(Embodiment 2) FIG. 3 is a perspective view showing the structure of an ink jet head of the bubble jet system used in this embodiment.

With an orifice density of 300 DPI, 2
It has 56 orifices. The substrate 402 and the glass top plate 403 are attached to each other, and the nozzle 31, which is a part of the ink flow path, is formed between them, as in the case of the first embodiment. A common liquid chamber 40 is provided behind the nozzle 31.
An ink reservoir called 6 is formed by digging the glass top plate 403, but it is not shown in FIG. 5 for easy viewing. The common liquid chamber 406 has an ink supply port 46 at the center of the head and supplies ink from the center of the orifice array.

FIG. 4 (a) is a sectional view showing the structure of the head having the above-mentioned structure and a cap for covering the orifice array provided in the head, and FIG. 4 (b) is a side view thereof.

The head 401 comprises a substrate 402, a top plate 403 and a common liquid chamber 4 which are constructed in the same manner as shown in FIG.
Has 06. These are mounted on the base plate 404 and supported by the cap contact member 405.

As shown in FIG. 4, the cap for covering the head 401 constructed as described above is a small cap 408 (second suction) which covers both ends of the orifice array inside the suction cap 407 which covers all the orifices. 2)
Are arranged. A pipe 411 is connected to the cap 408 and is connected to a suction pump (not shown). Small cap 408 and large cap 407 are O
There is no leakage through the ring 409. A spring coil 410 that constitutes a control mechanism is provided between the large cap 407 and the pipe 411.
Position adjustment is performed between them.

Next, the operation of this embodiment will be described.

When the suction operation is started, the heads move so as to face each other at the position where the cap is provided. The cap is pushed up by the pipe 411 in the upward direction in the figure by a motor (not shown). Then, the large cap 407 abuts on the head, and the suction pump reduces the pressure. At this time, the ink with increased viscosity is discharged from the orifice. However, since the ink is supplied from the central portion of the orifice array, bubbles may easily remain at both ends of the orifice array, and there may be a case where the recovery is not successful. The pipe 411 then also slowly rises, pushing up on the small cap 408.
When the small cap 408 comes into contact with the orifice row, the decompression ability of the suction pump concentrates on both ends of the orifice row, and the remaining bubbles and the like are sucked up by the small cap 408. In this example, a diaphragm pump was used as the pump. According to this example, a good print state was exhibited even when the ink was initially filled in the head and no bubbles remained during the recovery operation.

(Embodiment 3) FIG. 5 is a sectional view showing the structure of the essential parts of a third embodiment of the present invention, and FIG. 5 (a) is a view showing the state at the beginning of the recovery operation. FIG. 6B is a diagram showing a state of the latter half of the recovery operation.

In the cap used in this embodiment, the first cap portion 507 covering all of the plurality of orifices and the second cap portion 508 covering only the central portion of the plurality of orifices were made of one rubber component. It is a thing. The other structure is the same as that shown in FIG.

The first cap portion 507 and the second cap portion 5
08 is made of a single rubber component, and has a thin center portion of the bottom surface of the second cap portion 508, which is easily deformed. During the recovery operation, the central portion of the cap is pushed and the first cap portion 507 abuts on the head as in the first embodiment. Here the suction pump is activated,
Suction is started and ink is discharged from the orifice. Further, the central portion of the cap is pushed, the rubber is deformed, and the second cap portion 508 covering the central portion of the orifice row comes into contact with the head. At this time, the first cap portion 507 is deformed and starts leaking and returns to atmospheric pressure. Therefore, suction is performed only in the central portion of the orifice, and the bubbles and the like remaining in the central portion of the orifice are completely discharged.

In this example, the same head as in the first example was used, and the recoverability was good. However, since the first cap portion 507 is at atmospheric pressure, if the orifice diameter is too large, air may be sucked from the orifices at both ends when the ink is sucked from the central orifice. . In this case, the rigidity of the rubber may be increased so that leakage does not occur even when the second cap portion 508 at the center contacts the head.

The present invention brings excellent effects particularly in an ink jet type recording head and a recording apparatus for recording by forming flying droplets by utilizing thermal energy among the ink jet recording systems.

Regarding the typical structure and principle thereof, see, for example, US Pat. Nos. 4,723,129 and 4740.
What is done using the basic principles disclosed in 796 is preferred. This method can be applied to both the so-called on-demand type and continuous type, but especially in the case of the on-demand type, liquid (ink)
By applying at least one drive signal to the electrothermal converter arranged corresponding to the sheet or liquid path in which is stored, which corresponds to the recorded information and causes a rapid temperature rise exceeding nucleate boiling. , It is effective because it generates heat energy in the electrothermal converter and causes film boiling on the heat-acting surface of the recording head, resulting in the formation of bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis. Is. The liquid (ink) is ejected through the ejection openings by the growth and contraction of the bubbles to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, further excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the ejection port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned specifications, The present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose a configuration in which a heat acting portion is arranged in a bending region.

In addition, JP-A-59-123670 discloses a structure in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and a pressure wave of thermal energy is absorbed. The present invention is also effective as a configuration based on Japanese Patent Application Laid-Open No. 59-138461, which discloses a configuration in which an opening corresponds to a discharge portion.

Further, a full line type recording head having a length corresponding to the width of the maximum recording medium which can be recorded by the recording apparatus is obtained by combining a plurality of recording heads as disclosed in the above-mentioned specification. The present invention can exert the above-mentioned effects more effectively, although it may have a configuration that satisfies the above requirement or a configuration as one recording head integrally formed.

In addition, by being mounted on the apparatus main body, it can be electrically connected to the apparatus main body and can be supplied with ink from the apparatus main body by a replaceable chip type recording head or the recording head itself. The present invention is also effective when a cartridge-type recording head provided with an ink tank is used.

Further, it is preferable to add recovery means for the recording head, preliminary auxiliary means, etc., which are provided as a configuration of the recording apparatus of the present invention, because the effects of the present invention can be further stabilized. If you list these specifically,
Capping means, cleaning means, pressurizing or sucking means for the recording head, preheating means using an electrothermal converter or another heating element or a combination thereof, and a preliminary ejection mode for performing ejection other than recording It is also effective to perform stable recording.

Further, as the recording mode of the recording apparatus, not only the mainstream color such as black is recorded but also the recording head may be integrally formed or a plurality of them may be combined. The present invention is also extremely effective for a device provided with at least one of full colors by color mixing.

In the embodiments of the present invention described above, the ink is described as a liquid, but it is an ink that solidifies at room temperature or lower and softens at room temperature, or is a liquid, or the above-mentioned. In the inkjet method, the temperature of the ink itself is generally adjusted within a range of 30 ° C. or higher and 70 ° C. or lower to control the temperature of the ink so that the viscosity of the ink is within a stable ejection range. It may be in a liquid form.

In addition, the temperature rise due to the thermal energy is positively prevented by using it as the energy for the state change of the ink from the solid state to the liquid state, or the ink is solidified in the left state for the purpose of preventing the evaporation of the ink. In some cases, such as ink that is liquefied by applying heat energy according to a recording signal and ejected as a liquid ink, or one that has already started to solidify when it reaches a recording medium. The use of an ink having a property of being liquefied only by heat energy is also applicable to the present invention. In such a case, the ink is disclosed in JP-A-54-5684.
No. 7 or JP-A-60-71260, a mode in which the porous sheet is opposed to the electrothermal converter in the state of being held as a liquid or solid in the recess or through hole of the porous sheet. May be 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, as a form of the recording apparatus according to the present invention, in addition to a recording apparatus integrally or separately provided as an image output terminal of information processing equipment such as a word processor or a computer, a copying apparatus combined with a reader or the like, and May take the form of a facsimile machine having a transmission / reception function.

[0049]

According to the present invention, the suction recovery which is an inexpensive recovery method in the ink jet recording method is adopted, and the cap covering a part of the orifices is arranged in all the caps covering the plurality of orifices. The operation of the cap is simple (one direction in this embodiment), and there is an effect that it is possible to provide an inkjet recording apparatus equipped with a highly reliable and inexpensive recovery device.

[Brief description of drawings]

FIG. 1 is a perspective view of a head used in first and third embodiments of the present invention.

FIG. 2 is an explanatory diagram of a cap according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a head used in a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a cap according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram of a cap according to a third embodiment of the present invention.

[Explanation of symbols]

 1,401 Head 2,402 Substrate 3,403 Top plate 4,404 Base plate 5,405 Cap contact member 6,406 Supply liquid chamber 7,8,407,408 Cap 9,409 O-ring 10,410 Coil 11,411 Pipe 31,201 Nozzle 202 Orifice 507 First cap part 508 Second cap part

Claims (2)

[Claims] 1. An inkjet recording apparatus comprising: an inkjet head having a plurality of orifices for ejecting ink; and a suction cap covering all of the plurality of orifices for sucking and discharging the ink from the plurality of orifices. A second suction cap provided at least one inside the suction cap; and a control mechanism for causing suction and discharge by the suction cap and then suction and discharge by the second suction cap only at the time of suction and discharge. An inkjet recording apparatus comprising: 2. The ink jet recording apparatus according to claim 1, wherein a suction cap covering all of the plurality of orifices and at least one second suction cap provided in the cap are integrally formed. An ink jet recording apparatus characterized by the above.