JPH0781079A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To enhance the use efficiency of ink by holding the interior of an ink container to a specific negative pressure and simplifying the constitution of the ink container. CONSTITUTION:Each of recording heads 1 and an ink container 3 are connected by a supply means and, when the ink container 3 is mounted on an ink jet recording apparatus, a valve means 9 becomes a closed state and the ink container is hermetically closed. When ink is consumed accompanied by recording, the negative pressure in the ink container 3 increases. When the number of recording heads reaching preset negative pressure is counted, the valve means is opened.

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 apparatus.

[0002]

2. Description of the Related Art Conventionally, in an ink jet recording apparatus, in order to maintain the performance of the ink jet recording head and prevent ink leakage from the ejection port of the recording head, the ink surface of the ink container is arranged at a position lower than the ejection port. By doing so, the ink supply pressure applied to the inkjet recording head was maintained at a predetermined negative pressure. However, in this conventional method, there is a restriction on the arrangement position of the ink tank with respect to the ink jet recording head, and it is spatially difficult to arrange the ink tank on the carriage in the serial scan type ink jet recording apparatus.

As a means for solving the above-mentioned restrictions, it has been proposed to provide means for generating a negative pressure in the ink tank itself, which will be described below in (1), (2),
(3) etc. are known.

(1) The opening of the container is covered with a flexible member 200 as shown in FIG. 8, and the flexible member 200 is elastically deformed in response to a negative pressure in the container (Japanese Patent Publication No. 249
(See Japanese Patent Publication No. 00).

(2) As shown in FIG. 9, a movable wall 204 that moves toward the ejection port 203 according to the amount of ink ejected from the ejection port 203 is provided in the ink container main body 201. The negative pressure of the ink in the ink container body 201 is controlled by the frictional force at the contact interface between the movable wall 204 and the inner surface of the ink container body 201. As the movable wall 204, a movable wall 204 having an O-ring 202 provided around it as shown in FIG. 9A or a movable wall 304 made of a diaphragm-like elastic material as shown in FIG. 60-
No. 204355).

(3) As shown in FIG. 10, ink is held in a porous body 400 such as a sponge and a negative pressure is generated by utilizing the capillary force of the porous body.

However, these conventional methods have the following problems. That is, with respect to (1), since the opening of the ink container that contains the ink is elastically deformed and crushed, the deformation of the flexible member increases as the ink is consumed to some extent, The distortion becomes large. As a result, further deformation becomes difficult, and the negative pressure generated in the flexible member suddenly increases,
Ink is not supplied to the recording head. Further, since the flexible member is deformed from the side surface portion, the flexible member cannot be deformed at the opening of the container to which the flexible member is attached. Therefore, the ink cannot be supplied.

According to an experiment, the ink use efficiency in the configuration (1) is only about 50% at maximum, and the ink use efficiency is low. In addition, when the configuration of (1) can be separated from the ink ejection portion, the flexible member is restored,
There is a risk of inhaling air into the flexible member.
When the air is sucked in this way, there is a risk that the ink will not be ejected normally again and the ink will run out.

By the way, in Japanese Utility Model Application Laid-Open No. 60-93246, as a means for improving the use efficiency of ink, the thickness of the flexible member is made different, and the ink is crushed positively from the thin side. There is something I did.

However, even in this conventional example, the use efficiency of ink is not improved to a satisfactory level.

Further, in the conventional example (2), in order to maintain the airtightness between the movable wall and the ink container body and prevent the movable wall from collapsing, the rigidity of the O-ring or the diaphragm is set to be large, or the O-ring is set to a large rigidity. The contact area with the ink container must be increased by increasing the thickness of the diaphragm and the diaphragm.
As a result, the frictional force at the contact interface between the movable wall and the inner surface of the ink container main body becomes large, and the starting pressure of the movable wall, that is, the differential pressure required to start moving from the stationary state of the movable wall becomes large. For example, it is difficult to set the necessary conditions for highly accurate adjustment of the ink negative pressure.

In the conventional example (3), since a high-density porous material needs to be used in order to generate a negative pressure by the capillary force, the amount of ink that can be filled with respect to the volume of the ink container becomes small. . In addition, the control of the ink supply pressure will not work properly, and it will not be possible to use the ink while leaving the ink in the ink container. Therefore, the amount of ink that can actually be used is less efficient than the ink container. In addition, since the porous body is discarded together with the ink container after use, there is a problem that the environment is adversely affected or that recovery / reproduction requires a considerable cost.

Therefore, an object of the present invention is to eliminate the above-mentioned conventional problems, maintain a predetermined negative pressure in the ink container, and simplify the structure of the ink container to increase the ink use efficiency. An object of the present invention is to provide an inkjet recording apparatus that is inexpensive and does not harm the environment.

[0014]

In order to achieve such an object, an ink jet recording apparatus of the present invention uses a recording head, and the recording head ejects ink droplets onto a recording medium to perform recording. In the recording apparatus, an ink container that stores ink, and an ink supply unit that supplies ink from the ink container to the recording head,
It is characterized by further comprising: counting means for counting the number of recording dots ejected from the recording head; and pressure adjusting means for adjusting the pressure in the ink container based on the output result of the counting means.

[0015]

According to the present invention, in the sealed ink container,
The negative pressure amount in the ink container increases as the ink is consumed for recording. The increase in the negative pressure amount is predicted by the recording dot counting means, and when a certain negative pressure amount is reached, the pressure adjusting means is driven to increase the pressure in the tank to a predetermined value. As a result, the negative pressure in the ink tank can be maintained within a certain range, and normal recording is possible. Moreover, since the pressure adjusting means is provided in the main body of the ink jet recording apparatus,
The structure of the ink container, which is a replacement part, is simplified, and the use efficiency of ink and the cost reduction are achieved.

[0016]

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

(Embodiment 1) FIG. 1 is a schematic sectional view showing a state in which an ink container 3 and a recording head 1 are mounted on a carriage 50.

A recording head 1 having an energy converter for ejecting ink droplets and an ink container 3 are connected by a supply means 2. The ink container 3 is the ink container body 4
A flexible member 5 formed of a bag or thin rubber is provided inside. The ink is stored inside the flexible member 5 and liquid-tightly supplied by the joining member 7 such as a rubber stopper.
Connected to. A sealing member 8 provided on the carriage is hermetically connected to the opening 6 provided in the ink container body 4, and one end of the sealing member 8 is connected to the valve means 9 open to the atmosphere. Further, a controller 10 is connected to the valve means 9 to control the opening / closing thereof.

The operation of the ink jet recording apparatus shown in FIG. 1 will be described with reference to the time chart of FIG. FIG. 6A is a characteristic diagram showing a change in supply pressure (negative pressure) applied to the recording head with recording time. (B) is a characteristic diagram showing the number of recording dots of the counter in the controller according to the recording time. (C) is an explanatory view showing how the valve means 9 is opened and closed depending on the recording time. The time of recording time T _{0 is set as} the time of replacement of a new ink container 3. At this time, the pressure applied to the recording head is initially the pressure of the water head difference because the ink container itself does not have a negative pressure generating means. In this embodiment, a case where the head pressure is almost zero will be described. When the ink container 3 is mounted, the valve means 9 is closed and hermetically closed. Recording is started from this state (state of recording time 0), and the negative pressure amount increases due to air expansion of ink consumption due to recording. At this time, the pressure change inside the ink container 3 due to consumption of ink is expressed by the following equation.

[0020]

[Formula 1] P ₂ = (V ₁ / (V ₁ + ΔV)) · P ₁ (1) P ₁ : Pressure before printing P ₂ : Pressure after printing V ₁ : Air volume in tank before printing ΔV: Printing Ink consumption by

[0021]

[Number 2] _{ΔV = V d × N (2} ) V d: 1 volume of the ink droplets per dot N: the relational expression is input to the recording dot number controller 10.
Here, V _d and V ₁ and P ₁ of the unused ink container are
It is preset in the controller as a known value.
At the time of exchanging the ink container, the values of V ₁ and P _{1 in} the controller 10 are set and the value of the recording dot counter in the controller 10 is reset by a signal from an ink container detecting means (not shown). Then, when recording is started, the value of the recording dot counter is added along with the print data. When the controller 10 counts the number of recording dots at which the value of P ₂ reaches the preset negative pressure amount P _max , the controller 10 opens / closes the valve means 9 and resets the recording dot counter (time T ₁ ). As a result, the inside of the ink container 3 is opened to the atmosphere. By the control as described above, the amount of negative pressure applied to the recording head can be changed from “head pressure (atmospheric pressure) to
It can be maintained within a certain range of P _max ″.

Further, in the structure of this embodiment, since the flexible member 5 for storing ink does not need to generate a negative pressure, a soft material can be selected, so that the use efficiency of ink is improved. As the material, a three-layer structure of polyethylene / vinylidene chloride / nylon or a two-layer structure of polypropylene / polyethylene terephthalate is suitable from the ink tank side.

Further, since the structure is simple, it is advantageous in terms of cost and environment.

(Embodiment 2) FIG. 3 is a schematic sectional view of the second embodiment, in which the pressure range applied to the recording head is maintained at a constant range regardless of the head pressure.

In the present embodiment, a fluid resistor 11 is provided on the atmosphere opening side of the valve means 9 to adjust the inflow velocity of the air flowing in when the valve means 9 is open.

FIG. 4 is a time chart for explaining the operation of FIG. When the ink container 3 is replaced, the negative pressure amount applied to the recording head is set to P _min by sucking the air in the ink container 3 by a pump means (not shown). When recording is started, the value of the recording dot counter is added with the recording data. The controller 10 is P
_{When the} number of recording dots at which the value of ₂ reaches the preset negative pressure amount P _max is counted, the valve means 9 is opened and the recording dot counter is reset (time T ₁ ). Further, the controller 10 controls the opening time of the valve means 9 according to the characteristics of the fluid resistor 11 which is input in advance so that the inflow amount of air becomes the ink consumption amount ΔV for recording. This allows
When P _min is reached again, the valve means 9 is closed (time T
₂ ). By the control as described above, the amount of negative pressure applied to the recording head can be maintained within a fixed range of P _{min to} P _max .

As the fluid resistor 11, a filter made of film, paper, ceramic, fiber or the like having fine pores is suitable.

In this embodiment, the pump means is used to set the initial negative pressure amount to P _min , but preliminary ejection that does not contribute to printing may be performed.

(Embodiment 3) FIG. 5 is a schematic sectional view of a third embodiment, in which a second valve means 13 is provided instead of the fluid resistor 11 of FIG. Also, controller 1
The volume of the connecting means 12 connecting the valve means 9 and 13 is input to 0.

The operation will be described with reference to the time chart of FIG. 6 (a), (b) and (c) are shown in FIG.
The same structure as (a), (b) and (c) is shown. In FIG. 6, FIG. 6D shows opening and closing of the second valve means 13.
Similar to the second embodiment, when the controller 10 counts the number of recording dots where the negative pressure amount of P ₂ reaches P _max , the valve means 9 is opened / closed and the recording dot counter is reset (time T ₁ ). As a result, the pressure inside the connecting means 12 and the pressure inside the ink container 4 are balanced, and the amount of negative pressure is reduced. After closing the valve means 9, the second valve means 13 is opened and closed to bring the inside of the connecting means 12 to atmospheric pressure. Then, the first valve means 9 is opened and closed again to reduce the negative pressure amount in the tank. The controller 10 calculates the number of times of opening / closing of the valve means until the negative pressure amount reaches P _min from the relationship between the volume in the connecting means 12 and the amount of air in the tank, and when the predetermined number is reached, the controller 10 opens / closes the valve means. Stop (time T ₂ ). By the control as described above, the amount of negative pressure applied to the recording head can be maintained within a certain range of "P _{min to} P _max ".

In the above embodiment, since the environmental temperature and the pressure inside the ink container are in inverse proportion to each other, when the environmental temperature changes greatly, the negative pressure amount can be controlled more strictly by performing temperature correction in the control of the controller. You can control.

FIG. 7 is a schematic perspective view showing a main part of an ink jet recording apparatus according to an embodiment of the present invention.

In FIG. 7, the recording head 701 has eight ink ejection ports (not shown) on the surface facing the recording paper 707 in the conveying direction of the recording paper 707. In addition, the recording head 701 is provided with an ink path (not shown) communicating with each of these eight ejection ports, and ink is ejected onto a substrate constituting the recording head 701 corresponding to each ink path. An electrothermal converter that generates the heat energy of is formed. The electrothermal converter generates heat by an electric pulse applied thereto according to the drive data, whereby film boiling occurs in the ink, and the ink is ejected from the ejection port as bubbles are generated by the film boiling. Is ejected. Each ink path is provided with a common liquid chamber that communicates with them in common, and the ink stored therein is supplied to the ink path according to the ejection operation in each ink path.

The carriage 702 carries the recording head 701 and slidably engages with a pair of guide rails 703 extending parallel to the recording surface of the recording paper 707. As a result, the recording head 701 can move along the guide rail 703, and along with this movement, recording is performed by ejecting ink toward the recording surface at a predetermined timing. After the above movement, the recording paper 707 is conveyed by a predetermined amount in the direction of the arrow in the figure, and the above movement is performed again for recording. By repeating such an operation, the recording paper 70
In 7, we will record sequentially.

The above-mentioned conveyance of the recording paper 707 is carried out by a pair of conveying rollers 7 arranged above and below the recording surface.
This is done by rotating 04 and 705. Further, a platen for maintaining the flatness of the recording surface is provided on the back side of the recording surface of the recording paper 707.

The above-mentioned movement of the carriage 702 is made possible by driving, for example, a belt (not shown) attached to the carriage 702 by a motor, and the rotation of the transport rollers 704 and 705 is also performed by the motor. It becomes possible by being transmitted to.

(Others) The present invention is provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for ejecting ink, particularly in the ink jet recording system. The present invention brings about excellent effects in a recording head and a recording apparatus of the type in which the state of ink is changed by the heat energy. This is because such a system can achieve high density recording and high definition recording.

Regarding the typical structure and principle thereof, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal in a one-to-one correspondence
It is effective because bubbles can be formed inside. Due to the growth and contraction of the bubbles, the liquid (ink) is ejected through the ejection opening to form at least one droplet. It is more preferable to make this drive signal into a pulse shape, because the bubble growth and contraction are immediately and appropriately performed, so that the ejection of the liquid (ink) 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, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of No. 59600 is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of the electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely 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 which can be recorded by the recording apparatus. 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 recording head integrally formed.

In addition, even in the case of the serial type as in the above example, the recording head fixed to the main body of the apparatus or the electrical connection to the main body of the apparatus and the ink from the main body of the apparatus by being attached to the main body of the apparatus. 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 integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add an ejection recovery means of the recording head, a preliminary auxiliary means and the like because the effect of the present invention can be further stabilized. Specifically, heating is performed by using a capping unit, a cleaning unit, a pressure or suction unit for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type and number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet system, it is common to control the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change of the ink from the solid state to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying thermal energy such as ink that is liquefied by applying thermal energy according to the recording signal and liquid ink is ejected, or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the 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, as the form of the ink jet recording apparatus of the present invention, in addition to the one used as an image output terminal of information processing equipment such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function can be used. It may be a form or the like.

[0046]

As described above, according to the present invention,
Since the ink jet recording apparatus main body is provided with the counting means for counting the number of recording dots and the means for adjusting the pressure in the ink container according to the output of this counting means, the inside of the ink container should be maintained within a predetermined negative pressure range. It is possible to provide an inkjet recording apparatus capable of performing the above.

Further, it has become possible to simplify the structure of the ink container, improve the efficiency of use of the ink, and make it advantageous in terms of cost and environment.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a first embodiment according to the present invention.

FIG. 2 is a time chart showing the operation of the first exemplary embodiment of the present invention.

FIG. 3 is a schematic perspective view showing a second embodiment according to the present invention.

FIG. 4 is a time chart showing the operation of the second exemplary embodiment of the present invention.

FIG. 5 is a schematic perspective view showing a third embodiment according to the present invention.

FIG. 6 is a time chart showing the operation of the third exemplary embodiment of the present invention.

FIG. 7 is a schematic perspective view showing a main part of an inkjet recording apparatus according to an embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a conventional ink container.

FIG. 9 is a cross-sectional view showing another conventional ink container.

FIG. 10 is a sectional view showing still another conventional ink container.

[Explanation of symbols]

 1 Recording Head 2 Supplying Means 3 Ink Container 4 Ink Container Main Body 5 Flexible Member 6 Opening Hole 7 Joining Member 8 Sealing Member 9,13 Valve Means 10 Controller 11 Fluid Resistor 12 Connecting Means

Claims (4)

[Claims] 1. In an ink jet recording apparatus for recording by using a recording head and ejecting ink droplets onto a recording medium by the recording head, an ink container for storing ink, and the ink from the ink container to the recording head. An ink supply unit for supplying, a counting unit for counting the number of recording dots ejected from the recording head, and a pressure adjusting unit for adjusting the pressure in the ink container based on the output result of the counting unit. An inkjet recording device characterized by the above. 2. The ink jet recording apparatus according to claim 1, wherein the pressure adjusting means is a valve means. 3. The ink jet recording apparatus according to claim 1, wherein the pressure adjusting unit is a valve unit and a fluid resistor. 4. The ink jet recording apparatus uses thermal energy to generate bubbles in a recording liquid, and ejects recording droplets based on the generation of the bubbles. The inkjet recording device according to item 1.