JPH02198864A - Ink tank integral type recording head and ink-jet recorder using said head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording head with an integrated ink tank and an inkjet recording apparatus using the same.

[Prior Art] Conventionally, inkjet recording devices have a cartridge-type ink tank that stores a predetermined amount of ink, separate from the recording head, and is replaced when the remaining amount is empty or low. It was common to replenish ink by However, if the recording head body that ejects ink is inexpensive (one that uses an electrothermal converter as the energy generating element for ink ejection), the ejection ports can be arranged in high density using a manufacturing process similar to that of semiconductors. (Since it is possible to mass-produce the ink tank and the recording head body, various types have been proposed in which the ink tank and the recording head body are integrated and the cartridge is removably attached to the apparatus body.)

In the latter form, by integrating the ink tank and the print head main body, the print head can be reliably and automatically updated every predetermined print amount commensurate with the ink capacity.
It becomes possible to always maintain good recording quality. In addition, even if a problem occurs in the recording head that degrades the recording quality and is irreparable, the recording head, which is the heart of the device, can be easily replaced, making it possible to improve the performance of the recording device. It is possible to significantly reduce the period of inoperability (downtime). Furthermore, problems that may occur when the print head main body and ink tank are separate bodies, such as the incorporation of foreign matter during ink replenishment and air bubbles in the ink supply path between the ink tank and the print head main body, etc. Problems such as contamination are also less likely to occur.

Ink tanks used in such cartridges, particularly those used in cartridges that can be installed in inkjet recording apparatuses in the form of so-called serial printers that print while scanning a recording head in a predetermined direction with respect to a recording medium, include: A method has been adopted in which an absorbent body is provided and the absorbent body is impregnated with ink. This not only stabilizes the pressure generated at the ejection port due to the water head difference, but also prevents gas dissolution and ink leakage caused by ink shaking during scanning, scanning reversal, transportation, and other impacts. It is valid.

[Problem N to be solved by the invention] However, in a recording head with an integrated ink tank, the running cost includes the cost of the main body of the inkjet recording head in addition to the ink.
The disadvantage is that running costs are higher than ink-only cartridges.

In order to reduce running costs, it is possible to increase the ink capacity, but this results in an increase in the size of the cartridge. In serial printers, the cartridge of a recording head with an integrated ink tank can usually be moved from side to side within the main body of the inkjet recording device. An increase in the size of the main body is unavoidable. Furthermore, in this case, it is difficult to repeatedly move a large and heavy cartridge with high precision, which may lead to deterioration in recording quality.

Therefore, in this case, a method has been proposed in which the head main body part and the ink tank part are separated and mounted on separate moving means, and they are connected with a tube etc. so that they can scan at the same time, but the ink tank can be replaced. This means that the advantage of using cartridges for the head, which avoids the risk of foreign matter being mixed in when replenishing ink, cannot be taken advantage of.

In particular, in a recording head that integrates an ink tank with a built-in absorber impregnated with ink, the volume of the absorber itself accounts for several tens of percent of the internal volume of the ink tank, and the final amount of the initial ink amount is The amount of ink that cannot be taken out from the absorber is 10
% or more, the net usable amount of ink relative to the internal volume is low, and the above-mentioned problem becomes significant.

Also, by impregnating the ink absorber, the pressure at the ejection port due to the difference in water head can be stabilized considerably compared to simply storing ink and providing a free surface, but the pressure fluctuations from the ejection port are It should be strictly stabilized because it causes "kinks" due to ink leakage, the ejection direction, or wetting of the ejection port forming surface, and furthermore, fluctuations in the ejection amount. However, when an absorber is provided, the ink is drawn toward the absorber by its capillary force, so in the conventional structure in which the absorber is filled inside the ink tank, the force fluctuates significantly depending on the amount of ink remaining. There was a limit to stabilizing the pressure at the discharge port.

It is an object of the present invention to reduce running costs or reduce the scanning space by increasing the ink storage capacity relative to the internal volume of the tank, and to suppress pressure fluctuations at the ejection port to stably obtain good images. The goal is to make it possible.

[Means for Solving the Problems] To achieve this, the present invention provides an integrated ink tank that integrally includes an ejection section that ejects ink to perform recording, and an ink tank that houses ink to be supplied to the ejection section. In the recording head, the ink tank is divided into a supply section that has an absorber and supplies the ink impregnated into the absorber to the ejection section, and a storage section that stores the ink to be impregnated into the absorber. The present invention is characterized in that it includes an ink replenishing means for replenishing ink from the accommodating portion to the supplying portion accordingly.

Further, an inkjet recording apparatus according to another aspect of the present invention is characterized by comprising means for detachably supporting the ink tank integrated recording head and operating means for performing predetermined operations.

[Function] According to the present invention, by dividing the supply section and the storage section in the ink tank, the net storage capacity of usable ink can be increased, and the absorber disposed in the supply section can be By performing replenishment, the pressure at the discharge port can be maintained within an appropriate range.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of an ink jet recording apparatus including an ink tank integrated recording head cartridge according to a first embodiment of the present invention. Here, reference numeral 1 denotes a printhead chip which is a main body portion of the inkjet printhead, and moves in opposition to the print medium 20 while ejecting ink in accordance with a print signal. The ink tank 2 that stores a predetermined amount of ink is
Partition plate 3 that has a communicating part at the top and functions as a supply means
The supply unit 6 having an absorber 4 and an electrode 5 for detecting the amount of ink and a recording chip 1 are integrated in a divided form, and the head is replaced according to consumption of a predetermined amount of ink. has been done. The supply section 6 of the ink tank 2 is connected to the head chip 1 via a porous filter 7 having a pore size that does not allow air bubbles to pass through easily, and the upper part of the supply section 6 is filled with an absorber 4 having pores. The absorber 4 holds ink.

At the top of the ink tank 2, fine air communication holes 8 are provided through a hydrophobic open cell 9, and as the ink from the head chip is consumed, the ink held in the absorber is transferred to the head chip. Ink is supplied from the supply unit 6 to the RAD chip 1 for recording without producing bubbles.

Incidentally, the liquid path array lO of the recording RAD chip 1 and the supply section 4 of the ink tank 2 are equipped with an ejection energy generating element such as an electrothermal transducer that generates energy for ejecting ink according to a recording signal, respectively. A bottle-shaped ink remaining amount detection electrode 5 is formed to be inserted into the absorber 4, and electrodes for electrical connection to these electrodes are grouped together in an electrode row 11. Note that 15 is a liquid chamber that receives ink from the absorber 4 side and supplies it to each liquid path.

The cartridge is mainly handled by holding it by the ink tank 2 side, and installation and removal from the main body are performed in the directions of arrows A and B in FIG. When installing, the cartridge lever 12 that holds the tank 2 is pushed in the direction (D direction) opposite to the biasing direction (C direction), and is dropped into the carriage from almost above, each having a mutually inclined surface. Cartridge engaging portion 14
The flexible cable 15 is connected to the electrode array 11 and the main body control section by engaging the receiving section 13 of the carriage.
and are pressed together. After inserting the cartridge, the cartridge lever 12 is slowly operated in the C direction to urge the cartridge downward and fixedly supported on the carriage 13. Furthermore, the cartridge can be removed by simply opening the cartridge lever 12 and pulling it upward, making it easy to attach and detach.

When recording with the recording apparatus according to this embodiment, the guide 18 is
The rollers 21 of the carriage 23 are scanned along the carriage shaft 22 with respect to the recording medium 20 that is conveyed in the F direction above.
The carriage scan is performed while pressing the recording medium 20 onto the guide 18 by the paper presser rail 17 via the paper presser rail 17.

FIG. 2 shows a plan view of the apparatus according to this embodiment. The carriage 23 is fixed to a drive wire 26 wound around a scanning drum 27 that rotates in synchronization with the recording signal, and is scanned in the direction of arrow C by reciprocating between pulleys 2B and 29. The reference numeral 31 is a motor for rotating the carriage 23 in the E direction in FIG.
A gear (carriage rotating gear) 30 that can mesh with the carriage is provided.

When the amount of ink inside the absorber 4 decreases due to the consumption of small but conductive ink, the electrical resistance value of the absorber 4 increases as shown in FIG. It can be detected that the detected value between the electrodes 5 has changed and the amount of ink in the absorber 4 has become less than a predetermined amount. that time,
The carriage 23 is moved to a position where the carriage gear 25 and the carriage rotation gear 3o mesh with each other, and the ink replenishment operation to the absorber 4 is performed.

The operation will be explained using FIG. 4. When the carriage rotation motor 31 rotates, the carriage 23 rotates in the E direction about the carriage shaft 22 and assumes a posture as shown in FIG. At this position, the ink in the ink tank 2, which is an ink storage part, is supplied from the upper part of the partition plate 3 to the supply part 6, and the absorber 4 again holds sufficient ink. Thereafter, the motor 31 may be reversely rotated to return the carriage 23 or the cartridge to its original position.

Note that during such ink replenishment, it is conceivable that an amount of ink exceeding the holding power of the absorber may flow into the supply section. In such a case, as shown in FIG. 5, a suction means consisting of a suction cap 32, a suction hole 33, and a suction pump 34 may be used to suction an appropriate amount from the nozzle row lθ side depending on the case of the suction cap 32. The discharge port portion can be maintained at an appropriate water head.

By the way, in the absorber 4 used in this example, when the amount of ink exceeds about 70% of the volume, the water head pressure at the ejection port exceeds the appropriate negative range (-20 to -40imaqu), Leakage from the outlet and wetting of the surface on which the ejection port is formed are likely to occur, and on the other hand, if the amount of ink is less than 20%, the ejection may become unstable. However, when comparing the conventional configuration and the configuration of this example in terms of ink capacity, the configuration of this example can effectively use more ink in the same volume than the conventional configuration. In other words, in the conventional configuration, the absorber was filled throughout the interior, so it alone took up 3 of the internal volume.
In addition to wasting 0% of the ink, there was also more than 10% of the ink that could not be drawn out from the absorbent body.

On the other hand, in this example, since the absorber is provided in a part of the cartridge, the ratio of the absorber to the internal volume of the cartridge is reduced, so that the effective amount of ink used can be increased.

Note that in this example, the means for performing the predetermined operation for rotating the carriage 23 or the cartridge is not limited to the one using the motor 31 as described above, but various other configurations can be adopted. For example, a member is provided at a predetermined position to engage with the carriage 23, rotate it in the E direction, and guide it, and when the residual amount detection electrode detects that less than a predetermined amount is present, the member Alternatively, the operator may remove the cartridge from the carriage 23 and shake it to replenish ink.

Further, it is also possible to provide a means for opening/closing the ink communication path between the ink tank section and the ink supply section in the cartridge itself without displacing the cartridge, so that the ink can be replenished when the ink communication path between the ink tank section and the ink supply section is opened. .

FIG. 6 shows an embodiment of a recording head cartridge according to such a configuration. Unlike the above embodiment in which the ejection direction is vertically downward, FIG. 6 shows one in which the ejection direction is horizontal. However, the same reference numerals are given to corresponding parts of the parts similar to those in the configuration shown in the first figure.

Here, 117 is a valve body serving as a replenishing means for opening/closing a communication portion provided in the partition portion 3 between the ink tank 2 and the absorber 4, and is made of a magnetic material or a permanent magnet. 18
is a spring that presses the valve body 117 in the closing direction (leftward in the figure). 19 is a communication part for communicating the absorber 4 with the atmosphere. Further, 127 is a valve body driving member that is provided on the cartridge or carriage and can be slid in the direction shown by the arrow by combining with a plunger (not shown) provided on the main body side, and is composed of a permanent magnet or an electromagnet. .

In this example, when it is detected between the remaining amount detection electrodes 5 that the amount of ink remaining in the absorber 4 is less than a predetermined amount, the plunger is driven to move the valve body driving member 127 to the right in the figure. When the valve body 117 is moved, the magnetic force causes the valve body 117 to move in the same direction against the biasing force of the spring 18. Then ink tank 2
The communication path between the absorber 4 and the absorber 4 is opened, and the absorber 4 is replenished with ink. When the valve body driving member 127 is then moved to the left in the figure, the valve body 117 also moves to the closed position, but the biasing force of the spring 18 quickly performs the movement and ensures the closed state. .

Note that the valve body 117 and the valve body driving member 127 may have any configuration as long as the communication path for ink replenishment is opened/closed by magnetic force.
It does not necessarily need to involve sliding as described above, and even if it is not based on magnetic force, the operator can remove the recording head and make it integral with the valve body so that it protrudes to the outside. It is also possible to replenish ink by operating a lever or the like.

In any case, according to this embodiment, instead of replenishing ink by rotating the carriage or the like as in the embodiment shown in the first figure, for example, the valve body driving member 127 and the recording head are connected together.
Since ink can be replenished by the recording head itself by making the recording heads correspond to one another, it is possible to perform ink replenishment operations separately for each recording head even in the case where a plurality of recording heads are provided on a carriage. Furthermore, since ink is replenished from below, air bubbles are less likely to enter the lower part of the absorber 4 where the supply port to the head section is located. Furthermore, in the above configuration, the ink replenishment operation is performed quickly and without displacement of the recording head, so it is not only possible to replenish the ink even during the recording operation, but also to perform this at short intervals depending on the remaining amount detection level. This also makes it possible to maintain a uniform water head at the discharge port.

Next, the relationship between the remaining amount of ink (the amount of ink held in the absorber) and the pressure (head pressure) applied to the ejection port in each of the above embodiments will be considered.

FIG. 7 shows this relationship, where curve a shows the case where the absorbing force by the absorber 4 is small, and curve s shows the case where it is similarly large. Also, the "maximum retention amount of the absorber" refers to the absorber 4
This is the state immediately after the ink has been replenished to the point that it overflows.

Here, it is desirable that the pressure near the ejection port be maintained at a negative pressure within a predetermined range.If this is positive, there may be ink leakage from the ejection port, or the ejection port may be due to such leakage or a defective ink drawing operation after the ejection operation. If the forming surface becomes wet and the negative pressure exceeds a predetermined value, the ejection operation may not be performed smoothly, or the area near the ejection port may need to be refilled with ink after ejection.
This is because it becomes difficult to perform this process, and in any case, the ejection characteristics, ejection amount, etc. are adversely affected, and the image quality is disturbed.

Figure 8 shows the relationship between the water head pressure at the ejection port and the amount of ink ejected.In order to make the diameter of the recording dots uniform and obtain images of good quality, it is highly desirable that the amount of ink ejected is stable. Since water head pressure is involved in the amount of ink ejected, the output of the remaining amount detection electrode 5 of the absorber 4 will be It is desirable that replenishment operations be performed based on

Referring again to FIG. 7, the pressure at the discharge port is determined by the capillary force of the liquid path, the absorbing force of the absorbent body 4, and the like. In particular, in the configuration shown in Fig. 1, in which the discharge direction is vertically downward, taking into account the influence of the pressure applied due to the positional relationship between the absorber part and the discharge port surface, the absorption capacity is large and the discharge port part quickly becomes negative pressure. Song #i! It is desirable to select an absorbent body exhibiting b.The absorbent body shown in one direction edge a is disadvantageous because the amount of ink stored in the absorbent body portion is small and the ratio of ink to the entire cartridge is small. On the other hand, in the configuration as shown in Fig. 6, in which the ink is ejected in the horizontal direction, it is easy to obtain negative pressure even if the remaining amount of ink is large due to the positional relationship between the absorber section and the ejection port surface, so that the ink exhibits curve a. It may be one with a small absorption capacity.

Note that the amount of fluctuation in head pressure is large in the curve, but as shown in Figure 8, it is sufficient to detect that there is no remaining amount before the amount of ink discharge drops suddenly. For head chips with large ejection energy, whose ejection characteristics are not easily deteriorated even by slight wetting of the ejection port, if the ink meniscus near the ejection port is not destroyed and no leakage occurs, the water head at that time is The pressure may be positive.

In addition, in the present invention, the inside of the ink tank is divided into a supply section that has an absorber and supplies ink to the head chip, and a storage section that stores ink, so that ink can be appropriately replenished from the ink storage section to the supply section side. It goes without saying that the present invention is not limited to the two embodiments described above, and that various configurations can be adopted as long as the configuration allows the above-mentioned configuration.

For example, it is possible to apply the ink replenishing means as shown in FIG. 6 to the configuration as shown in FIG. 1, and vice versa. In addition, we have installed a partition wall that completely separates the supply section from the storage section and has a part that can be manually destroyed, so that when the supply section runs out of remaining capacity, the section can be destroyed to maintain communication. It is also possible to provide a structure in which ink replenishment is performed only once, or it is also possible to provide a plurality of such storage sections or partitions so that ink replenishment is performed multiple times.

[Effects of the Invention] As explained above, according to the present invention, the inside of the ink tank is divided into a supply section that has an absorber and supplies ink to the head chip, and a storage section that stores ink. However, by adopting a structure that allows ink to be replenished more appropriately to the former than to the latter, the net amount of usable ink can be increased, preventing the scanning space from becoming larger or reducing running costs. It becomes possible to suppress pressure fluctuations at the exit portion and stably obtain good images.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of an inkjet recording device including an ink tank integrated recording head according to an embodiment of the present invention, FIG. 2 is a plan view of the recording device, and FIG. 3 is a diagram showing the remaining amount of ink and resistance value. FIG. 4 is an explanatory diagram for explaining the operation of this example, FIG. 5 is a schematic diagram showing a configuration example of a suction section applicable to this example, and FIG. A side cross-sectional view of an ink tank integrated recording head according to another embodiment. FIG. 7 is a diagram for explaining the relationship between the remaining amount of ink and the pressure at the ejection port. FIG. 8 is a diagram showing the pressure at the ejection port. FIG. 3 is a diagram for explaining the relationship between the amount of ink discharged and the amount of ink discharged. DESCRIPTION OF SYMBOLS 1... Head chip, 2... Ink tank part, 3... Partition plate, 4... Absorber, 5... Remaining amount detection electrode, 6... Supply part, 8... Atmospheric communication hole, 10... Liquid path row, 12... Cartridge lever 1B, 19-... Roller pair, 20... Recording medium, 23... Carriage, 31-... Carriage rotation gear, 34. ... Suction pump, 117... Valve body, 127... Valve body drive member. Figure 3 Figure 5 Figure 6 Water reserve Figure 7

Claims (1)

[Scope of Claims] 1) An ink tank integrated recording head that integrally includes an ejection section that ejects ink to perform recording, and an ink tank containing ink to be supplied to the ejection section, wherein the ink tank is divided into a supply part having an absorber and supplying ink impregnated into the absorber to the discharge part, and a storage part storing ink to be impregnated into the absorber,
An ink tank integrated recording head comprising an ink replenishing means for replenishing ink from the storage section to the supply section in accordance with a predetermined operation. 2) The ink tank integrated recording head according to claim 1, further comprising means for detecting the remaining amount of ink impregnated in the absorber. 3) The ink tank integrated recording head according to claim 1, further comprising a filter for removing air bubbles between the supply section and the discharge section. 4) The ink tank integrated recording head according to claim 1, wherein the ejection section has an electrothermal converter as ejection energy generating means. 5) The ink tank integrated recording head according to claim 4, wherein the electrothermal converter generates thermal energy for ejection in response to energization. 6) An inkjet recording apparatus comprising means for detachably supporting the ink tank integrated recording head according to claim 1, and operation means for performing the predetermined operation. 7) The inkjet recording apparatus according to claim 6, wherein the operating means is driven when the remaining amount of ink becomes less than a predetermined amount based on the output of the means according to claim 2.