JPS6345307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording apparatus that performs recording by directly jetting ink onto a recording medium.

Conventionally, many methods have been devised for inkjet recording devices, but among them is a method that performs recording by selectively ejecting ink only when necessary (Japanese Unexamined Patent Application Publication No. 1983-1999).
The method described in No. 35231, etc.) is a recording method that deserves attention because of the simplicity of the device. However, although many improvements have been attempted in the past, deficiencies in reliability have not been resolved and the technology has not reached the level of practical use. Furthermore, some of the products that have been put into practical use have significant restrictions in terms of handling and are not satisfactory. This is due to the fact that no definitive solution has been found to two major problems: air bubbles and clogging. Regarding air bubbles, see the above Japanese Patent Application Laid-Open No. 51-35231.
As can be understood from the recording principle described in the above issue, it is clear that if air bubbles enter the pressure chamber that increases the ink pressure, ink ejection will not be performed normally. This problem is not limited to inkjet recording in general, but it is particularly difficult to solve in this system because the cross-sectional area of the nozzle is relatively small. To explain the countermeasures that have been attempted in the past regarding these points, first of all, regarding air bubbles, there have been relatively many improvements in removing air bubbles that enter from outside, such as during initial filling of ink or when replacing ink (cartridge type, etc.). . A typical example is one that removes air bubbles through ink circulation (Japanese Patent Application Laid-open No. 159227/1983 and the same).
54-160242, etc.), and one in which a bubble removing device (Japanese Patent Application Laid-open No. 51-88224) is provided in the middle of the ink flow path. Furthermore, countermeasures against internally generated air bubbles (mainly caused by cavitation) are described in Japanese Patent Publication No. 1982-20882, but little consideration is given to them. Regarding clogging, there have been improvements to the ink, a lid on the nozzle part, and a forced release means in case of clogging (Utility Model Application Publication No. 66853/1983), but as described below, all of them are unsatisfactory. It has been found.

In order to solve the two major problems mentioned above, the inventor set all the conditions for the recording device and carried out an intensive analysis.As a result, the inventor found that the problem would be completely solved unless the following points regarding the inclusion of air bubbles and clogging were taken care of. came to the conclusion that it is not possible. In other words, as mentioned above, the causes of air bubbles being mixed include external factors, as well as internal factors such as cavitation, which has not been considered much in the past, and the problem with this cavitation is microbubbles in the ink. There was found. Generally, cavitation occurs due to high negative pressure, but when microbubbles exist, the negative pressure that becomes the limit becomes extremely low. Therefore, even a small negative pressure immediately after the ink is ejected is sufficient to cause cavitation. Although there are differences depending on the size, shape, etc. of the recording head that ejects ink, this can always occur. Furthermore, air (mainly oxygen and nitrogen) dissolved in the ink plays a major role in the existence of these microbubbles. That is, in the case of water-based ink, at 20°C, 1.6% of air is dissolved in water as shown in Figure 1, and this solubility decreases as the temperature increases. That is, when the temperature shifts from low to high temperature during recording, dissolved air becomes microbubbles and is precipitated into the ink. Although the above-mentioned ink circulation method is effective against large bubbles when exchanging ink, it becomes a source of microbubbles when ink containing bubbles is collected into a tank. Even if this is not the case, applying a stimulus such as vibration to the ink itself causes the generation of microbubbles. In addition, although the bubble removal device described above can capture relatively large bubbles, it is not very effective against microbubbles with a diameter of several micrometers, and the device described in the above-mentioned Japanese Patent Publication No. 53-20882 as a countermeasure against cavitation is However, it is clear that nitrogen is still dissolved in the ink and creates microbubbles due to temperature changes (even if only oxygen is removed, 2/3 of the volume is still nitrogen). (See Figure 1.) Therefore, consideration must be given to this point in order to perform stable recording no matter what conditions the recording device is placed under.

Next, regarding clogging, improvements have been made to inks that are less likely to evaporate, but factors that contradict the quick drying properties after printing are strongly unresolved. There are also improvements such as wet or dry lids on the front of the nozzle, but both are significantly more effective at high temperatures than at room temperature. Furthermore, it is important to note that not only the nozzle part of the recording head but also the ink conduit that leads the ink to the head is made of polymeric material because it requires flexibility to move freely as the recording head moves. . However, even with these polymeric materials, even with vinylidene chloride-based resins that are said to have good performance, ink evaporation through the wall surface can always occur. Especially in high temperature conditions,
Even if evaporation from the nozzle portion is suppressed, evaporation from this conduit will eventually cause clogging.

Furthermore, the one that caused the first jam was the above-mentioned Jitsukaiaki.
Even if a forced evacuation method such as No. 54-66853 is used, it is difficult to completely recover the extremely thin nozzle portion, and the linearity of ink flight is impaired. Furthermore, since air permeates through the walls of the conduit and saturates the ink in the conduit, recording may not be stable in the initial state anyway.

The present invention is intended to solve the above-mentioned problems, and its objectives are: (a) to reliably prevent clogging of ink from the ink conduit of the ink jet head to the nozzle portion of the recording head with a simple device; and (b) The object of the present invention is to provide an inkjet recording device with excellent quality that can prevent the generation of bubbles in the ink.

The inkjet recording device according to the present invention includes a switching valve provided in the middle of the ink conduit, one of which communicates with the inkjet head, and the other of which is selectively connected to the ink tank or the atmosphere by moving a slider; a rotary power source capable of forward and reverse rotation; an actuating plate that is rotated by the rotational force of the rotary power source and has a contact portion formed therein; and one end of the actuating plate that is in contact with the contact portion and the other end of the slider. a switching valve operating lever that engages with the rotary power source and moves the slider in two directions depending on the rotational direction of the rotary power source; a suction pump that supplies ink or air; and a suction lid that is in close contact with the front surface of the nozzle and sucks the ink or air from the nozzle with the suction force of the suction pump, the suction lid When the rotary power source is rotated in one direction, the switching valve is communicated with the atmosphere and the ink in the ink jet head is drawn out by the suction pump, and the rotary power source is rotated in the other direction. When the switching valve is rotated in the direction of , the switching valve is communicated with the ink tank, and the ink jet head is filled with the ink by the suction pump. The present invention will be explained below with reference to the drawings. Figure 2 shows a schematic configuration example of the recording apparatus of the present invention. In the figure, 1 is a recording head, 2 is an ink tank (cartridge, etc.), and 3 is an ink This is an ink conduit that guides ink from the tank 2 to the recording head 1. A switching valve 4 is provided in the middle of the ink conduit 3, and one end is connected to the atmosphere 5 and the other end is connected to the ink tank 2.
Furthermore, an ink suction lid 6 is disposed on the front surface of the recording head 1 and has a space so as to be engaged with a nozzle section 10 at an appropriate position of the recording apparatus. is connected to. Before explaining the operation of the recording apparatus having such a configuration, the recording head 1 will be described in detail.

The configuration of the recording head 1 is as shown in FIG. 3a, in which grooves for a plurality of pressure chambers 22, nozzles 23, etc. are formed by etching on both sides of a glass substrate 21, and ink is guided to these pressure chambers 22. The structure is such that ink is supplied from the pipe 15 via the ink reservoir section 24 having a large capacity. To describe the structure of this head in more detail, a piece of glass 25 with the same thickness as the glass substrate 21 with grooves formed on both sides.
are arranged side by side as shown in FIG. 3b, and relatively thin glass plates 26 and 27, which will become diaphragms (flexible walls), are adhered to both sides by a method such as fusion bonding. At this time, the glass substrate 24, the glass piece 25, and the glass plates 26, 2
The space created by 7 forms a reservoir 24.
Therefore, this space is a pressure chamber 2 made by etching.
2. The volume is sufficiently large compared to the groove portion of the nozzle 23 etc., which has a depth of 10 to several 100 μm. Note that one side of the reservoir portion is closed by a stopper 16. Furthermore, a filter portion 29 can also be formed by etching between the reservoir 24 and the pressure chamber 22 at the same time. A piezoelectric element (not shown) is arranged above the diaphragms 26 and 27 (a portion corresponding to the pressure chamber 22), and ink is ejected from the nozzle 23 in response to an electric pulse.
In order to improve the ink filling performance, island-shaped protrusions 28 may be provided before and after the circular pressure chamber 22 so as to direct the flow of ink along the wall surface like a misprint.

Next, FIG. 4 shows how the suction lid 6 engages with the nozzle portion 23 of the recording head 1. The suction lid 6 has a structure that moves in the direction of the arrow and has a space 6a, and tightly engages the nozzle part 23 as necessary, and this space is connected to the conduit 7.
Further, as shown in FIG. 5, a suction lid 6' having a space 6a' that tightly engages with the front surface of the head cover 11 provided for the purpose of protecting the head 1 can also achieve the same purpose.

The operation of the recording apparatus of the present invention will be explained based on FIGS. 2, 3, and 4. When trying to start recording (including initial filling of the recording head 1 with ink or replacement of the ink cartridge 2), the recording head 1 moves to the position where the suction lid 6 is installed, and the space 6a becomes the nozzle part 23. Closely engages the surroundings.

Thereafter, the switching valve 4 is switched so that the recording head 1 and the ink tank 2 are connected, and the pump 8 is operated. Through the conduit 7, the space 6a becomes under negative pressure and begins to suck ink from the ink tank 2. Eventually, the ink reservoir 24 of the recording head 1 and the pressure chamber 2
2. Nozzle 23 is filled with ink. In order to remove air bubbles and ensure complete filling, a little extra ink is sucked and disposed of into the waste liquid tank 9. Compared to the method of pressurizing the ink tank 2 and pushing out the ink from the nozzle part 23, this method of sucking ink from the nozzle part 23 using negative pressure prevents ink from staying in the ink reservoir 24 and pressure chamber 22, resulting in a smooth flow. Filling is possible and air bubbles can be efficiently discharged.
Incidentally, the extra ink consumed by the 23 nozzles is less than 1 c.c. and is hardly wasted. After the recording head 1 is completely filled in this way, the recording head is guided to the recording position by a carriage (not shown) and starts recording. Now, when recording is completed, the recording head is moved again to the suction lid section, and the switching valve is switched to the atmospheric side 5. The pump 8 is now activated to draw air into the recording head 1 through the conduit 3-2. With this operation, the ink in the conduit 3-2 and the recording head 1 is discarded from the suction cap 6 through the conduit 7 and the pump 8 to the waste liquid tank 9, and there is no ink in the recording head 1 and the conduit 3-1. state. With the above operations, there is no ink left in the recording head 1, so there is no fear of clogging under any environmental conditions, and nozzles 2
No minute dust such as dye scum will adhere to the area around 3, ensuring stable ink flight at all times.

In the above, the switching valve 4 is provided in the middle of the ink conduit 3 that connects the ink tank 2 and the recording head 1, and divides the ink conduit 3 into conduits 3-1 and 3-2; Since the portion 3-2 needs to move flexibly following the movement of the recording head 1 and is therefore made of a polymer material, ink evaporation and air inflow from this portion cannot be avoided. Therefore, not only recording head 1 but also this conduit 3-
This is because it is preferable to extract ink from the two parts as well. The conduit 3-1 part does not need to move and can be made of metal such as stainless steel, so there is no need to worry about evaporation. The amount of ink consumed in this discharge operation is that the inner diameter of the conduit 3-2 is 1 mm and the length is 500 mm.
Approximately 0.4cc in mm The inside of the recording head 1 (reservoir + pressure chamber + nozzle) is approximately 0.1cc The total is approximately 0.5cc
Therefore, it can be said that almost nothing is wasted. When it is time to start recording again, the valve 4 is switched and the ink filling operation described above is performed.

Clogging can be completely eliminated by the ink discharging and suction filling operations as described above. Regarding air bubbles, air bubbles that enter through the nozzle 23 during initial filling, when replacing the ink tank, or due to an unexpected impact can be reliably expelled by the suction operation. However, additional consideration is required regarding the air dissolved in the ink. That is, as explained above, it is necessary to completely remove the air from the ink, and for this purpose it is necessary to bring the ink into a completely deaerated state and to maintain this state for a long period of time. Therefore, the ink tank 2 shown in FIG. 2 must be isolated from the outside air. Therefore, in the present invention, a bag 31 made of aluminum foil laminated with other polymeric films (polyethylene, nylon, etc.) as shown in FIG. 6 can be connected to a needle-like pipe 32 provided at the tip of the conduit 3-1. An ink cartridge equipped with a member 33 made of rubber or the like is used. Generally, vinylidene chloride resin is known as a material with extremely low evaporation rate or air permeability, and laminated films using this resin have been put into practical use, and there are conventional examples of ink cartridges constructed using these materials. .
However, even in these materials, the air permeability coefficient increases significantly especially at high temperatures. Theoretically, the gas permeability coefficient P is P=P ₀ sxp (-E/RT) (E:
Activation energy (T: absolute temperature, R: gas constant) is temperature dependent, and tends to increase as the temperature rises. Taking as an example a composite film using vinylidene chloride resin under the trade name "Saranex #26" (manufactured by Asahi Dow Co., Ltd., approximately 60 μm thick), the oxygen permeation rate is, for example, 7 c.c./m ² ．．
24hr.1atm (room temperature) and the shape shown in Figure 5 (for example, a water-based ink with a surface area of 200cm ² and an internal volume of 200c.c.)
The ink becomes completely saturated in about 40 days. At high temperatures (65°C), the transmittance increases several to ten times more, making it unsustainable for long-term storage. Therefore, in the present invention, a bag laminated with aluminum foil of several micrometers was used. Aluminum foil can significantly lower the transmission coefficient even with a vapor-deposited film of several 100 Å, but a thin film of several μm is more desirable due to the presence of pinholes. Aluminum foil with a thickness of several μm has a permeability coefficient and evaporation rate (water vapor transmission rate) of almost 0, and can withstand long-term storage. Aluminum foil with a thickness of only a few μm has high rigidity when used as a bag, so it is necessary to construct a flat airtight bag with a relatively large surface area as shown in FIG. That is, it is necessary for the bag to collapse gradually and naturally as the ink is consumed, so it is not possible to have a shape that can be freely deformed. This type of ink tank (cartridge) configuration is essential along with the ink draining and filling system described above.

Next, in order to explain the present invention more specifically, FIG. 7 shows an embodiment in which the above-described configuration of the present invention is applied to a serial printer. 34 is a platen 35 that supports the head, 36 is a carriage that supports the head 35, and 2
It is driven parallel to the platen 34 along book guide shafts 37 and 38 by a motor and a drive belt (not shown). When recording paper is mounted on the platen 34 and printing is performed while driving the carriage 36 as described above, the head mentioned above has 24 nozzles, so it is printed vertically.
Characters and images composed of 24 dots are recorded. If the range 39 in which the carriage 36 is driven opposite the platen 34 is defined as the recording position, as described above, the head 35 is filled with ink,
A home position is provided as a position 40 where ink is drained. At the home position 40, devices for performing such various operations are arranged. That is, a brush 41 is used to clean the nozzle surface of the head 35 as necessary.This brush 41 is used to move the head 35 to the brush 41 part of the home position 40 when dust such as paper powder adheres to the nozzle surface. Rotate the brush 41 to remove dust from the nozzle surface. Reference numeral 42 designates a suction cap similar to that shown in FIGS. 2 and 4, and when the head 35 comes to the position of this suction cap 42, the cap can be attached to and removed from the nozzle as necessary. Reference numeral 43 denotes an ink system block that includes the switching valve 4, pump 8, and their driving mechanisms shown in FIG. Since the details of this ink system block 43 will be described later, it is shown here as a cubic block as shown in the figure. Between the suction cap 42 and the ink system block 43 is a conduit 44 for ink or air suction.
is provided. As will be understood from FIG. 2, this conduit 44 is connected to a pump in the ink system block 43, and 45 is an ink tank. The ink tank 45 here is constructed by integrating the ink tank and waste liquid tank shown in FIG. 2.
Also, from this ink tank 45 are arranged a switching valve for the ink system block 43, a conduit to the pump, and a conduit from the ink system block 43 to the head 35, etc., as shown in FIG. Such detailed configuration has been omitted.

Next, the operation of this serial printer will be explained. When the printer is at rest, the carriage 36 is in the home position 40, the nozzle surface of the head 35 is capped by the suction cap 42, and the ink in the head 35 is drawn out. When the printer is powered on, the ink system block 43 operates as described above, fills the head 35 with ink, waits for a print command, and with the print command, the carriage 36 moves to the print position 39 and records according to the command. conduct.
When the printer is turned off, the carriage 36
moves to the home position 40 and caps the nozzle surface of the head 35 with the suction cap 42. You can continue to drain the ink from the head 35 at this point, but the amount of ink consumed will be approximately 1 to 2 c.c. if the operation of draining ink and filling the ink is performed once.
If the power is turned on and off frequently during the day, the amount consumed will not be a problem if it is used once a day. Therefore, we studied the conditions that lead to nozzle clogging due to ink, and adopted a method in which ink is drained only when the risk of clogging is recognized. The details of this operation will be described later, but the general outline is: when a certain period of time has passed after the printer is turned off or after the printing operation has finished, when the printer is exposed to a high temperature above a certain temperature, and when the temperature is below a certain temperature. Ink removal is performed when at least one condition is met when the ink is exposed to low temperatures. The reason for this is of course that if left for a long time, the water in the ink will evaporate and cause clogging of the nozzle, so the above conditions are necessary, and the specific time is about 1 day to 1 week to be extremely safe. Just set it. For example, even if it is set to 1 day, if the printer is operated every day, there is no loss of ink due to ink draining, so there is no practical problem. Next, evaporation of ink is suppressed to a very low level at normal temperatures due to effects such as moisture within the ink, but at high temperatures, this evaporation is greatly accelerated. Therefore, under the above conditions, the ink is removed at a high temperature of 50 to 60°C or higher. The above conditions are
On the other hand, if the temperature drops below the freezing temperature of the ink, the ink filled in the head and other parts will freeze, and there is a risk that the head, conduit, etc. will be destroyed. Therefore, when there is a risk that the temperature will drop below the freezing temperature of the ink, the ink is drained to ensure safety.

To ensure that the operations described above are performed,
Since the carriage 36 must be reliably in place at the home position 40, a sensor is required to detect this. Although not shown in FIG. 6, this can be realized using a commercially available reed switch, photoelectric conversion, or the like. Additionally, a timer and temperature sensor are also required, which will be explained later.

Next, the details of the ink system block 43 shown in FIG. 7 are shown in FIGS. 8 and 9, and further shown in FIGS. 10 and 11.
The figure shows details of the switching valve and pump. FIG. 8 is a side view of the ink system block, and 46 is a DC motor which is a power source for the switching valve and the pump. Since the operating time is short and durability is not an issue, an inexpensive motor is sufficient. Reference numeral 47 denotes a gear attached to the rotating shaft of the DC motor 46, and the rotation of the DC motor 46 is decelerated by the following gear trains 48 and 49 and transmitted to the operating wheel 50.

A pin 51 for operating the switching valve 55 is attached to one surface of the operating wheel 50, and a pin 58 for operating the pump 60 is attached to the other surface (see FIG. 8). When the actuation plate rotates, the pin 51 moves around the dashed line 61 and engages with the switching valve actuation lever 52. This switching valve operating lever 5
2 is rotatable around its center, but its resting position is restricted by a tension spring 54 attached to the other end of the switching valve operating lever 52, as shown in the figure.
The engaging portion with the pin 51 is located at the center axis of the operating wheel 50. A pin 59 is attached to the other end of the switching valve operating lever 52, and this pin 59 is connected to the opening 5 provided in the slider 56 of the switching valve 55.
7. The detailed structure of the switching valve 55 will be explained with reference to FIG. 9, and the flow path can be switched by moving a slider 56. At this point, the DC motor 46 operates, and the operating plate 50
When the pin 51 is rotated in the direction of arrow 63, the pin 51 engages with the switching valve operating lever 52 and rotates it in the direction of the arrow 63. The rotation of this switching valve operating lever 52 is controlled by a pin 59.
The end face of the opening 57 of the slider 56 is pushed to move the slider 56 in the direction of the arrow 64, thereby switching the flow path of the switching valve 55. Further, when the motor 46 is reversed and the actuating plate 50 is rotated in the direction opposite to the arrow 62, the slider 56 moves in the opposite direction to the arrow 64, and the flow path of the switching valve 55 is switched to its original state. In this way, the DC motor 46 is operated, and the switching valve 55 is switched depending on the direction of rotation. Furthermore, the operating plate 5
0 continues to rotate, the pin 51 causes the slider 5 to pass through the switching valve operating lever 52 during the first rotation.
0, but the slider 56 maintains its position unless there is an external force, so from the next rotation, only the switching valve operating lever 52 is operated.
When the pin 51 and the lever 52 are disengaged, the lever 52 is returned to the center position by the spring 54 as shown in the figure, but there is an escape between the pin 59 and the opening 57 and the slider is not returned.

The actuating plate 50 also actuates the pump 60, but the eighth
Since the side is opposite to that shown in the figure, only the pump operating section is shown in FIG. A pin 58 is attached to the actuating plate 50, and this pin 58 engages with a groove 67 of a pin follower 65 fixed to a piston shaft 66. As shown in the figure, this groove 67 is formed in a direction perpendicular to the axial direction of the piston shaft 66, and as the actuating plate 50 rotates, the pin 58 moves along the dashed line 68, actuating the pin follower 65, and moving the piston shaft 66 along the arrow. 6
Make a reciprocating motion as shown in 9. The internal structure of the pump 60 is shown in FIG. 11, and the pump function is achieved by the reciprocating movement of the piston shaft. It goes without saying that the actuating plate 50 drives the piston shaft 66 regardless of its rotating direction.

As mentioned above, in this embodiment, the switching valve 55 and the pump 60 are operated by one DC motor 46, and the method of filling and draining ink from the head will be explained using this. When filling ink, the switching valve 55 must be in the direction that connects the head and the ink tank. If this direction is shown in FIG. 8 and the slider 56 of the switching valve 55 is pushed in the opposite direction to the arrow 64, then
The DC motor 45 is operated in a direction in which the actuating plate 50 rotates in the opposite direction to the arrow 62. Then, during the first rotation of the actuating plate, the slider 56 moves toward the arrow 64.
The pump 60 is moved in the opposite direction to connect the head and the ink tank conduit, and as the operating plate 50 continues to rotate, the pump 60 is driven to suck ink in the ink tank to the head and fill the head.

Next, when removing ink, use the DC motor 46.
, and rotate the actuating plate 50 in the direction opposite to the upward direction.
2, move the slider 56 in the direction of arrow 64.
The pump 60 is operated by the subsequent rotation of the actuating plate 50 to suck air from the atmosphere into the head, replacing the ink in the head with air and drawing out the ink. It will be understood that the same functions as shown in FIG. 2 can be achieved as described above.

FIG. 10 is a sectional view showing the internal structure of the switching valve. Numeral 70 is a gasket molded from rubber, which is held in a gasket holder 71 and installed inside the slider 56.A spring 72 is inserted between the slider 56 and the gasket holder 71, and the gasket 70 is held in place by a gasket 70.
is pressed against the inner wall of the switching valve 55 main body.

This inner wall has a passage hole 73 connected to a conduit to the head, and a passage hole 7 connected to a conduit to the tank.
4. Further, a flow passage hole 75 connected to the atmosphere is provided. Further, these passage holes 73 to 75 are arranged linearly in the moving direction of the slider 56, and the interval between the passage holes 73 and 74 and the interval between the passage holes 73 and 74 are approximately the same. are becoming equal. Also, a recess 76 is formed in the gasket 70, and is sized and arranged so that the recess 76 in the gasket 70 connects the flow path hole 73 and the flow path hole 74 when the slider 56 is at the rightmost end as shown in the figure. There is. When the slider 75 is moved to the left in the figure, the packkin 70
similarly moves to the left, and the recess 76 is switched to connect the channel hole 73 and the channel hole 75. Therefore, by adjusting the amount of movement of the slider 56 to the distance between adjacent flow passage holes, and moving the slider 56 to the right, the flow passage holes 93 and 74 will be connected, the head and tank conduits will be connected, and the slider 56 will be moved to the left. When moved, the passage holes 73 and 75 are connected, and the conduit to the head is connected to the atmosphere. Therefore, the function of the switching valve described above is exhibited. By providing an air filter 77 on the outer wall side of the passage hole 75 leading to the atmosphere, it is possible to avoid the danger of introducing dust and dirt from the atmosphere into the head.

FIG. 11 is a sectional view showing the internal structure of the pump 60. The inside of the pump 60 is a cylinder, and a piston 78 is fixed to a piston shaft 66 and slides inside the cylinder. Therefore, the piston shaft 6
As the cylinder 6 reciprocates up and down, the inside of the cylinder 81 is repeatedly pressurized and depressurized. 79 and 80 are respectively equipped with directional valves in opposite directions, and 79
is a one-way valve that communicates from the outside to the inside 81 when the cylinder interior 81 is depressurized, and 80 is a one-way valve that communicates from the interior 81 to the outside when the cylinder interior 81 is pressurized. Specific examples of one-way valves that utilize rubber, holes, etc. are generally well known, so they will not be described here. This pump 60 reciprocates the piston shaft 60 up and down to repeatedly pressurize and depressurize the cylinder interior 81, and the one-way valve 7
9 is sucked in from the external port 82 and discharged to the external port 83 of the one-way valve 80, thereby exerting a pump function. Therefore, by connecting the external port 82 to the suction cap 42 of FIG. 7 via a conduit, and by connecting the external port 83 to the waste liquid tank via a conduit, the above-mentioned function can be provided.

Next, FIG. 12 is a configuration block diagram including the electric circuit of the serial printer shown in FIG.
Reference numeral 5 represents a printer mechanism, and reference numeral 86 represents an electric circuit for controlling the printer mechanism 85, which is powered by commercial power. Normally, a general printer consists of only the above configuration, but in this embodiment, as mentioned above, the ink circuit shown at 87 is installed to perform operations of the ink block, such as draining ink from the head after the power is turned off. It is operated by a rechargeable battery 88. Since it is not necessary to explain the electric circuit 86 here, the ink system circuit 87 will be explained in detail below based on FIGS. 12 to 14.

Figure 13 is a flowchart of the operation of the ink system block, Figure 13A is when ink is discharged, Figure 13B is
is when filling with ink. To briefly explain the operation in Fig. 13A, when printing stops or the power switch of the printer is turned off, the timer of the ink circuit starts, and if the carriage is not in the home position, it drives the carriage motor.
Return to the home position, cap the head nozzle surface with a suction cap, and wait. Then, the timer monitors whether 50 hours have elapsed or the temperature falls outside the permissible temperature range (here, t<-10℃ or t>60℃), and when this condition is met, the ink removal operation begins. For safety, check again whether the cap is in the home position, and if it is not in the home position, operate the carriage motor, and when the cap is not in the home position, turn the DC motor so that the operating plate rotates counterclockwise. Activate for seconds. It will be clear from the above explanation that the operation of the DC motor during this last 30 seconds drives the switching valve and pump to remove ink.

The operation shown in Fig. 13B is performed when the power switch is turned on or the purge switch, which is operated when there is a printing failure, is turned on, and the timer is set depending on whether the switching valve is on the atmosphere side or the tank side. and drive the DC motor for the time set on the timer so that the actuating plate rotates clockwise. This means that when the switching valve is on the atmospheric side, the ink is drained from the head, and when the switching valve is on the tank side, the ink is not drained, so in the former case, you need to refill from the beginning. There is a DC motor driven for 20 seconds,
In the latter case, the ink inside the head has not been drained, so you only need to refresh it slightly. Therefore, the DC motor is only driven for a short period of time, 2 to 5 seconds. Then, release the suction cap, turn off the DC motor, and move the carriage to the printing position.

Since the ink filling operation shown in FIG. 13B is performed when the power is turned on and is included in the printer circuit 86 shown in FIG. 12, the circuit configuration for realizing FIG. 13A will be described below with reference to FIG. 14. In the figure, 90 is a timer composed of an oscillator and a frequency divider, and is set so that when the frequency division stage selection terminal 91 is High, an output with a 100-hour period is obtained, and when it is Low, an output with a 30-second period is obtained. has been done. 92 is a temperature detection terminal, and the sensor is a two-point temperature setting type thermal reed switch that combines a temperature-sensitive magnetic material using the Curie temperature of ferrite and a reed switch, and it is set at -10℃ or lower and at 60℃ or higher. , Others use Break's so-called make-break-make type sensor. Reference numeral 93 is a DC motor drive terminal, and when it is driven here, only the ink removal operation is performed in which the operating plate rotates to the left. The drive circuit for ink filling is integrated into the main printer circuit. Reference numeral 94 is a home position detection terminal of the carriage, and a break occurs when the home position is reached. Reference numeral 95 denotes a carriage motor drive terminal, the purpose of which is to move the carriage to the home position. 96 is the detection part of the power switch, 12V is applied when the power is on, and 12V is applied when the power is off.
goes down. 97 is a battery switch circuit. The battery is a rechargeable secondary battery that is charged when the printer is turned on, and when the printer is turned off, the following operations are performed using this battery as a power source. When 12V is applied, the timer FF1 and FF4 are reset, the timer 90 is not activated, and the battery switch circuit 97 is turned on. When 12 goes down, the timer starts. Further, when the carriage is not at the home position, the terminal 94 is set and FF5 is set to Low, and the terminal 95, that is, the carriage is driven. 50 hours have passed and the timer is 90
When the output changes from Low to High, FF1 is set and the timer 90 is switched to output for 30 seconds. When the terminal 92 enters the make state, FF1 is similarly set and the timer 90 is switched to output for 30 seconds. (15th
FF2 is set at the next rising edge of the timer 90 output. If the carriage is not at home, FF2 sets FF5 and returns the carriage to the home. timer 90
If the carriage is not at home at the next rising edge of the output, that is when FF3 is set (when it does not come home after driving the carriage motor for 30 seconds), FF6 is reset, FF4 is set, and the circuit is in power down mode. Therefore, no ink is removed. When the carriage is at home, FF6
is not reset and FF-3 is set.
The DC motor is driven while it is low. At the next fall of the output of timer 90, FF3 is reset and the DC motor is turned off.At the same time, FF4 is set, so it becomes Low and the battery switch circuit 97 is turned off. As mentioned above, the circuit of FIG. 14 performs the operation of the flowchart of FIG. 13A. Note that the timer can also be activated externally, and by starting it at times other than when the power is turned off, for example, it can be started when printing has stopped and the timer will last for 50 hours after printing has stopped (even if the power is turned on). Ink removal can be performed later.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments described here.
It goes without saying that all improvements and modifications, such as application to other types of ink jet heads, are included within the scope of the present invention without departing from the spirit of the present invention.

As described in detail above, the present invention provides an ink conduit that communicates between an ink tank filled with ink and an ink jet head, with one end communicating with the ink jet head and the other end communicating with the ink tank or the atmosphere. A switching valve that can be selectively connected is provided, and a suction lid is provided that is in close contact with the front of the nozzle as necessary to suck ink or air from the ink jet head using a suction pump. Since the configuration is such that the communication path of the switching valve is switched by using the power of the driving rotary power source and changing the direction of rotation, the following remarkable effects are achieved.

a. If the ink has been left unused for a long time, drain the ink in the ink jet head and the ink conduit from the switching valve to the ink jet head by suctioning the ink or air in the ink jet head through the suction lid, and then When reusing, reverse the rotary power source and change the route of the switching valve.
By forcing new ink in the ink tank to flow through the ink jet head and conduit using a suction pump, it is possible to prevent ink from remaining inside these areas for a long period of time, causing deterioration and solidification. Even if ink solids and foreign matter remain, they can be washed away by the forced ink flow. In this way, when not in use, the ink inside the ink jet head is removed and air is filled to prevent clogging due to solidification of the remaining ink.
Furthermore, since new ink is forced to flow during use, even if there is any remaining ink solid matter, it will be washed away and the ink flow path will always be kept free of clogging, allowing fresh ink to be ejected stably. Clear, high-quality characters and figures can be formed.

b) The suction of ink or air and the switching operation of the switching valve are performed by the same rotary power source, and the path of the switching valve can be switched by a mechanical mechanism by simply rotating the rotary power source in the opposite direction, so a mechanism using a solenoid valve, etc. Troubles due to valve malfunction due to circuit malfunction etc., which may occur in other systems, will not occur, and the valve switching operation will be reliable and reliable. Since the drive device is unstable, it is possible to provide an inkjet recording device with a simple configuration, low cost, and low current consumption.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the amount of air dissolved in water using temperature as a parameter. FIG. 2 shows a schematic configuration example of a recording apparatus according to an embodiment of the present invention. FIG. 3 shows the structure of a recording head used in the present invention. Fourth
Fig. 5 shows a suction cap as an embodiment of the present invention. FIG. 6 shows an embodiment of the ink tank of the present invention. FIG. 7 shows an embodiment in which the present invention is applied to a serial printer. FIGS. 8 and 9 show an embodiment of the ink strip block of the present invention. 10th
The figure shows an embodiment of the switching valve of the present invention. FIG. 11 shows an embodiment of the pump of the present invention. FIG. 12 is a block diagram of an embodiment of the present invention. FIG. 13 shows an operational flowchart of the ink strip block according to the embodiment of the present invention. FIG. 14 is an ink strip circuit diagram of an embodiment of the present invention, and FIG. 15 is a timing chart thereof. DESCRIPTION OF SYMBOLS 1... Ink jet head, 2... Ink tank, 3... Ink conduit, 4... Switching valve, 8... Suction pump, 31... Bag, 32... Pipe, 33... Rubber member,
35...head, 36...carriage, 42...suction cap, 43...ink strip block, 45...ink tank, 46...DC motor, 50...operating plate, 5
5...Switching valve, 60...Pump.

Claims (1)

[Scope of Claims] 1. In an inkjet recording device that forms characters or figures on recording paper by guiding ink filled inside an ink tank through an ink conduit and ejecting it from a nozzle of an inkjet head, an ink jet recording device is provided in the middle of the ink conduit. a switching valve that communicates with the ink jet head on one side and selectively connects the ink tank or the atmosphere with the other side by moving a slider; a rotary power source capable of forward and reverse rotation; and the rotary power source. an actuating plate that is rotated in response to the rotational force of the rotary power source and has a contact portion formed therein; a switching valve operating lever that moves the slider in two directions; a suction pump that is driven by the rotary power source and feeds the ink or air in one direction regardless of the rotational direction of the rotary power source; and a front surface of the nozzle. a suction lid that is in close contact with the nozzle as necessary to suck in the ink or air from the nozzle with the suction force of the suction pump, the suction lid is in close contact with the front surface of the nozzle, and the rotary power source When the rotating power source is rotated in the other direction, the switching valve communicates with the atmosphere and the ink in the ink jet head is drawn out by the suction pump, and when the rotating power source is rotated in the other direction, the switching valve communicates with the atmosphere. An inkjet recording apparatus, characterized in that the inkjet head is filled with the ink by the suction pump, which is connected to a tank.