JPH02231143A - Ink jet printer - Google Patents

Abstract

PURPOSE:To obtain clog preventing means in which air bubble is not introduced into a nozzle by coating it with a cover while slightly feeding ink from the nozzle. CONSTITUTION:When there is no information to be printed in a control circuit, a head 100 is fed leftward to stop in contact with an angle contact 31. When the current of a DC motor is interrupted, the head 100 and an ink vessel 7 are stopped at predetermined stopping positions. When a knob 17 is rotated at a cam shaft 16 as a center, a cleaner 21 is simultaneously rotated. As the knob 17 is rotated, the surface of a nozzle cover 24 is wiped off by a leaf spring 51, and the surface of a nozzle 4 is wiped by a wiper blade 52. In the meantime, a vent hole lever 25 is advanced to push a vent hole cover 12 to a vent hole 9 to close it. When the knob 17 is further rotated, a pump 11 is pressed to pressurize ink 8 in the vessel 7, and the ink 8 is slightly fed from the nozzle 2. The nozzle 2 is closed by the cover 24 while pressurizing it, and a pump lever 26 is then retreated. The ink in the head 100, the vessel 7 is not externally fed in this state, and its evaporation is eliminated.

Description

[Detailed description of the invention] The present invention relates to an inkjet printer.

Ink-on-demand type inkjet printers have the disadvantage that ink ejection becomes impossible if air bubbles enter the head. There is also the problem that nozzles become clogged due to ink evaporation.

To prevent nozzle clogging, the nozzle is usually covered with a lid to suppress ink evaporation to the outside.

However, it has been found through experiments by the inventors that simply capping the nozzle causes air bubbles to be generated within the head. As shown in FIG. 1, this is because air bubbles are trapped inside the nozzle when the lid 103 is closed due to the meniscus 102 of the nozzle 101, and when the lid 103 is closed, air bubbles are trapped inside the nozzle.
When the ink approaches the nozzle 101, it is possible that the ink will wet the ink unevenly and trap air bubbles into the nozzle.

Therefore, the object of the present invention is to prevent clogging of the IJ without trapping air bubbles in the nozzle. It is about providing the means.

The gist of the present invention is to eliminate the concave meniscus by closing the lid while allowing ink to flow out slightly from the nozzle, and to uniformly wet the lid with ink to eliminate air bubbles from being drawn into the nozzle. It is something.

FIG. 2 shows a schematic diagram of an embodiment of the present invention. This is a top plan view of the device.

1 is a polysulfone substrate with nozzle 2 and pressure chamber 3 on its surface.
, the supply channel 4 is formed as a groove.

5 is a polysulfon sheet diaphragm laminated with the substrate 1, and a piezoelectric element 6 is bonded to the surface thereof. These constitute the head 100. 7 is made of polysulfone and has a volume of approximately 10 m, l! The ink container is bonded to the substrate 1 and contains up to 6 mg of ink 8 inside. 9 is a vent hole with a diameter of 0.8+nn provided at the top of the ink container 7;
0 is a pump hole with a diameter of 0.4 mm provided in parallel with the ventilation hole 9. The reason why the diameter of the ventilation hole 9 is large is to prevent insufficient ventilation when wet with ink, and the reason why the pump hole is small is to suppress evaporation of the ink. 11 is a hemispherical pump with a radius of 5 dragons made of butyl rubber with low vapor permeability.
Reference numeral 2 denotes a vent cover integrally formed with the bomb 11, with an air vent 13 opening in a part thereof. The bomb 11 and the vent cover 12 are attached to the ink container 7 with a holding frame 14 made of polysulfone.
is fixed. Note that the substrate 1, the diaphragm 5, the ink container 7, and the holding frame 14 are bonded together with solvent cement. The ink container integrated with the head described above is mounted on a carriage that is not visible in the figure, and moves left and right along the guide 15.

Reference numeral 16 denotes a camshaft to which a knob 17 is fitted. Cams 18, 19, 20 and a cleaner 21 are attached to the knob 17 and rotate integrally with the knob 17. Reference numeral 22 is a coil spring whose one end is attached to the knob 17 and wrapped around the camshaft 16 to form a spring clutch so that the knob 17 can only rotate in one direction. 23 is a lid lever, 24 is a silicon rubber nozzle lid attached to the lid lever 23, 25
is a vent lever, and 26 is a bomb lever. The lid lever 23, the vent lever 25, and the pump lever 26 are the knobs 1
As the pump 7 rotates, the cams 18, 19, and 20 move to open and close the lid and drive the pump. In addition, in FIG. 2, the springs that press the lid lever 23, the vent lever 25, and the bomb lever 26 against the cam are omitted. 27 is knob 1
A magnet embedded in 7 and a reed switch 28 function to detect the rotational position of the knob 17. Two platens are placed to the right of the lid and cleaning means.

Reference numeral 30 denotes a frame of the printing device, from which part of the frame 31 protrudes.

The operation of the above configuration will be explained with reference to the cam diagram in FIG.

A normal printing operation is performed by ejecting ink onto recording paper set on two platens (not shown) with a recording head reciprocating left and right seven times at a position facing two platens partially shown in FIG. At this time, the angle of the camshaft is A as shown in Figure 3A.
, -0'. N indicates the movement of the lid lever 23
As shown in C (nozzle cap), the nozzle cap 24 is separated from the nozzle 2. In the following, the levers should be moved upward so as to move away from the head and ink container.

Similarly, the vent lever 25 is set to V(:(vent Cap
), it is separated from the vent cover 12.

Further, the pump lever 26 is also separated from the bomb 11 as shown by P (pump). Also, the cleaner 21 is (cl
eaner), it is spaced above the nozzle cover 24. Note that the shape of the cleaner 21 and the nozzle lid 24
, the positional relationship with the nozzle 2 will be described later. The reed switch 28 is turned on as shown by RS (reed switch).

When two seconds have passed since there is no more information to be printed in the control circuit (not shown), the head 100 is sent to the left by a DC motor (not shown) and stops when it hits the stroke 31. Immediately after that, if the applied current of the DC motor is cut off, the head 1
00, the ink container 7 stops at a predetermined stop position. If the user wishes to stop the printing device, press knob 17.
rotate it in the specified direction. The cleaner 21 rotates in synchronization with the rotation of the cam as shown in FIG. 3C to clean the nozzle 2 and nozzle cover 24. This situation is shown in FIG. When the knob 17 is rotated around the camshaft 16,
The cleaner 21 also rotates at the same time. A leaf spring 51 made of SUS is welded to the tip of the lever of the cleaner 21, and a wiper blade 52 made of butyl rubber is attached to the tip. As the knob 17 rotates, the leaf spring 51 closes the nozzle lid 2.
At the same time, the wiper blade 52 wipes the front surface of the nozzle 2. While the cleaner 21 is wiping the nozzle 2, the vent lever 25 moves forward and presses the vent cover 12 against the vent 9 to close it, as shown in FIG. 3VC.

At the knob rotation angle A2-160°, the nozzle 2 is open and the ventilation hole 12 is closed. In this state, barging, which will be described later, becomes possible. When the knob 17 is further rotated,
As the pump 11 is pushed, the nozzle cover 24 approaches the nozzle 2. Therefore, the ink 8 in the ink container 7 is pressurized, and the ink 8 slightly flows out from the nozzle 2 via the supply path 4 and the pressure chamber 3. The capacity of the pump 11 is such that the pressure inside the ink container 7 is 1 to 10 cITIH20 (approximately 100 Pa).
~IKpa), for example 2
At am H 2 0 (approximately 200 Pa), the ink 8 flows out from the nozzle 2 at about 0.01 rJ, which is enough to cause the ink 8 to swell on the front surface of the nozzle. The nozzle cover 24 closes the nozzle 2 while continuously pressurizing the bomb 11 for several tens of milliseconds to several hundreds of milliseconds, and then the bomb lever 26 retreats.

At the knob rotation angle A, the state in which the nozzle cover 24 is attached to the nozzle 2 is completed. In this state, the nozzle cover 24 and the vent cover 12 are closed, and the ink in the head 100 and ink container 7 does not flow out to the outside and evaporation is suppressed. In this state, the printing device is stored and transported.

When the operation is restarted next time, when the knob 17 is rotated, the vent cover opens first, and after the air pressure in the ink container 7 is equalized with the outside air, the nozzle cover 24 is opened. Knob rotation angle A,
The reed switch 28 is turned on to notify a control circuit (not shown) that it is ready for operation.

Note that the movement P of the bomb lever shows a sudden change from backward to forward at the knob rotation angles A1 and A in Fig. 3, but this is not directly related to the pump operation, and gives a click feeling to the rotation of the knob. In order to stabilize the knob stop position, a pressing force is generated against the cam.

Next, details of each lever, cam, etc. of the embodiment shown in FIG. 2 will be explained.

In FIG. 4, the lid lever 23 is shown by a two-dot chain line. The lid lever 23 rotates around a lever lever 53, and has a slightly convex silicone rubber nozzle lid 24 attached to its tip as shown in the figure. A spring 56 is set by hooking both ends of the lid lever 23 onto the bin 54 and a part 55 of the frame of the printing device, and pushes the lid lever 23 toward the lid 24.
A lid lever 23 is displaced by a cam 20, a portion of which is shown.

The bomb lever 26 is shown in FIG. A spring 62 engages with a pin 61 provided on the bomb lever 26 and a pin 63 provided on the vent lever 25, causing the bomb lever 26 to move toward the cam 1.
It's pushing towards 8.

The bomb lever 26 pushes the bomb 11 by the cam 18.

The bomb hole 10 is provided at the bottom of the bomb 11, and the bomb hole 10 is provided at the bottom of the bomb 11.
The ink accumulated in the ink container 1 can be easily returned to the ink container 7.

FIG. 6 shows the vent lever 25. As mentioned above, the air vent cover 12 is moved by the spring 62 common to the bomb lever 26.
It is supposed to be pressed. Note that the ink conduit 64 moves integrally with the vent lever 25 and comes into contact with and separates from the spongy ink retaining member 65 provided from below the nozzle 2 of the head 100 to below the vent 9. The ink conduit 64 is a bundle of fibers, and its lower end communicates with a discharge ink cartridge 66 containing an absorbing member. The ink 8 flowing out from the nozzle 2 and the vent hole 9 eventually accumulates in a discharged ink cartridge 66, and the cartridge is replaced as necessary.

Next, the barging at the knob rotation angle A2 in FIG. 3 will be explained. Barging is performed when air bubbles are generated in the pressure chamber 3 or when the nozzle 2 is clogged and ink cannot be ejected. When ink cannot be ejected at the knob rotation angle A1, the user inserts the ink cartridge 71 shown in FIG. 7 into the ink injection port 72, pushes down the piston 73, and injects the ink 8 to the bottom of the nozzle. Thereafter, the knob 17 is rotated to the rotation angle A2, and the piston 73 is further pushed down. At this time, since the vent hole 9 is closed, the pressure inside the ink container 7 becomes high, and the ink 8 flows out from the nozzle 2, clogging it and removing air bubbles. The cylindrical tip 74 of the ink cartridge 71 functions to completely seal so that ink does not leak from between the needle 75 and the rubber cap 76 due to the increase in pressure inside the ink container when pressurized. 79 is a metal electrode plate, 80 is a flexible substrate, and 81 is a head force bar.

Note that the reason why ink is injected at point A is to reduce the amount of air 82 in the ink container 8 so that the pressure during barging can easily increase. Further, ink replenishment accompanying normal ink consumption is performed in the state A1 in which the vent hole 9 is open.

As can be seen from the above description of the embodiments, according to the present invention, since the nozzle is capped while ink flows out from the nozzle, there is no possibility of air bubbles being drawn into the nozzle due to uneven wetting of the meniscus or the cap.

In particular, according to the above embodiment, since the bomb pressure is several cmH20, the amount of ink flowing out can be kept to a value close to zero, and the intake of air bubbles can be suppressed, so that there is no wasteful consumption of ink.

Additionally, the nozzle lid uses convex silicone rubber, which prevents air bubbles from being drawn in due to uneven wetting of the lid.

In addition, since the various levers are moved by cams that rotate in one direction, the various lever states can be easily set, and the nozzle lid does not flap around in front of the nozzle, preventing air bubbles from entering.

Furthermore, since the lid and nozzle are cleaned at the same time by a cleaning member that rotates in synchronization with the cam, there is no possibility of dirt existing between the nozzle and the lid, causing ink leakage or ink evaporation, and the number of parts can be reduced.

In addition, a signal output stage is provided to detect by the angle of the knob that the nozzle cover, vent cover, etc. are retracted and printing operation is possible, so there is no possibility of starting printing operation with the lid closed. On the other hand, if the lid is left open for a long time without printing, it is possible to issue a warning signal by monitoring the signal that no printing is being performed and the signal that the lid is open for a predetermined period of time.

In addition, by selectively moving the nozzle cover and vent cover toward and away from each other, conditions suitable for printing operation, ink injection, barging, storage, etc. can be easily set.

In addition, since printing begins after releasing the nozzle cover after releasing the ventilation hole to equalize the pressure inside the ink container with the outside air, ink ejection will not become impossible due to pressure changes in the ink container due to environmental temperature changes during storage. .

In addition, since the vent cover and pump are placed close to the ink container side, and the lever is used to push the vent cover and pump, external dust may adhere to the vent and pump holes, causing unstable operation. It never becomes.

Furthermore, the ink conduit that moves in synchronization with the vent cover allows the ink flowing out from the nozzle and the vent to flow into the discharge ink cartridge, so that the inside of the apparatus is not contaminated with the ink flowing out.

In addition, the positioning of the nozzle, vent cover, and corresponding lever is done by forcibly pressing the carriage against each other using a motor, so there is no need for a complicated position detector or complicated motor control, which improves accuracy. There are advantages.

In the above embodiment, the lid is closed while the ink is flowing with the cam, but in addition, the lid is first closed, and then the ink inside the head is pressurized with a pressure of about 200 cmH20 (about 20 KPa), and the ink is then closed with that pressure. You can also forcibly open the lid and let the air bubbles flow out along with the ink from the gap between the lid and the nozzle surface. In this case, the amount of ink consumed increases, but the sequence becomes simpler, which is mechanically advantageous.

Furthermore, although a rubber diaphragm bomb is used in the above embodiment, various pumps such as a piston type pump or a pump that pressurizes the ink by gravity may be used.

The present invention is applicable not only to ink-on-demand type inkjet using piezoelectric elements but also to those using heating elements.

In addition to serial printers, it can be widely applied to line printers, facsimile machines, copiers, blotters, etc.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the situation near the nozzles of a normal inkjet head, and FIG. 2 is a plan view of an embodiment of the present invention.
Fig. 3 is a cam diagram of the embodiment shown in Fig. 2, Fig. 4 is a diagram showing the cleaner and nozzle lid of the embodiment shown in Fig. 2, Figs.
This figure shows the pump lever and vent lever of the embodiment shown in FIG. 2, and FIG. 7 shows the barging situation of the embodiment shown in FIG. 2. 1 1 ・ 12 ・ 18, 21 ・ 23 ・ 24 ● 25 ・ 26 ・ 28 ・ 64 ・ 66 ・ 71 ● ...●...Pump...Vent hole cover...Knob l9, 20●Cam group・Fight ψ・・Cleaner - φφ ●● Lid lever ◆・●●●Fist nozzle lever・・・・Vent hole lever III 1st order●●●Bon lever・・・・Reed switch・・・・・Ink conduit ・・Discharge ink cartridge ・・・・Ink cartridge 2 100 Order 7 ・ 8 ・ 10 ◆ ・Nozzle and head ・Ink in ink container ・Vent hole Association Bomb hole Applicant Seiko Epson Agent for Co., Ltd. Patent attorney Kisaburo Suzuki (and 1 other person) Figure 1 Figure 2 Figure 3 Figure 4 Figure 7 bo Figure 6 Procedural amendment (voluntary) February 16, 1990 2. Name of the invention Inkje Ntofurinta 3. Relationship with the amended person case

Claims (1)

[Claims] An ink-on-demand inkjet head having a nozzle for ejecting ink, a lid means for closing the nozzle of the head, an ink retaining member attached to a lower part of an end surface of the head where the nozzle is formed, and the lid An inkjet printer comprising: an ink conduit for discharging ink that moves into and out of contact with the ink retaining member in conjunction with means.