JPH0410425B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle cap for preventing ink from drying out in printers used in calculators, computer terminals, etc., and particularly in printers equipped with an inkjet head.

A large number of printers equipped with inkjet heads have been commercialized in the past, but in order to ensure high reliability, they are equipped with advanced technology and have complex mechanisms. Especially the inkjet head,
Printers have unique problems such as ink drying, nozzle dirt, and air bubbles getting into the nozzles, and it can be said that solving these problems determines the printer's reliability. In the products that have already been commercialized, improvements have been made to the type of ink, the structure of the ink jet head, the nozzle cap, etc.

In conventional inkjet printers, the tip of the nozzle in the inkjet head is pressed with an elastic member to create a cap, the cap is released when printing starts, and ink is injected from the nozzle in the inkjet head while the printer is in the standby position. I injected it, did a test print, and then started the printing process. Here, a rubber-based member with elasticity is used for the cap,
It was firmly attached to the nozzle end face. However, rubber-based members having elasticity generally have a high gel permeability, making it difficult to prevent the evaporation of ink within the nozzle, and having the disadvantage of increasing the viscosity of the ink. Furthermore, rubber-based members have the disadvantage that dust and dirt easily adhere to them, and that dust and dirt adhere to the nozzle tip surface of the ink jet head during capping, which adversely affects ink ejection. Furthermore, there are many drawbacks, such as the material getting stuck inside the nozzle when a cap made of a soft material is used, and the generation of air bubbles inside the nozzle due to poor adhesion between the cap and the tip of the nozzle when using a cap made of a hard material. was.

The present invention was made in view of these problems, and its purpose is to firmly prevent ink from evaporating by adhering to the nozzle surface, and also to prevent ink from adhering to the nozzle surface without damaging it. An object of the present invention is to provide a new inkjet printer capable of removing dirt.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view showing the entire printer 1 of the present invention. Reference numeral 2 denotes printing means, and tanks 4 and 5 are mounted on an inkjet head 3. The printing means 2 reciprocates parallel to the printing paper 6 and prints one line at a time. A motor 7 serves as a driving source for reciprocating the printing means 2, and is located inside the paper feed drum 8. 9 is motor shaft 1 of motor 7
0, and 11 is a gear that rotates by receiving force from the motor gear 9, and is supported by a shaft 12. The gear 11 has a groove 11a on its outer periphery, a part of which is fixed and a rope 13 is wound around it, and the rope 13 is further wound around pulleys 15, 16, and 17 arranged on the bottom back side of the frame 14 and stretched. Furthermore, a part of the rope 13 is fixed to the printing means 2. On the inner periphery 8a of one end of the paper feed drum 8 is a rotating shaft 19 that is rotated by the force of the motor 18.
is inserted, and a coil spring 20 is arranged between the two.

Further, a nozzle cap 21 is inserted into the rotating shaft 19, and a coil spring 22 is arranged between the two. The nozzle cap 21 is a cylindrical rotating member, and has a structure in which a member 24 having elasticity and a member 25 having low gas permeability and water absorption are inserted in a multilayer structure into a frame 23. The printing means 2 includes
A leaf spring 26 is fixed, and a permanent magnet 27 is further fixed to the leaf spring 26. The permanent magnet 27 is attracted to the end surface 14a of the frame 14 when the printing means 2 is located at the left end in the figure (two-dot chain line);
An electromagnet 28 is arranged at.

The structure of printer 1 has been briefly described above, but
This operation is shown in Figures 1, 2, 3, and 4.
This will be explained in detail using FIGS. Printing means 2
It mainly consists of an inkjet head 3 and tanks 4 and 5. The ink jet head 3 shown in FIG. 2 is an ink-on-demand type ink jet head, and prints by ejecting ink 30 from a nozzle 3a by applying a high voltage to a piezoelectric element 29. Ink 30 is stored in tank 4 or 5. The printing means 2 is moved parallel to the printing paper 6 by the drive of the motor 7 via the gears 9 and 11 and the rope 13. The motor 7 is a pulse motor that performs step-like rotational motion in response to pulse input, and the printing means 2 also performs reciprocating motion in synchronization with the motor 7.

Next, paper feeding will be explained. Paper feed drum 8
In this case, rubber rings 31 and 32 are inserted around the outer periphery, and printing paper 6 is inserted between it and a paper press plate 33 (shown in FIG. 3) to feed the paper. A rotary shaft 19 is inserted into the inner periphery 8a of one end of the paper feed drum 8 and rotates by being transmitted with the force of the motor 18, and a coil spring 20 is disposed between the two. FIG. 3 is a side view showing the paper feeding operation. The rotating shaft 19 and the coil spring 20 are in close contact with each other, and one end 20a of the coil spring 20
is engaged with the notch 8b of the paper feed drum 8. The rotation of the motor 18 causes the rotating shaft 19 to rotate in the direction of the arrow. The coil spring 20 functions as a spring clutch and is wound around the rotating shaft 19, and the coil spring 20 20a catches the notch 8b of the paper feed drum 8 and rotates it in the direction of the arrow.
Thereby, the printing paper 6 is fed by a predetermined amount in the direction of the arrow. The motor 18 is a pulse motor similar to the motor 7 described above. When the motor 18 rotates clockwise in the opposite direction to that shown in FIG. 3, the rotating shaft 19 and the coil spring 2
The close contact with 0 becomes loose, causing slippage between the two.
Therefore, the rotation of the motor 18 is not transmitted to the paper feed drum 8. Similarly, when pulling out the printing paper 6 in the direction of the arrow in FIG.
It can be pulled out with a light force without causing any slippage between the two and transmitting force to the motor 18.

Next, regarding the nozzle cap, see Figures 1 and 4.
This will be explained using FIGS. 5 and 6. As shown in the perspective view of FIG. 6, the nozzle cap 21 is a cylindrical rotating member, and members 24 and 25 are inserted into a frame 23. As shown in the perspective view of FIG. In FIG. 4, the rotating shaft 19 and the coil spring 22 are in close contact with each other, and one end 22a of the coil spring 22 is engaged with the notch 23a of the frame 23, as in the paper feeding mechanism described above. The rotation of the motor 18 causes the rotating shaft 19 to rotate clockwise as shown by the arrow. The coil spring 22 acts as a spring clutch,
2 of the coil springs 22 are wound around the rotating shaft 19.
2a hooks the notch 23a of the frame 23,
Rotate in the clockwise direction of the arrow. This causes the nozzle cap 21 to rotate in the direction of the arrow. Also, when feeding paper, it rotates counterclockwise as shown in Figure 3.
In this case, the close contact between the rotating shaft 19 and the coil spring 22 becomes loose, causing slippage between them. Therefore, the rotation of the rotating shaft 19 is not transmitted to the nozzle cap 21. The nozzle cap 21 has a structure in which a resilient member 24 and a member 25 having low gas permeability and water absorption are inserted into a frame 23 in a multilayered manner.

The member 24 is mainly made of rubber, and has a hardness of about A15 to A30. Also, the thickness is 2mm to 10mm
It is. The member 25 is polyvinylidene chloride, polyethylene, polypropylene, aluminum foil, or a laminated film or sheet thereof, and has a thickness of 20 μm to 300 μm.
It is m.

Further, the nozzle cap 21 has a spatula-shaped wiper 24a having elasticity on its outer circumferential surface, which acts as a nozzle cleaner and prevents the rotation of the nozzle cap 21 when the printing means 2 is in the standby position A in FIG. Therefore, the tip surface of the nozzle 3a of the ink jet head 3 is rubbed and cleaned. At this time, a high voltage is applied to the ink jet head 3 and the ink 30 is ejected. In the event that air bubbles occur inside the ink jet head 3 or the viscosity of the ink 30 in the nozzle 3a increases, the ink 30 may be simply ejected from the ink jet head 3 by simply cleaning it. This is because doing so alone will not fully recover. By ejecting the ink 30 while cleaning, the ink 30 that oozes out little by little from the nozzle 3a is wiped off by the spatula-shaped wiper 24a, and by repeating ejection and cleaning, air bubbles inside the ink jet head 3 are removed. This is because the ink 30 and the like whose viscosity has increased is discharged, and the state is completely restored to a printable state. Also nozzle cap 21
Ink, dust, etc. adhering to the paper are removed by the porous member 34. The nozzle cap 21 has an outer diameter of φ30 mm and a rotation speed of 100 to 500 rpm.

FIG. 5 shows the capping state. In FIG. 1, when the printing means 2 is in the standby position A, a permanent magnet 27 fixed to one end 26a of the leaf spring 26 fixed to 2a of the printing means 2 is placed at 14a of the magnetically permeable frame 14. adsorbs to. The suction force at that time is 200g to 300g. The printing means 2 rotates around a shaft 35 via a leaf spring 26. The tip end surface of the nozzle 3a of the ink jet head 3 is pressed against the nozzle cap 21. The surface roughness of the tip of the nozzle 3a of the inkjet head 3 is 2μ.
m or less. The surface roughness of the member 25 is 1 μm or less, and a pressure of 50 g or more ensures that the two are in close contact with each other. Further, the member 25 is a member with low gas permeability and water absorption rate, and is a member that allows the ink 30 in the nozzle 3a to
It does not absorb moisture, evaporate water, or generate air bubbles.

Next, in order to release the ink jet head 3 from the nozzle cap 21, the electromagnet 28 is energized.
By forming a magnetic field opposite to that of the permanent magnet 27 in 14a of the frame 14, the permanent magnet 27 is separated. The printing means 2 is rotated by the spring force at 26b of the leaf spring 26 until it is reliably guided by the shaft 36, resulting in the state shown in FIG. When the printing means 2 is moved away from the position A in FIG. 1, it continues to maintain the state shown in FIG. 4 even if the electromagnet 28 is de-energized.

The operation of each mechanism has been explained above, but
The overall operation of the printer 1 will be explained. First, for printing, the motor 7 is energized to move the printing means 2.
The timing of printing is synchronized with the pulse signal to the motor 7. After printing is completed, the motor 18 is energized to feed a predetermined amount of paper. After printing is finished,
When printing is not performed for a long time or when the printer is turned off, the printing means 2 moves to the standby position A. At this time, the electromagnet 28 is energized,
A magnetic field opposite to that of the permanent magnet 27 mounted on the printing means 2 is applied, and the permanent magnet 27 is attached to 14a of the frame 14.
Avoid being absorbed by. When the printing means 2 has surely come to the standby position A, the electromagnet 28 is turned off. The permanent magnet 28 is attracted to 14a of the frame 14 and capped as shown in FIG. Next, when it is desired to start printing, the electromagnet 28 is energized, the printing means 2 is placed in the state shown in FIG. 4, and the motor 18 is rotated in the opposite direction to the direction used when feeding the paper. Then, by rotating the nozzle map 21 and applying a high voltage to the piezoelectric element 29, the wiper 24a cleans the end face of the nozzle 3a of the ink jet head 3 while ejecting ink 30 from the nozzle 3a.
The printing means 2 is moved by energizing the motor 7 to start printing. When the printing means 2 leaves the position A, the electromagnet 28 and the motor 18 are turned off. The subsequent operations are as described above. Also, if dust or the like adheres to the nozzle 3a of the inkjet head 3 during printing, the printing means 2 is moved to the standby position A, the electromagnet 28 and the motor 18 are energized, and the ink 30 is ejected from the inkjet head 3. It can be cleaned while cleaning.

In this embodiment, the nozzle cap 21 is a rotating cylindrical nozzle cap, but it is easily possible to use a rotating belt-like nozzle cap or a nozzle cap that reciprocates a plate-like nozzle cap.

As described above, according to the present invention, the structure of the nozzle cap is such that the first member is elastic, the first member has a low gas permeability and the water absorption rate, and the second member is on the first member and contacts the nozzle surface. Since it has a multilayer structure with the second member, the second member is firmly attached to the nozzle surface of the ink jet head by the elastic first member, thereby preventing air bubbles from forming within the ink jet head and preventing ink from forming. This can prevent the viscosity from increasing, drying out, and nozzle stains.

Moreover, since a part of the second member protrudes toward the nozzle side from the first member, when the nozzle cap is slid during cleaning, the elastic first member
The member bends and comes into soft contact with the nozzle surface, making it possible to reliably wipe the nozzle surface without damaging the nozzle surface.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention. FIG. 2 is a side view of the ink jet head as printing means, FIG. 3 is a side view showing the paper feeding mechanism, and FIGS. 4 and 5 are side views showing the nozzle cap mechanism. FIG. 6 is a perspective view of the nozzle cap. DESCRIPTION OF SYMBOLS 1...Printer, 2...Printing means, 3...Inkjet, 6...Printing paper, 7...Motor, 8...
... Paper feed drum, 14 ... Frame, 18 ... Motor, 19 ... Rotating shaft, 20 ... Coil spring, 2
1... Nozzle cap, 22... Coil spring, 2
4... (elastic) member, 24a... wiper, 25... (low gas permeability and water absorption)
Member, 27...Permanent magnet, 28...Electromagnet.

Claims (1)

[Scope of Claims] 1. An inkjet printer comprising a nozzle cap that presses against the nozzle surface of the inkjet head when the head is on standby and slides on the nozzle surface during cleaning, the nozzle cap comprising: is a multi-layered structure including a first member having elasticity and a second member having lower gas permeability and water absorption than the first member, and being on the first member and in direct contact with the nozzle surface. An inkjet printer comprising: an inkjet printer, wherein a portion of the first member protrudes toward the nozzle surface than the second member.