JPH043307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle cap mechanism for preventing ink from drying out in printers used in calculators, computer terminals, etc., and particularly in printers equipped with an ink jet 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. Although some innovations have been made in the type of ink, the structure of the ink jet head, the nozzle cap, etc. of the products that have already been commercialized, they have complicated mechanisms.

Here is an example of the simplest mechanism. Set the ink jet head in the standby position and press the elastic nozzle cap toward the nozzle end surface of the ink jet head to cap it. At the start of printing, the nozzle cap is released and the ink jet head is moved to perform printing. Furthermore, when the ink jet head and the nozzle cap are not in pressure contact, the nozzle cap is rotated by a mechanism consisting of a motor and a train of gears, thereby cleaning the nozzle cap. This mechanism used many parts, such as a dedicated motor, several gears, and a shaft, to rotate the nozzle cap. Furthermore, since there is no relationship with other mechanisms in the printer, the nozzle cap mechanism has the disadvantage of refusing to share parts with other mechanisms.

In order to eliminate these drawbacks, the present invention improves the drive of the paper feed drum and nozzle cap for feeding printing paper.
This is done using a motor that rotates forward and reverse. The aim is to provide a nozzle cap that is simple, reliable and easy to control due to common parts. Another object is to provide a nozzle cap that has a simple mechanism, has a small number of parts, requires no adjustment, and is easy to assemble.

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 drive 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, there is a rotating shaft 19 that rotates by being transmitted with 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), and an electromagnet 28 is arranged on the end surface 14a of the frame 14.

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 includes a motor 7
is moved in parallel to the printing paper 6 via the gears 9, 11 and the rope 13. The motor 7 is
The printing means 2 also performs reciprocating motion in synchronization with the motor 7, which is a pulse motor that performs step-like rotational motion in response to pulse input.

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. Due to the rotation of the motor 18, the rotating shaft 19
Rotate in the direction of the arrow. The coil spring 20 functions as a spring clutch and is wound around the rotating shaft 19.
The coil spring 20 20a pulls 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 close contact between the rotating shaft 19 and the coil spring 20 becomes loose, causing slippage between them. Therefore, the rotation of the motor 18 is not transmitted to the paper feed drum 8. Similarly, when the printing paper 6 is pulled out in the direction of the arrow in FIG. 3, slippage occurs between the coil spring 20 and the rotating shaft 19, and the paper 6 can be pulled out with a light force without 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
~10mm. The member 25 is polyvinylidene chloride, polyethylene, polypropylene, aluminum foil, or a laminated film or sheet thereof, and has a thickness of 20 μm.
~100 μm.

The nozzle cap 21 also 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 unlikely event that air bubbles occur inside the ink jet head 3 or the viscosity of the ink 30 in the nozzle 3a increases, it may be necessary to simply clean the ink 30 or to remove the ink 30 from the ink jet head 3 at an angle. This is because just taking it out 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 the ejection and cleaning, air bubbles and the like inside the ink jet head 3 are removed. This is because the ink 30, etc. whose viscosity has increased is discharged, and the state is restored to a completely printable state. Further, ink, dust, etc. adhering to the nozzle cap 21 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 ink jet head 3 is 2 μm or less, and the surface roughness of the member 25 is 1 μm or less.
A pressure of 50 g or more ensures that the two are in close contact. Further, the member 25 is a member having low gas permeability and water absorption rate, and does not absorb moisture in the ink 30 in the nozzle 3a, evaporate it, or generate 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 leaves the position A in FIG. 1, the electromagnet 2
Even if 8 is turned off, the state shown in Figure 4 continues to be maintained.

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 the paper by a predetermined amount. After printing is completed, if printing will not be performed for a long time or if the printer is turned off, the printing means 2 moves to the standby position A. At this time, the electromagnet 28 is energized to apply a magnetic field opposite to that of the permanent magnet 27 mounted on the printing means 2 to prevent the permanent magnet 27 from being attracted to 14a of the frame 14. Printing means 2 is definitely A
When it reaches the standby position, the electromagnet 28 is de-energized.

The permanent magnet 27 is attracted to 14a of claim 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, the nozzle cap 21 is rotated, a high voltage is applied to the piezoelectric element 29, and the wiper 24a cleans the end face of the nozzle 3a of the ink jet head 3 while injecting ink 30 from the nozzle 3a. The motor 7 is energized and moved 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. You can clean it 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.

The embodiments of the present invention have been described in detail above, but the main feature of the printer of the present invention is that the paper feed drum and spatula-shaped wiper that sends the printing paper are driven.
This is done using a motor that rotates forward and backward. As a result, parts can be shared, operation is simple and reliable, the number of parts is reduced, and adjustments are not required, making assembly easier.

Further, when paper is fed, the principle of a spring clutch using a coil spring does not affect the wiper mechanism at all, and conversely, even when the spatula-shaped wiper is operated, there is no effect on the paper feed mechanism. Therefore, even if the motor is shared as a drive,
Since each printer operates independently, the printer as a whole is not restricted in its operation, making it possible to provide a printer that is easy to control and easy to use.

[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...Ink jet head, 6...Printing paper, 7...Motor, 8...Paper feed drum, 14...Frame, 18...Motor, 19
... Rotating shaft, 20 ... Coil spring, 21 ... Nozzle cap, 22 ... Coil spring, 24 ... (Elastic member), 24a ... Wiper, 25 ... (Low gas permeability and water absorption) member, 27 ... Permanent magnet, 2
8...Electromagnet.

Claims (1)

[Scope of Claims] 1. An ink jet head that prints on printing paper by ejecting ink droplets from a nozzle and moves across the printing paper, and cleaning the nozzle surface of the head when the ink jet head is on standby. an inkjet printer, comprising: a spatula-shaped wiper; a paper feeding drum for feeding the printed paper; a rotating shaft having the spatula-shaped wiper and the paper feeding drum coaxially; What is claimed is: 1. An inkjet printer comprising: a clutch mechanism; and a forward-reversible motor that rotates the paper feed drum during forward rotation and rotates the spatula-shaped wiper during reverse rotation.