JPS5945164A - Nozzle cap for ink jet printer - Google Patents

Abstract

PURPOSE:To prevent the mixing of colors by the nozzle cap of an ink jet head for multi-color printing during the waiting period by using the nozzle cap made of a material having a permeability in one direction. CONSTITUTION:A slit is formed in the cap 24c of a nozzle cap 21 in such a way as to provide it close to the circumferential direction. With a depth as much as about half the diametral thickness of the part 24. The part 24 having small gas permeability, small water absorbability, and a high softness can be easily contacted closely with the slit. Under a condition that the ink jet head 3 and the nozzle cap 21 are contacted pressingly, the slit is closely blocked and the nozzles 3a and 3b are completely interrupted from the open air. Ink does not flow toward the thrust direction because the cap 24c has a permeability in one direction, and therefore, mixing of colors can be avoided even when different colors of inks are printed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to printers used for terminal equipment such as calculators and converters, and in particular, to problems such as drying of ink in the nozzles of the inkjet head of printers equipped with inkjet heads that perform multicolor printing. This invention relates to means for preventing clogging, air bubbles from entering the nozzle, etc.

Conventionally, printers equipped with inkjet heads are
Many products have been commercialized, but in order to ensure high reliability, they have sophisticated technology and complex mechanisms. Inkjet heads in particular have unique problems such as ink drying, clogging, and air bubbles entering the nozzle, and it can be said that solving these problems determines the reliability of the printer.

Conventional inkjet printers have been provided with nozzle caps to solve the above problems. This nozzle cap is good for inkjet heads that print in a single color, but when it comes to inkjet heads that print in multiple colors, problems such as color mixing may occur, and to avoid color mixing, a complicated mechanism is required such as providing a partition. It had many drawbacks such as:

In order to eliminate these drawbacks, the present invention is characterized in that the nozzle cap is a member that is permeable in one direction. The purpose is to prevent color mixing caused by the nozzle cap of an inkjet head for multicolor printing using a simple mechanism.
The objective is to provide a highly reliable printer.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially sectional 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 a pair of inkjet heads O that print in two colors. The printing means 2 reciprocates parallel to the printing paper B, and -
Print line by line.

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 a gear attached to the motor shaft 10 of the motor 7;
1 is a gear that rotates by receiving force from a motor gear 9, and a shaft 12
is supported by The gear 11 has a groove 11α on its outer periphery, a part of which is fixed and a lobe 13 is wound around it, and a lobe 13 is wound around the gear 11.
3 is a pulley 15 arranged on the bottom back side of the frame 14;
It is wound and stretched at 16.17 degrees. Furthermore, part of the lobe 13 is fixed to the printing means 2. 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 that acts during paper feed is disposed between the two. Further, a nozzle gap 21 is inserted into the rotating shaft 19, and a coil spring 22 that acts when the nozzle gap 21 rotates is arranged between the two. The nozzle cap 21 is a cylindrical rotating member, and has a structure in which a fully elastic member 24 is inserted into a frame 23. A plate spring 26 is fixed to the printing means 2,
Further, a permanent magnet 27 is fixed to the leaf spring 26. When the printing means 2 is located at the left end A, the permanent magnet 27 is attracted to the end surface 14α of the frame 14 shown in two-dot chain line, and an electromagnet 28 is arranged at the end surface 14σ. Further, rubber rings 31 and 32 are attached to the outer periphery of the paper feed drum 8, so that the recording paper 6 is fed reliably without slippage.

The structure of the printer 1 has been briefly described above, and its operation will be explained in detail. The printing means 2 mainly consists of an inkjet head 3 (shown in FIG. 2) and tanks 4 and 5. The ink end head 6 shown in FIG.
Printing is performed by applying a high voltage to the piezoelectric element 29 using an ink-on-demand type inkjet head to eject ink from the nozzle 3a. Ink 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 lobe 16. The motor 7 is a pulse motor that performs stepwise rotational motion in response to pulse input, and the printing means 2 also performs reciprocating motion in synchronization with the motor 7.

Each nozzle 3α communicates with a pressure chamber, and ink droplets are ejected from the nozzle 3a by driving a piezoelectric element 29 placed opposite the pressure chamber.

Further, the nozzle 3b is used exclusively for nozzle cleaning and is not involved in character formation. Like the nozzle 3a, the nozzle 3b communicates with a pressure chamber, and the piezoelectric element 2 arranged above the pressure chamber.
By driving 9α, the extruded ink is pushed downward along the nozzle end face.

Next, the operation of the nozzle cap will be explained with reference to FIGS. 1 to 3. The nozzle camp 21 is a cylindrical rotating member, and a frame 23 has an elastic member 24 inserted therein. The rotating shaft 19 and the coil spring 22 are in close contact with each other, and one end 22 of the coil spring 22 (+ indicates the notch 23 of the frame 23
It is engaged with α. Rotation of the motor 18 causes the rotation shaft 19
rotates clockwise as shown by the arrow. coil spring 22
acts as a spring clutch and is wound around the rotating shaft 19, and the end 22α of the coil spring 22 is connected to the notch 2 of the frame 23.
Hook the 3α and rotate it in the 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, but in this case, the rotation axis 1
The close contact between the coil spring 9 and the coil spring 22 becomes loose, causing slippage between the two.

Therefore, the rotation of the rotating shaft 19 is not transmitted to the nozzle camp 21.

The nozzle cap 21 will be explained in detail with reference to FIG.

As is clear from the perspective view of FIG. 4(A), the nozzle cap 21 is a cylindrical rotating member, and an elastic member 24 is inserted into a frame 23. The elastic member 24 is
It consists of a cleaner 24α, a recess 24b, and a cap 24C that is permeable in one direction. The same figure (B) is a sectional view of the nozzle camp 21, in which a slit is cut in the gap portion 24c in close contact with each other in the circumferential direction in order to provide permeability in one direction. The radial thickness of part 4A24 is approximately 4wh
The slits are approximately 2m deep. Further, the member 24 has a low gas permeability and a low water absorption rate, and has a hardness of Shore A of 15 to 30, which is very soft, and the slit can be easily brought into close contact with the pressure from the circumferential direction of 507 or more. Therefore, as shown in FIG. 4, the nozzle 3a of the inkjet head 6
, 3b and the nozzle gear knob 21, the slits are in close contact with each other, and the nozzles 3a, 3b are completely cut off from the outside air.

Next, another example of the nozzle cap 21 will be described. FIG. 4(0) shows a nozzle cap 211 made of a member 241 made by tightly wrapping a rubber string around a frame 231 to provide permeability in one direction. The hardness of the rubber string is A.
15 to 30, it is very soft and its action is the same as in the previous example.

FIG. 4(D) shows a nozzle in which a hydrophilic member and a member with low gas permeability (or water absorption rate) are laminated in the thrust direction, and a member 242 having unidirectional permeability is inserted into the frame 323. This is the gap 212.

The operation is the same as in the previous embodiment. FIG. 4(E) shows a nozzle cap 216 in which a member 243 made of rubber or plastic with fibers arranged in the radial direction is inserted into a frame 233. The operation is the same as in the previous embodiment.

When the nozzle gear knob 21 is released, the cap portion 2 of the member 24
Due to the unidirectional permeability of the cap portion 24C, the ink remaining in the cap portion 24c and the ink discharged during cleaning, which will be described later, does not flow in the thrust direction, and a pair of printing means print different colors. Even in case 2, inks of different colors will not mix.

The composition of the ink is: Dye...2 wt%
Surfactant ・・・・・・ 0.5 wt
%glycerin ・・・12wt% ethylene glycol ・・・28wt% water
...consisting of 57 wt%. Among these, glycerin and ethylene glycol are wetting agents, and the ink that has permeated into the slit of the cap portion 24c of the member 24 also functions as a wetting agent for the nozzle cap.

The fourth section 24b is particularly useful when camping when the printing gutter is not used for a long period of time. Recess 24
b is located at a position facing the nozzles 3α and 3b, and the nozzle gear knob 21 is pressed against the nozzle end face. At this time,
The gap formed by the four parts is filled with ink ejected from the nozzle 3α or 6b. Since the four ink-filled parts 24b cover the nozzle end face, clogging due to drying of the nozzle can be completely prevented.

Capping using the four parts 24b consumes a very small amount of ink at 15 .mu.l each time, and may be used not only when not in use for a long time as described above, but also during all capping operations.

Although the embodiments of the present invention have been described in detail above,
A major feature of the printer of the present invention is that the nozzle cap is a unidirectionally permeable member.

Conventional nozzle caps for inkjet heads for multicolor printing have had problems such as color mixing of ink due to the cap, and have complicated mechanisms such as partitions. By using a nozzle cap having features as in this embodiment, it is possible to eliminate color mixing of ink during capping.

Further, even in a color inkjet printer using several colors of ink, color mixing can be prevented by using completely similar nozzle caps, and a highly reliable printer with a simple mechanism can be provided.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an embodiment of the present invention, FIGS. 2 and 3 are side sectional views showing a cassock pin of an inkjet head, and FIG. 4 is a view showing details of a nozzle gear knob. 1... Printer 2... Printing means 3... Inkjet head 4.5... Tank 6... Printing paper 21... Nozzle canop 24... (Elastic) member 24a... Cleaner 24b...Four parts (gap) 2 Applicant Epson Corporation Agent Patent Attorney Mogami Figure 2

Claims (1)

[Claims] It consists of an inkjet head that performs printing by ejecting ink droplets, and a nozzle cap that comes into pressure contact with the nozzle of the inkjet head during standby.
A nozzle cap for an inkjet printer characterized by being a member that is permeable in one direction.