JPH0572264B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a print head that forms an image by ejecting ink droplets using electrostatic means.

Prior Art Conventionally, as shown in FIG. 11, a large number of recording electrodes 50 to which ink is supplied are arranged diagonally in a straight line on the opposite surface of recording paper located in front of the counter electrode.
There are color printers that supply ink of different colors to the recording electrodes 50 for each group.

Furthermore, as shown in FIG. 12, a plurality of recording electrodes 50 are arranged diagonally in a straight line within each group, but there are color printers in which the groups are arranged at the same height.

Problems to be Solved by the Invention In the printer shown in FIG. 11, the number of dots formed in the vertical direction during one reciprocating movement of the carriage increases, so the printing speed can be increased in monochrome printing. However, when performing multicolor printing by supplying ink of a different color to the recording electrodes 50 for each group, the interval B between the recording electrodes 50 located at the boundaries of the groups is the same as the arrangement pitch P of the recording electrodes 50 within the group. Because it is so small, there is a risk that inks of different colors will mix together.

In addition, in the case shown in FIG. 12, the distance between the recording electrodes 50 located at the boundaries of the groups is wide, so it is possible to prevent color mixing during multicolor printing, but when printing in a single color, during one reciprocating movement of the carriage, Since the number of dots formed in the vertical direction is small, there is a problem that the printing speed cannot be increased.

The present invention has been made in view of these points, and an object of the present invention is to provide a printing head that can prevent color mixing when printing in multiple colors and can perform high-speed printing when printing in a single color.

Means for solving the problem A plurality of recording electrodes are arranged side by side so as to form a group and are sequentially shifted in a direction perpendicular to the direction of carriage movement as they move toward the direction of movement of the carriage. The arrangement pitch Py of all recording electrodes in the direction of
The arrangement pitch Px of the recording electrodes in each group in the direction along the carriage movement direction is determined uniformly, and the interval between the recording electrodes located at the boundary of the group is determined by the arrangement pitch Px.
Set it larger.

Function: Therefore, in multicolor printing in which ink of a different color is supplied to the recording electrodes for each group, the distance between adjacent recording electrodes at the group boundary is wide, preventing color mixing and ensuring that all recording electrodes are In monochrome printing, in which ink of the same color is supplied to the printer, the number of vertical dots formed during one reciprocation of the carriage is increased to achieve high-speed printing.

Embodiment An embodiment of the present invention will be described based on FIGS. 1 to 10. As shown in FIG. 3, a carriage 4 is slidably fitted onto a shaft 3 along a recording paper 2, which is a recording medium, held in front of the counter electrode 1. On both sides of this carriage 4, a fifth
As shown in the figure, a guide pin 5 and a locking piece 6 are formed, a circuit board 7 and a head body 8 are fitted into the guide pin 5, and the locking pieces 6 are elastically attached to both sides of the head body 8. A locking pawl 9 that engages actively is formed. The circuit board 7 has a guide hole 7a that fits into the guide pin 5 and a flexible cable 10 that is connected to an external circuit, and is urged upward by an elastic body such as a rubber plate 11 laid on the carriage 4. . A plurality of ink cartridges 12 are held in the head body 8.

As shown in FIG. 6, the head body 8 has a plurality of holders 14, which are holders, arranged side by side on a base 13 held by the carriage 4, and these holders 14 are sandwiched between the base 13 and a cover 15. be. That is, the base 13 has a guide hole 16 into which the guide pin 5 is fitted, and a screw 18 passed through a mounting hole 17 of the cover 15 is screwed into the upper part of the guide hole 16. The base 13 is formed with a plurality of ink tanks 20 that receive ink 19 from the ink cartridge 12, a plurality of ink supply sections 21 communicating with each of these ink tanks 20, and a plurality of ink reservoirs 22. .

Furthermore, each holder 14 holds a plurality of recording electrodes 23 with their tips facing the counter electrode 1, and a pressing member 24 that presses down these recording electrodes 23 from below is screwed. These needle-shaped recording electrodes 23 are made of twisted fiber materials,
Alternatively, a plurality of grooves are formed on the outer periphery along the longitudinal direction, or a through hole is formed inward along the longitudinal direction, and in either case, the ink 19 can be sucked by capillary action.

An impregnating member 25 for impregnating ink 19 is housed in an ink reservoir 22 whose one end is opened to the side below the tip of the recording electrode 23 .

Next, at the bottom of each ink supply section 21, an eighth
As shown in the figure, a plurality of bosses 26 whose top and bottom are open
are arranged in a staggered pattern when viewed from above. Single-core metal rods 27 are inserted into these bosses 26 when the base 13 is molded. As shown in an enlarged view in FIG. 10, the coil springs 28 elastically fitted to the upper ends of these metal rods 27 fit into the recesses 29 formed at the upper ends of the bosses 26.
The terminal portion 7b of the circuit board 7, which is supported on the bottom of the metal rod 2 and elastically contacted with the recording electrode 23 and urged upward by the rubber plate 11, elastically contacts the metal rod 2.
It is in contact with the lower end of 7. Further, an impregnating member 30 is provided that sucks the ink 19 from the ink supply section 21 by capillary action and supplies it to the recording electrode 23 .

Further, in the holder 14, a slit-shaped ink resupply path 31 that opens at the upper end opening surface of the ink reservoir 22 and the outer periphery of the recording electrode 23 is formed so as to be located closer to the tip of the recording electrode 23 than the impregnation member 30. ing. The cover 15 is formed with a plurality of connecting portions 32 that are fitted into the ink tanks 20 of the base 13, and the supply ports 33 of the ink cartridge 12 are removably fitted into these connecting portions 32.
The opening ends of these supply ports 33 are lower than the upper ends of the bosses 26.

All the recording electrodes 23 are connected to the carriage 4.
As shown in FIGS. 1 and 2, the holders 14 are arranged horizontally in groups of six in individual holders 14 arranged along the moving direction of the holder 14.
The positions in the vertical direction are sequentially shifted in the direction of movement of the carriage 4. The arrangement pitch Py of the electrodes 23 in the vertical direction (direction perpendicular to the moving direction of the carriage 4) is uniformly set to 1/180 throughout all groups.
2 recording electrodes within the same group
Lateral direction of 3 (same direction as the moving direction of carriage 4)
The array pitch Px is uniformly set to 1/12 inch, and the interval between adjacent recording electrodes 23 at the group boundary is
It is defined as 2Px or 1/6 inch.
Furthermore, a holder 1 is mounted on the base 13 of the head body 8.
A vertically long protrusion 34 is formed that abuts on both sides of the group 4 and partitions the group boundary.

In such a configuration, the recording electrode 23 on which dots are to be formed in the process of applying a negative charge to the counter electrode 1 and moving the carriage 4 along the recording paper 2
A positive charge is applied to the ink via the metal rod 27, and the recording electrode 23 is supplied from the ink supply section 21 via the impregnation member 30.
The ink 19 supplied to the leading edge of the recording paper 2 is made to fly onto the recording paper 2.

For multicolor printing, an ink cartridge 12 filled with yellow, magenta, cyan, and black inks is attached to the head main body 8, and different inks are supplied from each ink supply section 21 to the recording electrodes 2 for each group.
Supply to 3. In this multicolor printing mode, adjacent recording electrodes 2 at the boundary of the group, that is, the holder 14
Since the interval between 3 and 3 is wider than Px, color mixing can be prevented. Since adjacent recording electrodes 23 are separated by the protrusion 34 at the boundary of the holder 14,
Color mixing can be further prevented.

For monochrome printing, a specific group of recording electrodes 23
However, it is also possible to fill all ink cartridges 12 with ink of the same color and drive all recording electrodes 23 to print. In this usage mode, the number of dots formed in the vertical direction during one reciprocating movement of the carriage 4 increases, so that high-speed printing can be performed by reducing the feeding operation of the recording paper 2.

Note that a holder may be provided in which a plurality of holders 14 are continuously formed integrally, thereby reducing the number of parts. In this case, a longitudinal groove is formed on the front surface of the holder to be located between the recording electrodes 23 adjacent to each other at the group boundary, and this groove prevents ink from flowing into the adjacent group. Color mixing in multicolor printing may be prevented.

Effects of the Invention As described above, the arrangement pitch of the recording electrodes in the same group in the direction along the carriage movement direction is uniform, but the interval between adjacent recording electrodes at the boundary of the group is set wide. , it is possible to prevent color mixing when using multi-color printing, and
The positions of all the recording electrodes change in a direction perpendicular to the direction of carriage movement with a uniform pitch, so in monochrome printing, all recording electrodes are driven to achieve high-speed printing. It has effects such as being able to perform.

[Brief explanation of drawings]

Figures 1 to 10 show an embodiment of the present invention. Figure 1 is an enlarged explanatory diagram showing the arrangement of some recording electrodes, and Figure 2 is an illustration of the arrangement of all recording electrodes. An explanatory diagram showing , Figure 3 is a longitudinal side view,
Fig. 4 is a perspective view, Fig. 5 is an exploded perspective view showing how the circuit board and head main body are attached to the carriage, Fig. 6 is an exploded perspective view showing the structure of the head main body, and Fig. 7 is the same as Fig. 1. FIG. 8 is a plan view showing a part of the base, FIG.
The figure is an exploded perspective view showing the mounting structure of the holding member to the holder, FIG. 10 is a partial longitudinal sectional side view showing an enlarged connection structure between the recording electrode and the circuit board, and FIGS. 11 and 12 are conventional FIG. 2 is an explanatory diagram showing the arrangement of recording electrodes in FIG. 1... Counter electrode, 2... Recording paper (recording body), 14...
Holder (holding body), 19... ink, 21... ink supply section, 23... recording electrode, 34... protrusion.

Claims (1)

[Scope of Claims] 1. A counter electrode and a recording electrode whose tip portion is allowed to adhere ink by capillary action are arranged opposite to each other with a recording body interposed therebetween, and an electric field between these counter electrodes and the recording electrode causes the recording electrode to In a printing device that forms an image on the recording medium by ejecting ink from a tip, a plurality of the recording electrodes form a group on a head body that is mounted on a carriage that moves along the counter electrode. A plurality of ink supply units are arranged side by side in a direction perpendicular to the direction of carriage movement in a plurality of groups, and are arranged in parallel in a direction perpendicular to the movement direction of the carriage, and a plurality of ink supply units supplying ink to the recording electrodes for each group are connected to the head main body. established in
The arrangement pitch Py of all the recording electrodes in the direction orthogonal to the direction of movement of the carriage is determined uniformly, the arrangement pitch Px of the recording electrodes in each group in the direction along the direction of movement of the carriage is determined uniformly, A print head characterized in that the interval between the recording electrodes adjacent to each other at the group boundary is set to be larger than the arrangement pitch Px. 2. The printing head according to claim 1, characterized in that a vertically elongated protrusion is provided between adjacent recording electrodes at the boundary between the two groups. 3. The print head according to claim 1, wherein a longitudinal groove is formed between adjacent recording electrodes at the boundaries of the groups. 4. The printing head according to claim 1, wherein the head main body is provided with a plurality of holders for holding a plurality of recording electrodes in groups.