JPS6123117B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adjustment device for adjusting the ejection height of ink droplets in an inkjet printer that controls the amount of charge of ink droplets in accordance with information to be printed.

The main components of the print head in such an inkjet printer are at least nozzles that eject ink droplets and charging electrodes that charge the ink droplets. Pressurized ink is introduced into the nozzle, and ink particles ejected from the tip of the nozzle are separated into ink particles of the same size at a frequency equal to the vibration frequency excited by the piezoelectric element. The ink terminals necessary for printing are given a charge amount corresponding to the print information by the charged electrodes, and unnecessary ink particles that are not printed are not given a charge. A constant voltage is applied to the deflection electrode, and the ink particles are deflected in proportion to the amount of charge. The charged ink particles pass above the gutter and reach the printing paper surface. Uncharged ink particles are collected in the gutter.

In order to print with good quality, it is necessary to adjust the positions of the main components such as the nozzle, charged electrode, deflection electrode, and gutter according to the purpose. The vertical positional relationship with is important. That is, ink particles that contribute to printing pass above the gutter, while ink particles that do not contribute to printing are collected by the gutter. Let D _CH be the amount of deflection required to obtain the height H of the currently printed character, for example, and let D _G be the amount of deflection required to allow the lowest ink droplet forming the character to pass through without coming into contact with the top surface of the gutter. Then, the total deflection amount becomes D=D _CH +D _G. In order to effectively utilize the amount of deflection D, it is necessary to set D _G as small as possible.

However, ink particles are not necessarily ejected from the nozzle accurately and in the right angle direction.
Furthermore, due to dimensional errors in the nozzle and other parts, it is almost impossible to mechanically accurately determine the dimension H _G between the position where the gutter enters and the top surface of the gutter. Therefore, if the above-mentioned dimension H _G can be adjusted with high precision, the lowermost ink particles forming the letters can be passed through while maintaining a small interval without coming into contact with the upper surface of the gutter, so that the above-mentioned D _G can be made smaller. It becomes possible to set.

However, until now, an accurate and simple structure for adjusting the H _G dimension has not been realized.

An object of the present invention is to eliminate the above-described drawbacks of the prior art and to enable the relationship between the position of undeflected ink particles in the gutter portion and the upper surface of the gutter to be adjusted easily and with high precision.

In the present invention, a nozzle assembly consisting of at least a nozzle and a charged electrode is mounted so as to be rotatable in the vertical direction using its tip as a rotational fulcrum, and the height of ink droplets ejected from the nozzle assembly is adjusted. It is characterized by being adjustable.

Nozzle assembly 1, deflection electrode 20 and gutter 21
The base 4 on which the base 4 is mounted runs along the guide bars 2 and 3 in the width direction of the printing paper 24, and while the base 4 is running, ink particles 30 ejected from the nozzle assembly 1 are applied to the printing paper 24 to perform printing. Do the following. The nozzle assembly 1 includes a nozzle 11, a piezoelectric element 12, a charging electrode 14, a case 10 for holding these, a partition disc 13, a cap 15, and the like. The nozzle 11 is held between the case 10 and the partition plate 13 via an O-ring 16, and the charging electrode 14 is held between the partition plate 13 and the cap 15. Ink pressurized by a pressure pump (not shown) is supplied to the nozzle assembly 1 via an introduction pipe 18 and guided into the nozzle 11 . Nozzle 11 is piezoelectric element 1
2, the ink particles 3 are ejected from the small hole at the tip of the nozzle 11 at a frequency equal to the excitation frequency.
0 is injected.

The ink particles 30 necessary to form characters are given a charge amount corresponding to the character signal by the charging electrode 14, and the ink particles 30 that do not form characters are given a charge amount corresponding to the character signal.
is not charged and the tip 1c of the nozzle assembly 1
jump out from At the deflection electrode 20, the ink particles 3
0 is deflected in proportion to the amount of charge, passes above the gutter 21 and reaches the printing paper 24. Ink particles 30 that do not form characters are collected by the gutter 21 without being deflected by the deflection electrode 20, and enter the drain 22 and collection container 23 to be reused.

As mentioned above, the dimension H _G between the position of the ink particles 30 arriving at the gutter 21 and the top surface of the gutter 21
must be adjusted with high precision. First, this adjustment device will be described. The case 10 of the nozzle assembly 1 has a recess 1 of the nozzle assembly 1 connected to the fulcrum pin 5 near the tip 1c of the nozzle assembly 1.
0b is provided, and the nozzle assembly 1 can rotate around the fulcrum pin 5 in the vertical direction. On the other hand, the leaf spring 6 whose lower end is attached to the base 4 via the screw 7 pushes the pin 17 passing through the case 10, and pushes the fulcrum pin 5 and the recess 1 of the nozzle assembly 1.
A force is applied to ensure the connection with b and to return the nozzle assembly 1 clockwise. A sloped portion 10a that contacts the tip of the adjustment screw 8 is provided at the bottom of the case 10. When the adjusting screw 8 is moved forward, that is, to the left in the figure, the nozzle assembly 1 rotates counterclockwise about the fulcrum pin 5, and when the adjusting screw 8 is moved backward, that is, to the right in the figure, the nozzle assembly 1 rotates counterclockwise about the fulcrum pin 5. The solid body 1 rotates clockwise.

Next, a method for adjusting the dimension H _G will be described.
Before adjustment, remove the deflection electrode 20 and remove the ink particles 3.
0 is made to fly out of the assembly 1 without being charged. First, the adjustment screw 8 is used to allow the ink particles 30 to pass over the top surface of the gutter 21, and the adjustment screw 8 is sent to the left in the figure until the ink particles 30 come into contact with the top surface of the gutter 21. That is, the ejection height of the ink droplets 30 of the nozzle assembly 1 is lowered. When it is confirmed that the ink particles 30 have contacted the upper surface of the gutter 21, (dimension H _G + diameter of ink particles 30 /
Send the adjustment screw 8 further to the left by 2). Now, if the pitch of the adjustment screw 8 is, for example, 0.5 mm, it is easy to determine the dimension H _G with an accuracy of about 20 μ.
After completing the adjustment, fix the nozzle assembly 1 with the fixing screw 2.
5 to the base 4. The deflection electrode 20 can then be attached and the entire operation completed.

In this embodiment, a nozzle 11 and a charging electrode 14 are built into the nozzle assembly 1. The purpose of this is to make the positional relationship between the nozzle 11 and the charging electrode 14 accurate. The same effects as the present invention can be expected even if the device has a structure in which in addition to the nozzle 11 and the charging electrode 14, components such as an ink particle phase sensor are incorporated.

Further, in this embodiment, the plate spring 6 is used to ensure the connection between the fulcrum 5 and the recess 10b of the case 10 and push it clockwise, but even if it is replaced with a coil spring, there will be no change in the basic structure of the present invention. It can be considered that it does not give

As described above, according to the present invention, the nozzle assembly is mounted so that it can rotate in the vertical direction using the vicinity of the tip of the nozzle assembly as a rotation fulcrum, so that the angle of the nozzle assembly can be adjusted to eject ink particles. When adjusting the height, the change in the position of the tip of the nozzle assembly in the horizontal and vertical directions can be made very small, so the horizontal and vertical positional relationship with other parts, such as the deflection electrode, remains unchanged, so the deflection electrode is mechanically It has the advantage of being easy to install.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, with FIG. 1 being a side sectional view and FIG. 2 being a plan view showing the main parts. In the figure, 1 is a nozzle assembly, 2 and 3 are guide bars, 4 is a base, 5 is a fulcrum pin, 6 is a leaf spring, and 8
is an adjustment screw, 10 is a case, 11 is a nozzle, 12
is a piezoelectric element, 14 is a charged electrode, 17 is a pin, 20
21 is a deflection electrode, 21 is a gutter, and 30 is an ink particle.

Claims (1)

[Scope of Claims] 1. A nozzle assembly that includes at least a nozzle in its rear position, a deflection electrode that deflects ink particles ejected from the nozzle according to the amount of charge thereof, and a gutter that collects unnecessary ink particles that are not charged. In an inkjet printer in which a base carrying a base is reciprocated along the printing direction and printing is performed during this reciprocating movement, a fulcrum pin provided on the base near the tip of the nozzle assembly; a recess provided at the tip of the nozzle assembly, one end of which is attached to the base, the other end of which is in contact with the nozzle assembly, presses the recess of the nozzle assembly against the fulcrum pin, and presses the recess of the nozzle assembly against the fulcrum pin; a spring that acts to push down the nozzle assembly around a fulcrum pin, and an adjustment body that is attached to the base so as to be movable back and forth and whose tip pushes up the rear of the nozzle assembly. . 2. The ejection height adjusting device for an inkjet printer according to claim 1, wherein the nozzle assembly is fixed to the base by tightening in a direction perpendicular to its rotating surface. 3. The jetting height adjusting device for an inkjet printer according to claim 1, wherein the spring is a plate spring.