JPH02227253A - Ink jet printer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an in-fetch printer, and more particularly to a technique for correcting dot formation positions. [Prior Art] In order to increase the number of dots per unit length in order to improve printing quality, a plurality of nozzles n, n, n...・Nozzle row N1. An inkjet head U having a diameter of Nm is attached to a base B, and the distance between each nozzle n is εr+
12m for 2 dots and 1 dot, and further nozzle row N+. An inkjet head is used in which the distance iJlβ3 between N2 is set to an integral multiple, for example, 6 dots. Note that the symbol P in the figure indicates printing paper. According to such an inkjet head, the nozzle rows N,
On the other hand, by ejecting droplets with the nozzle row N2 delayed by a time difference ΔT of, for example, 6 dots, which corresponds to the distance β between the nozzle rows, it is possible to form a straight line with a large number of dots in the same straight line. As a result, high-density printing can be performed. [Problem to be solved by the invention 1] However, the nozzle rows N+ and N forming the same row
Although each individual nozzle forms a dot on the same line, between different nozzle rows. As will be described later, there are differences in the flying direction of ink droplets due to the nozzle shape and the state of ink accumulation on the nozzle surface, so in reality, there may be deviations e and d in the dot formation position (Fig. 7 (a) (b)).
)), resulting in a decrease in print quality. The present invention has been made in view of these problems, and its purpose is to provide an inkjet printer with high print quality by correcting dot formation positions between nozzle rows. [Means for Solving the Problems] In order to solve such problems, a drive circuit that drives each nozzle and a delay means that sets a delay time of a print timing signal that drives a nozzle array are provided, and the delay means The actual distance between nozzle rows was made larger than the determined distance between nozzle rows. [Operation] By setting the actual distance between nozzle rows by taking into account the variation in the dot formation position due to bending of ink droplets with respect to the distance between nozzle rows set by the delay means, the dot formation position can be corrected and the dots can be printed at the same distance. Dots are formed on the line. [Example] The details of the present invention will be explained below based on the illustrated example. FIG. 1 is a block diagram showing an embodiment of the present invention, in which symbols l and 2 are connected to a data bus 8 that receives print signals from a host device (not shown), and is similarly activated by a select signal from the host device. The output side of this circuit is connected to a signal input terminal of a drive circuit 21, 22 for driving a nozzle array via a latch circuit 11, 12, respectively. Reference numerals 21 and 22 are drive circuits for driving the nozzle arrays, which are connected to piezoelectric elements DI that drive the nozzle arrays N, , N, . 30 is a print timing correction circuit which delays the timing signals Tsl and Ts2 inputted from the host device by a certain time, and delays each nozzle row latch circuit 11, 12 and drive circuit 21.
Delay circuit 31.3 that outputs a start signal to the control terminal of No. 22
It is composed of 2. When the data to be printed is output from the host device to the bus 8, the main selector 6 divides the data into column-by-column data of the nozzle columns N, , N, and then the pre-latch circuits 1 and 2 select the data into row-by-row data. The signals are latched into latch circuits 11 and 12 as signals for each dot. On the other hand, the timing signal Ts inputted to the timing correction circuit 30 generates a pulse mark delayed by a set ΔT time, and outputs it to the drive circuits 21 and 22. As a result, the nozzle row N+ of each row is changed from the timing signal Tsl to △T1.
Since it is driven with a time delay, the moving speed of the carriage v
The dot formation position changes by a distance corresponding to x△TI,
Similarly, the timing signal Ts2 for driving the nozzle row N is delayed by the time ΔT2 set by the delay circuit 32, and a dot is formed at the reference position. FIGS. 2(a) and 2(b) are nozzle layout diagrams of an inkjet head showing an embodiment of the present invention, and the arrangement is similar to FIGS. 6(a) and 6(b) of the conventional example described above. Here, for example, the distance between each nozzle n is 20, I2□ is 1/90 inch and 1/180 inch, respectively, and the distance I2 between nozzle rows N+ and Nw is
．． Set to 1/30 inch (6 dot spacing). Each interval dimension shall be measured at the center of each nozzle n. Same figure'
('b) shows the shape and ejection direction of ink droplets when ink is ejected with this head.According to detailed observation, there is more ink between the nozzle rows N, , N than on the outside. It was found that a pool 5 was formed, and therefore the ink droplet flew inward as shown in the figure. When the ink droplet is divided into main drop 3 and satellite drop 4, the flight speed of main drop 4 is fast and the flight speed of satellite drop is slow, arrow 7
represents the moving direction of the carriage. In the explanation of FIG. 1, the delay time of the drive timing of nozzle row N2 with respect to the drive timing of nozzle row N+ and ΔT
Let the moving speed of the carriage be V, and the actual nozzle row N,
, N, when linear printing is performed with the interval ΔT-V=l/30 inches, the shape of the ink droplets and the inward flight described above result in the formation of dots as shown in FIG. 7(a),
When a sufficient straight line is not obtained, that is, when printing is performed while the carriage moves in the direction of arrow 7, the ink droplets fly inwards, causing the dots produced by nozzle row N1 to move toward nozzle row N1.
The dots produced by the nozzle row N3 are laterally elongated compared to the dots produced by the nozzle row N3, and the dots produced by the nozzle row N1 advance (to the left), so that the center of gravity of the dots does not lie on a straight line. Therefore, the distance β between the nozzle rows N, , Na is enlarged and corrected so that the dot positions are on a straight line. For example, in the delay means, when the distance between the nozzle rows is set as 1/30 inches, when the platen gap is l-1.5 mm, the actual distance between the nozzle rows N+, Ns is corrected by 20 to 30 um, β, C, ff-=
β is determined to be 1/30 inch 20 to 30 μm. In this way, nozzle row N1. By increasing the Ni distance β than the value determined by the delay means, when printing in a straight line, the deviation e of the center of gravity position can be reduced as shown in Fig. 2(c), and the dots on the straight line can be made smaller. Obtainable. FIG. 3(b) shows another typical situation that is likely to occur during ink droplet ejection.The main drop 3, which has a flight speed, travels almost straight, but the satellite drop 4, which has a flight speed, It is easily influenced by the pool 5 and shows a state in which it flies inward. At this time, nozzle row N,
The dot formation state before correction of the distance C1 between N1 is shown in Figure 7 (b
), the main drop moves almost straight, so the dot formation positions by the main drop are almost aligned between rows, but regarding the dot formation by the satellite drop, the satellite drop by the nozzle row N is absorbed by the main drop part and is not noticeable. , on the other hand, the satellite drop produced by the nozzle row N forms a horizontally long dot on the printing paper surface P, as if trailing in the direction in which the carriage moves. Therefore, if the distance mlβ between the nozzle rows is expanded so that the deviation amount d in Fig. 7(b) is evenly distributed to the left and right, Fig. 3(C
), the amount of deviation d can be reduced. According to the results of verifying printed samples for each product value of the amount of deviation d by a large number of people, it was found that if d≦0.1 mm, the printing quality would not be noticeable and would not pose a problem. Distance between nozzle rows I2. must be set so that d≦0.1mm. FIG. 4 shows another embodiment of the ink jet head, in which flow channels and nozzles n are formed on both sides of a substrate 13 by photoetching, and a diaphragm 14 is bonded thereon. However, in the flow path formed by photoetching, the shape of the nozzle n becomes a dome shape as shown in the figure due to the effect of side etching. In such a shape, it is observed that ink droplets fly more easily toward the curved portion of the nozzle having a longer circumference and fly inward. In particular, satellite drops tend to fly inwards. Therefore, also for the inkjet head manufactured in this way, the distance β between the nozzle rows N3 and N3 described above,
A dot formation position correction method that enlarges and corrects the dot formation position is very effective. FIG. 5 shows another embodiment of the inkjet head, and shows nozzle rows N1 to N in which a plurality of nozzles n, n, . . . are arranged in a row.
This is an inkjet head for a color printer, in which the vertical relative positions of the nozzles n in each row are the same, and the ink color is changed for each row. It is clear that the above-described method of the present invention has similar effects on this head as well. In this case, the distance between Na and Ns will be corrected to be smaller than the actual printing interval. [Effects of the Invention] As explained above, in the present invention, by designing the actual distance between the nozzle rows to be larger than the electrically determined distance between the nozzle rows, it is possible to reduce the deviation in the dot formation position that occurs between the nozzle rows. It is possible to reduce the size and achieve high quality printing.

[Brief explanation of the drawing]

Figure 1 is a block diagram of an apparatus showing an embodiment of the present invention, Figures 2 (a) and (b), Figures 3 (a) and (b), and Figure 4 (a).
(b), FIG. 5(a), and (b) are diagrams showing an example of the nozzle arrangement of an inkjet head, and FIG. 2(C),
FIG. 3(C) is a diagram showing the corrected dot formation state, FIGS. 6(a) and (b) are diagrams showing the conventional example, and FIGS. 7(a) and (b).
) are diagrams showing conventional dot misalignment states. n... Nozzle P... Printing paper, g... Gap Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki (and 1 other person) 3 ・ ・
... 31, 32 ・ ・ N+, ~N4 ・Main drop, ・Satellite drop, ・Ink pool.・Carriage movement direction, ・Latch circuit, ・Substrate, ・Diaphragm, ・Drive circuit, ・Timing adjustment circuit, ・Delay circuit, ・Ink nozzle row, Figure 4, Figure 5, Figure 6, Figure 70

Claims (1)

[Claims] An inkjet printer comprising an inkjet head formed by arranging a plurality of nozzles arranged in rows in a row direction, the inkjet head being movable in the row direction, and a drive circuit for driving each nozzle and the nozzle row. 1. An inkjet printer comprising a delay means for setting a delay time of a print timing signal that drives the inkjet printer, and an actual distance between nozzle rows is made larger than a distance between nozzle rows determined by the delay means.