JPS6294071A - Head drive method for printer - Google Patents

Abstract

PURPOSE:To adjust the positioning of each recording head >=1 dot unit by delaying a drive signal for a printer by an optional time with respect to a signal outputted whenever the prescribed angle of a rotating drum rotates. CONSTITUTION:Ink heads 4, 5, 6 and 7 and emitting ink droplets different in color are arranged at different positions in terms of circular directions by facing the outer periphery of the rotating drum 3. According to the counted value of a pulse signal B from a rotary encoder 13, which is outputted whenever the prescribed angle of the rotating drum 3 rotates, the timing when each ink head during one rotation of the rotating drum 3 starts and ends recording is set, and pulse signals Py, Pm and Pb permitting the recording action of each ink head are formed. A delay circuit 14 forming any delay time is installed at the preceding stage of a head drive waveform generator circuit 14 at every head. In each head, the delay time of the delay circuit 15 is individually set, and each ink head is driven at independent timing.

Description

[Detailed description of the invention] [Industrial application field] The present invention is a rotating drum scanning type printer.

In particular, the present invention relates to a head driving method in a printer equipped with a plurality of recording heads for color printing or the like.

[Conventional technology]

In the conventional inkjet printer, which is an example of a single-rotation drum scanning printer,
The 5j: eel/rad drive method shown in Japanese Patent No. 984 is adopted.

That is, this head driving method will be explained using the drawings from FIG. 3 onwards. FIG.
) is rotated via the belt (2) by a rotating drum (
3) in a way facing the outer periphery of 1. There are four ink heads (4), (51, (6+), (71) or JL'C supported by a common support member (head carriage) (8).This ink head f41, (5), (6)
, (7) are respectively yellow.

Magenta, cyan, black ink drops? Rotating drum (
3) The ink heads f41, i51, f print each color by ejecting it toward the upper recording paper.
61.

The attachment positions of (7) to the support member (8) (and the jetting positions of Q-1 ink droplets) differ in the circumferential direction of the rotating drum (3), but are the same in the axial direction. .

Moreover, the support member (8) has two boots January 91,01
The supporting member (8) is intermittently moved from left to right by a pulse motor α connected to one pulley (9). There is.

Furthermore, in the rotary encoder 03 connected to the rotating drum (3), as shown in FIG.
Pulse signals A and B in which one pulse appears each time the rotary drum (3) rotates by a predetermined angle (recording density on the circumference of the rotary drum (3), that is, equivalent to one dot) and each time the rotary drum (3) rotates once. Pulse signal 2 in which one pulse appears is output, and here, the phase of pulse No. 1a A and B is 9.
The difference is only 0°, which identifies the direction of rotation of the rotating drum (3).

Then, the servo motor (1) rotates the rotary drum (3) to perform main scanning, and the pulse motor α moves the support member (8) that supports each ink head +41, (51, +61, and (7)) left and right. The ink heads f41 and (51
, (6) and (7) to eject ink droplets and perform predetermined recording.

Here, it is necessary to specify the printing position of each color for each head, but each ink head (4), (51, +6),
(7) has a different physical position in the inner circle direction of the rotating drum (3), so the position of each recording position in the circumferential direction is determined by the output pulse of the low reencoder. It will be done.

Figure 5 shows this relationship, and shows the rotating drum (3
), after one elementary pulse of pulse signal 2 appears per rotation of the drum, the yellow ink head (4) located on the upstream side in the rotational direction of the drum starts recording, and then, with a delay of time T, magenta .

Each ink head for cyan and black +51, +6
1. Recording according to (7) is started sequentially. here,
The time T is determined by the rotational speed of the rotating drum (3) and the distance between each ink head (41, (51° (61, [7)). , (51, +61,
(7) Pulse signals Py, Pm, P that permit the recording operation
c and Pb (recordable at high level) are created by output pulses from rotary encoder αJ.

That is, each ink head f41, (51, (61
, (7), recording start and end timing setting means consisting of digital switches are gold-plated, and each setting means sets pulse number 1d B corresponding to the rising timing of each of the pulse signals Py, Pm, Pc, and IFb. The prime pulse numbers are +, 2, and 3.

K4 and Q pulse signals Py, Pm, Pc, P
The number of elementary pulses Kw of the pulse signal B corresponding to the high level time width of b is set in advance, and the standing-elbow timing of the pulse signal 2 is set to 0 during one rotation of the rotating drum (3).
Then, the elementary pulses of pulse signal B are started to be counted, and this count value is +, 2, Kg, 4.
(recording! 7fJ start timing), each pulse signal Py, Pm.

Pc, Pb? '1. -Ff′? 1 stand 1-ke, roughly, count value crab + +FIW, K2-) K,
w, K, a + K, w, K4-4- When reaching Kw (recording end timing), each pulse signal "L"
Prn, Pc, and Pb are respectively f h standing T' If le.

And each ink head (4), (51, +6)
, (7), each pulse signal Py,
While Pm, Pc, Ph are at the high level, as shown in FIGS. 6 and 7, each head drive signal generation circuit (L (a) A head drive signal of a predetermined drive waveform is generated at the rising timing of the elementary pulse of the pulse signal B, and the head drive is performed under the AND condition of the number and the recording data.

By the way, in the printer, each ink head (
4) , +51 , (6) , and (71) vary depending on the mechanism error and the way they are attached to the support member (8), resulting in misalignment of each color during recording.

Therefore, each ink head (41, +51, (6)
(In order to improve the positional deviation between records due to force,
Conventionally, each ink head had +41, +5), (
6) +, 2, Ka to the set value of the timing setting means using the digital switch in (7).

Change K4 and install each ink head (41, (51, (6)
), (pulse signal Py that permits the recording operation of 71
, Pm, , Pc, and Pb, positioning between each head is performed by changing the rising timing of Pb.

[Problem that the invention attempts to solve]

However, in the above method, each ink head f41, +5+, +6 in each rotation of the rotating drum (3)
) and (7) are adjusted (smooth) in units of one pulse of pulse signal B from the low reencoder o3, that is, in units of one dot in the recording density.
Since positioning is performed by doing this, it is not possible to improve minute positional deviations of one dot or less. Assuming that the distance between dots is 100 μm, alignment in units of ]00)lrn is possible, but positional deviations less than +00)tm cannot be adjusted, and there is a limit to the improvement of recording quality (image quality). .

Note that if a high-resolution rotary encoder is used in which the number of elementary pulses of pulse signal B in one revolution of the rotating drum (3) is greater than the recording density in the circumferential direction of the drum, the interval of one pulse unit of pulse signal B , each ink head +4) , (51,
(61, (7) minute positioning becomes possible, but in reality there is no rotary encoder suitable for this purpose, and even if it existed, it would be unnecessary because the number of elementary pulses would be greater than the recording density.) There will be many pulses,
This causes the disadvantage that the control becomes complicated, and it is desirable that the number of pulses of the pulse signal B of the low reencoder and the number of dots of the recording density be the same.

Therefore, in the present invention, when each of a plurality of recording heads is driven using a pulse number outputted every time the rotary drum rotates by a predetermined angle, that is, a pulse signal corresponding to one dot of recording density, each recording head is It is an object of the present invention to provide a head driving method capable of performing minute blue and blue matching on the order of one dot or less.

[Means for solving problems]

In this invention, a plurality of recording heads are arranged at different positions in the circumferential direction of a rotating drum, and a drive signal for each of the recording heads is formed by a pulse signal output every time the rotating drum rotates by a predetermined angle. The head driving method for a printer as described above is characterized in that a delay circuit is provided to delay the pulse signal by an arbitrary time, and the output pulse signal of the delay circuit is used as the output timing of the drive signal for the recording head. be.

[Effect]

Therefore, in the printer head driving method of the present invention, the recording head driving signal is outputted at a timing in which pulse No. 48 is delayed by an arbitrary period of time in the delay circuit with respect to the pulse signal outputted every time the rotary drum rotates by a predetermined angle. By adjusting the delay time of the delay circuit within the range of the period of the pulse signal corresponding to the distance between the dots of the recording density, the alignment of each recording head can be adjusted in a minute range of one dot or less. It becomes possible.

〔Example〕

Next, the present invention will be explained in detail with reference to FIGS. 1 and 2 showing one embodiment thereof.

Similar to Ail's description, yellow is placed at different positions in the circumferential direction so as to face the outer periphery of the rotating drum (3).

Ink heads (4), +5), (6), which eject magenta, cyan, and black ink droplets, respectively.
(7) and each ink head (4) in one rotation of the rotating drum (3).

The recording start and recording end timings of +51, +6) and (7) are output every rotation of the rotating drum (3) at a predetermined angle (corresponding to one dot of recording density on the circumference of the rotating drum (3)). Based on the count value of the pulse signal B from the low reencoder q3,
7, each ink head +41, +51, +6)
, (7) Pulse signals Py, P that permit the recording operation
m, Pc, Pl).

Then, each ink head (41, (51, (61, (7)
1, each of the pulse signals Py, Prn, Pc
, Pb: While at high level, the rotary encoder 0: outputs L'L pulse signal BK to each ink head (41, (51, (63).

When forming each drive signal in (7), as shown in FIG.
A delay circuit αυ for forming an arbitrary delay time is provided in the preceding stage of 4), and the pulse equalization signal B is input to the delay circuit QQ to form an output pulse signal delayed by the delay time ゛rS. The head drive signal is inputted to a generation circuit to generate a head drive signal that is driven at the rising timing of the output pulse signal.

Figure 2 shows this relationship.

Here, each ink head (4), (51, +6)
, (7), if the delay time Ts of each delay circuit 09 is set individually, each ink head (4),
(51, +6) and (7) are driven at independent timings.

Furthermore, when the period of pulse IA No. B is Tu, the delay time Ts of the delay circuit (19) can be set in the range of O~',ru.As a result, the distance between the dots of the recording density is set] OO )tm, each ink head (4)
.

By setting the delay time Ts of the delay circuit 09 for each of t51, (6), and (7), the delay time Ts of the delay circuit 09 can be set from 0 to 100! rn
Positioning is possible within the range of .

Then, each ink head (4), (5), (6
), (7), by changing the setting value of the timing setting means using a digital switch, each ink head +41, (5),
f6), f7) pulse signals Py, Pr port, Pc
, the conventional coarse adjustment method that changes the rise timing of Pb in units of dots, and the delay circuit a! '9 delay time ゛P
Each ink head +41, (
5], t'6), and (7) are performed.

Note that the delay time TS of the delay circuit a9 can be set and changed either analogously or digitally depending on the configuration of the delay circuit α9.

Moreover, it goes without saying that the present invention C-1 can be widely applied not only to the inkjet printer G but also to other printers and printers using a rotating drum scanning method.

〔Effect of the invention〕

As described above, according to the printer head driving method of the present invention, minute positioning of one dot or less is possible in multiple recordings, and positional deviations between recordings of the recording head can be prevented. It can be greatly improved and allows recording of higher quality images.

[Brief explanation of drawings]

1 and 2 show one embodiment of the printer head driving method of the present invention, FIG. 1 is a block diagram of the main part of the recording head driving circuit, and FIG. 2 (21) and (b) are waveform diagrams of pulse signal B and head drive signal, respectively;
Fig. 3 is a schematic configuration diagram of an inkjet printer, Fig. 4 is a waveform diagram of the pulse signal output from the low reencoder, Fig. 5 is a waveform diagram of the pulse signal for ink head drive control, and Fig. 6 and the following diagrams. The drawings show a conventional head driving method, and FIG. 6 is a block diagram corresponding to FIG. 1, and FIG. 7(a)
and (IJ)? Figure 2 (a) and (b)
) is a waveform diagram corresponding to. (3)...1.1121 rotation drum, (41, (5),
(6), (7)...Ink head, rm...Delay circuit.

Claims (1)

[Claims] (1) A plurality of recording heads are arranged at different positions in the circumferential direction of a rotating drum, and a drive signal for each of the recording heads is formed by a pulse signal output every time the rotating drum rotates by a predetermined angle. In the printer head driving method according to the present invention, a delay circuit is provided to delay the pulse signal by an arbitrary time, and the output pulse signal of the delay circuit is used as the output timing of the drive signal of the recording head. Driving method.