JPH10291310A - Inkjet drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a driving voltage for every nozzle, correct an irregularity in weight of ink and achieve high image quality, by constituting the apparatus of a plurality of waveform generation devices corresponding to a plurality of nozzle rows and a waveform selection device selecting a waveform corresponding to the nozzle row thereby driving a predetermined part. SOLUTION: A first waveform generation device 1, a second waveform generation device 2, a third waveform generation device 3, a fourth waveform generation device 4 and a waveform selection device 9 on a head are connected by an output 5 of the first waveform generation device, an output 6 of the second wave form generation device, an output 7 of the third waveform generation device and an output 8 of the fourth waveform generation device. Each output of the waveform selection device 9 on the head after selecting a waveform is connected to one end of a piezoelectric body 10. The other ends of the piezoelectric body 10 are connected to a GND by a common line. Since the waveform generation device is provided for every row, a weight of ink can be corrected. Moreover, since a logic signal for controlling of the selection of the waveform is shared, the waveform selection device can be small in size, and the apparatus can be reduced in cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head control technique for an ink jet printer, and more particularly, to a control technique for an ink jet printer having a plurality of nozzle arrays in the same head.

[0002]

2. Description of the Related Art A configuration example of a conventional ink jet recording head will be described with reference to FIG.

In FIG. 4, an ink chamber 12 is provided by a chamber frame 11 and a vibration plate 13 to hold ink. The reduced ink used for the flight is supplied from the ink supply port 14. 10 is a piezoelectric body, one end is a diaphragm 13 and the other end is a fixed end,
Electrode pairs 15 are provided above and below in FIG. When the actuator of the head is configured as described above and a voltage is applied to the electrode pair 15 in advance and the charge is gradually discharged, the piezoelectric body 10 contracts rightward in the drawing, and the ink chamber 12 expands. Here, when a voltage is suddenly applied, the piezoelectric body 10 suddenly returns, the ink chamber 12 is also rapidly compressed, and the ink is pressed to eject the ink droplet 17 from the nozzle 16.

An ink jet recording head operates according to such an operation principle, and an actuator as shown in FIG.
It is composed of 56 (1000 in most cases) and is usually mounted on a serial printer and used.

FIG. 5 shows an actual operation example. (A) shows an example of a drive voltage waveform, and (b) shows a state of expansion / compression of the diaphragm 3 or the ink chamber 2, and the downward direction in the figure is the expansion direction.

In (a), the drive voltage starts from Vm and is directed toward GND and is held at GND (t1 + t2). However, the drive voltage is expanded during the ink chamber 2 and is held at Vp1 toward Vp1 (t).
(3 + t4) is related to the ink ejection amount in the compression process, and is maintained at Vm toward Vm (t5 + t6) is the pause process.
t1 to t6 indicate time, and the sum is the repetition period.
Vp1 is generally 10 to 50 [V] although it depends on the configuration of the actuator and the ink characteristics.

[0007] In (b), the applied voltage is statically changed to GN.
The maximum expansion of the ink chamber when D is set is shown. In the actual operation, an overshoot operation is performed as shown in the figure. Also,
Since the actuator forms a vibration system, the vibration is moderately damped as shown by the dotted line, and may greatly affect the next ink ejection. This is prevented by the voltage gradient in the pause process and the timings of t4 and t5, which are matched and attenuated quickly.

[0008] The weight Iw of the ink droplet is determined by the magnitude of the drive voltage Vp1 if the above timing is accurately controlled. The proper ink weight Iw of the head is
It is represented by a function of the drive voltage Vp1.

Iw = k · Vp1−Equation 1 The proper ink weight Iw of the head is obtained by measuring the weight of each ink when two points of Vp1 are applied, and calculating k in Equation 1 from the ink weight and the applied voltage. The appropriate ink weight Iw is determined. In addition, in order to efficiently process the ink, all the nozzles are caused to fly at once, and the average ink weight is measured.

Conventionally, as shown in the circuit diagram of FIG. 6, a drive voltage waveform is output from a waveform generator 18, input to a waveform selector 9, and applied to a piezoelectric body 10. At this time, the waveform selection device 9 is in an all-output ON state.

[0011]

However, when such an ink weight determination method is used, in an ink jet head having a plurality of nozzle rows in the same head, there is a possibility that dot weight variation may occur between the nozzle rows. .

Cyan is added to row 1 of a four-row head as shown in FIG.
Magenta is assigned to column 2, yellow is assigned to column 3, and black is assigned to column 4, and the driving voltage waveform of FIG.
When the voltage is applied to the column head, the average ink weight of the entire head is Iw as shown in FIG. 8, but column 1 is Iw, column 2 is 1.17 Iw, column 3 is 0.83 Iw, and column 4 is Iw It may be. When such variations occur, a print result in which red is strong as a whole is obtained. In order to reduce the variation, a method has been adopted in which the values of the capacitance of the piezoelectric material used in the nozzle row and those with similar displacements of the piezoelectric material are matched in four rows. Error cannot be corrected.

Accordingly, an object of the present invention is to provide a high quality ink jet printer which corrects variations in ink weight by setting a drive voltage for each nozzle row even when a plurality of nozzle rows exist in the same head. To provide.

[0014]

According to the present invention, there is provided an ink jet recording head comprising: a nozzle;
An ink chamber is composed of a plurality of actuators each composed of a piezoelectric material connected to the ink chamber, and a drive voltage having a predetermined waveform is selectively applied to each piezoelectric material to rapidly compress the ink chamber to eject ink. An inkjet driving device,
The first feature is that it comprises a plurality of waveform generators corresponding to a plurality of nozzle arrays, and a waveform selector which selectively drives a waveform corresponding to the nozzle arrays to a predetermined portion. It is sent from the device via a separate signal line,
A second feature is that a signal of the waveform generator corresponding to the plurality of nozzle rows is selected.

[0015]

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

(First Embodiment) FIG. 1 is a circuit diagram of a first embodiment of the present invention, in which a first waveform generator 1, a second waveform generator 2, and a third waveform generator are shown. 3. The fourth waveform generator 4 and the waveform selector 9 on the head are connected to the output 5 of the first waveform generator, the output 6 of the second waveform generator, the output 7 of the third waveform generator, It is connected to the output 8 of the fourth waveform generator. The outputs of the waveform synthesizing device 9 on the head are connected to one end of the piezoelectric body 10 after selecting the waveform. The other end of the piezoelectric body 10 is connected by a common line and connected to GND.

When the driving waveform (driving voltage Vp1) shown in FIG. 5A is commonly applied to the nozzle row shown in FIG. 7, the weight of the ink droplet flying from the nozzle row becomes Iw, as shown in FIG.
Column 2 is 1.17 Iw, column 3 is 0.83 Iw, column 4 is Iw
And it varies. In the present invention, the ink weight variation is corrected by providing a waveform generator for each column.

First, since the ink weight Iw can be obtained by applying the drive voltage Vp1 to the columns 1 and 4, the drive voltage Vp1 is applied to the two columns as they are.
That is, from the output 5 of the first waveform generator and the output 8 of the fourth waveform generator, the drive waveform shown in FIG. 2A is applied to the waveform selector 9.

Next, in column 2, since the ink weight becomes 1.17 Iw by applying the drive voltage Vp1, the drive voltage Vp1 is reduced by 14.5% and applied so that the ink weight becomes Iw. That is, from the output 6 of the second waveform generator, the drive waveform Vp2 of FIG. 2B is applied to the waveform selector 9. The relational expression with Vp1 is as follows.

Vp2 = 0.855 × Vp1−Equation 2 Finally, in column 3, since the ink weight becomes 0.83Iw by applying the drive voltage Vp1, the drive voltage Vp1 is set to 20 so that the ink weight becomes Iw. % And apply. That is, from the output 7 of the third waveform generator, FIG.
Is applied to the waveform selecting device 9. Vp
The relational expression with 1 is as follows.

Vp3 = 1.20 × Vp1-Equation 3 As a result, in the circuit configuration of FIG. 1, the ink weights of the ink droplets flying from columns 1, 2, 3, and 4 are all I as shown in FIG.
w, and ink droplets having no variation can be obtained.

Further, since one waveform selection device is provided for four waveform generation devices, the size of the waveform selection device can be reduced by using a common logic signal for waveform selection control, and the cost can be reduced. Becomes possible. Further, when the number of nozzles in one nozzle row is as small as 8, 16, and 32, the use of the waveform selection apparatus of the present invention, in which the ratio of the control unit is smaller, is more compact than mounting the waveform selection apparatus for each row. It becomes possible.

Since the waveform generator is divided into four or more by one head, the heat generation of the power amplifier which is the output device of the waveform generator can be reduced to 1/4. The maximum current of the power amplifier is also 1
/ 4, and the power amplifier can be configured without a small transistor or a radiator.

The variation of the dot droplets was reduced by correcting the driving voltage. However, when the variation of the dot droplets occurred due to the difference in the composition of each color ink, the driving waveform itself was set individually for each nozzle row. By doing so, it is needless to say that the variation can be reduced.

The present invention is as described above. However, the number of waveform generators and the number of driving waveforms in one cycle described in the above embodiment are merely examples, and four or more nozzle arrays are divided into a plurality of nozzle arrays. Of course, it can be embodied.

[0026]

As is apparent from the above description, according to the present invention, it is possible to provide an ink jet head driving device in which the ink weights between the nozzle rows in the same head are matched. Also, since the waveform generator was divided into multiple parts,
A printer set can be designed without any restrictions due to power consumption.

[Brief description of the drawings]

FIG. 1 is an inkjet drive circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a drive waveform diagram output to a piezoelectric body corresponding to a nozzle row in the configuration of FIG.

FIG. 3 is a diagram of ink droplets corresponding to each nozzle row in the configuration of FIG. 1;

FIG. 4 is a view for explaining an example of an actuator using a piezoelectric material constituting an ink jet recording head.

FIG. 5 is a diagram illustrating a waveform example of a drive voltage for driving a piezoelectric body, and the expansion and contraction processes of an ink chamber in response thereto.

FIG. 6 is a diagram of a conventional inkjet drive circuit.

FIG. 7 is a diagram of a nozzle plate of the inkjet head.

FIG. 8 is a diagram of ink droplets corresponding to each nozzle row in the configuration of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st waveform generator 2 ... 2nd waveform generator 3 ... 3rd waveform generator 4 ... 4th waveform generator 5 ... Output of 1st waveform generator 6 ... 2nd waveform generator 7 ... Output of the third waveform generator 8 ... Output of the fourth waveform generator 9 ... Waveform selector 10 ... Piezoelectric 11 ... Room frame 12 ... Ink chamber and ink 13 ... Vibration plate 14 ... Ink supply port 15 ... Electrode pair 16 ... Nozzle 17 ... Ink droplet 18 ... Waveform generator 19 ... Output of waveform generator

Claims (2)

[Claims] An ink jet recording head comprising a plurality of actuators each comprising a nozzle, an ink chamber, and a piezoelectric body connected to the ink chamber, and selectively applying a drive voltage having a predetermined waveform to each of the piezoelectric bodies; An ink jet driving apparatus for rapidly compressing an ink chamber and discharging ink, comprising a plurality of waveform generators corresponding to a plurality of nozzle rows, and a waveform selecting apparatus for selectively driving a waveform corresponding to a nozzle row to a predetermined portion. An ink jet driving device, comprising: 2. The apparatus according to claim 1, wherein the waveform selecting device selects a signal of the waveform generating device which is sent from each of the plurality of waveform generating devices via an individual signal line and corresponds to the plurality of nozzle rows. Inkjet drive device.