JP2000135780A - Method and device for image recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for image recording in which dispersion of density recorded by each nozzle or each head is eliminated. SOLUTION: Impressed times (t), (τ) corresponding to a standard minimum density level DL and a standard maximum density level DH, which are present from linear pulse impressed time-density characteristic in each nozzle A, B or each head of a recording head, are obtained respectively. The interval between impressed time (t) and (τ) is divided equally by gradation number. A time corresponding to the required gradiation is obtained from the above characteristic of each nozzle A, B or each head. A pulse voltage is impressed to the electrodes of each nozzle A, B or each head for the above time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image recording method and apparatus using a multi-nozzle type or multi-head type recording head.

[0002]

2. Description of the Related Art Recently, a printer using a drop-on-demand type multi-nozzle type ink jet head using electrostatic force or electrostatic force and air flow has been put to practical use. As this ink jet head, for example, the one shown in FIG. 2 is known. Air discharge ports 82 to 85 are perforated in the insulating substrate 81 at equal intervals.
Orifice plate 87 parallel to insulating substrate 81 around 82 to 85
Are arranged, and the ink discharge ports 88 to 91 are air discharge ports 82.
Perforated facing ~ 85. The ink chamber 93 communicated with the ink reservoir via the ink supply pipe 92 is filled with ink, and ink meniscuses are generated in the ink discharge ports 88 to 91, respectively.

On the other hand, an air flow is sent into an air chamber 95 through an air supply pipe 94, passes through an air layer 96 formed by an insulating substrate 81 and an orifice plate 87, and sharply bends from air discharge ports 82 to 85, respectively. Is spouting.

Electrodes are formed independently on the ink chamber 93 side of the ink discharge ports 88 to 91 so that signal potential differences are applied between these electrodes and the common electrode 86 by signal sources 97 to 100. The meniscus of the ink generated at the ink discharge port corresponding to the electrode where the potential difference has occurred is stretched by electrostatic force, and a sudden change in the pressure gradient causes the ink liquid to flow from the air discharge port corresponding to the electrode where the potential difference has occurred. Discharges and flies.

In this type of ink jet head, ink droplets are pulled out by electrostatic force generated by application of a discharge signal, and the recording density, that is, the ink discharge amount is applied to each nozzle of the head as shown in FIG. It is almost proportional to the pulse width (application time) of the ejection signal.

[0006]

However, in the case of the multi-nozzle type, the applied pulse width (time) -density characteristics also vary as shown in FIG. 4 due to variations in the processing accuracy of the ink discharge ports (nozzles) 88 to 91. There was a problem that variation occurred.

[0007] A similar problem also occurs in a head other than the ink jet system such as a multi-head type ink jet head or a thermal transfer multi head type.

The present invention has been made to solve the above-mentioned problems of the prior art, and has as its object to eliminate variations in density recorded by each nozzle or head.

[0009]

According to the present invention, a reference minimum density level DL and a reference maximum density level DH are respectively added to a pulse width-density characteristic measured for each nozzle or head in advance.
Is obtained for each nozzle, and the application time T at an arbitrary gradation N when the number of gradations is N is
Calculate based on the following (Equation 3), create a table of gradation and application time for each nozzle or head, and determine the time corresponding to the required gradation from the table of each nozzle or head, The pulse voltage is applied to the electrode of each nozzle or each head for that time.

[0010]

(Equation 3)

In the above configuration, since the pulse voltage for a predetermined application time is applied to the electrodes in accordance with the ink ejection characteristics measured for each nozzle or head, the density printed by each nozzle or head becomes uniform. Become.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the characteristics of two arbitrary nozzles A and B among the pulse application time-density characteristics to the nozzle electrodes of the multi-nozzle type inkjet head according to the embodiment of the present invention.
The reference minimum density and maximum density are DL and DH, respectively, the pulse application time when the minimum density DL is t, and the maximum density DH.
Let τ be the pulse application time when In the region from the minimum density DL to the maximum density DH, the application time and the density have a substantially linear relationship. When the number of gradations is K, the relation between an arbitrary gradation N and the application time T is as follows. It can be represented by the following equation (Equation 4).

[0013]

(Equation 4)

Therefore, assuming that t in nozzles A and B is tA and tB, τ is τA and τB, and application time (pulse width) T is TA and TB, gradations N and TA, and N and TB
Each table can be created. In the multi-nozzle type ink jet head having M nozzles as described above, M tables can be formed, and this table is used as a reference table, and a pulse width corresponding to each gradation, that is, a density, is set for each nozzle. By applying the voltage to the electrodes, a uniform density can always be obtained even in a multi-nozzle type ink jet head having a variation in nozzle perforation, that is, a variation in ink ejection amount.

In the above description, the density uniformity of the ink jet type head has been described. However, the density uniformity can be achieved in the same manner for other types of heads such as a thermal transfer type head.

[0016]

As described above, according to the present invention, the characteristics of each nozzle or head are taken, the application time corresponding to the reference minimum density DL and maximum density DH is determined, and the application time at an arbitrary gradation is determined. The time is calculated from the above (Equation 1), a table is created for each nozzle or head, the table is referred to, and a pulse corresponding to the recording characteristics is applied to each nozzle or head, so that the recording of each nozzle or head is performed. By correcting variations in density, a uniform density can be obtained,
The effect is great.

[Brief description of the drawings]

FIG. 1 is a concentration-application time characteristic diagram of a multi-nozzle type inkjet head according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a multi-nozzle type inkjet head used in the present invention.

FIG. 3 is a graph showing concentration-application time characteristics of one nozzle of the inkjet head of FIG. 2;

FIG. 4 is a diagram showing one example of a concentration-application time characteristic in each nozzle of the inkjet head of FIG. 2;

[Explanation of symbols]

 82 to 85 Air outlet 86 Common electrode 87 Orifice plate 88 to 91 Ink outlet 95 Air chamber 97 Signal source

Claims (2)

[Claims] 1. An application time t corresponding to a reference minimum density level and a reference maximum density level predetermined in a pulse application time-density characteristic in each nozzle or each head of a multi-nozzle type or multi-head type print head. ,
τ is obtained, and the application time T at an arbitrary gradation N when the number of gradations is K is calculated based on the following (Equation 1), and a table of the gradation and the application time is provided for each nozzle or head. An image recording method comprising: obtaining a time corresponding to a required gradation from the table of each nozzle or each head; and applying a pulse voltage to each nozzle or an electrode of each head for the time. (Equation 1) 2. An application time t corresponding to a reference minimum density level and a reference maximum density level predetermined in each nozzle or each head of the multi-nozzle type or multi-head type recording head or pulse application time-density characteristics. ,
τ is calculated, and the application time T at an arbitrary gradation N when the number of gradations is K is calculated based on the following (Equation 2), and a table of the gradation and the application time is provided for each nozzle or head. An image recording apparatus, wherein a time corresponding to a required gradation is created from the table of each nozzle or each head, and a pulse voltage is applied to each nozzle or an electrode of each head for the time. (Equation 2)