JPH03166959A - Image recording - Google Patents

Abstract

PURPOSE:To uniform density to be printed with each nozzle or head by a method wherein pulse voltage is impressed for specified impressing time to an electrode to meet an ink discharge characteristic measure for each nozzle or head. CONSTITUTION:Lowest density and highest density which become reference are taken respectively as DL, DH. Pulse impressing time when the lowest density DL is obtained, is taken as t, and pulse impressing time when the highest density DH is obtained, is taken as gamma. Since relation between impressing time and density is almost linear within a region from the lowest density DL to the highest densi ty DH, when the number of gradations is taken as K, a relation between optional gradation N and impressing time T can be expressed by the formula (1). There fore, where t for nozzle A and nozzle B is taken as tA, tB, gamma being taken as gammaA, gammaB, and impressing time T is taken as TA, TB, tables for gradation N and TA, and N and TB can be respectively prepared. M tables can be thus prepared for a multinozzle type ink jet head having M nozzles. Those tables are used as reference tables, and each gradation for each nozzle, i.e. a pulse width accord ing to density is applied to each nozzle electrode. Thereby, always uniform ink density can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image recording method using a multi-nozzle type or multi-head type recording head.

2. Description of the Related Art Recently, printers using drop-on-demand multi-nozzle inkjet heads that use electrostatic force or electrostatic force and air flow have been put into practical use. As this inkjet head, for example, the one shown in FIG. 2 is known. Air discharge ports 82 to 85 are perforated at equal intervals in the insulating substrate 81.
An orifice plate 87 is arranged parallel to the peripheral insulating substrate 81, and b1 ink ejection ports 88-91 are bored opposite to air ejection ports 82-85. Ink supply pipe 9
The ink chamber 93, which communicates with the ink reservoir through the ink reservoir 2, is filled with ink, and an ink meniscus is formed at each of the ink discharge ports 88 to 9l.

On the other hand, an air flow is sent into the air chamber 95 via the air supply pipe 94, passes through the air layer 96 formed by the insulating substrate 81 and the orifice plate 87, and passes through the air discharge ports 82 to 85 through sharp bends. It is arising and gushing out.

Electrodes are formed independently on the ink chamber 93 side of the ink discharge ports 88 to 9l, and these electrodes and the common electrode 8
A signal potential difference is applied by signal sources 97 to 100 between 6 and 9, and the meniscus of ink generated at the ink ejection port corresponding to the electrode where this potential difference occurs is stretched by electrostatic force, resulting in a rapid pressure gradient. This type of inkjet head ejects ink droplets by pulling them out using electrostatic force generated by applying an ejection signal. As shown in FIG. 3, the recording density fluctuates, and the amount of ink ejected is approximately proportional to the pulse width (application time) of the ejection signal applied to each nozzle of the head.

Problems to be Solved by the Invention However, in the case of a multi-nozzle type, the ink ejection opening (
Due to variations in the machining accuracy of the nozzles 88 to 91, there was a problem in that the applied pulse width (time)/concentration characteristics also varied as shown in FIG.

Similar problems also occur in heads of systems other than inkjet, such as multi-head type inkjet heads or thermal transfer multi-head types. The purpose of this is to eliminate density variations recorded in

Means for Solving the Problems The present invention provides an application time t1τ corresponding to a reference minimum density level DL and a reference maximum density level DH, respectively, to the pulse width-density characteristics measured for each nozzle or head in advance for each nozzle. This time interval is divided equally by the number of gradations K, and a pulse voltage is applied to each nozzle or head electrode for each application time depending on the required gradation. With the above configuration, a pulse voltage is applied to the electrode for a predetermined application time according to the ejection characteristics measured for each nozzle or head, so the density printed by each nozzle or head is becomes uniform.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows the characteristics of two arbitrary nozzles A and H among the pulse application time-density characteristics to the nozzle electrodes of a multi-nozzle type inkjet head according to an embodiment of the present invention. Minimum standard concentration,
The pulse application time when the maximum concentration becomes D L % D H % and the minimum density DL is t1, and the pulse application time when the maximum density becomes Do is τ. In the region from the lowest density DL to the highest density Do, there is an almost linear relationship between the application time and the density, so when the number of gradations is K, the relationship between any gradation N and the application time T is as follows. It can be expressed by the following formula.

Therefore, t at nozzle A1 and nozzle B is tAsta
Also, if τ is τA, τB1 application time (pulse width) is TeT, and Ts, tables for gradations N and TA and N and TB can be created, respectively. In this way, a multi-nozzle type inkjet head with M nozzles creates M tables, and this table is used as a reference table.
By applying a pulse width to each nozzle electrode according to each gradation and density for each nozzle, multi-nozzle type Even with an inkjet head, uniform density can always be obtained.

In the above explanation, the density uniformity of an inkjet type head has been explained, but density uniformity can be achieved for other types of heads such as a thermal transfer type head using a similar method.

Effects of the Invention As described above, the present invention takes the characteristics of each nozzle or head, determines the application time corresponding to the reference minimum density DLX maximum density DH, and further calculates the application time at any gradation. By calculating, creating a table for each nozzle housing or head, and referring to the table, and applying a pulse according to the recording characteristics to each nozzle or head, it is possible to eliminate variations in the recording density of each nozzle or head. can be corrected and a uniform density can be obtained, which is highly effective.

[Brief explanation of the drawing]

Fig. 1 is a density vs. application time characteristic diagram of a multi-nozzle type inkjet head according to an embodiment of the present invention, Fig. 2 is a sectional view of a multi-nozzle type inkjet head used in the present invention, and Fig. 3 is a , FIG. 2 shows an example of the density-applied voltage characteristic for one nozzle of the inkjet head of FIG. 2, and FIG. 4 shows an example of the density-applied voltage characteristic for each nozzle of the inkjet head of FIG. It is a diagram. 82-85...Air discharge port, 86...Common electrode, 8
7... Orifice plate, 88-91... Ink discharge port, 95... Air chamber, 97... Signal source.

Claims (1)

[Claims] Determine the pulse application time t and τ corresponding to the reference minimum density level and reference maximum density level predetermined in the pulse application time-density characteristics for each nozzle or each head of a multi-nozzle type or multi-head type recording head, respectively. , dividing the application time from t to τ equally by the number of gradations,
An image recording method characterized in that a time corresponding to a required gradation is determined from the characteristics of each nozzle, and a pulse voltage is applied to each nozzle electrode for that time.