JPH0195057A - Ink discharge adjuster of ink jet recording head - Google Patents

Abstract

PURPOSE:To enable stable image formation by altering the driving condition for an ink jet recording head from the data on ink discharge preset in the recording head, so as to adjust the discharge amount. CONSTITUTION:Upon inspection of a recording head for example, a semi-fixed resistor 2 mounted on recording head 1 is fixed at a suitable value according to the discharge amount such as an ink droplet diameter regarding to a drive voltage of fixed value. Comparators 3a, 3b each receives voltage divided by the resistance value of resistor 2 and compares it with reference voltages Va and Vb. An encoder 4 receives the output of the comparators 3a, 3b, codes it '0'-'2' according to input signal, and sends the result via data bus DB. MPU5 reads an output of the encoder 4 after reset action at the time of Power-on to identify where the amount of ink droplets of the head 1 ranks. A correction is obtained by reference to look-up table 7 loaded with values after correction of each input value for every rank of the amount of ink droplets.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application in Ea Industry 1 The present invention relates to an inkjet recording apparatus.

[Prior art 1] An inkjet recording device, in which ink, which is a recording liquid, is ejected in small droplets from an ink discharge port and performs recording by adhering these droplets to a recording surface is one of the various currently known recording devices. Among these, it is recognized as an extremely effective recording device because it performs non-impact recording with almost no noise during recording, is capable of high-speed recording, and can record on plain paper. It is being

A recording head applied to such an inkjet recording device generally includes a minute liquid ejection opening (orifice),
A fluid flow path, an energy acting part provided in a part of this liquid flow path, and an energy generating means such as an electromechanical transducer or an electrothermal converter that applies droplet formation energy to the liquid in the action part. have.

Furthermore, it is of course desirable that the printing conditions and images produced by the recording device be beautiful and precise, and for this purpose, inkjet recording devices are known that include a recording head in which a plurality of small orifices are arranged closely together.

Furthermore, an inkjet recording apparatus is provided in which a predetermined number of such print heads are arranged corresponding to a predetermined number of ink colors to perform color recording, or a predetermined number of such print heads are arranged corresponding to a predetermined number of ink densities. An inkjet recording device that is capable of halftone recording has been developed.

[Problems to be Solved by the Invention] However, when there are individual differences between recording heads, that is, when the shapes and dimensions of orifices, liquid flow paths, and energy generating means vary among recording heads. In this case, even if the energy generating means is driven with a required voltage, the diameter of ink droplets ejected from head to head or the diameter of dots on the recording medium vary. As a result, the ink density on the recording medium differs depending on the recording head, and it is conceivable that the desired color tone and gradation may not be obtained, or that the formed image will not be uniform between devices.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink ejection amount adjustment device for an inkjet recording head that enables stable image formation by correcting variations in ink ejection amount due to individual differences among the recording heads.

[Means for Solving the Problems] To this end, the present invention provides information presentation means that is provided in an inkjet recording head and presents information indicating an evaluation of the amount of ink ejection when driven under predetermined conditions; The present invention is characterized by comprising an adjusting means for changing the driving conditions of the inkjet recording head based on the presented information and adjusting the ink ejection amount.

[Function] According to the present invention, variations in ejection amount between print heads due to individual differences in the print heads are corrected by the adjustment means based on information indicated by the presentation means provided in the print heads.

Therefore, stable image formation is possible regardless of individual differences among recording heads.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

(Example 1) FIG. 1 shows an example of an inkjet recording apparatus according to the present invention. Here, 1 is an inkjet recording head having an electrothermal converter as an energy generating means, and has a liquid ejection opening (orifice) for ejecting recording ink droplets to form flying ink droplets, and each orifice. The liquid flow paths are arranged in high density and communicate with each other, and each liquid flow path has an electrothermal converter arranged therein.

Reference numeral 2 denotes a semi-fixed resistor mounted on the recording head 1. For example, during inspection in the manufacturing process of the recording head, an appropriate resistor is set according to the ejection amount such as the diameter of the ink droplet for a predetermined drive voltage applied to the electrothermal transducer. Fixed to a value. 3a and 3b
are comparators, each receiving a voltage divided by the resistance value of the semi-fixed resistor 2 at one input terminal, and comparing it with reference voltages Va and Vb (Va>Vb), respectively. Here, the reference voltages Va and vb are set in advance so that the set value of the resistor 2 can be determined.

4 is an encoder which inputs the outputs of the comparators 3a and 3b, encodes "0" to "2" according to the input signal, and sends the encoded data to MPIJ 5 via the data bus DB. .

Reference numeral 5 denotes a control device in the form of an MPU (microprocessor unit), which controls the operation of the entire device. An interface (1/F) 6 receives commands, image data, etc. from the host computer, and sends them to the MPU 5 via the data bus DB.

Reference numeral 7 denotes a look-up table (LtlT) constructed of a ROM-type memory, for example, in which several types (three types in this embodiment) of density correction coefficients are written depending on the amount of ink droplets ejected from the recording head. . Reference numeral 8 denotes an image buffer composed of, for example, a RAM, in which the image data corrected by the LUT 7 is expanded so that it can be recorded by the recording head 1, and the image data is sequentially transferred to the recording head 1 during a recording operation. .

Next, a mode of correcting ink density differences due to individual differences in heads using the above-described configuration will be described.

FIG. 2 is a flowchart showing an example of the correction procedure, and FIGS. 3 (A) to (C) explain the relationship between human data (input density) and recorded data (recorded density) due to individual differences in the head 1. FIG. In FIG. 2, MPυ5 first reads the output of the encoder 4 in step S1 after a reset operation at power-on. Then, the process moves to step S2, and it is determined in which rank the amount of ink droplets ejected from the mounted recording head 1 is, based on the value read in step S1. In this embodiment, depending on the read value, the ink droplet amount is 0...small, 1...
・It is judged as standard, 2...high.

Next, MPPb0 determines whether or not image data has been received from the host computer in step S3.
If the determination is negative, step S3 is executed again and this step is repeated until data is received or received. On the other hand, if the data has been received, the process moves to step S4 and the lookup table 7 is referred to.

Here, in this embodiment, the image data is 8bit.
It is input as t (0 to 255). When this is recorded using the area gradation method, Figures 3 (8), (B) and (C
) is obtained, and in order to correct this (one curve), the values shown by the broken lines are added to the input values. In order to execute this process at high speed, in step S4, the look-up table 7 in which the corrected values for each human power value are written for each rank of appropriate ink amount is referred to, and the corrected value is immediately obtained from the input value. .

Then, in step S5, dot development is performed on the image buffer 8 using the area coverage modulation method from the read correction values. Furthermore, the process moves to step S6 to start a recording operation, and the data in the image buffer 8 is transferred to the head 1 for recording. When the recording operation is completed, the process returns to step S3, and it is again determined whether or not data has been received.

(Embodiment 2) FIG. 4 shows another embodiment of the present invention, in which corresponding parts are given the same reference numerals as those in the embodiment shown in the first diagram. In the above (Example 1),
When performing density correction, the lookup table 7 was used to correct the data itself, but in this embodiment shown in FIG.
) 9 to perform the correction. This head controller 9 includes a timer that determines the head drive pulse width;
Alternatively, it can be configured as having a head temperature controller or the like. For example, instead of referring to the look-up table in the same procedure as shown in FIG. 2, after determining the rank (step S2), by setting the head drive pulse width or head temperature according to the rank of the head, it is possible to The ink ejection amount can be corrected.

(Example 3) FIG. 5 shows still another example of the present invention. In this embodiment, instead of recognizing and correcting the rank information of the head read from the head 1 in the recording apparatus main body, the information is sent to the host computer 20 via the bidirectional interface 16. The γ correction described in 1) is performed by the host computer 20.

That is, a look-up table 27 similar to that shown in FIG. 1 is provided in the host computer 20, and correction is performed based on rank information when transmitting image data to the recording apparatus main body, and the recording apparatus uses the corrected image. The recording operation is performed using the data as it is.

Note that it goes without saying that the present invention is not limited to the above-mentioned (Example 1) to (Example 3), and can have various configurations.

For example, as means for setting the rank information of the recording head 1, semi-fixed resistors 2 are used on each side described above, but for example, D
It is also possible to use an IP switch, an optically readable mark, etc., and it goes without saying that the rank information reading means on the recording apparatus main body side can be appropriately configured depending on the form of such means.

Further, instead of automatically reading the rank information, the operator may look at a mark provided on the recording head or its packaging, and manually set the rank information on the printer body or host using a switch or key.

Further, regarding the ranking of the recording heads 1, although three levels were used for each side described above, it goes without saying that the ranking can be made into an appropriate number of levels, such as two levels or four or more levels.

Furthermore, it goes without saying that the present invention can be effectively applied regardless of the number of recording heads included in an inkjet recording apparatus. That is, when performing color recording, a plurality of recording heads are provided for each ink color, and the present invention is suitable for correcting individual differences among these recording heads, but the number of recording heads is one, Considering that the recording head can be replaced even in an apparatus that performs monochrome recording, the configuration of the present invention is extremely effective.

In addition, it goes without saying that the present invention can be applied to any serial type or full multi-type scanning system, monochrome recording or multicolor recording, and any energy generation means.

[Effects of the Invention] As described above, according to the present invention, a means for presenting information indicating the evaluation of the ink ejection amount to the recording head is provided, and the recording data and drive pulse width are determined based on the presented information. , the ink ejection amount of the print head is adjusted by correcting the print head driving conditions such as head temperature.
Stable image formation is now possible regardless of individual differences in recording heads.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart showing an example of an ink ejection amount correction procedure according to the configuration shown in FIG. 3, and FIGS. FIG. 4 is a block diagram showing another embodiment of the present invention. FIG. 5 is a block diagram showing still another embodiment of the present invention. 1... Recording head, 2... Semi-fixed resistor, 3a, 3b... Comparator, 4... Fist encoder, 5... MPII. 6.16...Interface, 7...Lookup table, 8...Buffer. Figure 2 - Recording Taiyu Figure 5

Claims (1)

[Scope of Claims] Information presenting means provided in an inkjet recording head and presenting information indicating an evaluation of ink ejection amount when driven under predetermined conditions, and an inkjet recording method based on the presented information. An ink ejection amount adjusting device for an inkjet recording head, characterized in that the ink ejection amount adjustment device for an inkjet recording head is provided with an adjusting means for changing the driving conditions of the head and adjusting the ink ejection amount.