JPH04110159A - Controlling method for print head - Google Patents

Abstract

PURPOSE:To obtain a high printing position accuracy even if printing hammers have a variation in production or the like by a method wherein an exciting current value is adjusted by changing an exciting current start timing for an electromagnet of each hammer so that a timing that each hammer separates from a magnetic pole surface at the time of printing or a timing that it reaches a printing surface can have a constant relationship with a timing determined by a printing condition. CONSTITUTION:Start timing adjusting circuits 7-1-7-n can respectively correct a start timing by external adjusting signals S1-Sn. Therefore, the start timing adjusting circuits 7-1-7-n previously adjust a start timing by the external adjusting signals S1-Sn in accordance with a variation produced in the production of printing hammers. whereby a timing that each hammer of a print head separates from a magnetic pole surface or a timing that it reaches a printing surface can be determined to have a constant relationship with a timing determined by a printing condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of controlling a spring-charged print head for a dot impact printer.

[Conventional technology]

FIG. 1 shows an example of the structure of a puff charge type printing head. In line printers, a suitable number of units are arranged in a straight line, and in serial printers, they are arranged radially.

This spring-charged print head usually uses a permanent magnet 1 to attract a hammer spring 3 equipped with a hammer pin 2 to a magnetic pole 4, and when print data is given, current is applied to a degaussing coil 5 to demagnetize it. This is to release the hammer spring 3 that has been used for printing.

FIG. 2 shows the current in the degaussing coil 4 and the movement of the hammer. Due to variations in the spring characteristics of the hammer spring 3, variations in the height of the magnetic pole 4, etc., the hammer A A discrepancy occurs between the movements of and B. Therefore, in line printers, the print head normally performs printing operations while moving horizontally at a constant speed, so the current in the degaussing coil is started after a certain period of time has passed after a print command is issued, so the movement of the hammer in response to the print command is There was a drawback that misalignment occurred and printing position accuracy deteriorated.

This is a particularly serious problem in applications such as barcode printing, which require high printing position accuracy.

[Problem to be solved by the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a print head control method that allows high print position accuracy to be expected even if each print hammer has manufacturing or other variations.

[Means to solve the problem]

The present invention was made to solve the above problems,
By adjusting the timing of applying current to the degaussing coil so that each printing hammer moves at the same timing in response to a printing command, variations in startup timing are corrected and peak current value correction control is performed, improving printing position accuracy. The principle of the present invention will now be described for ease of understanding.

FIG. 3 is an operation curve showing the current of the degaussing coil 4 and the movement of the hammer in the case of the present invention. In the case of the conventional example, as shown in FIG. Therefore, the operating curve is shifted for the same degaussing coil current. That is, hammer A leaves the magnetic pole and begins to move when the current rises to iA, whereas hammer B begins to move when the current reaches i.

As a result, the timing at which the hammer hits the printing paper is shifted in response to the printing command, resulting in a shift in the printing position.

In contrast, in the present invention, as shown in FIG. 3, the timing of applying current to the degaussing coil 4 of hammer B is shifted so that both hammers start moving at the same timing (ta=tyo) in response to a printing command, and LA (-t!l) so that the currents become IA+il+, respectively.

Note that the current cutoff timing T is set so that both hammers with different spring characteristics start moving at the same time and reach the print medium at the same time.
2 is assumed to be the same, but by changing it, more delicate adjustments can be made.

According to the present invention, as shown in FIG. 4, the printing energy of hammer A (the shaded area) and the energy of hammer B (the area surrounded by broken lines) are the same, so the printing density due to variations in the hammers is Variations are eliminated and good print quality can be obtained.

Furthermore, even if there is no variation in the characteristics of the hammers, the demagnetization characteristics will vary depending on the printing conditions due to magnetic interference caused by the movement of adjacent hammers. It is also possible to prevent the decrease.

〔Example〕

FIG. 5 shows an embodiment of the present invention, in which 6 is a drive circuit for the degaussing coils Ll to L, and 7-1 to 7-n are startup timing adjustment circuits.

Each of the startup timing adjustment circuits 7-1 to 7-n can modify the startup timing using an external adjustment signal S I'=S-.

Therefore, depending on the manufacturing variation of the printing hammer, the activation timing adjustment circuits 7-1 to 7-n are controlled by the external adjustment signals 31 to 31.
By adjusting the startup timing using Sfi, the timing at which the printing hammer of each print head leaves the magnetic pole surface or the timing at which it reaches the printing surface can be made constant with respect to the timing determined by the printing conditions. Therefore, the drawbacks of the conventional method are eliminated.

〔Effect of the invention〕

As described above, according to the present invention, the accuracy required for print head parts is reduced, the structure is simplified without the need for an adjustment mechanism, and productivity can be improved and costs can be reduced.

Furthermore, since it is a firmware-based countermeasure, it is possible to program even when there are multiple causes of variation, which is difficult to do with conventional mechanical adjustment work, and it is effective because high print quality can be obtained regardless of various printing conditions.

[Brief Description of the Drawings] Fig. 1 is a side view showing the structure of a conventional spring-charged print head and an embodiment of the present invention, Fig. 2 is an operation curve of the printing hammer when using a conventional control method, and Fig. 3 is an operation curve of the printing hammer when using the control method according to the present invention, FIG. 4 is a force-displacement characteristic diagram of the print head when using the control method according to the present invention, and FIG. 5 is an embodiment of the present invention. FIG.・Permanent Magnet Hammer Bin Hammer Buff Magnetic Pole Demagnetizing Coil Patent Applicant YE Datani Co., Ltd. Agent Osamu Hattori

Claims (1)

[Scope of Claims] A print head having a plurality of printing hammers having leaf springs, a magnetic circuit having a permanent magnet that attracts the printing hammers to a magnetic pole surface against the spring force, and an electromagnet that releases the printing hammers during printing, During printing, the excitation current value is set by changing the activation timing of the excitation current of the electromagnet for each hammer so that the timing at which each printing hammer leaves the magnetic pole surface or reaches the printing surface is constant with respect to the timing determined by the printing conditions. A method of controlling a print head, the method comprising adjusting the print head.