JPS6295233A - Drive circuit of printing head - Google Patents

Abstract

PURPOSE:To reduce the unevenness of density without altering the deflection amount of a printing hammer, by differentiating the excitation widths of drive excitation signal applied onto a plurality of printing units. CONSTITUTION:Two kinds of excitation signals T1 and T2 having different excitation widths are applied to a hammer driver 12. As to the hammer driver 12, the current I1 of a width T1 is applied to the printing unit near both ends of a printing head 13 depending by on the excitation signal T1 of a narrow excitation width. By applying a required minimum electric energy, the printing hammer is released to carry out printing. In the other hand, the current 12 of a large excitation width T2 is applied to the printing unit at the central part of the printing head 13 dependingly on the excitation signal T2 and electric energy necessary sufficient for release of the printing hammer is applied to carry out printing. Because drive current of a broad range is thus applied to the printing head requiring much electric energy by using a plurality of kinds of excitation widths of drive current, the printing of little uneven density can be obtained.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a printing method for a dot matrix line printer in which a plurality of printing units are assembled which use strain energy accumulated in a printing hammer bent by a permanent magnet or an electromagnet as printing energy. The present invention relates to a drive circuit that drives a head.

Prior Art In the conventional drive circuit for this type of print head, the second
As shown in the figure, an excitation signal is applied from the control section 11 to the hammer driver 12, and current flows from the hammer driver 12 to the coils of each unit of the print head 13. There is only one type of excitation signal for the hammer driver 12, and the same current flows through each unit. That is, exactly the same electrical energy is applied to each unit.

By applying this same electrical energy to each unit 1, the following disadvantages arise.

This will be explained with reference to FIG. 3, which shows the configuration of the print head.

In FIG. 3, a permanent magnet 1 is sandwiched between yokes 2 and 3, a coil spool 6 is inserted into the yoke 5 corresponding to the printing hammer 4, and a current is applied around it to release the printing hammer 4. A flowing coil 7 is wound.

The printing hammer 4 is a type of cantilever leaf spring, and a printing wire 8 for printing dots is attached to the free end side of the leaf spring. A side yoke 9 forming a side magnetic path is fixed to the yoke 3 with screws 10 so as to sandwich the printing hammer 4 therebetween.

Normally, the printing hammer 4 is moved to the third position by the attractive force of the permanent magnet 1.
As shown in Figure (b), it is bent and adsorbed to the yoke 5. By applying current to the coil 7 during printing to cancel the magnetic flux of the permanent magnet 1, the printing hammer 4 is released from the yoke surface, and the strain energy accumulated in the printing hammer 4 itself is converted into kinetic energy. The printer moves and prints.

It is known that print units in the center of the print head require more electrical energy to release the print hammer from the permanent magnet than print units near the ends of the print head. This is because the print head shares a structure with a permanent magnet, so the permanent magnet involved in releasing the hammer in the center of the print head is strong.

If the same electrical energy is applied to each printing unit of such a print head, there is a drawback that the print power decreases due to insufficient energy in the center of the print head, resulting in uneven print density. Conventionally, in order to eliminate this density unevenness,
Increase the amount of deflection of the print hammer in the center of the print head.
In other words, the strain energy was increased. This secondarily caused the problem of poor suction of the printing hammer.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a drive circuit for a print head for a dot matrix line printer that has less density unevenness without changing the amount of deflection of a print hammer.

Structure of the Invention According to the present invention, a print head for a dot matrix line printer is driven, which includes a plurality of print units that use the strain energy accumulated in a print hammer bent by the attractive force of a magnet as printing energy. There is obtained a drive circuit for a print head for a dot matrix line printer, which is characterized in that the excitation width of the drive excitation signal applied to the plurality of print units is varied.

EXAMPLE Next, the present invention will be explained in more detail with reference to the drawings showing an example of the present invention.

Referring to FIG. 1, in one embodiment of the present invention, two types of excitation signals T1 and T2 having different excitation widths are applied from the control section 11 to the hammer driver 12. The hammer driver 12 applies a current of width T1 to printing units near both ends of the print head 13 in response to an excitation signal QT1 having a narrow excitation width.
1 is applied. The minimum necessary electrical energy is applied to the printing units near both ends of the print head to release the printing hammers and perform printing.

On the other hand, a current I2 having a large excitation width T2 is applied to the printing unit at the center of the print head 13 in response to the excitation signal T2, and sufficient electrical energy is applied to release the printing hammer to perform printing.

In this embodiment, two types of excitation signals were used, but if the number of types is increased, density unevenness will be reduced. In addition, although a large amount of electrical energy is applied to the central portion, if a printing unit that requires a large amount of electrical energy is installed in a location other than the central portion due to the structure of the print head, a large amount of electrical energy will be applied there. Just apply.

As explained above, according to the present invention, multiple types of excitation widths of the drive current applied to the print unit of the print head are used, and a wide drive width is applied to the print unit that requires a large amount of electrical energy. Since a current is applied, printing with less uneven printing density can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a conventional drive circuit, and FIG. 3(a). (b) and (C) are a front view, a side view, and a plan view, respectively, of the print head. Explanation of symbols of main parts 11...Control unit 12...Hammer driver 13...Print head

Claims (1)

[Claims] A drive circuit for driving a print head for a dot matrix line printer in which a plurality of printing units are assembled, each of which uses strain energy accumulated in a printing hammer bent by the attractive force of a magnet as printing energy, the plurality of printing units comprising: A drive circuit for a print head for a dot matrix line printer, characterized in that the excitation width of the drive excitation signal applied to the print unit is varied.