JP2734090B2 - Print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding the structure of the print head of a wire dot printer, it is possible to perform high-speed, high-quality printing without causing a malfunction of the printing wire without being affected by fluctuations in the heat generation temperature. The armature is attracted to the core of the print magnet against the urging of the spring means by the magnetic flux of the permanent magnet, and the current flowing through the print magnet cancels the magnetic flux of the permanent magnet. In a release type print head that releases an armature and performs printing with a print wire provided on the armature, a temperature detection unit that detects a temperature of the print head, and an auxiliary coil that generates a magnetic flux in the same direction as a magnetic flux of a permanent magnet. And a control unit for supplying a current corresponding to the detection information of the temperature detecting means to the auxiliary coil.

[Industrial applications]

The present invention relates to a structure of a print head of a wire dot printer.

2. Description of the Related Art In recent years, an input / output terminal of a data processing device, a serial printer that prints characters or the like by using dots in a word processor or the like has been frequently used.

Printheads used in these printers are required to have high-speed printing and high-quality printing.

[Conventional technology]

As shown in the side sectional view of FIG. 2, the print head 1 is driven by a print magnet 2 by intensively aligning a plurality of print wires 3 guided by a wire guide 4 projecting from the center thereof. Is configured.

The printing magnet 2 is formed by winding a coil 6 around a core 5, and an armature 7 is arranged so as to contact an end face of the core 5.

The armature 7 is made of a magnetic material, and is elastically fixed to the tip of a spring means (hereinafter referred to as a leaf spring) 8 so as to face the core 5. 3 is fixed.

The magnet base 10a and the magnetic path portion 10b are provided with a permanent magnet 11 therebetween, and a magnetic path portion 10d arranged with a spacer 10c made of a magnetic material therebetween.
When the print magnet 2 is not operating, the armature 7 is driven by the magnetic force of the permanent magnet 11.
Are adsorbed on the core 5.

Here, the permanent magnet 11 is attached to the coil 6 of the print magnet 2.
When current is applied so that the NS pole and the magnetic pole of core 5 are opposite,
The core 5 works so as to cancel the attractive force of the permanent magnet 11.

Then, the armature 7 jumps upward in the drawing due to the reaction force stored in the leaf spring 8, and the printing wire 3 simultaneously projects from the wire guide 4 to perform printing.

Printing is thus performed by selectively driving a plurality of print magnets 2 in the print head 1.

[Problems to be solved by the invention]

The print head is configured as described above,
The energization of the coil produces considerable heat.

Then, due to this heat, 10a 'shown by a two-dot chain line in FIG.
As shown in FIG. 3, the surface of the core 5 is bent downward as indicated by a two-dot chain line in the enlarged side view of the main part in FIG. 3, and the gap with the armature 7 is increased.

As a result, the amount of deflection of the leaf spring 8 increases as indicated by the dotted line 8 ', but the recovery force of the leaf spring is also affected by the increase in the spring constant due to the demand for higher speed. There is a problem that the suction force is not enough to prevent the printing wire 3 from recovering or following the printing wire 3 poorly.

That is, as shown in the table of FIG.
The restoring force of the permanent magnet 11 is reduced by reducing the gap between the core 5 and the armature 7 so that the permanent magnet 11
Is set within the range of the suction force.

However, when the amount of deflection of the leaf spring 7 increases due to the thermal deformation as described above, the restoring force of the leaf spring 7 does not fall within the range of the attraction force of the permanent magnet 11 as shown by the two-dot chain line.

SUMMARY OF THE INVENTION It is an object of the present invention to perform high-speed, high-quality printing without causing a malfunction of a printing wire without being affected by a change in a heating temperature.

[Means for solving the problem]

As shown in the side sectional view of FIG. 1A, a temperature detecting means 12 for detecting the temperature of the print head, an auxiliary coil 13 for generating a magnetic flux in the same direction as the magnetic flux of the permanent magnet 11, and a detection of the temperature detecting means 12 Control unit 14 that supplies current corresponding to information to auxiliary coil 13
It is provided with.

[Action]

When the print head generates heat, the heat is detected by the temperature detecting means 12, and the control unit 14 supplies a current corresponding to the detected information to the auxiliary coil 13, thereby generating a magnetic flux in the same direction as the magnetic flux of the permanent magnet 11. Armature 7 against the bias of leaf spring 8
The suction power to the is increased.

〔Example〕

 FIG. 1 shows an embodiment of the present invention.

 The same parts are denoted by the same reference numerals throughout the drawings.

As shown in the side sectional view of FIG. 1A, the print head 15 of the present invention includes a temperature detecting means 12 such as a thermistor for detecting the temperature of the print head 15, a magnetic flux in the same direction as the magnetic flux of the permanent magnet 11, and the like. And a control unit 14 for supplying a current corresponding to the detection information of the temperature detecting means 12 to the auxiliary coil 13.

That is, A- of FIG.
As shown in section A, the auxiliary coils 13 are further individually wound on the individual coils 6 wound on the core 5, and the auxiliary coils 13 are connected in series.

On the other hand, the control unit 14 includes a sensor amplifier 16 for amplifying the detection signal of the temperature detection unit 12, an A / D conversion circuit 17 for converting an analog signal of the sensor amplifier 16 into a digital signal, and an auxiliary coil for detecting the detected temperature in advance. A table 18 for storing data in which the energization amount for 13 is stored, and data of the table 18 are read out according to a digital signal from the A / D conversion circuit 17,
The control circuit 19 instructs the auxiliary coil energizing circuit 20 with the amount of energization.

Therefore, the print head is attached to the auxiliary coil 13 by the control unit 14.
A current corresponding to the temperature rise of 15 flows to generate a magnetic flux in the same direction as the magnetic flux of the permanent magnet 11, thereby increasing the attractive force of the permanent magnet 11 as shown by the dotted line in FIG.

According to this, the core 5 and the armature 7 are accompanied by thermal deformation.
Even if the gap between them increases and the amount of flexure of the leaf spring 8 increases, the armature 7 is reliably attracted to the core 7 against the bias of the leaf spring 8 and the printing operation is reliably performed. Become.

〔The invention's effect〕

According to the print head of the present invention, even when the gap size between the core and the armature increases due to thermal deformation and the amount of deflection of the leaf spring increases, the printing operation is performed such that the armature is securely attracted to the core. It has a great effect on industry, such as being certain.

[Brief description of the drawings]

1 (a) is a side sectional view of a print head of the present invention, FIG. 1 (b) is a sectional view taken along line AA of FIG. 1 (a), FIG. 2 is a side sectional view of a conventional print head, FIG. 3 is an enlarged side view of a main part of FIG. 2, and FIG. 4 is an attractive force of a permanent magnet, a restoring force of a leaf spring, and
FIG. 4 is a diagram showing a relationship between armature gap dimensions. In the drawing, 1, 15 is a print head, 2 is a print magnet, 3 is a print wire, 4 is a wire guide, 5 is a core, 6 is a coil, 7 is an armature, 8 is spring means (leaf spring), 9 is Holder, 10a is a magnet base, 10b is a magnetic path, 10c is a spacer, 10d is a magnetic path, 11 is a permanent magnet, 12 is a temperature detecting means, 13 is an auxiliary coil, 14 is a control section, 16 is a sensor amplifier, 17 is an A / D conversion circuit, 18 is a table, 19 is a control circuit, and 20 is an auxiliary coil energizing circuit.

Claims (1)

(57) [Claims] An armature (7) is attracted to a core (5) of a printing magnet (2) against the bias of a spring means (8) by a magnetic flux of a permanent magnet (11), and the printing magnet (2) is attracted. ), The armature (7) is released by the restoring force of the spring means (8) by applying a current for canceling the magnetic flux of the permanent magnet (11), and printing is performed by a printing wire provided on the armature (7). A temperature detecting means (12) for detecting the temperature of the print head; an auxiliary coil (13) for generating a magnetic flux in the same direction as the magnetic flux of the permanent magnet (11); A print head comprising: a control unit (14) for flowing a current corresponding to the detection information of the means (12) to the auxiliary coil (13).