JPH01114456A - Dot printer printhead - Google Patents

Abstract

PURPOSE:To decrease the difference between a permanent magnet attraction force and a spring force and provide high speed driving, by placing a Piezoelectric element in parallel to the permanent magnet with respect to the bias direction of a plate spring. CONSTITUTION:When not in printing operation, an armature 4 is attracted to the face end of a core 3 by a permanent magnet 7 to bias the tongue piece of a plate spring 2 toward the core. During printing operation, a voltage is applied to a piezoelectric element 15 to separate the core 3 from the armature 4, increase the bias amount of the plate spring 2, and decrease the difference between the magnet attraction force and spring force. Now, the armature 4 can be easily separated from the core 3. A gap 16 is produced between the magnet 7 and a yoke 9 by the deformation if the piezoelectric element 15 to increase the reluctance of a magnetic force of the magnet 7. This further decreases the difference between the attraction and spring forces, providing a high speed driving of a printhead.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) This invention relates to a print head for a wire dot printer.

(Conventional technology) The energy of a spring that was deflected by the attractive force of a permanent magnet is
It is released by excitation of the coil and operates the printing hammer.
In a so-called spring-charge type print head, the relationship between suction force and spring force greatly affects the operating speed of the printing normal.

As shown in Figure 6, the button that operates the printing hammer needs to cancel the attractive force of the permanent magnet, which is larger than the spring force, and the attractive force that is canceled by passing current through the coil is
The printing hammer starts to move when it reaches A in Figure 6. However, from the relationship between the operation waveform of the printing hammer and the applied current of the fill shown in Figure 7, there is a time constant for the rise of the applied current, and it takes time for the attraction force to be canceled to reach A, so the printing There is a time delay T in the action of the hammer. Therefore, we would like to set A as small as possible, but if we set A small, as shown in Fig. 7, the rebound upon collision with the iron core after the impact was completed became large, and the operation became unstable9. Ghosts, which are unnecessary prints, may occur on the print medium.

Therefore, as shown in Fig. 8, a piezoelectric element is placed at the base of the printing gauge spring, and a voltage is applied to the piezoelectric element in synchronization with the excitation timing of the drive coil, thereby increasing the amount of deflection of the spring. As shown by the dotted line in Figure 6, a print head was invented that reduces the difference between the attractive force of the permanent magnet and the spring force during printing from A to B, and increases the initial operating speed of the printing machine. It was done.

However, the operation of the printing hammer: I! : The deformation of the piezoelectric element is about 1i10 microns for 300 microns, and A
The difference between and B was very small, and no significant effect was obtained.

Furthermore, in a print head having such a structure, since the piezoelectric element, which is a brittle material, is in contact with the leaf spring, it may be worn out or destroyed by the operation of the print hammer.

(Problems to be Solved by the Invention) This invention has been made in view of the above points, and its purpose is to improve the shortcomings of the conventional device described above, and to achieve printing that can include speed driving. The purpose is to provide the head.

[Structure of the invention]

(Means for Solving the Problems) The configuration of the present invention is that the print head of a dot printer has a pressure of 1! Place the element in parallel with the permanent magnet.

(Function) By arranging the piezoelectric element in parallel with the permanent magnet in this way, the present invention not only increases the amount of deflection of the spring by deforming the piezoelectric element, but also increases the attractive force by increasing the magnetic resistance of the magnetic circuit. can be made small, so the difference between the above-mentioned suction force and spring force can be significantly reduced.

As a result, a print head capable of high-speed operation can be easily provided. Furthermore, since there is no piezoelectric element at the base of the spring, no impact force is applied to the piezoelectric element, thereby preventing wear and destruction.

(Example) The present invention will be described in detail below using examples shown in the drawings.

FIG. 1 is a schematic sectional view showing one embodiment of a print head of a dot printer according to the present invention. There are N code 1s (N=1
．． 2. ), 2 is a leaf spring with N tongues, 3 is N iron cores located at positions corresponding to the grooves of the yoke plate, and 4 is each tongue of leaf spring 2. N armatures are attached to a piece, 5 is N printed wires attached to each armature, 6 and 6' are guides that regulate the direction of movement of the printed wires, 7 is a permanent magnet, and 8 is an iron core. N coils wound around, 9 is the yoke, 1
0.11 is a spacer, 12 is a nose, 15 is a piezoelectric element,
18 is a substrate.

Next, the assembly and processing method will be explained. First, as shown on the right side of FIG. 2, the armatures 4 to which the printing wire 5 is soldered are brazed to the tongues of the leaf spring 2, respectively, and attached by laser welding or the like to assemble the printing hammer 17. Next, pass the printed wire 5 through the wire guide 6.6', and insert the yoke plate 1, spacers 10, 11, leaf spring 2, nose 1,
2 using screws, etc., and glue the guide 6.61 to the nose.

After configuring as described above, the printed wire 5 is pushed and fixed by a predetermined amount onto the iron core side using a jig (not shown), and the back of the armature 4 shown by the dotted line on the left side of FIG. Process the tsuri so that it is flush with the surface on the iron core side.

By performing the above assembly and processing, the driven side 13 of the print head is completed.

Next, a method of assembling the core side 14 will be explained.

As shown in Fig. 3, a permanent magnet 7 and a piezoelectric element 1 are attached to the iron core 3.
5 is bonded, and the yoke 9 is bonded to the piezoelectric element 15. Next, the coil 8 is attached to each iron core, the coil 8 and the wiring 19 of the piezoelectric element 15 are attached to the base plate 18 by soldering, and the end surfaces of the iron core 3 and yoke 9 are processed into a zigzag shape on the core side. 14 is completed.

Finally, the driven side 13 and core side 14 are fixed with screws or the like and magnetized to complete the print head.

As shown in FIG. 8, in a conventional print head using a piezoelectric element, the piezoelectric element is placed at the base of the leaf spring on the driven side.
Workability is poor because work can only be done after the driven side and core side are assembled.

Next, the operation of this print head will be explained. First, when not performing a printing operation, as shown on the left side of Figure 1, the permanent magnet 7
, yoke 9, yoke plate 1, armature 4, iron core 3
In the magnetic circuit constituted by, the armature 4 is attracted to the end face of the iron core 3 by the magnetic force of the permanent magnet 7, so the tongue piece 2 of the leaf spring is biased toward the iron core 3.

Next, when performing a printing operation, a voltage is applied to the piezoelectric element 15 to extend it in the direction of increasing the distance between the iron core 3 and the armature 4, thereby increasing the amount of deflection of the leaf spring as shown in FIG. , the difference between the attractive force of the permanent magnet and the spring force from A to B
and make it smaller. By creating such a state, the air 4 can easily separate from the iron core 3. Furthermore, due to the deformation of the piezoelectric element, there is a gap 1 between the permanent magnet 7 and the yoke 9.
6 is formed, and the magnetic resistance of the magnetic circuit increases, so the attractive force of the permanent magnet 7 decreases. For this reason, the difference between the suction force and the spring force becomes smaller from B to C, allowing high-speed operation.

When the difference between the attractive force and the spring force becomes small, a current is applied to the coil 8 paired with the desired printed wire 5 by a drive circuit (not shown) to generate a magnetic field in the opposite direction to the magnetic field of the permanent magnet 7. By canceling the magnetic field of the permanent magnet 7 and eliminating the attractive force, the armature 4 is separated from the iron core 3 by the spring force of the biased leaf spring 2, and the printed wire 5 is guided by the guide 6.61. , protrudes from the tip of the nose and collides with an ink ribbon (not shown) and a printing medium to form a dot. At this time, when the current applied to the coil 8 and the voltage applied to the piezoelectric element 15 are cut off, the armature 4 is attracted to the iron core 3 again by the attractive force of the permanent magnet 7, and becomes in a non-printing state.

As detailed above, when a piezoelectric element is placed in parallel with a permanent magnet, the deflection of the spring becomes large due to the deformation of the piezoelectric element, and furthermore, the magnetic resistance of the magnetic circuit increases and the attractive force decreases. The difference between suction force and spring force is significantly small, allowing high-speed operation.

〔Effect of the invention〕

According to the present invention, by arranging the piezoelectric element in parallel with the permanent magnet, the difference between the attraction force and the spring force when printing can be greatly reduced, making it possible to realize a print head for a dot printer that can be driven at extremely high speed. .

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a print head showing an embodiment of the present invention, FIG. 2 is a schematic sectional view of the driven side, FIG. 3 is a schematic sectional view of the core side, and FIG. 4 is a schematic sectional view of the print head of the present invention. The relationship between the suction force and the spring force, FIG. 5 is an operational diagram of the printing hammer of the present invention,
FIG. 6 is a relationship between suction force and spring force of a conventional print head, FIG. 7 is an operational diagram of a conventional print hammer, and FIG. 8 is a schematic sectional view of a conventional print head. 2...-plate spring, 5... printed wire, 7... permanent magnet, 8... coil, 15... piezoelectric element. Agent Patent Attorney Nori Ken Yudo Chika Hikaru Matsuyama 2 1 Figure 2 Figure 3 Figure 0 1 Figure 4 Figure 5 From O to Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] In a print head of a dot printer, a leaf spring is biased by a permanent magnet, and the biased leaf spring is released by deformation of a piezoelectric element and excitation of a magnetic coil to drive a print wire. A print head for a dot printer, characterized in that the print head is arranged in parallel with the permanent magnet in a direction.