JPH02297451A - impact head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an impact head with low power and low heat generation.

[Conventional technology]

Among printers that print characters or bit images using a dot matrix, serial type printers that use a wire as a print head are widely used because they can produce copies and have excellent cost performance.

As an example of the conventional wire driving method,
43088 is shown. Figure 4 shows its structure. The magnetic flux of the permanent magnet 33 passes through the frames 31, 32, the yoke 35, and the armature 37 integrated with the spring 36, so the armature 37 is attracted to the frame 32 side. When the wire is driven, the coil 34 is energized to eliminate the magnetic flux in the frame 32, and the spring force of the spring 36 performs (Φj impact printing).

[Problem to be solved by the invention]

With conventional drive methods, it is necessary to energize the coil to cancel the magnetic flux of the permanent magnet in the magnetic path, which requires a large amount of power to drive the head, and the heat generated by the coil makes it difficult to print continuously for a long time. There was a drawback that it could not be done.

[Means to solve the problem]

The first feature of the present invention is that in an impact head of a printer that has a permanent magnet and performs impact printing, the magnetic flux density passing through the plunger portion of the printing lever is changed by switching the magnetic path of the permanent magnet to drive a wire. A second feature is that a movable magnetic member is provided for switching the magnetic path of the permanent magnet, and a third feature is that a piezoelectric element is used as a means for driving the movable magnetic member. A fourth feature is that a plurality of piezoelectric elements for driving the movable magnetic member are used when driving the printing wire lever, and a piezoelectric element different from the piezoelectric element for driving the movable magnetic member is used when driving the printing lever. A fifth feature is that the print lever is displaced by driving the print lever.

[Effect]

As described above, by using the impact head of the present invention, it is possible to drive with low power and low heat generation.

〔Example〕

Hereinafter, the present invention will be explained based on examples.

FIG. 1 shows a cross-sectional view of an embodiment of the invention. 1 is a permanent magnet, 2 is a frame, 2a is a core provided in the frame, 3 is a yoke, 16 is a side yoke, 21 is a plunger, and 15 is a movable yoke, all of which are made of the magnetic material 1.

Reference numeral 8 denotes a printing lever, which has a printing wire 22 at the front end and is fixed to the plunger 21 together with a leaf spring 9. 15 is a movable yoke made of magnetic barbs, and 18 is a piezoelectric element fixed to a movable plate 23 having spring properties. When the print lever is not driven, most of the magnetic flux passes through the magnetic path of the frame 2, plunger 21, side yoke 16, and yoke 3, and the plunger 21 is attracted to the frame 2 (magnetic loop shown in the figure). Strain energy is stored in the leaf spring 9 that is integrated with the cage plunger. At this time, since there is a gap G in the magnetic path of the movable yoke 15, the magnetic resistance is large and almost no magnetic flux flows.

When the printing lever is driven, a voltage is applied to the piezoelectric element 18 through the substrate 20 and the connecting wire 17, and the piezoelectric element 18 is displaced in six directions in the figure. Therefore, the movable yoke 15 fixed to the piezoelectric element 18 is bent by the bimetal principle, and the air gap G between the movable yoke 15 and the frame 2 disappears, and the magnetic resistance of the magnetic path including the movable yoke 15 decreases rapidly, and magnetic flux flows. . (
(Magnetic loop indicated by M in the figure) As a result, the attraction force between the plunger 21 and the frame 2 decreases, and the strain energy stored in the spring 9 overcomes the magnetic attraction force, driving the printing lever 8 to perform fffij impact printing. . When the voltage application to the piezoelectric element 18 is finished, the movable yoke 15 returns to its initial position due to the spring force of the integrated movable plate 23, so the attraction force between the plunger 21 and the frame 2 is restored, and the wire lever is moved when not driven. Return to position. In the above series of operations, an appropriate voltage waveform is applied to the piezoelectric element 18 so that the movement of the movable yoke 15 matches the movement of the print lever 8, and a plurality of piezoelectric elements are used to displace the movable yoke. Good too. These operations are selectively performed on each of the print levers constituting the head in accordance with print commands to perform printing.

FIG. 2 shows a cross-sectional view of another embodiment of the invention. In the figure, 1 is a permanent magnet, and its magnetic flux passes through the magnetic path of the frame 2, core part 2a, plunger 21, side yoke 16, and yoke 3 when the printing lever 8 is not driven. magnetic loop) plunger 21
is attracted to the frame 2, and strain energy is stored in the leaf spring 9 integrated with the plunger. At this time,
Since there is an air gap G in the magnetic path of the movable yoke 15, magnetic resistance is large and almost no magnetic flux flows. When the print lever is driven, the piezoelectric element 1 is fixed to the side yoke 16.
A voltage is applied to 8 through the substrate 20 and connection wire 17, causing displacement in six directions in the figure. Therefore, the movable yoke 15 fixed to the piezoelectric element 18 is bent by the bimetal principle, and the air gap G between the movable yoke 15 and the frame 2 disappears, and the magnetic resistance of the magnetic path including the movable yoke 15 decreases rapidly, and magnetic flux flows. . (Magnetic loop indicated by M in the figure)
As a result, the attraction force between the plunger 21 and the frame 2 decreases, so that the strain energy stored in the spring 9 overcomes the magnetic attraction force, and the printing lever 8 is driven to perform impact printing. When the voltage application to the piezoelectric element 18 is finished, the movable yoke 1
5 returns to the initial position by the spring force of -g1; of the integrated side yoke 16, the suction force between the plunger 21 and the frame 2 is restored, and the printing lever returns to its non-driven position. In the above series of operations, an appropriate voltage waveform is applied to the piezoelectric element 18 through the substrate 20 and the connecting wire 17 so that the movement of the movable yoke 15 matches the movement of the printing lever 8, and the appropriate voltage waveform is applied to the piezoelectric element 18 to displace the movable yoke. For this purpose, a plurality of piezoelectric elements may be used. These operations are selectively performed on each of the print levers constituting the head in accordance with print commands to perform printing.

FIG. 3 shows a sectional view of yet another embodiment. The component structure is almost the same as that of the embodiment shown in FIG. 2, except that a plurality of piezoelectric elements (two in this embodiment) are used, the structure around the movable yoke 5 and the plunger 21, and the method of switching the magnetic path. are different. When not driven, the magnetic flux flows through the frame 2 and core part 2a.
, the plunger 21, the side yoke 4, and the yoke 3 (magnetic loop shown in the figure), the plunger 21 is attracted to the frame 2, and strain energy is applied to the leaf spring 9 integrated with the plunger. is stored. At this time, since there is a gap G in the magnetic path of the movable yoke 5, magnetic resistance is large and almost no magnetic flux flows. When the printing lever is driven, the piezoelectric element 6 fixed to the side yoke 4
A voltage is applied to the substrate 20 and the connecting wire 13, causing displacement in the direction of C in the figure. Further, when the piezoelectric element 6 is driven, another piezoelectric element 7 fixed to the side yoke 4 is also connected to the substrate 20.
, which is driven through the connecting wire 12 to push out the plunger 21 from the frame 2 in the direction B in the figure. the result,
The attraction force between the plunger 21 and the frame 2 quickly decreases (the main magnetic loop changes from C to M in the figure).

) Strain energy stored in spring 9 becomes magnetic attraction force 1]
The winning printing lever 8 is driven and impact printing is performed. When the voltage application to the piezoelectric element 6 is finished, the integrated movable yoke 5 returns to the initial position, and since the voltage application to the piezoelectric element 7 is finished before the voltage application to the piezoelectric element 6 is finished. When the suction force between the plunger 21 and the frame 2 is restored, the printing lever 8 returns to its non-driven position. In the following series of operations, an appropriate voltage waveform is applied to the piezoelectric elements 6 and 7 so that the movement of the movable yoke 15 matches the movement of the print lever 8. In this embodiment, the piezoelectric element is fixed to the movable yoke and the side yoke, but a structure in which a movable plate is provided and fixed via the movable plate as in the embodiment shown in FIG. 1 may also be used. These operations are selectively performed on each of the print levers constituting the head in accordance with print commands to perform printing.

〔Effect of the invention〕

As described above, if the impact head of the present invention is used,
It becomes possible to drive with low power and low heat generation. □

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the impact head of the present invention. FIG. 2 is a sectional view showing another embodiment of the impact head of the present invention. FIG. 3 is a sectional view showing still another embodiment of the Invac L-head of the present invention. FIG. 4 is a sectional view showing a conventional impact head. 1... Permanent magnet 2... Frame 2a... Core portion 3... Yokes 4, 16... Side yokes 5, 15... Movable yokes 6, 7. 18... Piezoelectric element 8... Printing lever 9... Leaf spring 10... Spring holding plate 11... Back cover 12.13.17... Connection line 20... Board 21... Plunger 22...Wire and above Applicant Seiko Epson Co., Ltd. Agent Patent attorney Kizobe Suzuki and 1 other person Figure 3

Claims (5)

[Claims] (1) In the print head of an impact printer that has a permanent magnet and performs impact printing, the impact is characterized in that the magnetic flux density passing through the plunger portion of the printing lever is changed by switching the magnetic path of the permanent magnet to drive the wire. head. (2) Claim 1 further comprising a movable magnetic member for switching the magnetic path of the permanent magnet.
Impact head as described. (3) The impact head according to claim 1, wherein a piezoelectric element is used as means for driving the movable magnetic member. (4) The impact head according to claim 1, wherein a plurality of piezoelectric elements for driving the movable magnetic member are used when driving the printing wire lever. (5) The impact head according to claim 1, wherein when the printing lever is driven, a piezoelectric element for driving the movable magnetic member and another piezoelectric element are driven to displace the printing lever.