JPS624238B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hammer spring member of a printing hammer drive device for a dot printer, particularly a dot impact type matrix printer that prints characters and symbols in a dot matrix. Regarding structure.

This type of dot-impact matrix printer requires high-speed responsiveness in printing operations, and since many printing hammers and their driving devices are usually incorporated into one printing head assembly, each printing hammer driving device is Small size and low power consumption are required. Conventionally, as a printing hammer drive device to satisfy high-speed response, a permanent magnet attracts and displaces a spring member, stores strain energy in the spring member, and energizes an electromagnetic device (release coil) during printing. Therefore, the attractive force of the permanent magnet is released, and the strain energy of the spring member at that time is used to strike the printing pin at the tip of the spring member against the printing surface.
FIG. 1 shows a conventional example of such a printing hammer driving device, and FIG. 2 shows a spring member used in this conventional device. Note that FIG. 2 is a view of the spring portion partially viewed from the printing surface (not shown) side. To briefly explain this conventional device, one end is two
Hammer spring member 2 with a fixed to the spring mounting member 1
is attracted and held in an arcuate manner by the permanent magnet 3 through the common yoke 4 and the yokes 5 corresponding to the individual hammers, and is attracted and held by the permanent magnet 3 by energizing the electromagnetic device 6 attached to the yoke 5. The hammer spring member 2 is opened, and a dot is printed using the printing pin 7 attached to the free end 2b of the spring member. The magnetic circuit by the permanent magnet 3 with this configuration is the first
As shown by the arrow in the figure, in this case, the hammer spring member 2 is usually made of a thin plate material with a thickness of about 1 mm, so the magnetic flux is saturated at the hammer spring member 2, making it difficult to improve the attraction characteristics. It was hot. The thickness of the hammer spring member 2 is mostly determined by the appropriate printing energy for printing dots with the printing pin 7 and the natural frequency required from the printing speed of the printer, etc., and the degree of freedom in selection is limited. Therefore, in order to improve the attraction characteristics, the only way to increase the attraction characteristics is to increase the magnetic energy of the permanent magnet 3 even slightly, but in this case, the energy required to cancel the magnetic flux of the permanent magnet 3 with the electromagnetic device 6 The disadvantage is that the power also increases.

It is an object of the present invention to improve the magnetic flux saturation in the hammer spring member without changing the configuration of the permanent magnet and the electromagnetic device, to increase the attraction characteristics and to minimize the magnetic flux cancellation energy, thereby reducing the overall size, lowering the power consumption, and increasing the speed. An object of the present invention is to provide an inexpensive printing hammer drive device for a dot matrix printer.

For this purpose, the printing hammer drive device according to the present invention has a plurality of U-shaped slits formed in the plate spring member at intervals in the axial direction of the platen, and the inner portion of the U-shaped slits is inserted through the U-shaped slits. a hammer spring member with a movable part and a stationary part surrounding the movable part; a printing pin provided at the free end of the movable part; a permanent magnet provided at the fixed end side of the movable part; an electromagnetic device including a common yoke magnetically communicating with a magnet; an individual yoke member facing a free end of the movable portion and magnetically communicating with the common yoke; and a coil wound around the individual yoke member. a first magnetic circuit including the individual yoke member and the movable portion; and a second magnetic circuit including the individual yoke member, the movable portion, the slit, and the stationary portion. is formed.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 shows a printing hammer drive device according to the present invention, and corresponds to FIG. 1 of the conventional device, and FIG. 4 is a partial front view of the hammer spring member in FIG. 3, viewed from the printing surface side. . In this embodiment, the permanent magnet 3, the common yoke 4, the individual yokes 5 corresponding to the individual printing hammers, and the electromagnetic device 6 attached to the individual yokes 5 are almost the same as those shown in FIG. The member 12 is made of a springy plate material as shown in FIG. 4, and a plurality of U-shaped slits 11 with small gaps are formed on the plate surface, thereby making a single stationary part 9 and a plurality of slits 11 as a whole. It is separated into two movable parts 10. One end 9a of the stationary portion 9 is fixed to the spring mounting member 1, and the other end 9b is
As shown in FIG. 3, it is supported at a neutral position by a pole 8 extending from the common yoke 4. Movable part 1
0 is connected to one end 9a of the stationary part 9 at its base 10a, and the printing pin 7 is attached to the other end 10b, that is, the free end of the movable part. The gap between the slits 11 is approximately 0.05 to 0.15 mm. Such minute slits can be easily formed with high precision using a wire cutting method or etching process. Free end 1 of movable part 10 with printing pin 7
0b is attracted and held by the permanent magnet 3 to each individual yoke 5 via the common yoke 4, and stores strain energy. In this case, the magnetic circuit by the permanent magnet 3 is composed of a first magnetic circuit A passing through the movable part 10 and a second magnetic circuit B passing through the side of the slit with a minute gap. That is, in the present invention, a first magnetic circuit including the individual yoke 5 and the movable part is formed, and a second magnetic circuit including the individual yoke 5, the movable part, the slit, and the stationary part is formed. Ru. In a conventional spring member consisting of only a movable part, there is only a first magnetic circuit, and compared to the attraction characteristics of only this first magnetic circuit, the magnetic saturation of the hammer spring member 12 is greatly improved in the present invention. become. Therefore, since the magnetic energy of the permanent magnet 3 can be used efficiently, the size of the permanent magnet 3 can be reduced, and the energy required to cancel the magnetic flux of the permanent magnet 3 with the electromagnetic device 6 can also be reduced, which reduces the amount of energy required. Power can be saved. Furthermore, since the slit width can be processed with high precision by wire cutting or etching as described above, the suction characteristics can be made constant and the printing operation can be stabilized. Furthermore, since the slit width is maintained with high precision even if it is minute, there is no mechanical interference between the movable part and the stationary part during operation.

Incidentally, in the above-described embodiment, a one-yoke type printing hammer drive device has been described, but the present invention is not limited to this embodiment, and the same effect can be obtained even with a two-yoke type. It is also clear that the same effect can be achieved even if the printing pin attached to the free end of the hammer spring member is in the form of a relatively long wire other than the illustrated embodiment. By dividing into a movable part and a stationary part, a composite magnetic path is formed of a first magnetic circuit generated in the movable part and a second magnetic circuit generated in the stationary part, thereby improving the attraction characteristics, This has the effect that the printing hammer drive device can be made smaller, consume less power, and be faster, and can be manufactured at a lower cost.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a conventional printing hammer driving device, FIG. 2 is a partial front view of the hammer spring member used in FIG. 1, and FIG. 3 is a printing hammer according to an embodiment of the present invention. A diagram corresponding to FIG. 1 showing the drive device, and FIG. 4 is a partial front view of the hammer spring member in FIG. 3. 3... Permanent magnet, 4... Common yoke, 5... Individual yoke, 6... Electromagnetic device, 7... Printing pin, 8... Pole, 9... Stationary part, 10... Movable part, 11... Slit, 12... Hammer spring member.

Claims (1)

[Claims] 1 A plurality of U-shaped slits are formed in a leaf spring member at intervals in the axial direction of the platen, the portion inside from the U-shaped slits is a movable portion, and the portion surrounding the movable portion is a stationary portion. a hammer spring member, a printing pin provided at the free end of the movable portion, a permanent magnet provided at the fixed end side of the movable portion, a common yoke magnetically communicating with the permanent magnet, and a common yoke of the movable portion. an electromagnetic device including an individual yoke member facing the free end and magnetically communicating with the common yoke and a coil wound around the individual yoke member, whereby the individual yoke member and the movable portion A printing hammer drive device for a dot printer, wherein a first magnetic circuit is formed including the individual yoke member, the movable part, the slit, and the stationary part. .