JPS5964B2 - Kogata Printer Nomojisen Takukikou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a character selection mechanism for a small printer using a type wheel, and more particularly to a mechanism using a permanent magnet as a character selection electromagnet.

The aims of the present invention are: (1) to reduce the load on the power supply and reduce costs by lowering the current value of the character selection electromagnet as much as possible;
) The aim is to improve reliability and reduce the cost of the printer itself by making the character selection mechanism smaller and simpler.

The present invention will be explained using figures.

FIG. 1 is a side sectional view showing a character selection mechanism of a small printer according to the present invention. In the figure, 10 is printed with 1 on the outer periphery.
1 is a type wheel having ratchet teeth 12 on its side, 13 is a type ring spring, 14 is a type wheel shaft, 15 is a selection pawl that rotates around the shaft 16, and 17 is a constant biasing of the selection pawl 15 in the direction of arrow B. 20 is a permanent magnet, and 21 and 22 are yokes having convex portions 21-1 and 22-1, respectively, which are arranged to sandwich the permanent magnet 20. 23 is an electromagnetic coil wound around a coil frame 24, and the convex portions 21-1 and 2 of the yoke are connected to each other.
2-1 is loaded in a staggered manner.

25 and 26 are movable iron cores that slide in the air core of the electromagnetic coil 23, and one end thereof is in surface contact with the convex portions 21-1 and 22-1 of the yoke, and is magnetically attracted and coupled.

The other end of the movable iron core is shaped like a key and engages with a portion 15-2 of the selection claw. The operation of the character selection mechanism having such a configuration is as follows. FIG. 1 shows the printer in a standby state. When the type wheel 10 comes out of this standby state and rotates in the direction A and the type to be printed appears at the printing position, when the electromagnetic coil 23 is energized, the electromagnetic coil 23 cancels out the magnetic flux from the permanent magnet 20, and the movable iron core 25 and yoke 2
Release the magnetic coupling with 1. The movable core 25, which has been disconnected from the yoke 21, moves in the direction of arrow D because it is always receiving the force of the leaf spring IT via the selection claw 15-2. Naturally, the selection pawl 15 also rotates in the direction of arrow B, and the pawl portion 15-1 engages the ratchet teeth 1 of the type ring 10.
2 to prevent rotation of the type wheel 10. Therefore, the type to be printed is placed at the printing position. Similarly, when the characters of each digit are arranged at the printing position, the platen 30 rotates in the F direction, presses the printing paper 31 against the character row via the ink ribbon 32, and printing is completed. When printing is completed, the reset shaft 40 rotates in the direction of arrow G, and the leaf spring 17
The protrusion 15-3 is pushed up against this, the selection pawl 15 is rotated in the direction of arrow C, and the engagement with the ratchet teeth 12 is released. On the other hand, the movable core 25 is moved in the direction of arrow E by the rotation of the selection claw 15, and is brought into contact with and magnetically engaged with the convex portion 21-1 of the yoke. This completes the series of operations and each part returns to its standby state. The character selection mechanism of the present invention having the above configuration and operation can be pointed out as follows.

Structurally, the torque by the leaf spring 17 that biases the selection claw 15 is 10 to 209r-? The force for holding the movable iron core 25 in the standby position against the leaf spring 17 is 109r-? considering the lever ratio. It's a good thing to some degree.

The fact that the attractive force of the permanent magnet is small in this way means that the magnetic circuit is sufficient as an oven magnetic path as in the present invention, and the structure is simple.
1 and 22-1 and the movable iron cores 25 and 26, the surface finish is as good as the fracture surface of a press, and it is extremely suitable for mass production, and even if the current value to the electromagnetic coil 23 is small, a sufficient demagnetizing effect can be obtained. Experimental values show that compared to conventionally commonly used suction iron single-sided electromagnet devices,
For example, a current value of about one-sixth, that is, about 40 to 80 mA is sufficient. Another reason why a small current value is sufficient is that the printing method uses a type wheel. In other words, in order for the selection pawl 15 to fall into a predetermined ratchet tooth 12, the time it takes to start rotating varies by about 10 ms. For example, if this type of electromagnetic device is used in the hammer of a flying printer, the time variation allowed for the hammer to start flying must be 1 to 2 ms or less, otherwise the character arrangement will be abnormal. If the allowable value of this temporal variation is small, the current value has to be increased. Another point that may be of concern is that in electromagnetic devices using permanent magnets, the functionality of electromagnetic devices that use permanent magnets is significantly degraded by adsorption of iron powder or abrasion particles.

As in the present invention, the convex portion 2 of the yoke which is important as a function
By providing the contact parts between 1-1 and 22-1 and the movable cores 25 and 26 in the hollow part of the coil frame, it is possible to protect them from the intrusion of paper fluff and the adhesion of iron powder and abrasion powder, which are common to printers. It is possible to provide an electromagnetic device that is stable over time. FIG. 2 is a perspective view of a portion of the electromagnet device in FIG. 1.

A wiring board 27 is arranged between the permanent magnets 20 and the electromagnetic coils 23 arranged in a staggered manner. Lead terminals of the electromagnetic coil 23 are soldered to this wiring board 27. Further, the spark killer 29 of the electromagnetic coil 23 is also wired to the wiring board 27. In the figure, a normal printed circuit board is used as the wiring board, but a flexible wiring board is used to wire the electromagnetic coil and spark killer, as well as to extend the electrical connection to the printer's control device. It can also be used as a substitute for a connector. Further, the coil frame 24 also serves as a guide member for the movable cores 25 and 26, and no new guide member is required. Furthermore, as is clear from FIG. 1, the mechanical connection between the movable iron core 25 and the selection pawl 15 is simplified, and sub-assembly of each program such as the electromagnet device, selection pawl, type wheel, etc. is made possible, and the overall assembly is simplified. I'm trying to simplify it.
As described in detail above, the character selection device of the present invention can significantly reduce the current value, make it possible to lower the price of the power supply, reduce the number of parts used as a printer to reduce costs, and furthermore provide excellent reliability. It can also provide sex.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing a character selection mechanism of a small printer according to the present invention. FIG. 2 is a perspective view of the electromagnet device in FIG. 1. In the figure, 10 is a type wheel, 13 is a type ring spring, 14 is a type wheel shaft, 15 is a selection pawl, 20 is a permanent magnet, 21 and 22
is a yoke, 25 and 26 are movable iron cores, 27 is a wiring board,
28 is a copper foil, 29 is a diode for spark killer, 3
0 is a platen, and 40 is a beam setting member.

Claims (1)

[Scope of Claims] 1. A small printer in which a plurality of type wheels are provided on the same axis, the type characters of each type wheel are selectively arranged at a printing position, and the characters are printed all at once using a platen, comprising: a permanent magnet; a yoke that forms a magnetic circuit with a yoke, an electromagnetic coil that includes a convex portion of the yoke, a movable iron core that is capable of sliding movement in an air core portion of the electromagnetic coil and whose one end can be in contact with the convex portion of the yoke, and the movable iron core. A character for a small printer, characterized in that it is comprised of a selection pawl that engages and cooperates with the other end to selectively stop the type wheel, and a reset means that returns the selection pawl and the movable iron core to a standby state. Selection mechanism.