JPH0351224B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a character selection device for a serial printer, and more particularly to a character selection device for a serial printer, and more particularly to a type selection device equipped with a simple braking mechanism that can reliably suppress residual vibration during positioning. .

[Conventional technology and problems]

For example, in a type serial printer used as one of the printing devices of a data processing device, the first
As shown in the figure, a print wheel 1 around which a large number of characters are arranged is struck with a hammer 2 to print on a paper P positioned on a platen 3.

In this case, type selection is performed by rotating the print wheel 1 by a predetermined amount using the stepping motor 4 for type selection, but when selecting type, the home position is determined by the home position sensor, and the home position is The stepping motor 4 for selecting a type is controlled by determining how far away the selected type is located. At this time, as a home position sensor, for example, a magnet 6 is attached to the tip of the arm 5 made of a thin stainless steel plate.
is fixed, and the arm 5 made of thin stainless steel plate is connected to the rotating shaft 9 of the stepping motor 4 using screws 8, 8.
sticks to. Separately, the Hall element 7 is fixed to the frame 10, so that when the magnet 6 faces the Hall element 7, an output is generated from the Hall element 7, and the position where the magnet 6 and the Hall element 7 face each other is the home of the print wheel 1. Match the position. Then, when desired characters are positioned on the platen, they are struck with a hammer 2 and printed on the paper P.

Incidentally, in order to perform the character selection operation quickly and stably, it is necessary to minimize the residual vibration during positioning of the stepping motor 4. For this purpose, the stepping motor 4 is accelerated and decelerated, and then locked and stopped by excitation of two specific sets, for example, AB phase. However, if the residual speed of the stepping motor 4 is large by the time it reaches this locking position, it will overshoot, and when it locks and returns, it will return too far. As shown, it is repeated to produce a state similar to a simple harmonic motion. If this continues for a long time and continues even during hammering, there is a drawback that the printing becomes very disordered.

[Purpose of the invention]

An object of the present invention is to provide a compact type selection device that stabilizes the type selection operation by improving the above-mentioned problem that the residual vibration during positioning is large, poorly damped, and the type selection operation is unstable. It is to be.

[Structure of the invention]

To achieve this object, the type selection device of the present invention includes a type wheel, a stepping motor that drives the type wheel through a rotating part, and a stepping motor that is installed in the rotating part and controls the home position of the type wheel. In a type selection device having a home position sensor section for detecting a type, a friction drum integrally configured with the home position sensor section is provided in a rotating section driven by the stepping motor, and the friction drum is in contact with the friction drum. A contact portion for suppressing rotation of the rotating portion is provided.

[Embodiments of the invention]

An embodiment of the present invention will be described based on FIGS. 4 to 6.

FIG. 4 is a side view of the main part of the present invention, FIG. 5 is an explanatory diagram of the state of contact between the friction drum and the friction spring taken from arrow A in FIG. 4, and FIG. 6 is an explanatory diagram of the operation of the present invention.

In the figure, the same reference numerals as in other figures indicate the same parts, and 9'
20 is a rotational shaft of the stepping motor 4 corresponding to the first rotational shaft 9; 20 is a friction drum;
21 is a friction ring of the friction drum 20, 22
is a mounting screw, 23 is a stainless steel thin plate arm,
24 is a rivet, 25 is a spring, and 26 is a fixing screw.

In the present invention, a friction drum 20 made of, for example, aluminum is fixed to the rotating shaft 9' of the stepping motor 4 with mounting screws 22, 23, etc., and a friction drum made of, for example, polyimide resin is attached to the outside of the friction drum 20. A ring 21 is glued and a spring 25 is provided which contacts the friction ring 21, and the spring 25 is fixed to the fixed part by means of a fixing screw 26. Then, an arm 23 made of a thin stainless steel plate is fixed to the upper surface of the friction drum 20 with rivets 24, etc., and a magnet 6 is fixed to the tip of the arm 23 with an adhesive or the like.

Therefore, the friction ring 21 is connected to the spring 25.
Since the print wheel is always lightly pressed down by the print wheel, even if the above-mentioned vibration occurs during positioning during type selection, the friction between the friction ring 21 and the spring 25 allows the print wheel to be accurately positioned at the predetermined position (not shown in FIG. 4). In addition to being able to stop the home position sensor, the arm 23 and magnet 6 that make up the home position sensor are integrated with the friction drum 20 and placed behind the stepping motor 4, making these structures extremely compact. It can be done.

Friction drum 20 and its friction ring 2
1. It is also within the scope of the present invention to integrally construct the arm 23 etc. with polyacetal resin, polyamide resin, etc., and since each of these parts can be constructed as an integrated component, its structure and assembly can be extremely simplified. can be converted into

〔Effect of the invention〕

According to the present invention, a stepping motor is provided with a friction drum, and a spring-like contact part that lightly contacts the friction drum is provided, and this friction drum and an arm for fixing a magnet are integrally provided, so that the stepping motor can be moved easily. It is possible to very easily suppress the occurrence of undesired vibrations during positioning of the motor, and the configuration thereof can also be made very simple.

[Brief explanation of drawings]

1 and 2 are explanatory diagrams of a conventional type selection device, FIG. 3 is an explanatory diagram of its operation, FIGS. 4 and 5 are configuration diagrams of an embodiment of the present invention, and FIG. 6 is an explanatory diagram of its operation. It is. In the diagram, 1 is the print wheel, 2 is the hammer, and 3
is a platen, 4 is a stepping motor, 5 is an arm, 6 is a magnet, 7 is a Hall element, 8 is a screw, 9, 9' are rotating shafts, 10 is a frame, 20 is a friction drum, 21 is a friction ring, 22 is a mounting screw, 23 is an arm, 24 is a rivet, 2
5 is a spring, and 26 is a fixing screw.

Claims (1)

[Scope of Claims] 1. A type wheel, a stepping motor that drives the type wheel via a rotating shaft, an arm portion that rotates in accordance with rotation of the rotary shaft, and a stepping motor that is attached to the arm portion and that drives the type wheel via a rotating shaft. A type selection device having an instruction section that indicates a home position, and a sensor section that recognizes the instruction section and detects the home position of a type wheel, comprising: a friction drum that rotates together with the rotating shaft; A biasing means for biasing the outer periphery of the friction drum to suppress rotation is provided, and the arm portion is fixedly and integrally formed on the bottom surface of the friction drum, and a part of the arm is attached to the surface of the bottom surface. A type selection device characterized in that the indicating portion is attached to the extended portion in a shape extending in the direction.