JPH0514860Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a type wheel selection mechanism for selecting appropriate type from a type wheel in a printer based on print command contents and stopping the type wheel at a printing position.

[Conventional technology]

In conventional type wheels and printers equipped with a type wheel selection mechanism, the type wheels, on which letters, numbers, symbols, etc. are formed on the outer periphery, are arranged in parallel in the axial direction for the same number of digits required for printing. Each type wheel is selected by driving a selection claw of a type wheel selection mechanism provided corresponding to each type wheel.

To explain further, the conventional type wheel selection mechanism is provided with the same number of electromagnetic means as the type wheels, and by energizing the electromagnetic means, the selection pawl is driven in the selection direction, and the selection pawl is inserted into the locking recess that stops the type wheel. is engaged to stop the type at the printing position.

In such a conventional type wheel selection mechanism,
Since the same number of electromagnetic means as selection claws are provided, the structure is complex, the number of parts is large, the overall shape of the printer is large, and the coils of each electromagnetic means must be energized, resulting in high power consumption. It was hot.

In particular, when the number of digits to be printed is large and high-speed printing is attempted, it is necessary to reduce power consumption.

Therefore, the present inventor has already proposed a type wheel selection mechanism in which two selection pawls are individually driven by one electromagnetic clutch to appropriately select each of the two type wheels. Figure and 3rd
As shown in the figure, when two selection pawls are driven separately by one electromagnetic clutch, the driving force is made smaller, and the coil used in the electromagnetic clutch is made smaller in capacity and smaller in size. We have also proposed a type wheel selection mechanism that uses less electricity and can be made more compact overall.

The type wheel selection mechanism shown in FIGS. 2 and 3 is as follows:
The type wheel unit (both not shown), which normally rotates together with the type axis, is stopped at the printing position for the appropriate type based on the type selection command, and the type wheel unit is held at that position until printing is completed. After printing is completed, the type wheel unit is released and reset to the initial position. That is, in order to carry out such type selection operation, electromagnetic clutches 2 are provided in the axial direction of the selection shaft 1 in half the number of type wheel units. This electromagnetic clutch 2 consists of an electromagnetic coil 4 in which a rotating sleeve 3 made of a magnetic material is rotatably loosely fitted into a center hole, and a support member 5 that supports the electromagnetic coil 4. The rotating sleeve 3 is connected to the selection shaft 1 by a spline connection (not shown), and is constantly rotated together with the selection shaft 1. A pair of plates 6, 6 made of a magnetic material are provided at both ends of the electromagnetic clutch 2 in the axial direction, respectively, and are loosely fitted onto the selection shaft 1. These pair of plates 6, 6 are connected to the end surface of the rotary sleeve 3 by the elasticity of the leaf spring member 7 interposed between the adjacent plates 6 of the other pair (not shown). It is in elastic contact with the inner surface of. The pair of plates 6, 6 are formed in a symmetrical shape, and extend from a central disk portion that comes into elastic contact with the end surface of the rotary sleeve 3 and covers the end surface of the electromagnetic coil 4 to a locking recess (1) for stopping the type wheel. a selection pawl 8 that selectively stops the type wheel by engaging with and disengaging from the casing (both not shown); and a locking spring 1 fixed to the case 9.
A locking pawl 11 that engages with and disengages from the peak portion 10a of 0, a magnetic field closing tongue portion 14 that clamps the drive plate 13 made of a magnetic material fixed to the drive shaft 12, and a tongue portion 14 that engages with the locking recess. A scooping protrusion 1 used to release the engaged selection claw 8 when resetting typefaces.
5 is provided protrudingly.

When the electromagnetic coil 4 is not energized, the pair of plates 6, 6 absorb the frictional force between the end face of the rotating sleeve 3 and its own inner surface, and the tongue portion 14 for closing the magnetic field.
Each locking pawl 11 is held down below the peak 10a of the locking spring 10 by a force greater than the frictional force between the micro protrusions 16 and the drive plate 13, and is held at the initial position.

When the electromagnetic coil 4 is energized, the pair of plates 6, 6 are attracted to the rotating sleeve 3 by magnetic force, and the locking pawl 11 is attracted by the rotational force of the selection shaft 1.
to get over the peak 10a of the locking spring 10. The drive plate 13 fixed to the drive shaft 12 at this time applies a triggering force in the direction to help the locking pawl 11 get over the peak 10a, and is made of a magnetic material. Therefore, it also plays the role of forming a magnetic field when the electromagnetic coil 4 is energized. This magnetic field comes out from the right end of the rotating sleeve 3, for example, and is transmitted to the center of the right plate 6, its magnetic field closing tongue 14, the drive plate 13, the magnetic field closing tongue 14 of the left plate 6, its center. 3 to the left side of the rotating sleeve 3 to form a closed loop. Drive plate 1 of magnetic field closing tongue 14
The micro protrusions 16 protruding from the surface of the drive plate 1
3 and both magnetic field closing tongues 14, 14, and also prevents a decrease in the magnetic flux density formed by the electromagnetic coil 4.

When resetting the type wheel, the scooping protrusion 15 of the plate 6 is moved by a reset cam (not shown).
The plate 6 is returned to its initial position by rotating the plate 6 clockwise in FIG. 2 to cause the locking pawl 11 to move downward over the peak 10a of the locking spring 10.

[Problem that the invention attempts to solve]

However, in the type wheel selection mechanism shown in FIGS. 2 and 3, the drive plate 13 is fixed to the drive shaft 12 and the two are directly spline-coupled in order to constantly rotate the drive plate 13, but the drive plate 13 is made of a magnetic material. Since both the drive shaft 12 and the drive shaft 12 are made of metal, a gap occurs at the spline joint between the two due to manufacturing errors, and play occurs between the two. On the other hand, the driving plate 13 is connected to the magnetic field closing tongue part 14 of the plate 6.
When high-speed printing is performed, the load applied to the drive plate 13 fluctuates in a short period of time. There is a risk that a situation may occur in which the magnetic field closing tongue part 14 of the plate 6 is not followed by the driving plate 13, and the auxiliary rotational force applied to the magnetic field closing tongue portion 14 of the plate 6 is also reduced, which is an inconvenience that there is a limit to the speeding up of type selection on the type wheel. It was hot.

The present invention was made in view of these points, and it is possible to connect the drive shaft and the drive plate without any play, and to constantly rotate the drive shaft and the drive plate as one unit, so that the plate It is an object of the present invention to provide a type wheel selection mechanism that can maintain a constant auxiliary rotational force applied to a type wheel and increase the speed of type selection.

[Means for solving problems]

The type wheel selection mechanism of the present invention includes a rotatable drive plate made of magnetic material splined to a constantly rotating drive shaft, and an electromagnetic coil through which a constantly rotating rotating sleeve passes. a pair of plates that are in elastic contact with both ends of the rotating sleeve and that are attracted to the rotating sleeve and rotate integrally when the electromagnetic coil is energized, the plate rotating in the rotating direction; In the type wheel selection mechanism, the type wheel selection mechanism has a plate including a selection pawl for stopping the type wheel and a magnetic field closing tongue portion that holds the drive plate and receives a driving force in the rotating direction. An annular coupling part made of a resin material and having a central shaft hole into which the drive shaft is press-fitted is provided in the center of the drive plate, which becomes a part of the path of the magnetic lines of force formed when the drive plate is energized. shall be.

[Effect]

According to the type wheel selection mechanism of the present invention, the drive shaft is press-fitted into the center shaft hole of the annular joint made of resin material formed at the center of the drive plate, and the two are integrally connected. The drive plate and the drive plate always rotate integrally, and the corrective rotational force applied from the drive plate to the plate via the magnetic field closing tongue remains constant, thereby speeding up character selection.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows an embodiment of the present invention, and the same parts as in FIGS. 2 and 3 are given the same reference numerals.

In this embodiment, the drive plate 13 made of magnetic material is
An annular coupling portion 17 made of a resin material is integrally formed in the center thereof, and has a central shaft hole 18 having an inner peripheral shape into which the drive shaft 12 is press-fitted.
This annular joint 17 may be made by insert molding a resin material in the center of the drive plate 13, or may be made separately from the drive plate 13 and attached to the drive plate 1.
It may be formed by press-fitting into the center hole portion of No.3. The other parts are formed in the same manner as before.

Next, the operation of this embodiment will be explained.

The connection between the drive plate 13 and the drive shaft 12 is the connection between the drive shaft 1
2 is press-fitted into the central shaft hole 18 of the annular coupling portion 17. As a result, the drive shaft 12 and the drive plate 13 are integrally coupled with no play between them, and both are rotated as one. Therefore, even if the load applied to the drive plate 13 through the magnetic field closing tongue part 14 of the plate 6 fluctuates, the magnetic field closing tongue part 14 is not removed from the drive plate 13.
The auxiliary rotational force applied to the plate 6 is always constant, and the drive of the plate 6 in the selection direction (counterclockwise direction in FIG. 1) is always performed smoothly.
It is also possible to speed up the selection of printed characters using the selection claw 8.

The present invention is not limited to the above-described embodiments and can be modified as necessary.

[Effect of idea]

Since the type wheel selection mechanism of the present invention is constructed and operates in this way, the drive shaft and drive plate can be connected without any play, and the drive shaft and drive plate can always be integrally connected. By rotating the plate, the auxiliary rotational force applied to the plate can be kept constant, and the printing speed can be increased.

[Brief explanation of drawings]

FIG. 1 is a side view showing an embodiment of the type wheel selection mechanism of the present invention, FIG. 2 is a side view of a conventional example, and FIG. 3 is an exploded perspective view of the conventional example. 2... Electromagnetic clutch, 3... Rotating sleeve, 4
... Electromagnetic coil, 6 ... Plate, 8 ... Selection claw, 12 ... Drive shaft, 13 ... Drive plate, 14 ...
Magnetic field closing tongue portion, 17... Annular coupling portion, 18...
Central axial hole.

Claims (1)

[Scope of utility model registration request] An electromagnetic clutch includes a rotatable drive plate made of a magnetic material splined to a constantly rotating drive shaft, an electromagnetic coil through which a constantly rotating rotating sleeve passes through, and an electromagnetic clutch comprising: a pair of plates that are in elastic contact with both ends and are attracted to the rotating sleeve and rotate integrally when the electromagnetic coil is energized, and the selection pawl rotates in the rotation direction to stop the type wheel; and a magnetic field-closing tongue portion that holds the driving plate and receives a driving force in the rotating direction, in which the magnetic field lines formed when the electromagnetic coil is energized are A type wheel selection mechanism characterized in that an annular coupling part made of a resin material and having a center shaft hole into which the drive shaft is press-fitted is provided in the center of the drive plate which becomes a part of the passage.