JPS5840515B2 - drum dot printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drum-type dot printer in which the rotation of a printing head drum is controlled by a pulse motor.

In general, a double-drum type dot printer has a plurality of printing dots protruding from the outer periphery of a printing base drum, with the phases shifted in the axial and circumferential directions, and by rotating the printing base drum, a desired dot is positioned at a printing position, and the dot is placed at a desired printing position. The printer is configured to hit a printing hammer on the drum and print dot marks on recording paper inserted between the drum and the hammer.

Conventionally, in this type of drum-type dot printer, the rotation of the stamping drum was controlled using an AC motor or servo motor, but such printers required a detector and a control circuit to detect the rotational position of the stamping drum. This resulted in problems such as a complicated circuit configuration, poor economic efficiency, and a high failure rate.

This invention was devised to solve these problems, and by controlling the rotation of the stamping drum using a pulse motor, it is possible to simplify the circuit configuration, reduce the failure rate, and improve economic efficiency. The purpose of this invention is to provide a type dot printer.

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

FIG. 1 is a plan view of a drum-type dot printer, and inside a base 1 there is a drum support fitting 2 which is bent into a U-shape.
is fixed, and the shaft 4 of the stamping drum 3 is fixed to both sides of this metal fitting 2.
Both ends are rotatably supported.

A pulse motor 5 is fixed to the left outer side of the base 1.

The shaft 6 of the motor 5 extends inside the base 1 so that its center line coincides with the shaft 4 of the stamping drum 3, and the shafts 4 and 6 are connected by a joint 7.

Further, a bevel gear 8 is fixed to the shaft 6 of the motor 5.

This bevel gear 8 meshes with another bevel gear 9,
The shaft 10 of this gear 9 is connected to a support base 11 fixed on the base 1.
is supported by

Both bevel gears 8 and 9 have the same number of teeth, and are adapted to rotate the shaft 4 of the marking drum 3 and the shaft 10 of the bevel gear 9 at the same speed.

The shaft 10 of the bevel gear 9 is perpendicular to the shaft 4 of the marking drum 3, and a rotary cam 12 is fixed to the shaft 10.

A carrier 13 is mounted on the base 1 so as to be movable forward and backward in a direction parallel to the axis 4 of the drum 3.

A cam roller 14 is attached to one end of the carrier 13 on the cam 12 side.
is supported, and a compression coil spring 15 is inserted between the other end of the carrier 13 and the right edge of the base 1.

The axis 16 of the cam roller 14 is parallel to the axis 10 of the cam 12, and the cam roller 14 is rotated by the spring 15.
It is elastically in contact with the outer periphery of 2.

The pulse motor 5 is a driving source for the printing stand drum 3, and at the same time functions as a carrier driving means together with the bevel gears 8, 9 and the cam 12.

The spring 15 is supported within a cylindrical spring guide 17 fixed to the base 1.

A large number of printing dots 18 are provided on the outer periphery of the printing stand drum 3.
They are arranged in a so-called spiral shape with the phases shifted in the axial and circumferential directions.

On the front edge of the carrier 13 near the drum 3, a large number of printing hammers 19 each holding the same number of printing dots 18 are arranged at equal intervals.

As shown in FIG. 2, each printing hammer 19 is attached to a portion of the carrier 13 that faces the printing stand drum 3 so as to be able to move forward and backward in a direction toward and away from the printing stand drum 3 (that is, in a direction perpendicular to the operating direction of the carrier 13). has been done.

A nut 20 is screwed onto the rear end of the printing hammer 19, and the nut 20 is pushed from the front by a spring 21, so that the printing hammer 19 is always held at a position away from the printing base drum 3.

Further, electromagnetic plungers 22 corresponding to each printing hammer 19 are mounted on the carrier 13 in a staggered manner.

The movable body 23 of the plunger 22 and the nut 20 are connected by a thin wire-shaped connecting rod 24, and by energizing the coil 25 of the plunger 22 and moving the movable body 23 in the direction of the printing stand drum 3, A hammer 19 is struck against a printing dot 18 on the printing stand drum 3.

Note that the movable body 23 is always urged in the opposite direction to the drum by the plate spring 26.

As shown in FIG. 3, the printing dots 18 provided on the printing stand drum 3 are arranged so that the angle between the lines connecting two adjacent ones in the circumferential direction and the center axis 0 is θ, and the printing dots 18 are arranged at intervals of a in the axial direction. There is.

Further, each row of printed dots 18 is arranged with a different inclination by half a circumference, as shown in an expanded view in FIG.

On the other hand, the cam 12 has a line-symmetric shape as shown in FIG. 5, and the radius decreases by a each time it rotates by an angle θ to the left or right from the maximum radius position.

That is, when the maximum radius of the cam 12 is r, the radius at a position nθ rotated from the maximum radius position is r−na.

When the maximum radius position of the cam 12 comes into contact with the cam roller 14, the carrier 13 is located at the rightmost position as shown in FIG. Print the rightmost dot with hammer 1
9, that is, at a predetermined printing position.

Both ends of a shaft 28 of an ink roller 27 are rotatably supported on both sides of the drum support fitting 2, so that the outer periphery of the ink roller 27 is always in contact with the dots 18 of the printing stand drum 3.

A recording paper 2 is provided between the printing stand drum 3 and the printing hammer 19.
9 is inserted.

The pulse motor 5 is, for example, of a four-phase two-excitation type,
One step angle advanced by one excitation switching is set to θ degrees, which is equal to the angle between the lines connecting the aforementioned adjacent dots and the center axis 0.

FIG. 6 is a block diagram showing the control circuit, in which 30 is a central processing unit (CPU), 31 is a RAM (random access
32 is a clock generator.

The CPU 30 connects to the storage device 31 via a data bus.
It is connected to the input port 33, output ports 34, 35, and 36.

The output port 34 supplies data from the CPU 30 to a motor drive circuit 37 that drives the pulse motor 5, and the output port 35 supplies data from the CPU 30 to a plunger drive circuit 38 that drives the electromagnetic plunger 22 of the print hammer 19. and the output port 36
supplies data from the CPU 30 to a motor drive circuit 40 that drives the paper feed motor 39.

When data is input through the input port, the CP
The U 30 stores the data in the RAM of the storage device 31, performs arithmetic processing, and converts it into a character generator address.

The CPU 30 then controls a motor drive circuit 37 via an output port 34, and the motor drive circuit 3 drives the pulse motor 5.

In synchronization with the excitation switching of the pulse motor 5, a plunger drive circuit 38 is controlled via the output port 35 according to the output of the character generator, and the plunger drive circuit 38 controls several electromagnetic plungers 2.
2 is energized and the printing hammer 19 is operated.

In this way, when printing for the - column of dots is completed, the CPU
30 is a motor drive circuit 40 via an output port 36
and operates the paper feed motor 39 to put the recording paper 29 on standby for the next dot printing.

Now, for example, when the excitation signals of each phase shown in a, b, c, and d of FIG. 7 are input to the pulse motor 5, the pulse motor 5 operates at time t.

, T1 t 12 'tt'3 tt4 The excitation is switched at the timing of excitation switching, and at the timing of the excitation switching, a current as shown in e in FIG. 7 flows through the electromagnetic plunger,
The printing hammer is operated at the timing shown at f in FIG.

Note that in the period from t2 to t1 in the figure, the printing hammer is not operated even if the excitation of the pulse motor 5 is switched.

In such a dot printer, the pulse motor 5 is rotated step by step by an angle .theta. by excitation switching, and thereby the printing stand drum 3 is rotated by an angle .theta. in a constant direction.

If a certain printing dot row is now in a position facing the printing hammer 19, when the pulse motor 5 rotates one step, the next printing dot row will come to face the printing hammer 19.

This is because the printing dots are arranged on the stamping drum 3 so that the angle between the line connecting two adjacent printing dots in the circumferential direction of the stamping drum 3 and the center axis 0 of the stamping drum 3 is θ. , and the one-step rotation angle of the pulse motor 5 is also set to θ.

Therefore, if the printing hammer 19 is operated at the timing when the excitation switching of the pulse motor 5 is performed, the printing dot is always located in front of the printing hammer 19.
This allows you to reliably hit the printed dots.

In other words, in this dot printer, there is no need to perform control to detect the rotational position of the printing base drum and set the printing dots at a predetermined position facing the printing hammer. Since it is only necessary to perform control to operate the rotational position, a detector for detecting the rotational position, a control circuit thereof, etc. can be omitted, and the circuit configuration can be simplified and economical efficiency can be improved.

Furthermore, since there is no need to use a rotational position detector which has a relatively high failure rate, the failure rate can also be reduced.

In the above embodiment, the angle of inclination of two print dots adjacent to each other in the circumferential direction of the stamping drum with respect to the central axis of the stamping drum is set to θ, and the one step angle of the pulse smoke is also set to θ, but the present invention is not necessarily limited to this. The point is that the angle of inclination of the two printed dots with respect to the central axis should be an integral multiple of the angle of one step of the pulse motor.

As described in detail above, according to the present invention, a plurality of printing dots are provided on the outer periphery of the stamping base drum with the phases shifted in the axial direction and the circumferential direction, and by rotating the stamping base drum, the printing dots can be placed on any dot. In a drum-type dot printer, in which a printing hammer hits an arbitrary dot by rotating a drum, and a dot matrix is printed on recording paper inserted between the drum and the hammer, the rotation of the printing drum is controlled by a pulse motor. The angle θ between the lines connecting the two circumferentially adjacent center axes of the printing dots protruding from the printing drum is calculated using the pulse motor 1.
The step angle is set to be an integral multiple of the step angle, and the striking operation of the printing hammer is performed at the timing when the rotation angle of the pulse motor reaches the angle θ.
It is possible to provide a drum-type dot printer that does not require a detector or a control circuit for detecting the rotational position of the printing drum, and can simplify the circuit configuration, reduce the failure rate, and improve economic efficiency. be.

[Brief explanation of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a sectional view showing an enlarged part of the same embodiment, and FIG. 3 is a perspective view showing an enlarged part of the same embodiment. FIG. 4 is a partially exploded view of the stamping drum of the same embodiment, FIG. 5 is a plan view showing the cam of the same embodiment, FIG. 6 is a block diagram showing the control circuit of the same embodiment, and FIG.
The figure is a waveform diagram showing the operation timing of the pulse motor and the printing hammer. 3...Marking stand tram, 5...Pulse smoke, 13...Carrier, 18...Printing dot, 19...Printing hammer, 30・・・・・・
-Central processing unit (CPU), 37--Motor drive circuit, 38--Plunger drive circuit.

Claims (1)

[Claims] 1. A plurality of printing dots are provided on the outer periphery of the printing drum, with the phases shifted in the axial and circumferential directions, and by rotating the printing drum, a printing hammer is hit on any dot, and the contact between the drum and the hammer is made. A drum-type dot printer that performs dot matrix printing on recording paper inserted between the printers includes a pulse motor that controls the rotation of the printing drum, an electromagnetic plunger that is operated by striking the printing hammer, and a drive that drives the electromagnetic plunger. A plunger drive circuit is provided, and an angle θ between a line connecting two circumferentially adjacent printing dots protruding from the printing drum and the central axis is set to an integral multiple of one step angle of the pulse motor. . A drum-type dot printer, characterized in that the plunger drive circuit is driven at a timing when the rotation angle of the pulse motor reaches the angle θ.