JPS5854995B2 - Printing machine ribbon feed control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ribbon feed control device for a printing machine for winding an ink ribbon pulled out from one ribbon shaft onto the other ribbon shaft via a printing section, and particularly to a ribbon feed control device for a printing machine. A device that rotates the ribbon shaft using a DC motor.

Conventionally, for example, when moving the ink ribbon 2 wound around one ribbon shaft 1a between the type drum 3 and paper 4 and winding it around the other ribbon shaft 1b, the connection between the one ribbon shaft ibt and The winding is done by driving only the motor that has been
The other ribbon shaft 1a is driven via the ink ribbon 2, but when the paper is sent in a damaged or folded state, the ink ribbon 2 is moved when the paper is fed in a damaged or folded state. While the ink ribbon 2 is being fed from the curved portion, it may be pressed against the outer circumferential surface of the type drum 3 due to a damaged or bent portion of the paper and may adhere to it.

At this time, since the type drum 3 is rotating at a higher speed than the ribbon shafts 1a and 1b, the ink ribbon 2 is rotating faster than the type drum 3.
Accidents such as being pulled along the outer peripheral surface of the ink ribbon 2 and getting caught up in the type drum 3 as shown in FIG. 2, preventing the rotation of the type drum 3 or breaking the ink ribbon 2 This has the drawback of causing failure and shortening the life of the device.

The purpose of this invention is to eliminate the drawbacks of the above-mentioned conventional devices.

Hereinafter, embodiments of this invention will be described based on the drawings.
at6b are DC motors that perform one drive rotation in opposite directions.

In the braking circuit 7, a thyristor 8, a resistor 9, a diode 10, a Zener diode 11, and a resistor 12 are arranged in this order to form a grid circuit.

The Zener diode 11 is connected in the opposite direction to the current direction when the gate of the thyristor 8 is open, and the diode 10 is connected in the forward direction.

Furthermore, the gate terminal of thyristor 8 is connected between resistor 9 and diode 10.

The Zener diode 11 and resistors 9 and 12 are used to adjust the operating sensitivity of the thyristor 8, and the diode 10 prevents current from flowing into the braking circuit 7 when the DC motor 6a is being driven. It is for.

The energization direction when the gate of the thyristor 8 is opened corresponds to the polarity of the induced voltage when the DC motor 6a is rotated in the opposite direction to the driving direction, and the braking circuit 7 is configured such that the thyristor 8 is connected in parallel with the DC motor 6a. DC motor 6at
I will be connected.

The DC motors 6a and 6bl each have a drive circuit 13.
a.

13b is connected.

A switching circuit 14 is provided, and a switch 15 selectively drives only one of the DC motor 6a and the DC motor 6b.

The type drum has 16 AC drive motors! This is connected,
A drum speed sensor 17 and a speed detection circuit 18 are arranged adjacent to the type drum 3, and the speed detection circuit 18 is connected to the switching circuit 1.
Connected to 4.

In such a configuration, the ink ribbon 2 is attached to the ribbon shaft 1.
a to the ribbon shaft 1b, the ribbon shaft 1a
The DC motor 6a connected to the ribbon shaft 1bl is not driving, and the DC motor 6b connected to the ribbon shaft 1bl is driving.

Therefore, due to the above-mentioned damage to the paper 4, etc., the ink ribbon 2
When the ink ribbon 2 is pressed against the type drum 3, the type drum 3 is rotating at a much higher speed than the DC motor 6b, so the ink ribbon 2 is caught by the type drum 3 and pulled downward at high speed.

At this time, the DC motor 6a, which is not being driven, is rotated clockwise (quickly), and a voltage opposite to the polarity of the power source is induced at both ends of the DC motor 6a through electromagnetic induction. Since 6a is rotated at a much higher speed than during normal driving rotation, the induced voltage is sufficiently larger than the power supply voltage.

Therefore, when this induced voltage is applied to the braking circuit 7f,
Zener diode 11 becomes conductive and voltage is applied to the gate terminal of thyristor 8, so thyristor 8 becomes conductive.

Then, the induced voltage by the DC motor 6a applied to both ends of the thyristor 8 acts to rotate the ink ribbon 2 in the counterclockwise direction (FIG. 2), which causes the ink ribbon 2 to wrap around the type drum 3 and be pulled downward. clockwise (second
The rotation of the ribbon shaft 1a, which is being rotated as shown in FIG.

On the other hand, the type drum 3 has a ribbon shaft 1a. Since the rotational speed ratio of the drive motor 1b is larger and the rotational torque is correspondingly smaller, the DC motor 6a is driven counterclockwise by the damaged paper or by the action of the braking circuit 7 as described above. When the ribbon 2 is pulled upward, the rotation speed of the type drum 3 decreases,
Or, in most cases, the rotation will stop.

Now, as described above, the ink ribbon 1a is braked by the action of the braking circuit 7, and the ink ribbon 2 is prevented from being drawn into the type drum 3, while the drive of the DC motor 6b is stopped in the following manner. Ru.

That is, the sensor 17 detects a decrease in the rotational speed of the type drum 3.
and is transmitted to the switching circuit 14 through the detection circuit 18.

Then, the switching circuit 14 opens the switch 15 leading to the drive circuit 13b, so that the drive of the DC motor 6b is stopped.

At this time, the ribbon shaft 1b stops rotating, so the ink ribbon 2 wrapped around the type drum 3 becomes slack.

Then, when the damaged paper is removed, the type drum 3 is released from the compression and begins to rotate normally.

Furthermore, when the DC motor 6b is rotated, the ribbon shaft 1b
starts winding up the ink ribbon 2 and returns to normal operation.

Here, when the ink ribbon 2 is fed from the ribbon shaft 1a to the ribbon shaft 1btc, even if the ink ribbon 2 tries to get caught on the outer circumferential surface of the type drum 3, the rotational torque of the type drum 3 as described above Since the rotational torque of the ribbon shaft 1a is sufficiently larger, the ink ribbon 2 is pulled up against the winding force due to the rotation of the ribbon shaft 1a.

Therefore, in this embodiment, no braking circuit is provided on the DC motor 6b side.

As mentioned above, this invention is equipped with a braking circuit using a DC motor for feeding the ink ribbon, and a braking circuit using a cylinder. When it becomes
Since the direct current motor for feeding the ink ribbon is braked immediately, damage to the print drum and ink ribbon is prevented and the life of the device is extended.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the ribbon feeding state of a printing machine normally used, and Figure 2 is a diagram showing the state of ribbon feeding in a printing machine that is normally used.
FIG. 3 is a circuit diagram of the ink ribbon feeding motor control circuit according to the present invention. In the figure, 1a and 1b are ribbon shafts, 2 is an ink ribbon, 3 is a type drum, 5 is a hammer, 6a + 6b is a DC motor, 7 is a braking circuit, 8 is a silisk, 14 is a switching circuit, 16 is a drive motor 17 is a sensor , 18 is a detection circuit.

Claims (1)

[Scope of Claims] 1. A type drum 3 having types on its outer peripheral surface and supported on a machine frame so as to be rotatable about a fixed axis, a drive motor 16 connected to the type drum, and a type drum 3 arranged correspondingly to the type drum. a hammer 5, and a pair of ribbon shafts 1a rotatably supported on the machine frame at intervals parallel to each other on both sides of the rotary axis of the type drum. 1b and both ends of which are wrapped around both ribbon shafts separately so that they can be moved between the type drum and the hammer in the direction crossing the axis of the type drum. One DC motor 6a is connected to the other ribbon shaft and is slower than the drive motor and can be driven in the same direction as the drive motor (this is the other DC motor 6a that can be driven). A motor 6b, a sensor 17 that detects a decrease in the rotational speed of the type drum, and a sensor 17 that detects a decrease in the rotational speed of the sensor (
A detection circuit 18 generates a signal in connection with this, and a detection circuit 18 allows the operation to be switched to drive only one of the DC motors and stops driving the other DC motor in relation to the signal of the detection circuit. This switching circuit 14 is connected to a braking element that conducts and brakes one DC motor by a back electromotive force generated when only the other DC motor is driven and one DC motor is driven faster than its driving speed by the ribbon. A ribbon feed control device for a printing machine, which is equipped with one DC motor (and a braking circuit 7 connected in parallel with the DC motor).