JPS6013286B2 - Printing magnet drive device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a driving device for a printing magnet used in a printing device such as a line printer.

Fig. 1 is a diagram showing an example of the conventional configuration of a printing magnet drive device in which printing magnets are divided into two groups of odd number digits and even number digits. and 2 are connected to both ends of a power supply (not shown) via switching transistors 3 and 4, and a backflow prevention diode 5 and a switching transistor 6, respectively.

In addition, a diode 7 and a constant voltage diode 8 are connected to both ends of the printing magnets 1 and 2, which constitute a flyback absorption circuit.
A series circuit of is connected. The switching transistors 3 and 4 are alternately turned on by a shuttle switching control circuit 9 via an inverter 10. That is, when printing odd numbered digits, transistor 3 is turned on, and when printing even numbered digits, transistor 4 is turned on. In such a configuration, the printing magnet 1
Since the number of constant voltage diodes 8 constituting the flyback absorption circuit connected to both ends of the magnets 1 and 2 is equal to the number of printing magnets 1 and 2, the parts cost is high and mounting and assembly becomes troublesome. There were drawbacks.

An object of the present invention is to provide a printing magnet drive device that does not require the constant voltage diode required in the above-mentioned prior art, and is easy to mount and assemble at a low cost.

FIG. 2 is a diagram showing an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same parts.

The power supply terminals of the printing magnets 1 and 2 are connected to a power supply via control transistors 2 and 22, respectively. The emitters and collectors of auxiliary transistors 23 and 24 are connected between the collector bases of these transistors 21 and 22. The collector-emitter voltages of the transistors 21 and 22 are controlled to a predetermined value via transistors 27 and 28 by error amplifiers 25 and 26 that amplify the output terminal voltage, that is, the difference voltage between the emitter voltage and the reference voltage. Ru. That is, the emitter voltages of transistors 21 and 22 are controlled to a predetermined voltage. error amplifier 25,2
The collector-emitters of clamp transistors 29 and 30 are connected to the output terminal of 6, and the transistors 27 and
The base voltage of 28 is clamped to a predetermined value. That is, when printing odd number digits, the shuttle switching control circuit 9 turns on the clamp transistor 30,
The base voltage of transistor 28 is approximately at ground potential. As a result, transistors 28, 24 and 22 are turned off.
, only the odd numbered digit printing magnets can be driven. Further, when printing even number digits, the clamp transistor 29 is turned on and the base voltage of the transistor 27 becomes approximately the ground potential. As a result, the transistors 27, 28, and 21 are turned off, and only the printing magnets 2 of even-numbered digits can be driven. The emitter voltages of the transistors 21 and 22 are detected by voltage dividing resistors 31 and 32, and a reference voltage is obtained by a resistor 33 and a constant voltage diode 34.
The flyback voltage of the printing magnets 1 and 2 is returned to the collectors of the control transistors 21 and 22 via the diode 35, and is clamped to the collector-emitter voltage of the transistors 21 and 22. In other words, since the control transistors 21 and 22 are used in a linear region during their operation, their collector-emitter voltage is large;
It has exactly the same clamping effect as the constant voltage diode 8 shown in FIG. As a result, the constant voltage diode 8 for each of the printing magnets 1 and 2 is completely unnecessary, making the configuration and mounting extremely simple and reducing the price. As described above, according to the present invention, the flyback voltage of the printing magnet is clamped by the control transistor, eliminating the need for a constant voltage diode, resulting in effects such as extremely simple mounting and assembly and low cost. Can be done.

[Brief explanation of the drawing]

Fig. 1 is a connection circuit diagram of a conventional device; Fig. 2 is a connection circuit diagram showing an embodiment of the device of the present invention. Control transistor, 25
, 26 are error amplifiers. Figure 1 Figure 2

Claims (1)

[Claims] 1. A printing magnet that biases each printing hammer arranged in a plurality along the printing position, a switching means connected to an end opposite to the power supply of each printing magnet, and between a power supply and the power supply end of the printing magnet. In the printing device, the connection point between each of the switching means and the printing magnet is connected to the power supply and the control transistor through a diode, and the control transistor is arranged to control the output terminal voltage to a predetermined value. A printing magnet drive device characterized by being connected between.