JPS644524Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in wire dot printers.

As is well known, in a wire dot printer, the print head moves, and while the print head is running, pulses at a fixed period are selectively input to the required solenoid among the plurality of wire drive solenoids built into the print head, thereby printing. The wire flies and prints dots.

Now, in such wire dot printers, there is a problem of heat generation in the solenoid and the switching element that turns the solenoid on and off. and,
Due to this thermal factor, the printing speed (the driving interval of the solenoid and the running speed of the printing head) and the copying performance are in a contradictory relationship. In other words, as the speed increases, the cycle of pulses input to the solenoid and print head feed motor becomes smaller, and the drive current that drives the solenoid is limited by the thermal factors of the solenoid and switching elements, reducing the printing energy. ability will be reduced. On the other hand, in order to improve the copying ability, the solenoid drive current must be increased so that the flying speed of the wire becomes faster, so the printing speed must be lowered due to thermal factors. Therefore, conventionally, high-speed wire dot printers that place emphasis on printing speed and low-speed wire dot printers that place emphasis on copying ability have been used. However, it is disadvantageous for the user to prepare two machines in terms of equipment and availability, so generally the model is selected depending on whether high-speed printing or copying ability is given priority. The reality is that there are.

The present invention was developed against the above background, and it is an object of the present invention to provide a wire dot printer that can satisfy both the functions of high-speed printing and high copying ability in one unit.

The present invention will be explained below with reference to an illustrated embodiment.
In the figure, except for blocks 3 and 4 surrounded by two-dot chain lines, this circuit is exactly the same as the constant current drive circuit already disclosed in Japanese Utility Model Application No. 55-3377, so its principle will be briefly explained. That is, the constant current drive circuit has a constant voltage circuit 1 and a drive circuit 2 that drives the printing wire drive solenoid S, and these are connected to a DC power supply.
Operates with operating current from E ₁ and also solenoid S
is supplied with a drive current from a DC power supply _E2 .

Now, when the voltage at the input terminal P changes from the L level to the H level, the diode D becomes reverse biased and turns OFF, and the two Darlington-connected transistors TR ₁ , which constitute the switching element,
TR ₂ turns ON. As a result, the solenoid S is connected to the power source _E2 , and a drive current I flows through the solenoid S. Also, the voltage at input terminal P is L.
When the level is reached, both transistors TR ₁ and TR ₂ are turned off, resulting in a switching operation. Furthermore, as the emitter voltage of the transistor TR ₂ increases, the current flowing into the constant voltage circuit 1 through the transistor TR ₃ increases.

A voltage divided by a resistor _R1 and a variable resistor _VR1 is applied to the base of the transistor _TR4 of the constant voltage circuit 1. Therefore, transistor TR ₂
Although the details are omitted, the drive current _I1 of the solenoid S when it is ON is a resistor connected to the emitter of the transistor _TR2 and the negative side of the power supplies _E1 and _E2 .
Assuming R ₂ , I ₁ = VR ₁ / R ₂ (R ₁ + VR ₁ )・E ₁ = E ₁ / R ₂ (R ₁ / VR ₁ + 1
) becomes.

Now, in this invention, a switch is connected in parallel to variable resistor VR ₁ .
Variable resistor VR ₂ is connected via SW ₁ . Therefore, when the switch SW ₁ is turned on, the drive current I ₂ of the solenoid S at this time becomes I ₂ =E ₁ /R ₂ (R ₁ ·VR ₁ ·VR ₂ /VR ₁ +VR ₂ +1).

Here, 1/VR ₁ > VR ₁・VR ₂ /VR ₁ + VR ₂ , so I
₂ > I ₁ .

In this way, by turning on the switch _SW1 , the driving current I of the solenoid S changes from the small current _I1 to the large current _I2 , so that the copying ability is increased. However, if the drive current I of the solenoid becomes large, thermal factors become a problem, so the present invention is further configured to automatically change the printing speed to a low speed in conjunction with the operation of the switch _SW1 .

That is, the input terminal P is supplied with a solenoid energization cycle setting circuit 5, and the motor 6 that runs the print head is supplied with a motor energization cycle setting circuit 7, and these circuits 5 and 7 each receive a drive current I _{1 .} The high speed 51, 71 generates pulses at the optimum energization period t ₅₁ , t ₇₁ and the energization period t ₅₁ ,
Low speed _52, 72 that generate pulses at energization periods t ₅₂ and t ₇₂ that are larger than t 71 and are optimal for the drive current I ₂
It is designed to emit pulses with two types of energization cycles. _{The high speed 51, 71 and the low speed 52, 72 are respectively switched by switches SW 2 ,} SW ₃ which are interlocked with the switch SW _1.
When is ON, switch SW ₂ , SW ₃ is for high speed 51,
71 to 52 and 72 for low speed.

Therefore, when switch SW ₁ is OFF, the solenoid drive current I is a small current I ₁ , the printing solenoid is energized at a small energization cycle t ₅₁ from the solenoid energization cycle setting circuit 5, and the print head is energized by the motor. They are each driven with a small energization period _t71 from the period setting circuit 7. That is, although the copying ability is inferior, the printing speed is increased. Also, when switch SW ₁ is turned on, the solenoid drive current I becomes a large current I ₂ , and switches SW ₂ and SW ₃ are activated in conjunction with switch SW _1.
, so the printing solenoid is energized at the large energization cycle _t52 from the solenoid energization cycle setting circuit 5.
Also, the print head feed is controlled by the motor energization cycle setting circuit 7.
They are each driven with a large energization period _t72 from . That is, although the copying ability is improved, the printing speed is reduced.

As is clear from the above description, according to the wire dot printer of the present invention, high-speed printing and high copying ability can be easily selected and used by switching a switch.

[Brief explanation of drawings]

The figure is a driving circuit diagram showing an embodiment of the wire dot printer according to the present invention. S...Solenoid, _SW1 , _SW2 , _SW3 ...Switch, _VR1 , _VR2 ...Variable resistor, 5...Solenoid energization cycle setting circuit, 6...Motor, 7...Motor energization cycle setting circuit.

Claims (1)

[Scope of utility model registration request] A printing wire driving solenoid, a driving circuit for selectively passing current through the printing wire driving solenoid, and a drive circuit that cooperates with the driving circuit to limit the current flowing to the printing wire driving solenoid to a predetermined value. By connecting the constant voltage circuit in parallel with one of the two voltage dividing resistors connected to the base of the transistor of this constant voltage circuit, and placing it between the base and the negative side of the power supply, and turning it on. a switch for increasing the limit value of the current flowing through the printing wire driving solenoid; a solenoid pulse cycle setting circuit for setting the period of the pulse energized to the printing wire driving solenoid to be large or small; A switch for switching the cycle of pulses energized to high or low, a motor pulse cycle setting circuit for setting the cycle of pulses energized to the print head feed motor to large or small, and a cycle of pulses energized to the motor to be set high or small. The three switches are connected, and the connected switches are operated to increase the current flowing through the printing wire drive solenoid.
By switching the cycle of the pulses energized to the print wire drive solenoid to a higher frequency and the cycle of the pulses energized to the print head feed motor to a higher frequency, printing with high copying performance is achieved, and by switching the switch to the opposite side, high-speed printing is achieved. A wire dot printer characterized by: