KR930011184B1 - Hammer solenoid bi-level driving circuit - Google Patents

Abstract

This driving circuit for driving a hammer solenoid comprises a Bi- level driver (10) connected to a driving hammer signal port (P) of a central processing unit and a comparator (3) comparing the output values of resistances (R1),(R2),(R3) and a sensor resistance (Rs) and a Bi-level signal generator (20) connected to the output unit of Bi-level signal generating Bi-level signal.

Description

Bi-Level Driving Circuit of Hammer Solenoid

1A to 1D are conventional constant voltage solenoid drive circuit diagrams, solenoid current waveform diagrams, hammer signal waveform diagrams, and hammer trajectory diagrams, respectively.

2A to 2D are conventional constant current solenoid driving circuit diagrams, solenoid current waveform diagrams, hammer signal waveform diagrams, and hammer trajectory diagrams, respectively.

3A to 3D are bi-level solenoid current waveform diagrams, solenoid control signals (P), (PL) waveform diagrams, and hammer trajectory diagrams according to the present invention, respectively.

4 is a correlation position diagram of round, daisy wheel and hammer.

* Explanation of symbols for main parts of the drawings

1: central processing unit 2: inverter

3: comparator 10: bi-level drive unit

20: Bi-level signal output section R1 to R5, RS: resistor

Q1, Q2: Transistor ZF: Flywheel Element

D1: diode

The present invention relates to an electronic typewriter, and more particularly to a bi-level drive circuit of a hammer solenoid, which increases the printing speed of the hammer by reducing the settling time, which reduces the recursion occurring after the solenoid printing. It's about the furnace.

FIG. 1A is a constant voltage solenoid driving circuit diagram. When the hammer of the central processing unit (CPU) is in a low state as shown in FIG. B, the output of the inverter 1 becomes a logic high state and the current Flows through the resistor Rp to the base of the transistor Q1, and the transistor Q1 is turned on to operate the hammer. The flywheel element ZF and the clamp diode Dc form a flywheel loop for protecting the transistor Q1 from back electromotive force generated in the solenoid at turn-off of the solenoid Q1.

When the transistor Q1 is turned on, the hammer moves in the same waveform as 1d degree, and it takes a certain time until the bending stops after the hammer is operated. The first bending amplitude A1 and the second bending amplitude A2 are stopped. Has

Since the constant voltage hammer solenoid driving circuit as described above is a constant voltage driving method, the rising time of the solenoid driving current is long, so that a large amount of energy cannot be transferred to the hammer within a short time, and thus there is a limit in terms of printing speed improvement. After the hammer solenoid is operated, the bending occurs until the stop, and the setting time is long, and if the amplitude during the bending is large, the contact with the Daisy-Wheel causes interference. The speed was limited because the daisy wheel could not be driven immediately afterwards. In other words, in the constant voltage driving of FIG. 1, the energy transfer time to the hammer solenoid is long, and the hammer recursion after the printing and the interference with the daisy wheel are severe. Therefore, the printing speed of the hammer is limited. There was a problem that it was not suitable.

2a to d are diagrams showing the circuit diagram, current and signal waveforms, and the trajectory of the hammer in the constant current solenoid driving circuit, and have similar characteristics to those of the constant voltage solenoid driving circuit of FIG. 1 except for the constant current driving. Since the constant current solenoid driving circuit performs constant current driving, the hammer driving voltage can be larger than the driving voltage of the hammer during constant voltage driving, and thus, the rising time of the current can be shortened, and thus the energy can be supplied to the hammer in a short time. It is determined by the resistance values of the resistors R1, R2, and Rs. However, the constant current hammer solenoid driving circuit acting as described above is a constant current driving method, so even if the rising time of the current is short and a large amount of energy can be supplied within a short time, the recursion component generated after printing is large and the setting time is long. Interference with the daisy wheels also occurs and there is a limit of printing speed, which is not suitable for high speed electronic typewriters.

The present invention is to solve this problem, the object of the present invention is to reduce the hammer's setting time (Bi-Level) of the hammer solenoid to increase the printing speed by reducing the interference with the daisy wheel In providing the furnace.

A feature of this invention for achieving this object is an electronic typewriter; A bi-level driver connected to the hammer signal port and the bi-level drive port of the central processing unit to drive the bi-level; A comparator connected to an output of the bi-level driver to compare an output value of a time constant adjusting resistor and an output value of a sensor resistor; And a bi-level driving circuit of a hammer solenoid, which is connected to an output terminal of the comparator and configured to output a bi-level signal.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

3A is a bi-level hammer solenoid driving circuit diagram according to the present invention, in which a bi-level driving unit 10 is connected to the central processing unit 1.

The bi-level driver 10 connects an inverter 2 for inverting a signal to a hammer signal port P of the central processing unit 1 and switches a switching transistor to a port PL for bi-level driving. Connect Q1).

The transistor Q1 turns on when the output signal of the port PL is at a high level to change the voltage applied to the comparator 3.

Then, the time constant adjusting resistors R1, R2, and R3 are connected to the output terminal of the inverter 2 and the collector terminal of the switching transistor Q1, and the bias resistor R5 is connected to the voltage source Vcc. Is connected.

On the other hand, the output terminal of the bi-level drive unit 10 is connected to the comparator 3 for comparing the two input signals. The comparator 3 compares the output of the sensor resistor Rs with the outputs of the time constant adjustment resistors R1, R2, and R3.

The bi-level signal output unit 20 is connected to the output terminal of the comparator 3. The bi-level signal output section 20 connects a flywheel loop to the solenoid 4 in parallel, a switching transistor Q2 to the solenoid 4, and a sensor resistor on the emitter side of the transistor Q2. Configure by connecting (Rs).

4 is a correlation diagram of platen, daisy-wheel and hammer, where Dw is the distance from the hammer tip to the daisy wheel and Dp is the distance from the hammer tip to the round. Distance.

Referring to the operation of the present invention configured as described above in more detail.

의 값이 인가되고 이에따라 비교기(3)의 출력은 ＂하이＂상태가 되어 트랜지스터(Q2)가 ＂턴온＂되어 솔레노이드의 전류는 급격히 상승한다.3A is a constant current bi-level hammer solenoid driving circuit diagram according to the present invention, in which the hammer signal port P of the central processing unit 1 is a hammer signal port, and the hammer signal port P is a low level. When it is in the state, the output of the inverter 2 goes from low to high level, and the non-inverting input terminal (+) of the comparator 3

Is applied and the output of the comparator 3 is in a high state, and the transistor Q2 is turned on so that the current of the solenoid rises rapidly.

On the other hand, when the voltage drop of the sensor resistor Rs becomes larger than the voltage V + of the non-inverting input terminal + of the comparator 3, the output of the comparator becomes a low to low level state and the transistor Q2 When the current is turned off, the current decreases, and as the current decreases, when the voltage drop of the sensor resistor Rs becomes smaller than the voltage of the non-inverting input terminal (+) of the comparator, the output of the comparator 3 is again in the high level state. Transistor Q2 turns on and the current increases again. In this way, the constant current is driven.

로 되어 이 전압이 센서저항(Rs)에서의 전압강하와 비교기(3)에서 비교되며 이때 솔레노이드전류 파형은 제3b도와 같이 된다.The current at this time is defined as i1. If at time T0 (which defines the time on the X-axis line at which the current is generated), the port PL goes from a low level state to a high level state, the transistor Q1 is turned on and the comparator 3 is turned on. Non-inverting input terminal (+) voltage is

This voltage is compared with the voltage drop at the sensor resistance Rs at the comparator 3, where the solenoid current waveform is shown in FIG. 3b.

The VCE (sat) is a voltage between the collector and the emitter in the saturation state of the transistor, and its value is 0.2V.

When the current waveform as shown in FIG. 3b is formed, the motion trajectory of the hammer becomes as in FIG. 3c.

On the other hand, since the current i1 is turned off at the time T0 and the current i2 is newly supplied, the restoring force to be restored to its original position after the hammer printing and the driving force by the current i2 are opposite to each other. Since the restoring force generated is greatly reduced, the rear bending amplitude is greatly reduced, thereby reducing preparation time and greatly reducing the rear bending amplitude, thereby significantly reducing interference with the daisy wheel.

In more detail, the position of the flanger (not shown) of the hammer solenoid is stopped at the position where the spring elastic force and the suction force by the energy of the electromagnet are balanced. Since the direction of spring elastic force and electromagnet suction force is reversed when interpreting this exclusively, when the current of the driving coil is changed from i1 to i2 in the bi-level driving, the electromagnet suction force by i2 cancels the elastic force, so The restoring force is reduced and the amplitude of the bouncing becomes small. Therefore, since i2 becomes zero from the initial position to the end of the first bouncing, it does not affect the second bouncing, thereby effectively reducing the hammer's recursion.

As described above, the present invention reduces the settling time by reducing the hammer's recursion through the bi-level solenoid driving, and reduces the interference with the daisy wheel, thus enabling the driving of the daisy wheel immediately after printing. The driving force of the hammer is possible.

That is, the present invention can be applied to an electronic typewriter for an office electronic typewriter and a printer for a personal computer that require a high printing speed because the hammer can be driven at a high speed.

Claims (2)

In an electronic typewriter; A bi-level driver 10 connected to the hammer signal port P and the bi-level drive port PL of the central processing unit 1 to drive the bi-level; A comparator 3 connected to an output terminal of the bi-level driver 10 for comparing output values of time constant adjusting resistors R1, R2, and R3 with output values of sensor resistance Rs; Bi-level drive circuit of a hammer solenoid, characterized in that consisting of a bi-level signal output unit 20 is connected to the output terminal of the comparator (3) to output a bi-level signal. The bi-level drive unit (10) of claim 1, further comprising: an inverter (2) connected to the hammer signal port (P) of the central processing unit (1) and inverting a signal; A switching transistor Q1 connected to a port PL of the switch, time constant adjusting resistors R1, R2, and R3 connected to an output terminal of the inverter 2 and a collector terminal of the switching transistor Q1. Bi-level driving circuit of a hammer solenoid composed of

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