KR940002879B1 - Strove pulse control circuit in led printer - Google Patents

Abstract

The circuit comprises a microcomputer for controlling the overall operation of the system and outputting a strobe starting signal to an output port, pulse width generating means for counting the strobe starting signal of the microcomputer and generating a strobe pulse width, time interval generating means for receiving the output of the pulse width generating means and generating the time interval between strobe signals, and strobe signal generating means for receiving the strobe starting signal of the microcomputer and the output of the time interval generating means and outputting a final strobe signal, thereby preventing crosstalk between strobe signals.

Description

Strobe pulse control circuit of LED printer

1 is a conventional circuit diagram.

2 is a waveform diagram of a strobe signal according to FIG.

3 is a circuit diagram of the present invention.

4 is a waveform diagram of each part according to FIG.

* Explanation of symbols for main parts of the drawings

5: MCU 10: counter

The present invention relates to a strobe signal generation circuit for driving an LED head of a light emitting diode (LED) printer, and in particular, crosses between strobe signals without relying on time control of a micro control unit (MCU). It is about strobe pulse control circuit of LED printer which can prevent crosstalk.

In general, the LED head is a part that is responsible for exposure to the photoconductor drum and the LED array is driven by the strobe signal. When there are a plurality of cells of the LED head, the LED head is divided into four areas and is divided into four strobe pulses. I'm in control.

1 is a conventional circuit diagram.

1 is a microcontroller 10 for outputting the strobe signal to the output terminals P1-P4 at predetermined time intervals by a built-in program, and a strobe signal output from the output terminals P1-P4 of the MCU 10. The first buffer fourth buffer 21-24 for latch output, and the LED head head unit 30 that emits light according to the strobe output of the first buffer fourth buffer (21-24).

Briefly describing the conventional circuit of FIG. 1 according to the waveform diagram of FIG. 2, the waveforms (2a) to (2d) of FIG. 2 are output from the first buffer-fourth buffer 21-24 of FIG. These are the waveforms that need to be done.

This means that the strobe signal for the LED head unit 30 to be ideally driven should be a waveform such as (2a) → (2d) in FIG.

The time interval t1 of (2a) is the time that the LED cell of the LED head unit 30 is turned on, this time is determined according to the characteristics of the LED cell and the photoconductor.

For example, if the total number of cells of the LED array of the LED head unit 30 is 2560, it is divided into 4 and 640 are a set, and the 1-640 LED cells are strobe signals of the first buffer 21, namely (2a). Driven by the output waveform, the LED cell 641-1280 is driven by the strobe signal of the second buffer 22, that is, the output waveform (2b).

Subsequently, the LED cells 1281-1920 are driven by the output waveform of (2c), and the LED cells of 1921-256 are driven by the output waveform of (2d).

In this case, the sequential control of the (2a) → (2d) strobe output signal is generated by an internal timer interrupt of the MCU 10.

Here, the time interval t2 of the waveforms (2a) and (2b) is for stabilizing the driving power of the LED head unit 30, which should always be maintained at the margin (t2). .

For example, when the maximum current required to emit light of the LED cell during the strobe signal of the waveform (2a) is 2 Amps, if the time interval t2 is not present, two sets of LED cells are active at the same time. This is because a maximum of 4 amps of current flows in.

Therefore, the MCU 10, which has to keep the interval t2 constant and keeps the strobe signal from (2a) to (2d) constant, must operate accurately at high speed.

In addition, due to the internal factors of the MCU10, when there is no time interval between the strobe signals, cross-talk often occurs. Therefore, in the related art, the load of the MCU for generating the strobe signal cannot be reduced, and accordingly, there is a problem that a high-cost MCU is required.

Accordingly, an object of the present invention is to provide a strobe pulse control circuit of an LED printer that can prevent crosstalk between strobe signals without depending on the time control of the MCU.

Another object of the present invention is to provide a strobe pulse control circuit of an LED printer that can be controlled by a low-speed MCU by reducing the load of the MCU.

Hereinafter, the present invention will be described in detail with reference to the drawings.

3 is a strobe pulse control circuit of the present invention, which controls the overall operation of the system and outputs the strobe start signal to the output terminal P1, and the strobe start signal of the strobe start signal of the micom 50 is strobe. Pulse width generating means for generating a pulse width, time interval generating means for generating a time interval between strobe signals by inputting the output of the pulse width generating means, a strobe start signal of the microcomputer 5 and the time interval Strobe signal generating means for inputting the output of the generating means for outputting the final strobe signal.

The pulse width generating means includes an AND gate AND5 for ANDing the strobe start signal of the MCU 5 and an output of the first inverter INV1 of the time interval generating means, and an output of the AND gate AND5. The clock terminal CK is connected to a clock terminal CLK that is connected to an input terminal Load and is applied from the outside, and comprises a counter 10 that outputs a counting pulse to the output terminal RP every predetermined period, and the time interval is generated. The means includes a first flip-flop D1 for outputting the counter RP of the counter 10 to a clock terminal and an input terminal D to a power supply voltage VCC for latching and outputting the input to the output terminal Q. And a second flip-flop for latching and outputting the input to the output terminal Q by connecting an input terminal D to an output terminal Q of the first flip-flop D1 and a clock terminal connected to the external clock terminal CLK. (D2) and the input terminal (D) is connected to the output terminal (Q) of the second flip-flop (D2) A clock terminal is connected to the stage CLK to invert the output of the third flip-flop D3 for latching the input to the output terminal Q and the output of the output terminal Q of the first flip-flop D1. Noah gating for inputting the first inverter INV1 and the output of the output terminal Q of the first flip-flop D1 to one side and the output of the output terminal Q of the second flip-flop D2 to the other side Noah gate (NOR10).

The strobe signal generating means may include a clock terminal connected to the strobe start signal output terminal P1 of the MCU 5 and an input terminal D connected to the power supply voltage VCC to latch the input to the output terminal Q. An input terminal D is connected to a fourth flip flop D4 and an output terminal Q of the fourth flip flop D4, and a clock terminal is connected to an output terminal Q of the first flip flop D1. A fifth flip-flop D5 for latching the input to Q), an input terminal D is connected to an output terminal Q of the fifth flip-flop D5, and a clock is output to the output of the first inverter INV1. A sixth flip-flop D6 for latching and outputting an input to an output terminal Q, an input terminal D is connected to an output terminal Q of the sixth flip-flop D6, and the first inverter The clock terminal is connected to the output of INV1, and the input terminal D is connected to the seventh flip-flop D7 for latching and outputting the input to the output terminal Q, and the output terminal Q of the seventh flip-flop D7. And a clock terminal is connected to an output of the first inverter INV1 to latch an output to the output terminal Q, and an output terminal Q of the fourth flip flop D4. The first end gate AND2 for outputting the second strobe signal by inputting one side of the output and the other side of the output of the NOA gate NOR1, and the output of the output terminal Q of the seventh flip-flop D7. One side input and a third input gate AND3 for outputting the third strobe signal by inputting the output of the NOA gate NOR1 to the other side, and the output of the output terminal Q of the eighth flip-flop D8. And a fourth end gate AND4 for outputting the fourth strobe signal by inputting the output of the noble gate NOR1 to the other side.

로 나타내기로 한다. (4b)는 MCU(5)의 스트로브시작신호 출력단(P1)의 파형을 나타낸 것이다.FIG. 4 is a waveform diagram of each part according to FIG. 3, and FIG. 4A shows a reset pulse input from an external input terminal.

It is represented by. 4b shows the waveform of the strobe start signal output terminal P1 of the MCU 5.

로 나타내기로 한다. (4d)는 외부입력단으로 입력되는 클럭신호를 나타낸 것이다.(4c) shows the input waveform of the input terminal (Load) of the counter 10.

It is represented by. 4d illustrates a clock signal input to an external input terminal.

The waveform of 4d is provided from an external clock generator. 4e shows the output waveform of the output terminal RP of the counter 10. (4f) is the output waveform of the first inverter (INV1), (4g) is the output waveform of the NOR gate (NOR1), (4h) is the output of the first and gate AND1, (4i) Is an output of the second and gate AND2, 4j is an output of the third and gate AND3, 4k is an output of the fourth and gate AND4, and 4l is an output of the second and gate AND3. The waveform of the port P0 of the MCU 5 is shown.

Hereinafter, the present invention will be described in detail with reference to FIGS. 3 and 4 based on the above-described configuration. First, the MCU 5 transmits a strobe start signal through the output port P1 after data latching to the LED head unit of FIG. The output is as shown in (4b).

Here, the initial state of the port P0 of the MCU 5 is high and the initial state of the output port P1 is low.

The counter 10 is a counter for counting predetermined bits and is fixed to a preset value when the input of the input load is low and counts all of the predetermined bits by counting the clock of the clock stage CK when the input is high. The output terminal RP outputs high.

That is, the counting time of the predetermined bit is the time for generating the strobe pulse width, which is the output of (4e) of FIG.

In other words, this is to provide the strobe pulse width generation time t1 of (4i).

The output of the output terminal RP of the counter 10 is input to the clock terminal of the first flip-flop D1.

The input terminal of the first flip-flop D1 is fixed high by the power supply voltage VCC.

When the input of the clock terminal of the first flip-flop D1 is high, the first flip-flop is a D flip-flop that latches the input of the input terminal and outputs the result to the output terminal Q. The output of the output terminal Q of the first flip-flop D1 becomes the input of the first inverter INV1.

The output of the first inverter INV1 becomes one input of the AND gate AND5.

Here, the output of the AND gate AND5 is the output waveform of (4f) in FIG.

The second flip flop D2 and the third flip flop D3 are the same D flip flops as the first flip flop D1.

The first flip-flop D1 outputs the output of the output terminal Q and the output terminal Q of the second flip-flop D2 by noah gate NOR1, which is the output waveform of FIG. 4 (4g). .

Here, the low section of (4g) provides the time interval signal between the strobe signal, that is, the time interval t2 indicated in (4i).

The strobe start signal of the output port P1 of the MCU 5 is input to the clock terminal of the fourth flip-flop D4.

The input terminal D of the fourth flip-flop D4 is fixed high by the power supply voltage VCC.

The fourth flip flop D4 and the fifth to eighth flip flops D5-D8 are the same D flip flops as the first flip flop D1.

The output of the output terminal Q0 of the fourth flip-flop D4 is provided to one input terminal of the first and gate D1 to generate the first strobe signal S1, which becomes the waveform (4h) of FIG.

The first AND gate AND1 is an AND output of the output of the output terminal Q of the fourth flip-flop D4 and the output of the NOR gate NOR1.

The output of the output terminal Q of the sixth flip-flop D6 is provided to one input of the second and gate AND2 to generate the second strobe signal S2, which becomes the waveform (4i) of FIG.

The output of the output terminal Q of the seventh flip-flop D7 is provided to one side input of the third and gate AND3 to generate the third strobe signal S3.

This becomes the (4j) waveform. The output of the output terminal Q of the eighth flip-flop D8 is provided to one side input of the fourth and gate AND4 to generate the fourth strobe signal S4.

This results in a (4k) waveform. When the waveform (4l) in Fig. 4 is low to high, the output port Pl of the MCU 5 is set low, and the strobe start signal is stopped.

This is to use the handshake function of the MCU (5).

As described above, the present invention has the advantage of preventing crosstalk between strobe signals without depending on the time control of the MCU, thereby reducing the load of the MCU and having the advantage of being controlled by a low speed MCU.

Claims (4)

In the strobe pulse control circuit for driving the LED head of the LED printer, the microcomputer (5) for controlling the overall operation of the system and outputting the strobe start signal to the output terminal (P1), and the strobe start signal of the microcomputer (5) Pulse width generating means for generating a strobe pulse width by input counting, time interval generating means for generating a time interval between strobe signals by inputting the output of the pulse width generating means, and a strobe start signal of the microcomputer 5; And a strobe signal generating means for inputting the output of the time interval generating means to output a final strobe signal. The end gate AND5 of claim 1, wherein the pulse width generating means end-gates the strobe start signal of the MCU 5 and the output of the first inverter INV1 of the time interval generating means. The input terminal Load is connected to the output of AND5, and the clock terminal CK is connected to the clock terminal CLK applied from the outside, and the counter 10 is configured to output a counting pulse to the output terminal RP every predetermined period. Strobe pulse control circuit of an LED printer. According to claim 1, wherein the time interval generating means latches the input to the output terminal (Q) by the clock terminal is connected to the output terminal (RP) of the counter 10 and the input terminal (D) is connected to the power supply voltage (VCC) An input terminal D is connected to the first flip flop D1 and an output terminal Q of the first flip flop D1, and a clock terminal is connected to the external clock terminal CLK to the output terminal Q. A second flip flop D2 for latching an input, an input terminal D is connected to an output terminal Q of the second flip flop D2, and a clock terminal is connected to the external clock terminal CLK. A third flip-flop D3 for latching the input to Q, a first inverter INV1 for inverting the output of the output terminal Q of the first flip-flop D1, and the first The output of the output terminal Q of the flip-flop D1 is input to one side, and the output of the output terminal Q of the second flip-flop D2 is input to the other side, and the gate is configured as a noar gate NOR1 for noah gating. Characterized in that a strobe pulse control circuit of the LED printer. According to claim 1, wherein the strobe signal generating means is connected to the strobe start signal output terminal (P1) of the clock terminal of the MCU (5) and the input terminal (D) is connected to the power supply voltage (VCC) is input to the output terminal (Q). A fourth flip-flop D4 for latching the output, an input terminal D is connected to an output terminal Q of the fourth flip-flop D4, and a clock is output to the output terminal Q of the first flip-flop D1. A fifth flip-flop D5 for latching and outputting an input to the output terminal Q and an input terminal D are connected to an output terminal Q of the fifth flip-flop D5, and the first inverter A clock terminal is connected to the output of INV1, and a sixth flip-flop D6 for latching and outputting an input to the output terminal Q and an input terminal D are connected to an output terminal Q of the sixth flip-flop D6. And a clock terminal connected to an output of the first inverter INV1 to a seventh flip-flop D7 for latching an input to an output terminal Q, and an output terminal Q of the seventh flip-flop D7.An output terminal (d), a clock terminal is connected to an output of the first inverter (INV1), and an eighth flip-flop (D8) for latching and outputting an input to the output terminal (Q), and the fourth flip-flop (D4). A first input gate AND1 for outputting a first strobe signal by inputting one output of the output terminal Q of the output terminal and a second input of the output of the NOA gate NOR1, and an output terminal of the sixth flip-flop D6. A second end gate AND2 for outputting a second strobe signal by inputting the output of Q on one side and the output of the NOR1 on the other side, and an output terminal Q of the seventh flip-flop D7. Of the third end gate AND3 and the output terminal Q of the eighth flip-flop D8 for outputting a third strobe signal by inputting one side of the output and the other side of the NOR1. To output the fourth strobe signal by inputting one side of the output and the other side of the output of the NOA gate NOR1. Strobe pulse control circuit of the LED printer, characterized in that the fourth and gate (AND4).

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