JPS58391B2 - Serial printer position pulse check device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position pulse check device for a serial printer, and is intended to prevent a current position counter of a printed character from miscounting due to noise.

A serial printer, which is used as an output device for electronic computers, uses a carrier to move a type wheel holding multiple types to a predetermined printing position, rotates the type wheel to select the type to be printed, and then prints the type. The desired characters are printed on the printing paper by hitting the platen with a hammer.

Control for selecting the desired type is performed by driving a servo motor and rotating the type wheel using a signal representing the difference between the current output of the type device counter and the commanded type position signal for the type to be printed. .

Conventionally, the operation of the current position counter of the type for this purpose was
This was done using the method shown in the figure.

That is, in the circuit diagram shown in FIG. Let them input.

The waveform shown in the loss is a position signal; the first half of the continuous sine wave shows the waveform when the type wheel rotates clockwise, and the second half shows the waveform when the type wheel rotates counterclockwise.

Also, at the location marked with an ○ in the figure, the type on the type wheel faces the platen, and the type wheel is at the stop position.

The figure C is a rotation direction signal, and when the rotation is clockwise, the logic signal is H1, and when it is counterclockwise, it is L.

The fork indicates a timing difference between two position pulse trains, and each pulse is generated at the peak and valley positions of the position signal.

Now, when this rotation direction signal is applied to the other input of gate 3 via inverter 6 and directly to the other input of gate 4, gate 4 opens during clockwise rotation, and gate 3
Close.

Further, when the direction is counterclockwise, the gate 3 is opened and the gate 4 is closed.

Therefore, the OR gate 5 outputs only the pulse train of the position pulse PP2 when the direction is clockwise, and only the pulse train of the position pulse PP1 when the direction is counterclockwise.

By counting these pulses with a current position counter C, the current position of the printed characters is known.

However, in the above method, only pulses from one pulse train are counted in a constant rotational direction, so if pulses from a nozzle other than the regular pulses are superimposed, it may be counted incorrectly, and the actual position of the type and the current position counter may be The instructions for C may be different.

An object of the present invention is to eliminate such drawbacks and provide a highly reliable serial printer. To this end, according to the present invention, a plurality of printers having a certain phase difference are generated by rotating a transducer. By generating a pulse train and alternately detecting pulses from a plurality of pulse trains, consecutive counting of two or more pulses from the same pulse train is prohibited.

Next, the present invention will be explained in detail based on the embodiment shown in FIG.

Note that the position signal, rotation direction signal, and position pulse PP1. The relationship of PP2 is the same as that shown in Figure 1, Part 3, C, and 2.

The position pulse generation circuit 2 alternately generates position pulses PP1 and PP2 with the same period and different phases, and both output terminals are connected to AND gates 8 and 11, which constitute a pulse selection circuit, through inverters 19 and 20, respectively. 10,
It is connected to one input terminal of 9.

Among these, the rotation direction signal terminal 7 is directly connected to the other input terminal of the AND gate 8.9, whereas the other input terminal of the other AND gates 1O and 11 is connected via the inverter 12. connected.

The output sides of AND gates 8 and 10 are connected to the input side of NOR gate 13, and the output sides of the other AND gates 9 and 11 are connected to the input side of another NOR gate 14.

Both Noah games) 13 and 14 are separately AND gate 15,
16 to the input side of a NOR gate 17, and the output terminal of one AND gate 16 is connected to a current position counter C.

Now, if the direction of rotation of the transducer is clockwise, a logic H is applied to the terminal 7 as a rotation direction signal.

Then, AND gates 8 and 9 are opened, and the other AND gates 10 and 11 are closed because they are inputted via inverter 12.

First, position pulse PP1. Considering the state when PP2 is not input, the output of AND gate 8.9 is logic H1 and the output of other AND gates No. 11 is logic.

Therefore, the outputs of the NOR gates 13 and 14 become logic logic, and the outputs of the next gates N5 and 16 also become logic logic, and the output of the NOR gate 17 becomes logic H.

The flip-flop 18 inverts the output of the terminal Q or Q when a pulse signal is applied to its terminal T.
Now, the output of the terminal Q is connected to one input of the AND gate 16, and the output of the terminal arithmetic is connected to the terminal RI, and also connected to one input of the AND gate 15, and the terminal circuit outputs a logic H. It is assumed that there is

When the transducer 1 then rotates clockwise, a position pulse PP1 is first generated.

Since the position pulse PP1 is input to the ant games 8 and 11 via the inverter 19, the inverter 19
The output of is normally a logic H, but falls when a pulse is applied.

Simultaneously with the fall of the pulse, the output of the AND gate 8 also falls, thereby causing the output of the NOR gate 13 to rise.

Since AND gate 15 is opened by the signal at terminal Q of flip-flop 18, its output rises from logic low to logic high.

Therefore, the output of NOR gate 17 falls, inverting the output of flip-flop 18.

That is, the terminal Q becomes a logic H, and the terminal Q becomes a logic L.

As a result, the other AND gate 16 is opened, and the AND gate 15 is closed so that its output becomes a logic logic high, and the output of the NOR gate 17 returns to a logic high.

Next, when the position pulse PP2 is input, the output of the AND gate 16 rises after passing through the AND gate 9 and the NOR gate 14 as before.

Then, the output of the NOR gate 17 falls, inverting the output of the flip-flop 18 again, closing the AND gate 16, and opening the other AND gate 15.

That is, the flip-flop 18 is inverted by a pulse from the NOR gate 17, and the AND gates 15 and 16 are opened alternately.

Then, by counting the output pulses of the AND gate 15 or 16 with the current position counter C, the current position of the printed characters is known.

During the above operation, if noise N is mixed into the position pulse train PP2, for example, as shown in FIG. 16 is closed.

Therefore, the noise N cannot pass through the AND gate 16, and a miscount of the current position counter C due to the noise is prevented.

When noise is mixed in before the regular pulse PP21,
The noise is calculated as one pulse, and the normal pulse PP
Since 21 is prohibited, miscounts are prevented as a result.

The same thing happens when noise mixes into the pulse train of PP1.

When the transducer 1 rotates counterclockwise, the AND gates 1O and 11 on the inverter 12 side open and the other AND gates 8 and 9 close, contrary to the case when the transducer 1 rotates clockwise, so the position pulse train PP becomes an AND gate. gate 11,
The position pulse train PP2 passes through the NOR gate 14 and the AND gate 16, and the position pulse train PP2 passes through the NOR gate 10 and the NOR gate 13.
, and the AND gate 15.

The subsequent operations are the same as those for clockwise rotation.

As described above, according to the present invention, the pulse train switching circuit that operates to immediately close the gate of a certain pulse train after counting one pulse from a certain position pulse train and open the gate of another pulse train can be used as a position pulse generating circuit. By providing it between the current position counter and the current position counter, it is prohibited to continuously count two or more from the same pulse train, thereby preventing a count error of the current position counter due to noise or the like.

Therefore, failures such as incorrect printing and poor alignment caused by misrecognizing the current position of printed characters are eliminated, and the reliability of the serial printer is significantly improved.

[Brief explanation of the drawing]

Figure 1A is a circuit diagram explaining the operation of the current position counter in a conventional serial printer, the opening in the figure is a position signal output from a transducer, the figure C is a rotation direction signal based on the rotation direction of the type head, indicates a two-phase position pulse based on a position signal. FIG. 2 is a circuit diagram of a position pulse check device according to the present invention. In the figure, 1 is a transducer, 2 is a position pulse generation circuit, 7 is a rotational direction signal input terminal, C is a current position counter, N is a noise, 8, 9°, 10.11, 15,
16 is an and gate, 13°14.17 is a noah gate,
18 is a flip-flop, and 12, 19, and 20 are inverters, respectively.

Claims (1)

[Scope of Claims] 1. A position pulse generation circuit that generates two or more pulse trains having the same period and a mutual phase difference for every one type pitch rotation of a type wheel; It is equipped with a pulse selection circuit that selects and outputs one pulse train from among the pulse trains from the position pulse generation circuit, and a counter that counts the output pulses of the pulse selection circuit. In a printer that selects type by rotating the drive motor of the type wheel and transducer according to the deviation between the current position and the position commanded by the type selection command signal, one pulse of two or more pulse trains from the position pulse generation circuit is used. This position pulse checking device for a serial printer is characterized in that it is provided with a pulse train switching circuit that switches and outputs the pulse train to the counter every time, and is configured to prohibit consecutive counting of two or more pulses from the same pulse train.