JPS62286752A - Character pattern alteration circuit in dot printer - Google Patents

Abstract

PURPOSE:To eliminate timewise loss in alteration and to prevent the damage of a printing head caused by the out of control of a program, by providing a circuit prohibiting the input of a printing data signal to the printing head only for an interval of a predetermined number of clocks after the dot pulse input of the printing data signal. CONSTITUTION:When one dot pulse is generated in a printing data signal (a), said dot pulse passes through an AND gate 1 to be inputted to a latch circuit 3. As a result, the dot pulse is sent out from the output terminal Q of the latch circuit 3 by the clock next to a clock signal (b). When one dot pulse is inputted to the data input terminal D of a shift register 2, since a mode control terminal S1 is at an H-level, the set values of data input terminals A-D, that is, a predetermined number 1 is acquired. As a result, the shift register 2 starts the count operation of the number of the clocks of the clock signal (b). Therefore, when the next dot pulse continues in succession to the first one dot pulse in the printing data signal (a), the succeeding dot pulse does not pass through the AND gate 1.

Description

3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a dot printer that prints out dot pattern characters, and particularly to a character pattern changing circuit in a dot printer that changes character patterns.

[Prior Art] Generally, in a dot printer that prints out dot pattern characters, a character generator is formed that stores the dot pattern of each character to be printed out in an internal storage section. At least 1 piece of printing paper is removed from the outside.
Once the character code for a line has been manually generated, one line of print data including the print position information of each dot constituting each line of each dot matrix indicating the dot pattern of the character corresponding to this one line of character code is generated. To edit. For example, if a character is composed of 24 dots, 24 print data signals are edited in order to print out the characters for one line of printing paper.

Each of the 24 print data signals, each containing a dot pulse indicating print position information, is moved at a constant speed along a platen on which print paper is set, and a print element consisting of 24 dot bins or heating elements is incorporated. is sent to the print head in synchronization with a clock signal.

Then, at the rising edge of each pulse of the clock signal, if each print data signal is at an H level due to the presence of a dot pulse, the corresponding print element is energized. When the print head moves on the printing paper by the width of the paper, one line of dot pattern characters is printed out.

In a dot printer configured in this manner, it may be necessary to change the dot pattern of characters actually printed without changing the dot pattern stored in the character generator. For example, although the dot pattern of printed characters does not need to be very precise, there may be cases where it is desired to increase the printing speed. In such a case, the moving speed of the carriage carrying the print head is increased and the clock interval of the clock signal is shortened. Then, by changing the program, the dot matrix data forming the dot pattern characters stored in the character generator may be read out every other column, for example, to generate a print data signal for one line.

[Problems to be Solved by the Invention] However, in a dot printer that actually prints and changes the dot pattern using the above-mentioned method, a special program is required to change the print pattern as described above. becomes. □ Therefore, extra effort and time are required for program development. In addition, changing the dot perk using software requires processing time, and there is a concern that the overall printing speed may decrease.

Furthermore, since the dot pattern conversion is performed by software, if the control unit that controls program execution, such as the CPU, goes out of control, there is a possibility that the above-mentioned dot data will not be thinned out, for example, every other column. . In such a case, there is a fear that the number of times of energization to the printing element per unit time may exceed the limit number and damage the printing element.

The present invention was made based on these circumstances,
The purpose of this is to provide a circuit that prohibits the input of the print data signal to the print head for a predetermined number of clock intervals after the dot pulse input of the print data signal. While preventing damage caused by program runaway,
To provide a character pattern changing circuit for a dot printer that can change the dot pattern of printed characters.

[Means for resolving gap points] The character pattern changing circuit in the dot printer of the present invention uses print data including dot pulses indicating print position information of each dot constituting each column of a dot matrix forming a dot pattern character. A counting circuit that counts the number of clocks of a predetermined number of clock signals from the input of one dot pulse of the signal and starts counting the number of clocks again from the inputted dot pulse after the counting ends, and the output from this counting circuit. and a gate circuit that prohibits sending of the print data signal to the print head during the input period of the counting signal.

[Operation] With the character pattern changing circuit in a dot printer configured as described above, when one dot pulse of the print data signal is input, this dot pulse is input to the print head via the gate circuit and is also input to the counting circuit. is input. In response to this dot pulse input, the counting circuit starts counting the number of clocks of the clock signal. At the same time, a counting signal is sent to the gate circuit. As a result, the gate circuit prohibits further input of print data signals to the print bed. When the number of clocks reaches a predetermined number, the inhibited state of the gate circuit is released, and at the same time, the counting operation of the number of clocks is started in response to a dot pulse manually applied thereafter. Thus, if there are consecutive dot pulses in the print data signal, after the first dot pulse is delivered to the printhead, a predetermined number of subsequent dot pulses will not be delivered to the printhead. Therefore, as a result, the dot pulses are thinned out.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a character pattern changing circuit in a dot printer according to an embodiment. One print data signal a out of, for example, 24 print data signals read from the character generator and edited into one line of characters is input to one input terminal of AND gate 1 as a gate circuit and is counted. The signal is input to the data input terminal of the shift register 2 as a circuit. Further, the clock signal S is applied to the clock terminal of the shift register 2, and is also input to the clock terminal of the latch circuit 3 constituted by a flip-flop (7474). Note that the clock cycle of this clock signal is synchronized with the dot pulse cycle when each dot pulse of the print data signal a is continuous.

The shift register (SN74194) 2 is set at four data input terminals A, B, C, and D when the clock signal S is input to the clock terminal with the mode control terminal S1 at H level. A predetermined number of set values are loaded into an internal register, and the number of clocks is counted every time a clock signal is input from the clock terminal. When the count value reaches the set value, the four output terminals QA-QD An L level count-up signal is output from the output terminal QD. That is, during the counting period of a predetermined number of set values set at each of the data input terminals A to D, an H level counting signal is sent from the output terminal QD.

The output signal of the output terminal QD of the shift register 2 is passed through the inverter 4 to the mode control terminal S1 and the AND gate 1.
is input to the other input terminal.

The output signal C of the AND gate 1 is input to the D input terminal of the latch circuit 3. The output signal from the output terminal Q of the latch circuit 3 is input to a print element drive circuit that energizes one of the plurality of print elements incorporated in the print head.

data input terminals A and B of the shift register 2;

Each signal level of C and clear terminal CL is set by a setting circuit 5. The setting circuit 5 has output terminals DO, D corresponding to the terminals CL, C, B, A of the shift register length.
I, D2. For D3, the operator selects ■, ■, ■ as necessary as shown in the figure.

It is possible to select from five types of level settings: (1) and (2). However, what is actually used is the level setting of ■ shown by [1000] most often.

Next, the operation of the character pattern changing circuit in the dot printer configured as described above will be explained.

However, as described above, the setting circuit 5 is set to the level (■) indicated by [1000]. That is, when the print data signal a is not inputted at all, the data input terminals A, B, C, and D are all at the L level, so there is no clock counting operation, and the output terminal Q
D is L level.

Therefore, the input terminal of the AND gate 1 on the inverter 4 side is at H level. After that, the print data signal a passes through the AND gate 1 and is input to the latch circuit 3.

When one dot pulse occurs in the print data signal a in this state, this dot pulse passes through the AND gate 1 and is input to the latch circuit 3. As a result, this dot pulse is sent out from the output terminal Q of the latch circuit 3 by the next clock of the clock signal S.

On the other hand, when the one dot pulse is input to the data input terminal of the shift register 2, the mode control terminal S1 goes high.
Since it is a level, the setting value of data input terminals A'-D,
That is, the predetermined number 1 is taken in. As a result, this shift register 2 starts counting the number of clocks of the clock signal.

That is, an H-level counting signal is output from the output terminal QD in synchronization with the next clock input.

As a result, the inverter 4 side terminal of the AND gate 1 changes to L level. Therefore, in the print data signal a, if the first dot pulse is followed by the next dot pulse, the latter dot pulse will not pass through the AND gate 1.

When the next clock is input to the shift register 2, an L level count-up signal is output from the output terminal QD, and the prohibition of passing through the AND gate 1 is canceled. At the same time, the mode control terminal S1 becomes H level, making it possible to take in dot pulses at the data input terminal. As a result, the next dot pulse in print data signal a passes through AND gate 1.

In this way, when the level setting of [1000] (■) is performed in the setting circuit 5, as shown in FIG. 2(a), when the dot pulses are continuous in the print data signal a,
The rear dot pulses are thinned out and are not printed. Furthermore, in the print data signal a, if there is an independent dot pulse that is not adjacent to the previous dot pulse, that independent dot pulse is always printed. Therefore, among the dots constituting the dot pattern character constituting one character stored in the character generator, the dots that are actually thinned out are only the rear dots among the consecutive dots. Therefore, even if the character pattern is changed using the character pattern changing circuit shown in FIG. 1, the skeleton of the character will not be significantly distorted, and the character will not become difficult to read.

In addition, in the setting circuit 5, when the level is set to [0000] (■), the clear terminal CL is always at the L level and the count value is not cleared, so the output terminal Q is temporarily
Once D reaches L level, it will never return to H level. Therefore, AND gate 1 remains open, and print data signal a is input to latch circuit 3 as is. That is, the character pattern is not changed.

Further, when the setting circuit 5 is set to the level 2 of [1100], when the dot pulses are continuous as shown in FIG. 2(b), two dot pulses are successively thinned out. In this case, since the ratio of the number of dot pulses to be thinned out increases, it is effective to apply this method when the characters in the dot pattern originally stored in the character generator are thick.

By changing the level setting of the setting circuit 5 from ■ to ■, the degree of thinning of dot pulses in the print data signal a can be arbitrarily changed and set.

In this way, shift register 2. Since the character pattern changing circuit is made up of logic circuit elements such as AND gate 1, there is no need to change the character pattern using software as in conventional devices. As a result, software processing time can be omitted and printing speed can be improved.

In addition, each dot in the dot pattern data read from the character generator is not thinned out by software, so even if the program runs out of control, as long as the clock signal maintains the regular clock interval, the dot pulses will continue to be generated. It is never applied to the print head.

Therefore, even if the CPU runs out of control, damage to the printing bed can be prevented.

[Effects of the Invention] As described above, according to the present invention, a circuit is provided that inhibits the input of the print data signal to the print head at intervals of a predetermined number of clocks after the dot pulse input of the print data signal. Therefore, the dot pattern of the printed characters can be changed without losing the time required to change the character pattern, and while preventing damage caused by program runaway of the print head.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a character pattern changing circuit in a dot printer according to an embodiment of the present invention, and FIG. 2 is a time chart showing the operation of the same embodiment. 1 AND gate, 2... Shift register, 3... Latch circuit, 4... Inverter, 5... Setting circuit, a
...print data signal, b...clock signal.

Claims (1)

[Claims] In a dot printer that obtains dot pattern characters by sending a print data signal containing dot pulses indicating print position information of each dot constituting each row of a dot matrix forming a dot pattern character to a print head in synchronization with a clock signal. , a counting circuit that counts a predetermined number of clocks of the clock signal from the input of one dot pulse of the print data signal and starts counting the number of clocks again from the input dot pulse after the count ends; , and a gate circuit for prohibiting sending of the print data signal to the print head during the input period of the counting signal output from the counting circuit.