JPS62199169A - Printing method for thermal printer - Google Patents

Abstract

PURPOSE:To prevent uneven print by generating the print data of plural dot strings and driving a heat element based on the print data of plural dot strings so as to avoid simultaneous heating of adjacent heat elements. CONSTITUTION:Level '1' indicates printing and level '0' indicates non-printing in an output data from a P/S converter 10. Further, a D FF 11 is triggered by a clock pulse CK. At the time of the first data '1' is outputted from a P/S 10, the Q output of the D FF 11 goes to logical '1' and then an AND 1 is opened and the data '1' is inputted to a multiplexer 13. At the time of the 2nd data '0' is outputted from the P/S 10, the Q output of the D FF 11 goes to '0', the AND 1 is closed and its output goes to '0'. The similar operation is repeated, the AND 1 extracts the output data of an odd number order of the P/S 10 and to output data inserted with data '0' in each data segment. At the time of the level of a terminal C of a multiplexer is logical '1', the output of the AND 1 is written in a register 6, and fed to a heater 9 via a latch 7 and a driver 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing method for a thermal printer that aims to reduce printing unevenness.

[Prior Art] FIG. 3 is a block diagram showing an example of the configuration of a conventional thermal printer, and FIG. 4 is a circuit diagram showing details of the thermal head 5 in FIG. 3.

In FIG. 3, 1 is an input terminal to which print data is supplied, 2 is an interface circuit, 3 is a buffer memory for reading the print data supplied via the interface circuit 2, and 4 is a print control circuit (CPU). The print control circuit 4 generates a write/continuation address for the buffer memory 3 and outputs it to the memory 3, and also outputs various control signals to the thermal head 5. The thermal head 5 is of a so-called serial line type, and is composed of a shift register 6, a latch 7, a driver 8, and a heating element 9, as shown in FIG. The shift register 6 is a serial-in-parallel-out shift register, reads the print data output from the buffer memory 3 based on the clock pulse CK supplied from the print control circuit 4, and outputs it to the latch 7. The latch 7 reads the output of the shift register 6 based on the latch signal LA supplied from the print control circuit 4 and outputs it to the driver 8 . The driver 8 is composed of Nant gates Nl to N12. The output of the latch 7 is applied to each first terminal of the Nant gates N'' to N12, and the output of the latch 7 is applied to each first terminal of the Nant gates N1 to N4.
The strobe signal 5 output from the print control circuit 4 is input to each second input terminal of the Nantes gates N5 to N8, and to each second input terminal of the Nantes gates N9 to N12.
TRI-STR3 is applied.

The heating element 9 is composed of heating elements S1 to S12, and each heating element S1-S12 is connected to a Nant gate N1.
-Nl2 outputs are applied. Note that although an actual thermal head is provided with several hundred or more heating elements, in this specification, for convenience of explanation, only 12 heating elements are provided.

In the above configuration, reading from the buffer memory 3,
When the print data of the dot rows are sequentially read into the shift register 6, the print control circuit 4 outputs a latch signal LA. As a result, the print data read into the shift register 6 is read into the latch 7 and output to the driver 8. Next, the print control circuit 4 receives the strobe signal 5.
Output TRI. As a result, Nl-N
4 becomes active, and the heating elements 5l-S4 are driven based on the output of the latch 7. Next, the print control circuit 4 sequentially outputs the strobes 5TR2 and 5TR3 after a certain period of time. As a result, heating elements S5 to S8. S9～
S12 is driven. In this way, the first line of dot printing is performed. On the other hand, when the first line of print data in the shift register 6 is read into the latch 7, the second line of print data is sequentially output from the buffer memory 3.
The data is read into the shift register 6. Then, when all the print data of the second row is read into the shift register 6, the print control circuit 4 outputs the latch signal LA again. Thereafter, operations similar to those described above are repeated, thereby performing dot printing on the second line. The third line... is printed in the same manner.

[Problems to be Solved by the Invention] By the way, in the above-mentioned conventional thermal printer, the print data of the dot row is "1., 1, 1, 1...
..." and "1, 0, 1.0..."
There is a problem in that the density of the printed dots differs depending on the case, and this causes uneven printing. That is, for example, when data "1" is applied to the first input terminals of the Nant gates N1-N4, the heating elements 5t-84 simultaneously generate heat by the strobe signal 5TRI. In this case, the heat of the heating element affects the adjacent heating element, resulting in printing darker than when heat is generated alone. on the other hand,
For example, when the print data is "1, 0, 1.0", the adjacent heating elements do not generate heat, so the printing is thinner than in the above case.

The present invention has been made in view of the above circumstances, and its object is to provide a method for printing heat generating elements in a thermal printer, which reduces printing unevenness.

[Means for Solving the Problems] The present invention provides a printing method for a thermal printer in which printing is performed by driving a plurality of heating elements based on a data string corresponding to a printing dot, in which printing is performed from the first data in the data string. Data is extracted every N (positive integer) pieces, N pieces of non-print data are inserted between each of the extracted data to form a first data string, and the second data string in the data string is
Extract data every N (positive integer) from the data, insert N non-print data between each extracted data to form a second data string, and similarly, (N
+1) data string, and these 1st to (N+1)th
The heating element is driven by a data string to print the same printing dot string.

[Example] Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2.

FIG. 1 is a block diagram showing the configuration of a printed circuit to which the printing method of this embodiment is applied, and FIG. 2 is a timing diagram for explaining the operation of the printed circuit of FIG. 1.

In FIG. 1, parts corresponding to those in the conventional example shown in FIGS. 3 and 4 described above are given the same reference numerals, and their explanations will be omitted.

In FIG. 1, IO is a parallel/serial converter, which converts print data corresponding to dots output in bytes from the buffer memory 3 into serial data,
It is output to one input terminal of each of the AND gates ANDI and AND2. ! 1 is a D-FF (delay flip-flop). This D-FFII has its input terminal connected to its output terminal Q, and as a result operates as a trigger flip-flop triggered by the clock pulse CK. 13 is a multiplexer, and when a "1" signal is supplied to its control terminal C, it outputs the data of the input terminal <1>, and the control terminals C to "0" are output.
When a signal is supplied, the data at the input terminal 0> is output.

Next, the operation of the above-mentioned circuit will be explained with reference to the timing diagram shown in FIG.

When the print data is read into the buffer memory 3, the print control circuit 4 first outputs the "l" signal to the control terminal C of the multiplexer 13, and then outputs the clock pulse CK to the buffer memory 3. 1st
Address data is sequentially output in order to read the print data of the dot column in the row. When the clock pulse GK (see FIG. 1 (b)) is output from the printing control circuit 4, the D-F
The signals shown in FIG. 2 (c) and (d) are outputted from the output terminals Q and Q of the FII, respectively. Further, when address data is supplied to the buffer memory 3, print data is read from the buffer memory 3, and this read print data is converted into serial data by the parallel/serial converter lO, and the AND gate ANDI , AND2.

By the way, at this point, a "1" signal is being supplied to the control terminal C of the multiplexer 13, so the output of the AND gate AND2 is not related to the circuit operation. Therefore, the output of the AND gate AND1 (see FIG. 2 (E)) will be considered below.

Now, assume that the output data of the parallel/serial converter lO is shown in FIG. 2(a). Note that "l" in this data indicates printing, and "0" indicates non-printing. At the time when the first data "l" of this output data is output from the converter IO, the Q output signal of the D-FF 11 becomes the "l" signal, and therefore, the AND gate AN
Dt is in the open state, and its data “1” is ant game)
Output from ANDI. Next, when the second data “0” is output from the converter 10, at this time D-FFI)
The Q output signal of becomes “0”, and the AND gate AND 1
Since is in the closed state, the output of the AND gate AND1 becomes "0" regardless of the output of the converter IO.

Next, when the third data "l" is output from the converter 10, the AND gate AND1 is in an open state, so that data "l" is output from the AND gate ANDI, and then, When the fourth data “1” is output from the converter 10, the AND gate AND I
Since the gate is closed, data "0" is output from the AND gate ANDl. Thereafter, similar operations are repeated. In this way, the AND gate AND l determines the first, third, fifth, and third output data of the converter IO.
... is extracted, and data “0” is inserted between each extracted data.
Output the inserted data. When the "L" signal is supplied to the control terminal C of the multiplexer 13, the output of the AND gate AND1 is supplied to the shift register 6 via the multiplexer 13 and read into the shift register 6. Next, the data read into the shift register 6 is supplied to the heating element 9 via the latch 7 driver 8, and thereby the first row of dots is printed.

On the other hand, the print control circuit 4 outputs the address data corresponding to the dot column of the first row to the buffer memory 3, then outputs a "0" signal to the control terminal C of the multiplexer 13, and then outputs the address data corresponding to the dot column of the first row again. The address data corresponding to the row of dots is output to the buffer memory 3. As a result, exactly the same data as in the above case is output from the parallel/serial converter 10, and therefore, exactly the same data as in the above case is output from the AND gates AND l , AN
Each is output from D2. Here, multiplexer 13
When a "0" signal is supplied to the control terminal C of the AND gate AND2, the output of the AND gate AND2 is outputted via the multiplexer 13. (See Figure 2 (a)). First, when the first data "l" (see Figure 2 (a)) is output from the converter IO, the D-FP l l
The Q output signal of is at "0" signal, and the AND gate AND
2 is in the closed state, data "0" is output from the AND gate AND2, and when the second data "0" is output from the converter IO, the AND gate AND2 is in the open state, and the converter 10 output data "0" is output from the AND gate AND2, and the same operation is repeated thereafter. In this way, the AND gate AND2 extracts the second, fourth, sixth, etc. of the output data of the converter IO, and between each of the extracted data is a data "0".
” is inserted. Then, when a “0” signal is supplied to the control terminal C of the multiplexer 13, the output of the AND gate AND2 is read into the shift register 6 via the multiplexer 13,
Dot printing of the first line is performed again using this read data.

Next, the print control circuit 4 moves the printing paper by one line,
Next, the second row of dots is printed in the same manner as described above.

In this manner, in the embodiment described above, the print data is divided into odd-numbered data and even-numbered data, and "θ" is inserted between each data, and the data is printed twice. As a result, two adjacent heating elements are not driven at the same time, thereby making it possible to prevent printing unevenness from occurring.

In addition to dividing the print data of the dot row into two for every odd and even number, it can also be divided into a plurality of dot rows at an appropriate number such as every second dot and sent to the thermal head 5. can. To divide print data into multiple columns, for example, divide the print data of a dot column into even and odd numbers, pool them in the buffer memory 3, and then insert non-print data "0" to divide the print data into multiple dots. It can also be a column. If the print data is a character code, it is sufficient to develop it into dots using a character generator, convert it into dot data, and store this dot data in the buffer memory 3.

Furthermore, the present invention can of course be applied even when the number of heating elements is several hundred or more.

[Effects of the Invention] As explained above, according to the present invention, print data of a plurality of dot rows can be obtained by capturing dot data of each predetermined number from the print data of a dot row and inserting non-print data between them. Since the heating elements are driven based on the print data of the multiple dot rows, it is possible to prevent adjacent heating elements from generating heat at the same time and avoid mutual thermal influence.As a result, printing unevenness can be reduced. In addition, it is possible to prevent partial trailing (bleeding) and blurred printing.

[Brief explanation of drawings]

1 and 2 are detailed diagrams illustrating an embodiment of the present invention, with FIG. 1 being a circuit configuration diagram and FIG. 2 being a timing diagram. FIG. 3 is a circuit configuration diagram for explaining a conventional example, and FIG. 4 is a circuit diagram showing details of the thermal head in FIG. 3. S 1-S 12... Heating element, 3...
・Buffer memory, 4...Print control circuit (CPU), 5...
・Thermal head, 6...Shift register.

Claims (1)

[Claims] In a printing method in a thermal printer in which printing is performed by driving a plurality of heating elements based on a data string corresponding to a print dot, N from the first data in the data string
(Positive integer) every other piece of data is extracted, N pieces of non-print data are inserted between each of the extracted data to form the first data string, and N pieces of data are inserted from the second data in the data string. (Positive integer) every other piece of data is extracted, N pieces of non-print data are inserted between each extracted data, and the second
Similarly, first to (N+1)th data strings are created as a data string, and the heating element is driven by these first to (N+1)th data strings to print the same printing dot string. A printing method in a thermal printer characterized by the following.