JPH0457269B2 - - Google Patents

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 that reads the print data supplied via the interface circuit 2, and 4 is a print control circuit (CPU). . The print control circuit 4 generates write/read addresses for the buffer memory 3 and outputs them 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 NAND gates N1 to N12. And Nand Gate N1~
The output of latch 7 is applied to each first terminal of N12, and the output of latch 7 is applied to each second input terminal of NAND gates N1 to N4, each second input terminal of NAND gates N5 to N8, and each second input terminal of NAND gates N9 to N12. Strobe signals STR1~ each output from the print control circuit 4
STR3 is now applied. heating element 9
is composed of heating elements S1 to S12, and each heating element S1 to S12 is connected to a NAND gate N1 to N1 to S12, respectively.
Each output of N12 is 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, when the print data of the dot row read out from the buffer memory 3 is sequentially read into the shift register 6, the print control circuit 4 outputs the 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 outputs a strobe signal STR1. As a result, the NAND gates N1 to N4 become active, and the heating elements S1 to S4 are driven based on the output of the latch 7. Next, the print control circuit 4 sequentially outputs the strobes STR2 and STR3 after a certain period of time. As a result, the heating element S
5 to S8 and S9 to S12 are 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 outputted from the buffer memory 3 and read into the shift register 6. When all the print data of the second line is read into the shift register 6, the latch signal LA is sent from the print control circuit 4 again.
is output. 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 way.

[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 difference in the density of the printed dots depending on the case.
Therefore, there is a problem that printing unevenness occurs.
That is, for example, when data "1" is applied to the first input terminals of the NAND gates N1 to N4, the heating elements S1 to S4 simultaneously generate heat by the strobe signal STR1. 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, when the print data is, for example, "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 an object thereof 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. N (positive integer)
Data is extracted every other piece, N non-print data are inserted between each extracted data to form the first data string, and N (positive integer) is inserted from the second data in the data string. Extract data every other piece, insert N non-print data between each extracted data to form a second data string, and similarly,
The present invention is characterized in that first to (N+1)th data strings are created, and the heating element is driven by these first to (N+1)th data strings to print the same print 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, reference numeral 10 denotes a parallel/serial converter, which converts print data corresponding to dots output from the buffer memory 3, for example, in bytes, into serial data, and converts it into serial data using an AND gate AND1,
Output to each one input terminal of AND2. 11 is D
-FF (delay flip-flop). This D-FF11 has its input terminal D and output terminal connected, and as a result, the clock pulse CK
It operates as a trigger flip-flop triggered by . 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 when a "0" signal is supplied to its control terminal C, it outputs the data of the input terminal <1>. Outputs <0> data.

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 a "1" signal to the control terminal C of the multiplexer 13, and then outputs the clock pulse CK and sends the first row to the buffer memory 3. Address data is sequentially output in order to read the print data of the eye dot row. When the clock pulse CK (see FIG. 1B) is output from the print control path circuit 4, the D-
The signals shown in FIG. 2 C and D are output from the output terminal Q of the FF 11, 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 10, and the AND gate AND1 , AND2. By the way, at this point, a "1" signal is being supplied to the control terminal C of the multiplexer 13, and therefore the AND gate AND
The output of 2 is not related to circuit operation. Therefore, below is the output of the AND gate AND1 (see Figure 2 E)
Let's consider.

Now, assume that the output data of the parallel/serial converter 10 is shown in FIG. 2A. Note that "1" in this data indicates printing, and "0" indicates non-printing. When the first data "1" of this output data is output from the converter 10, the Q output signal of the D-FF11 becomes a "1" signal,
Therefore, the AND gate AND1 becomes open, and the data "1" is output from the AND gate AND1. Next, when the second data "0" is output from the converter 10, at this time D-FF11
The Q output signal of becomes “0” and the AND gate
Since AND1 is in the closed state, the output of AND gate AND1 becomes "0" regardless of the output of converter 10. Next, when the third data "1" is output from the converter 10, the AND gate AND1 is in an open state, so the data "1" is output from the AND gate AND1,
Next, the fourth data “1” is sent from the converter 10.
When is output, the AND gate AND1 is closed, and therefore data "0" is output from the AND gate AND1. Thereafter, similar operations are repeated. Like this, and gate
AND1 is the first output data of the converter 10,
The third, fifth, etc. are extracted, and data with data "0" inserted between each of the extracted data is output. When the "1" signal is supplied to the control terminal C of the multiplexer 13,
The output of this AND gate AND1 is supplied to the shift register 6 via the multiplexer 13,
The data is read into the same 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.
As a result, the first line of dot printing is performed.

On the other hand, the print control circuit 4 outputs the address data corresponding to the first row of dots to the buffer memory 3, then outputs a "0" signal to the control terminal C of the multiplexer 13, and then outputs the "0" signal to the control terminal C of the multiplexer 13.
The address data corresponding to the dot column in the row 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 gate AND1.
Each is output from AND2. Here, when a "0" signal is supplied to the control terminal C of the multiplexer 13, the output of the AND gate AND2 is outputted via the multiplexer 13. The following data is output from this AND gate AND2 (see Fig. 2). First, when the first data "1" (see Figure 2 A) is output from the converter 10, the output signal of the D-FF11 is at the "0" signal, and the AND gate AND2 is in the closed state. Therefore, data “0” is output from the AND gate AND2, and the second
When the second data "0" is output, the AND gate AND2 becomes open, and the output data "0" of the converter 10 is output from the AND gate AND2, and the same operation is repeated thereafter. In this way, the AND gate AND2 extracts the 2nd, 4th, 6th, etc. of the output data of the converter 10, and places data "0" between each of the extracted data.
Output the inserted data. When a "0" signal is supplied to the control terminal C of the multiplexer 13, this AND gate AND2
The output is read into the shift register 6 via the multiplexer 13, and 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, and then moves the printing paper by one line, and then moves the printing paper to the second line in the same manner as described above.
Performs dot printing on the row.

In this manner, in the embodiment described above, the print data is divided into odd-numbered data and even-numbered data, and "0" 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 numbered and even numbered dot, 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. When dividing print data into multiple columns, for example, the print data of a dot column is divided into even and odd numbers and pooled in the buffer memory 3, and then,
It is also possible to insert non-print data "0" to form a plurality of dot rows. If the print data is a character code, it is sufficient to first develop it into dots using a character generator and convert it into dot data, and then 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 for 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 the drawing]

1 and 2 are diagrams for explaining one embodiment of the present invention, in which FIG. 1 is a circuit configuration diagram and FIG. 2 is 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. S1 to S12... Heat generating element, 3... Buffer memory, 4... Print control circuit (CPU), 5... Thermal head, 6... Shift register.

Claims (1)

[Claims] In a printing method for a thermal printer that drives a plurality of heating elements to perform printing based on a data string corresponding to a print dot, extracting data every N (positive integer) from the first data in the data string, Inserting N non-print data between each of the extracted data to form a first data string, and extracting every N (positive integer) data from the second data in the data string, N pieces of non-print data are inserted between each of the extracted data to form a second data string, and in the same way, the first to (N+1)th data strings are created, and these first to (N+1)th data strings are created. 1. A printing method for a thermal printer, characterized in that the heating element is driven by a data string to print the same print dot string.