JP2589858B2 - Heating element control method for thermal head - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heating element control method for a thermal head.

[Prior Art] Conventionally, a heating element of a thermal head is controlled by an energizing pulse, but how energy has been supplied to the heating element in a dot before the current dot, that is, the heat of the heating element Judging the history, the time width of the energizing pulse supplied this time was determined.

FIG. 7 shows an example in which a thermal head in which a plurality of heating elements are arranged in a line is used. In a heating element on a line, dot data of two lines before is not printed, that is, white printing is performed and one line is printed. The previous dot data is also printed in white,
When this dot data is black print energizing pulse width to the heating element in the current printing is in the t _1.

When the dot data two lines before is white printing, the dot data one line before is black printing, and the dot data this time is black printing, the dot data two lines before is black printing and one line before When the dot data is white printing and the current dot data is black printing, the current supply pulse width to the heating element is t ₂ (t ₁ > t ₂ ) in the current printing.

Further, the dot data of the previous two lines and the dot data of the previous line are continuously printed in black, and when the current dot data is printed in black, the energizing pulse width to the heating element in the current printing is t ₃ (t ₂ > t ₂ ). ₃ ).

Further, when the current dot data is white printing, the energizing pulse width to the heating element in this printing is "0", that is, no energizing is performed at all.

[Problem to be Solved by the Invention] In this energization control to the heating element, if even one of the past two lines has black printing, the current energization pulse width to the heating element is
t ₂ or t _3, and the relatively short because of the heat storage effect of the heating element of the width, the temperature of this printing heating element when the white printing with the last two lines is started in a state with a reduced For this reason, t _1, which is the current-period pulse width to the heating element, is considerably longer than t ₂ and t ₃ .

Accordingly to shorten the print cycle in order to realize high-speed printing to the time t ₁ of the configuration becomes difficult, shortening the time t ₁ provides high-speed printing can be possible printing quality is degraded problem and increase the printing quality In such a case, there has been a problem that sufficiently high-speed printing cannot be performed.

Therefore, an object of the present invention is to provide a heating element control method for a thermal head that can easily realize high-speed printing without deteriorating printing quality.

[Means and Actions for Solving the Problems] According to a first aspect of the present invention, there is provided a thermal head that controls energization and non-energization of a heating element in dot units based on a print dot pattern, and performs printing by generating heat from the heating element. In the above, the width of the energizing pulse to the heating element corresponding to the printing dot is controlled in a plurality of stages based on the printing history of the heating element, and n (n ≧ 2) dot data is continuously printed on the heating element. In the case of a dot, pre-energization is performed with an energizing pulse width generated by a difference between two predetermined steps of a plurality of steps, such that a heating element corresponding to a continuous non-printing dot after the n-th dot is not printed. Is to do.

According to a second aspect of the present invention, there is provided a thermal head which controls energization and non-energization of a heating element in dot units based on a print dot pattern, and performs printing by generating heat from the heating element. The energizing pulse width is controlled in a plurality of stages based on the printing history of the heating element, and the dot data to the heating element is n (n ≧ 2) dots continuously to the current data, and the next data is the printing dot. in the case of,
An object of the present invention is to pre-energize a heating element corresponding to a non-print dot of the current data with an energizing pulse width generated by a difference between two predetermined steps of a plurality of steps to such an extent that printing is not performed.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a thermal head in which _m heating elements H ₁ , H ₂ , H ₃ ,..., H _m are arranged in a line, and 2 denotes each heating element H _{1 to} H _m of the thermal head 1. On the other hand, a latch circuit 3 for controlling the supply of an energizing pulse,
A shift register that serially inputs DATA in synchronization with a clock and outputs the input data in parallel.

The latch circuit 2 is provided by a control unit. Is input, the print dot data is taken in from the shift register 3 and latched. There has been adapted to provide energizing pulses is input on the basis of the input period print dot data of the signal to each of the heating pair H ₁ to H _m.

FIG. 2 shows the configuration of the control unit. Reference numeral 11 denotes a frame memory storing print dot data in frame units. In this frame memory 11, it is assumed that storage addresses of dot data of one line are continuous.

Reference numeral 12 denotes an A address counter for generating an address of dot data two lines before the line to be printed this time, and reference numeral 13 denotes a B address for generating an address of dot data one line before the line to be printed this time. A counter 14 is a C address counter for generating an address of dot data of a line to be printed this time. Note that the initial value of each address counter 12, 13, 14 is the head address of each line.

The count-up operation of the address counters 12, 13, 14 and the like are performed by the count-up signals S ₁ from the sequence controller 15.

Reference numeral 16 denotes a selector for selectively supplying an address generated by each of the address counters 12, 13, and 14 to the frame memory 11. Selecting operation of the selector 16 is adapted to be performed by the address select signal S ₂ from the sequence controller 15.

17 and latches parallel input data of one word of two lines before the read out from the frame memory 11 by the address from the address counter 12 by a latch signal S ₃ from the sequence controller 15, and the latched data A shift register for serially outputting the data to the data generation logic circuit 20 bit by bit. The A shift register 18 reads the data of one word before one line read from the frame memory 11 by the address from the address counter 13 from the sequence controller 15. B shift register with parallel input and latched by the latch signal S _4, and serially outputs the latched data by one bit in the data generating logic circuit 20, 19 from the frame memory 11 by the address from the address counter 14 1 to be printed this time to be read And parallel input to latch over de of data by the latch signal S ₅ from the sequence controller 15, and a C shift register for serially outputting the latched data by one bit in the data generation logic 20.

The data supply from the shift registers 17 to 19 to the data generation logic circuit 20 is performed by the sequence controller 15.
And the like are performed simultaneously in synchronism with a clock S ₆ from.

Wherein the data generation logic circuit 20 is adapted to output data DATA on the basis of a preset association with data taken from the logic select signal S ₇ responsive to the respective shift registers 17 to 19 to from the sequence controller 15 ing.

As shown in FIG. 3, the set relationship is such that a certain heating element on a line has no printing of dot data of two lines before, ie, white printing, and dot data of one line before printing also white. energizing pulse width t ₁ next to the heating element in the current printing when the data is black printing, and in two lines before the dot data is white printing, and one line before the dot data is black printing, this dot data When the dot data is black printing, the dot data two lines before is black printing, the dot data one line before is white printing, and the current dot data is black printing, the energizing pulse width to the heating element in the current printing Is set to be t ₂ (t ₁ > t ₂ ).

Further, the dot data of the previous two lines and the dot data of the previous line are continuously printed in black, and when the current dot data is printed in black, the energizing pulse width to the heating element in the current printing is t ₃ (t ₂ > t ₂ ). ₃ ) In addition, when the dot data two lines before and the dot data one line before are continuously printed in white and the current dot data is also printed in white, the width of the energizing pulse to the heating element in this printing is t ₂ − is set in such a way that t _3. Here, the energizing pulse width t ₂ -t ₃ is such an energizing time that printing is not performed by the heating element even when the heating element is energized.

Further, when the white dot printing is not continuous over two lines and the current dot data is white printing, the energizing pulse width to the heating element in this printing is "0", that is, no energizing is performed at all.

Data DATA output from the data generation logic circuit 20
Are data (1), data (2),
Data (3), and these data Thus, the data is sequentially taken into the latch circuit 2 three times. Here is data for data (1) is to be energized by a time t _3, also the data (2) is the data for energizing only the time t ₂ -t _3, further wherein the data (3) time t data for energizing only ₁ -t _2, these data becomes energized at a high level,
It is configured to be de-energized at the low level.

Therefore, when making energization time t ₁ data (1)
(2) (3) all make by the high level, also in the case of making the energization time t ₂ data (1)
(2) make by data at a high level (3) becomes the low level, and the data (1) when making energization time t ₃ the data (2) at a high level (3) and a low level In the case where an energized state of time t ₂ -t ₃ is to be created, data (2) is at a high level and data (1) and (3) are at a low level.

In order to perform this processing, the data generation logic circuit 20 performs the following logical processing.

When the serial output of the respective shift registers 17, 18 and 19 and D _1, D _2, D _3, respectively, logic output to make data (1) is, the DATA = D _3. This will be this time of the dot data is needed is always time t ₃ if the black print data (1)
Is set to a high level.

To create data (2), the logical output is DATA =
_{1 · 2 · D 3 + 1} · D 2 · D 3 + D 1 · 2 · D 3 + 1 ·
The ₂ and _3. This is when two lines in the past are white and black is printed this time, and one of the past two lines is black and another line is white and each is printed this time.
This is because the data (2) needs to be set to the high level when the past two lines are continuously printed in white and this time also in white printing.

To create data (3), the logical output is DATA =
The ₁ · ₂ · D _3. This is because the current in the last two lines consecutive white printing has to be a high level data (3) in order to make time t ₁ when the black printing.

21 is started by a timer starting signal S ₈ from the sequence controller 15, and outputs a signal S ₁₁ after t ₃ hours had passed to the sequence controller 15, the signal after the lapse of t ₂ hours
Outputs S ₁₀ to the sequence controller 15, further t
_{After one} hour, the signal S ₉ is transmitted to the sequence controller 15.
Output.

Together with the sequence controller 15 also supplies the clock S ₆ to the shift register 3 To be supplied to the latch circuit 2.

In this embodiment having such a configuration, the sequence controller 15 to supply the address of the A address counter 12 to the frame memory 11 and supplies the address select signal S ₂ to the selector 16. As a result, the start address of the dot data two lines before is specified, and one dot of the dot data two lines before is read out and supplied to the A shift register 17. Sequence controller 15 to latch the data by supplying a latch signal S ₃ to the A shift register 17.

Then the sequence controller 15 to supply the address of the B address counter 13 supplies the address selector signal S ₂ to the selector 16 to the frame memory 11. As a result, the leading address of the dot data of the previous line is designated, the dot data of the previous line is read out by one word, and supplied to the B shift register 18. Sequence controller 15 is B
And supplies a latch signal S ₄ to latch the data into the shift register 18.

Further sequence controller 15 to supply the address of the C address counter 14 supplies the address select signal S ₂ to the selector 16 to the frame memory 11. As a result, the head address of the dot data of the current line to be printed this time is designated, and one dot of the dot data of the current line is read out and supplied to the C shift register 19. Sequence controller 15 supplies a latch signal S ₅ to C shift register 19 to latch the data.

Thus serially read data generation logic bit by bit dot data and supplies the clock signal S ₆ sequence controller 15 when the latch dot data is completed in the shift registers 17, 18, 19 for each shift register 17, 18, 19 The circuit 20 is supplied.

The address counters 12, 13, and 14 of A, B, and C are incremented by the count-up signal S1, and the above sequence is repeated until one line of data is transmitted.

The sequence controller 15 supplies a logic select signal S ₇ to the data generating logic circuit 20, two lines before the data from the data generation logic 20, one line preceding data, energizing pulse width of the current print data based on the current data The data (1), (2), and (3) are output three times, respectively, so that the relationship shown in FIG.

For example, since the current of the current line in the two lines before and 1 line before both white printing energizing pulse width is t ₁ when the black print, data (1), (2), output as all high level (3) Let it.

Since either of the two lines before and 1 line before energization pulse width is t ₂ when the current of the current line in the black printing black print data (1), (2) a high level, data (3) Is output as a low level.

The two lines before and 1 for the previous line is energizing pulse width is t ₃ when the both black printing is also black printing time of the current line, a high level data (1), data (2),
(3) is output as a low level.

Further, when both the previous line and the previous line are printed in white and the current line is also printed in white, the energizing pulse width is t ₂ −t _3.
Therefore, data (2) is output at a high level, and data (1) and (3) are output at a low level. At this time, the heating element does not perform black printing with the energization pulse width t ₂ −t ₃ . That is, pre-energization is performed in preparation for future black printing.

Further, when one or both of the two lines before and one line before are black printing and the current line this time is white printing, the energizing pulse width is “0” and data (1), (2) and (3) are all low level. Output.

Thus although energizing pulse width when the next black print when the last two lines white printing continues be next black print in white printing This time becomes t _1, the time when the heating element previous white printing at this time Since the pre-energization of t ₂ -t ₃ is performed, the temperature is maintained at a relatively high temperature even if the temperature does not reach the printable temperature. Thus it will be be quickly increased to printable temperature when the next black print, thus be short energizing pulse width t ₁ enables the degree of printing that can sufficiently guarantee the quality.

As described above, the time required to energize the heating element when black printing is performed after white printing can be shortened, so that high-speed printing can be performed. In addition, there is no fear that the printing quality is reduced.

Next, another embodiment of the present invention will be described with reference to the drawings.
The same parts as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 5, there is further provided a D address counter 22 for generating an address of dot data of one line next to the line to be printed this time, and the addresses from the D address counter 22 are A, B, The data is supplied to the selector 16 in the same manner as the address counters 12, 13, and 14 of C.

The data in parallel input latch, and that the latched by a latch signal S ₁₂ from the address counter 22, wherein the data for one line to be printed on the next sequence controller 15 to be read out from the frame memory 11 by the address from The data generation logic circuit 20 'is provided with a D shift register 23 for serially outputting one bit at a time.

Then the data generation logic 20 'is logic select signal S ₇ from the sequence controller 15' data DATA on the basis of a preset association with captured data from the response to each of the shift registers 17,18,19,23 in Is output.

As shown in FIG. 6, a certain heating element on a line has a white print of dot data two lines before, a white print of dot data of one line before, and a black print of dot data of this line as shown in FIG. In the case of, the energizing pulse width to the heating element in this printing is t ₁ regardless of the dot data of the next line.
The dot data two lines before is white printing, the dot data one line before is black printing, the dot data this time is black printing, the dot data two lines before is black printing, and 1 When the dot data before the line is white printing and the current dot data is black printing, the energizing pulse width to the heating element is t ₂ (t ₁ > t ₂ ) in the current printing regardless of the dot data of the next line. It is set as follows.

In addition, when the dot data of the previous line and the dot data of the previous line are continuously printed in black and the current dot data is also printed in black, the energizing pulse width to the heating element in the current printing is applied regardless of the dot data of the next line. Is t ₃ (t ₂ > t ₃ )
It has become.

When the dot data of the previous line is white printing, the dot data of the current line is white printing, and the dot data of the next line is black printing, the energizing pulse to the heating element in the current printing is performed regardless of the dot data of the previous line. If the width is t ₂ -t _{3 and} the dot data of the two lines before is white printing and the dot data of the next line is also white printing, the energizing pulse width to the heating element in this printing is “0”, that is, no energizing Not set. Here, the energizing pulse width t ₂ -t ₃ is such an energizing time that printing is not performed by the heating element even when the heating element is energized.

Further, the dot data two lines before is white printing, the dot data one line before is black printing, the dot data of the current line is white printing and the dot data of the past two lines are all black printing, and the dot data of the current line is When white printing is performed, the current pulse data is not continuous over two lines, and when the current dot data is white printing, the energizing pulse width to the heating element is "0" regardless of the dot data of the next line.

Further, when the dot data of the previous line is printed in white, and the current dot data and the dot data of the next line are also printed in white, the energizing pulse width to the heating element becomes “0” regardless of the dot data of the previous two lines. I have.

The data generation logic circuit 20 'is provided for each shift register 17, 1
Assuming that the serial outputs of 8, 19 and 23 are D ₁ , D ₂ , D ₃ and D ₄ respectively, the logical output is DATA = D ₃ to generate data (1).
Becomes This is because so that this dot data is a high level data (1) must always time t ₃ if black print.

To create data (2), the logical output is DATA =
_{1 · 2 · D 3 + 1} · D 2 · D 3 + D 1 · 2 · D 3 + 2 ·
A ₃ · D _4. This is when two lines in the past are printed consecutively in white and black is printed this time, and in the past two lines, one line is printed in black and the other one is printed in white and this time is printed in black.
This is because the data (2) needs to be set to the high level regardless of before the line, one line before and this time when white printing is performed and black printing is performed next time.

To create data (3), the logical output is DATA =
It becomes 1.2D3. This is because the current in the last two lines consecutive white printing has to be a high level data (3) in order to make time t ₁ when the black printing.

Since such that this current line in the present embodiment example 2 lines before and one line before are both white printed by construction the embodiment similarly energizing pulse width is t ₁ when the black print, data (1) , (2), and (3) are all output as high level.

Since either of the two lines before and one line before said embodiment similarly energizing pulse width when the current of the current line is black printing becomes t ₂ in black printing, data (1), high (2) The level and data (3) are output as a low level.

The 2 for energizing pulse width in the same manner in Example when the line before and one line before are both black printing is also black printing time of the current line is t _3, a high level data (1), data (2) , (3) are output as low level.

In addition, regardless of whether the current line is two lines before, when the previous line is white and the current line is white, the energizing pulse width is t ₂ −t ₃ when the next line is black and the data (2) is high level. Data (1) and (3) are output as low level. At this time, the heating element does not perform black printing with the energization pulse width t ₂ −t ₃ . That is, pre-energization is performed in preparation for future black printing.

However, when the previous line and the previous line are printed in white, the current line is printed in white, and the next line is printed in white, the energizing pulse width becomes "0" and data (1), (2), and (3) are printed.
Are all output as a low level.

Further, when one or both of the two lines before and one line before are black printing and the current line this time is white printing, the energizing pulse width becomes “0” and the data (1),
(2) and (3) are all output as low level.

Thus although one line before and this time energizing pulse width when the next black print becomes t ₁ when performing the next black print in white printing, the time t ₂ when the heating element previous white printing at this time
Since the pre-energization at −t ₃ is performed, the temperature is maintained at a relatively high temperature even if the temperature does not reach the printable temperature. Thus it will be be quickly increased to printable temperature when the next black print, thus be short energizing pulse width t ₁ enables the degree of printing that can sufficiently guarantee the quality.

As described above, in this embodiment, the same effects as those of the above embodiment can be obtained.

In the above embodiment, the heating element is pre-energized when the previous two lines are white and the current line is white, and when the previous line and the current line are white and the next line is black, the heating element is not necessarily limited to this. Needless to say, it is not done.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to provide a heating element control method of a thermal head that can easily realize high-speed printing without deteriorating printing quality.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 4 show an embodiment of the present invention. FIG. 1 is a block diagram of a thermal head driving unit, FIG. 2 is a block diagram of a control unit, FIG. The figure shows the relationship between the print contents of the past two lines and the current line and the energizing pulse width for the current print.
FIG. 4 is a diagram for explaining the relationship between the conduction time width and the output data of the data generation logic circuit. FIGS. 5 and 6 show another embodiment of the present invention, and FIG. FIG. 6 is a diagram showing the relationship between the printing contents of the past two lines, the current line and the next line and the energizing pulse width for the current printing, and FIG. 7 is a conventional printing contents of the past two lines and the current line. FIG. 6 is a diagram illustrating a relationship between the current pulse width and the current printing pulse width. 1 thermal head, 15 sequence controller, 17-19, 23 shift register, 20, 20 'data generation logic circuit.

Claims (2)

(57) [Claims] 1. A thermal head which controls energization and non-energization of a heating element in dot units based on a print dot pattern and performs printing by heat generation of the heating element. Controls in multiple stages based on the print history of the heating element. If dot data to the heating element is n (n ≧ 2) dots consecutively non-printing dots, it corresponds to continuous non-printing dots after the nth dot A method of controlling a heat generating element for a thermal head, comprising: pre-energizing the heat generating element with a power supply pulse width generated by a difference between two predetermined steps of the plurality of steps so that printing is not performed. 2. A thermal head which controls energization and non-energization of a heating element on a dot basis based on a print dot pattern and performs printing by heat generation of the heating element. The control is performed in a plurality of stages based on the print history of the heating element. If the dot data to the heating element is n (n ≧ 2) dots continuously up to the current data, and the next data is a printing dot, the current data Of the heating element corresponding to the non-printing dot of the predetermined number of the plurality of steps to the extent that printing is not performed.
A method for controlling a heating element of a thermal head, wherein a pre-energization is performed with an energization pulse width generated by a difference between two stages.