JPS61280954A - Print control circuit for thermal printer - Google Patents

Abstract

PURPOSE:To raise the quality of printing by suppressing the change of density as much as possible by controlling the heating time of heating elements more minutely by means of the first controller for within dot blocks and also by means of the second controller for dot block units. CONSTITUTION:To control the heating time of heating elements for dot block units, the second controller 8 to obtain reference pulse width data RPD in the following dot block BLOCKn according to printing data for the previous dot block BLOCK(n-1) is provided. Also, to control the heating time of the heating elements, the first controller 19 to obtain correcting pulse width data alphaA and alphaB for every one dot row separately for A-row and B-row each time one-dot row unit of thermal head is moved, regardless of dot blocks, is provided. (RPD+alphaA) and (RPD+alphaB) are added by adders 20 and 21 for A-row and B-row, and strobe pulse width data PWD-A and PWD-B for A-row and B-row are determined.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Field of Application The present invention is directed to a thermal printer for a cereal shop which is equipped with a row of heating elements perpendicular to the direction of movement of the thermal head and can move the thermal head one dot row at a time. Regarding printers, especially
The present invention relates to a printing control circuit that controls the heating time of a heating element.

(b) Prior Art In serial thermal printers, it has been conventional to control the next heating time of a heating element in accordance with past print data. The method is JP-A-59-
As disclosed in Japanese Patent No. 64373, the number of heating dots included in the print data of the previous dot row is counted,
In many cases, the heating time of the heating element in the next dot row is controlled based on the number of heating dots.

(c) Problems to be solved by the invention In the conventional technology, the heating time of the heating element was controlled every time the thermal head moved in units of one dot column in accordance with past printing data. Although it is relatively possible to prevent density changes over a wide range of printing results, such as the first half being lighter and the second half being darker, it is possible to prevent density changes between adjacent dots to be too large. However, there is a problem that the print quality deteriorates.

B.) Means for Solving the Problems The print control circuit of the present invention controls the heat generation according to past print data in a serial type thermal printer equipped with a row of heat generating elements perpendicular to the moving direction of the thermal head. a first control means for controlling the heating time of the element every time the thermal head moves in units of one dot row; and a second control means for controlling each dot block.

(e) Effect In the present invention, the heating time of the heating element of the thermal head is
Controlled by past printing data, more specifically, within each dot block corresponding to at least one character,
Rough control is performed by the second control means so that the heating time is uniform, and furthermore, the first
Fine control is performed by the control means.

(F) Embodiment FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 shows the configuration of the thermal head in this embodiment.

The thermal head (1) of this embodiment is perpendicular to the direction of movement of the thermal head, and includes two rows of heating elements, row A and row B, with a predetermined interval P, and each heating element A row is composed of 24 heating elements.

The drive circuit (2) of the thermal head (1), as shown by the broken line in FIG. 3a) and (3b), latch circuit (4a)
) and (4b), drivers (5a) and (5b), each driver (5a) and (5b) corresponding to the pulse width T of the applied strobe pulses S T B-A and 5TB-B. The corresponding heating element is heated in accordance with the time and print data input from the latch circuits (4a) and (4b). As shown in FIG. 1, the print control circuit (6) includes a CPU (7) that controls printing, an interface (8)
), a print buffer (9) that stores print data input via the carriage motor drive information CR, columns A and B
Interface Ql that outputs column selection signals 5L-A and 5L-B, ROMQυ that stores fixed information necessary for programming and control, RAM (13), which exchanges parallel print data serially, and a shift register ( 3
a) and (3b) K-supplying parallel-serial switching circuits (13a) and (13b), clock pulse oscillator I,
By counting the clock pulses CL, a strobe pulse S with a pulse width T according to the set data is generated.
The timer counter a9 that generates TB sends the 0-b pulse STB as a strobe pulse 5 TB-A or 5 TB-B to either one of the drivers (5a) or (5b) according to the selection signal SL-man and 5L-BK. It consists of a selector Ql that applies the voltage.

In addition, the thermal head is equipped with a temperature sensor α such as a thermistor.
η is attached, and temperature information TH from this temperature sensor 1η is input to the interface αIK.

Furthermore, information SW from the concentration switch for concentration adjustment,
The resistance rank information RR of the heating element is also provided by the interface Q.
It is input to l.

In this embodiment, based on the print data stored in the print buffer (9) K, when driving columns A and B,
respectively, control the strobe pulse width data PWD-A and PWD-B to be set by the timer counter (IsK), thereby controlling the strobe pulses 5TB-A and 5TB-B.
The heating time of the heating element is controlled by controlling the pulse width of the heating element.

Therefore, a functional block diagram of this embodiment is shown in FIG. 3, and an overview of the control will be explained. In the following explanation, it is assumed that an l character is composed of 24 x 24 dots, and as shown in FIG. BLOCKI, BLOCK
2, BLOCK3. The case of dividing into... will be explained.

In this embodiment, in order to control the heating time of the heating element in units of dot blocks, the previous dot block BLOCK(n
-1) Next dot block BL according to the print data
A second control means α for determining the reference pulse width data RPD in the OCK row, and a second control means α for determining the reference pulse width data RPD in the OCK row, and a second control means for determining the reference pulse width data RPD in the A row and B row in order to control the heating time of the heating element for each dot row unit movement of the thermal head, regardless of the dot block. Each column has a first control means 0 for calculating corrected pulse width data α and α for each dot column, and addition means (to) and Qυ for A column and B column respectively. , (RPD+αA) and (RPD+
The strobe pulse width data PWD-A and PWD-B of the A column and the B column are determined by adding the strobe pulse width data PWD-A and PWD-B, respectively.

That is, the second control means α calls: the previous dot block BLO.
an accumulating means (2) for accumulating the number of heat-generating dots in the print data regarding column A in CK (Rue 1) K; and a standard number M6 of heat-generating dots corresponding to a predetermined density of heat-generating dots in one dot block. % For example, if the heating dot density is 20
If it is %, 24X100X0.2X0.5=240,
A comparison means (c) for comparing the cumulative result M and a 1% increase value RPDCn- of the reference pulse width data RPD(,-,) in the previous dot block BLOCK(f&-1).
1) and a calculation means c! for calculating the 1% reduction value RPD(3-1)-. 4 and, depending on the comparison result, RPD (,,)
and RPD(nt)-, and outputs the selected value as reference pulse width data RPD(a) in the next dot block BLOCKt&. Therefore, the reference pulse width data RPD
changes depending on the number of heating dots in the previous dot block,
It is constant within the same dot block.

For example, RPD in BLOCKI is "440μs",
If the cumulative value is M6ir300J, RP with BLOCK2
D decreased by 1% to "436μs", and further KBLOCK2
Cumulative value at Mkr350J If tared, 13 L OC
K 3-eRP Dj2 change K 1% decrease "431μs"
becomes.

On the other hand, the first control means (1912, A row control section (a) and B
If the dot row to be printed is the i-th column (i: odd number), the A-column control section (c)
An accumulating means (total) for accumulating the number of heat generating dots included in the print data of the dot rows of the 2> column and the <1-4) column, and the cumulative result wind as the standard number of heat generating dots m1. Comparison means for comparing with - and a plurality of corrected pulse width data α, ~α,
Select the corrected pulse width data according to the comparison result from
It consists of a selection means (to) which outputs the corrected pulse width data α,(t) when printing the i-th column. Here, the relationship between the reference number of heating dots m1 to m. and the corrected pulse width data α1 to α is determined as shown in FIG.

Similarly, the B column control section (5) is composed of an accumulating means C11), a comparing means r33, and a selecting means (to), and the jth column ()°:
The corrected pulse width data α-<j) during printing (even number) is (j
α according to the cumulative result of the number n of heating dots included in the print data of the -2) and ()°-4) columns.

~α, is selected.

In this way, the first control means (1'J) drives the carriage motor one step to move the thermal head (1) one step.
Each time the dot row is moved, α or the α value is controlled.

Therefore, for example, the cumulative result m of the 101st and 103rd columns is
, is "21", then αA when printing the 105th column is "-"
25μs” and the 105th column is dot block BLO.
Since it is in the range of CK2, the strobe pulse width data PWD
-A is RPD+α.

=435-25=411μS. Also, if the cumulative result 71L of the 102nd and 104th columns is "16", 1
When printing the 06th column, α self is l”-15 μs”, and strobe pulse width data PWD-B is RPD + αm =
436 15 = 421μ3.

Next, a method of actually controlling the configuration shown in FIG. 1 will be explained with reference to the flowchart shown in FIG. 5.

First, by initial setting, buffers BUF4 to BUF8 of RAM (13) shown in FIG.
Set the initial value RPDo of the reference pulse width data, for example, "440 μsJ" in BUF3.

Then, as shown in the flowchart of FIG. 5, printing of columns A and B is performed alternately while moving the carriage motor one step.

First, when printing column A, read column A print data from the print buffer (9) and send it to the parallel serial switching circuit (1
3a) and (13b). Then, the print data exchanged with serial data is transferred to the shift register (3a).
and (3b), is further latched by latch circuits (4a) and (4b), and is transferred to drivers (5a) and (5b).
) is entered. Therefore, next, the A column strobe pulse width data PWD-A is read out from BUF2 and set in timer counter a9. In this case, an initial value of 1440 μs is set as PWD-A. Then, 440
A μs strobe pulse STB is output, and the selector 0
8, only the A row side is selected, and this 5TB4S8TR-A
K is applied to the driver (5a) as follows. Therefore, only the heating elements of the A row corresponding to the print data are heated for 440 μs, and the A row printing is executed.

Then, during this person's printing process, go to 5EP-5 or later. control.

That is, in order to execute the second control, in 8TEP3, the print buffer (9) is
The number of heating dots included in the print data sent to a) and (13b) is accumulated in BUF6. That is, B.U.
F6 is a buffer for obtaining the above-mentioned accumulation result M. In addition, in 5TEP-6 and 7, in order to execute the first control, m is obtained by adding the contents of BUF 7 and the number of heating dots rLA, and α is obtained from this mm. Then, from this α and the RPD stored in BUFI, PWD-A for the next A column printing is determined and stored in BUF2.

Furthermore, lume is stored in BUF7. Next, it is determined whether the accumulation in column A has reached one dot block, that is, 50 dot columns, and if not, the process is terminated.

As mentioned above, when the processing in column A is completed, the CPU
(71 drives the carriage motor one step and moves on to the B column printing process. In the B column printing, as in the case of the A column, the B column print data read from the print buffer (9) is transferred to the parallel serial conversion circuit (13a). ) and (13b), and set the B column strobe pulse width data PWD-B read from BUF3 to the timer counter rotor. In this case, PWD-B is also the initial value "440 μs". This B column is printed. In processing, 5TEP in A column processing
-5 accumulation processing is not performed and the process moves to the first control. In other words,
5 Add the number of heating dots contained in the print data sent in TEP-16 and the contents of BUF8 to calculate rIL.
Find wealth and find α1 from this rILI. Then, from this α1 and the content RPD of BUF1, PWD-B at the time of printing the next B row is determined and stored in BUF3. Furthermore, ns
is stored in BUF8. After this, in 5TEP23-26, the 1% increase/decrease value in the second control is calculated.

That is, the reference pulse width data RPD, here RPD, is 1
Calculate the % increase value RPD and 1% decrease value RPD,
BUF4 and BUF51C are stored respectively. With the above steps, the B column printing process is completed.

Similarly, when the processing of columns A and B is performed alternately, in each of columns A and B, the first control calculates αm and α■, and the accompanying PWD-A and PWD -B
The changes are made alternately for each step of the carriage motor.

When the printing of row A within the range corresponding to one dot block BLOCKIK is completed, the cumulative result M of the heating dots in one dot block is obtained in BUF6. Therefore, a comparison is made between M and the standard number of heating dots M0, and as a result, either one of RPD and RPD" calculated at the time of printing column B and stored in BUF4 and 5vc is selected.
Reference pulse width data RPD in BLOCK2 is determined. This value is then stored in BUFIK and BUF
The contents of 6 are cleared. Thereafter, in BLOCK2, αm and α, which are successively obtained, are added to this RPD, and PWD-A and PWD-B are determined. Furthermore, when all printing of the incoming dot block BLOCK2 is completed, new reference pulse width data RPD is determined by the same process as described above.

Note that the initial value RPD of the reference pulse width data RPD.

1. RR and SW input to interface α [.

It will be changed depending on THE, and regarding TH,
With a reference value of 440 μs, correction as shown in FIG. 7 is performed for each print line.

By the way, in the embodiment, the accumulated result M of one dot block was compared with the only fixed value Ma, but as in the case of the first control, it was compared with a plurality of fixed values, and as a result, not only ±1% but also The reference pulse width data may be changed by ±2% or ±3%.

In addition, in the first control, the corrected pulse width data α and α for the next dot train are determined based on the print data of the first and second times before the dot train to be printed.

However, it may be determined from only the previous printing data, or may also be obtained using printing data from 4 to 5 previous printings. Also, as one dot block, one character, that is, two
The number may be appropriately selected from 4 dot rows to about 250 dot rows.

Furthermore, in the above description, an example was given in which the first control means controls the heating time of all the heating elements of the next one dot row at once in accordance with the print data of several dot rows before printing. A method may be used in which each heating element in the dot row is controlled separately.

(G) Effects of the Invention According to the present invention, the heating time of the heat generating element is controlled by the second control means in units of dot blocks, and within each dot block, the heating time of the heating element is finely controlled by the first control means.
Print quality is improved by minimizing density changes. Especially the second
By providing the control means, it is possible to suppress the correction width by the first control means to a small value, and therefore, it is possible to prevent extreme density changes between adjacent dots.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
3 is a functional block diagram of this embodiment, FIG. 4 is an explanatory diagram showing the relationship between the reference number of heating dots and correction pulse width data, and FIG. 5 is an explanatory diagram for explaining the present invention in detail. A flowchart showing the processing contents of this embodiment, FIG. 6 is a RAM
FIG. 7 is an explanatory diagram showing a configuration of a buffer set in the buffer, and FIG. 7 is an explanatory diagram showing a specific example of a correction value based on temperature information. Explanation of main drawing numbers (1)...Thermal head, (2 voices...Drive circuit,
(6)...Printing control circuit, (7)...CPU
, (9)... Print buffer, (15) °°° timer counter, α mark... second control means, (11
. . . first control means, CI'Qel) . . . addition means. Applicant Sanyo Electric Co., Ltd. 1 other person and 1 representative Patent attorney Shizuka Sano Mistake 2 Figure 7

Claims (1)

[Claims] (1) In a serial type thermal printer equipped with a row of heating elements perpendicular to the direction of movement of the thermal head,
The heating time of the heating element is determined according to past printing data.
a first control means for controlling each movement of the thermal head in units of one dot row; and a first control means for controlling the heating time of the heating element for each dot block according to past print data in a dot block corresponding to at least one character. A printing control circuit for a thermal printer, characterized in that it has a second control means.