JPS6078770A - Driving method of line thermal head - Google Patents

Abstract

PURPOSE:To attain to improve and uniformize printing quality, by driving each heat generating element of a thermal head at every said element corresponding to the content of the dot printing data of each adjacent heat generating element. CONSTITUTION:The max. driving time tm during the printing treating time of one line is divided into three times t1-t3 and the data of each adjacent heat generating element is stored at every heat generating element. In this case, a current supply to each heat generating element is turned On and OFF at times t1-t3 corresponding to the content of each adjacent printing data shown by the drawing and the driving of each heat generating element is controlled corresponding to the driving state of each adjacent heat generating element at that times. That is, when both adjacent printing data are zero, a current is continuously supplied to the heat generating element from the time t1 to the time t3 and, contrarily, when both printing data are 1, a current is supplied at the time t1. As a result, the execution of printing is eliminated and printing quality can be make wall and uniform.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a method for driving a thermal head in a thermal dot printer and a thermal transfer dot printer that print dot patterns using a line thermal head in which heating elements are arranged in a straight line. be.

(Background technology) Due to the progress of precision technology, Shiraishi thermal helad is also 111I
High-resolution printing of 8 to 12 dots per m is now possible. However, by increasing the dot density, due to the influence of the adjacent heating elements, when the adjacent heating elements are being driven, the print smudges more sharply than when the adjacent heating elements are not being driven. The character rBJ shown in FIG. 1 has poor printing quality, unlike the printing shown in FIG. 2.

(Problem to be solved by the invention) The present invention takes into consideration the influence of heat of such adjacent heating elements,
The purpose of this method is to maintain good and uniform printing quality by appropriately selecting the driving time of each heating element according to the driving state of adjacent heating elements.

(Structure and operation of the invention) In order to achieve the above object, the present invention has a maximum driving time tm' in the printing processing time T of one line, as shown in FIG.
i5 For example, from t1 to t, the data of each adjacent heating element is stored for each heating element, and each heating element is divided into three periods, for example, from t1 to t. The energization is turned on and off between t and t3, and the driving and operation of each heating element is controlled according to the driving state of the adjacent heating element at that time.

That is, for example, if both adjacent print data are "0", the heating element is energized continuously from time t to t3, and on the other hand, if both of the print data are rlJ, the heating element is energized only from time to time. .

FIG. 5 shows a circuit according to an embodiment of the present invention, in which 1 is a register for temporarily storing dot data to be printed;
2 is a register for temporarily storing one adjacent dot data; 3 is a storage section for storing the printed dot data and the adjacent dot data; 4 is a register for storing the printed dot data stored in the storage section and the adjacent dot data. A determination circuit that determines the drive time according to the content of dot data; 5 is a shift register that outputs serially input data in parallel; 6 is a data buffer that stores one line of print dot data from shift register 5; is the register 1. Generation of set pulse to register 2, generation of shift clock to shift register 5'1. A main control unit that controls writing to the storage unit 3, generation of read signals, generation of cent pulses to the data buffer 6, etc., 8 is a pulse generation circuit for setting print drive time, and 9 is from the pulse generation circuit. a mode circuit that sets the mode from t1 to t, respectively, with the pulses of;
10 is a thermal head Tr equipped with heating elements #1 to #n.
l to Trn are drivers for energizing the heating element;
SD is serial dot data supplied line by line from a print format editing memory (not shown), and PRST is a print data that is used to set the first line dot data after the print data is edited for the print format. Data center start trigger, PT is print start trigger for each line:
DREQ is a data request signal for each dot.

Next, the driving method with the above configuration will be explained with reference to the time charts shown in FIGS. 6 and 7.

Before starting printing, it is first necessary to set the print data for the lth line. When the editing for the print formant is completed, the register 1. The register 2t is cleared and the storage section 30 address is set to rOJ address. Next, the data corresponding to thermal dot #1 of the print data signal SD is sent to the register 1 using a pulse delayed from this PRST, and at the same time, the signal DREQ ( Then, the data corresponding to the data stored in the register 1) 41-1 is set in the shift register 5, and at the same time, the SD data corresponding to the storage part 3 head 4L2 is set in the register 1. After storing all the contents of the data (data corresponding to ##1) and the data of register 2 (the data of register 2 stored at address "0" of the storage section is always rOJ), register 1
The SD data corresponding to register 2 and 4L2 are shifted to register 1, and at the same time, a signal DREQ is generated to request data corresponding to heating element #3, and the address of storage section 3 is set to address 11j, Next, in the same manner as described above, the data corresponding to the dot 142 stored in the register 1 is stored in the shift register 5, the SD data corresponding to the dot 413, the data in the register l, and the data in the register 2 are stored in the storage unit address 301, and the data in the register 1 is stored in the shift register 5. The dot data up to line dot #n is repeatedly sent to the shift register 5 and stored in the storage section 3.

When the data for one line of the lth line is set in the shift register 5, the first line of the shift clock 5 is printed by the printing start timing signal PT (see Fig. 6 (b) and Fig. 7 (a)). Drivers Trl to Trn for sending data to the data buffer 6 and driving the heating elements
Start printing with k enabled. At the same time, the PT multiplied signal drives the threshold generation circuit, changes the mode in the mode circuit from mode O to mode 1, and sets address 30 of the memory section to "0".
The street address. Next, a read signal is generated to the storage unit 3, the data of the first line don't I#1 accumulated at the time of the first line don't detent and the adjacent data are read out to the shift register 5, and the adjacent data is read out by the determination circuit 4. Dot #1 in the next mode 2 (t2) according to the dot data to be
If it is driving, it is determined whether or not to continue driving, and if driving is to be continued, driving data corresponding to dot #l is sent to the shift register 5. Thereafter, data in mode 2 (h) from dots 11.2 to 4Ln is sent to the shift register 5 in the same manner.

Next, when the time t1 for the mode l is reached, FIG.
As shown in (b), a pulse is sent from the pulse generating circuit to set the mode circuit to mode 2, and at the same time, the contents of the shift register 5 sent in mode 1 are sent to the data buffer G, and the memory section address 30 is stored in the same manner as in mode 1. 0'' address, reads out the data in the storage section 3, and sets the thermal head drive data at the next t3 in the shift register 5. When the time t2 of mode 2 is reached, the pulse generation circuit sends out a pulse to set the mode circuit to mode O. mode 2 at the same time
The contents of the shift register 5 set in step 1 are set in the data buffer 6, and the print data for the second line is processed in the same procedure as the print data for the first line. Here, the first line print data center start trigger is signal PR8.
However, the print data set start trigger for the second and subsequent lines is based on the pulse sent from the pulse generation circuit in mode 2 after time t22 has elapsed.

Furthermore, one line printing is completed by disabling the drivers Tr, -Trn, which are intended to drive the heat generating elements, when the time t3, which is reset by the pulse generated after the lapse of the time t2, is reached.

Note that the 11 AND circuits in FIG.
When storing the final data of a line, it is used to gate the dot print data of the next line. The same operation as the first line is repeated for the second and subsequent lines.

Thus, the data buffer 6 includes heating elements 4t1 to ltn.
3, 4, and 7 (each of the divided printing times t1 to t3 shown in FIG.
- t3, the on/off of energization of the heating elements 411 to 4Ln is controlled.

As described above (in the embodiments), the present invention divides the maximum driving time of the thermal head in the printing processing time of one line into several times, and for each heating element of the thermal head, the dots of the adjacent heating elements are divided. Print data is stored, and during printing, each heating element is turned on at each of the divided times according to the contents of the stored adjacent dot print data.

Since each heating element is turned off, each heating element is driven for a time corresponding to the thermal influence of the adjacent heating element, resulting in good and uniform printing quality.

FIG. 8 shows that the serial dot data SD supplied in units of one line is directly stored in the storage section 3 and sent to the shift register 5 at the same time. The dot data stored in the storage section 3 is read out and temporarily stored in registers 1 and 2, and the determination circuit 4 judges the contents read out in the storage section 3, the contents of register 1, and the contents of register 2. FIG. 9 shows an example of a circuit for sending data to the shift register 5.
9 is a timing chart for FIG. 8; In addition, the 8th
In the illustrated embodiment, serial dot data SD in units of one line is stored in the storage unit 3 from a printing format editing memory (not shown).
Since it is a method that stores the data as is, even if there is no storage section 3,
1 in Figure 7 (E). It goes without saying that serial dot data of the same line may be supplied from the print formant editing memory at times t2 and t2.

(Effects of the Invention) As explained above, since each heating element of the thermal head is driven according to the content of the dot printing data of the adjacent heating element, the printing quality is good and uniform. The 6D is a receipt issuing device used in customer service where clear printing is especially required.

It can be used in a wide range of fields such as ticket issuing devices.

[Brief explanation of the drawing]

Figure 1 is a diagram showing an example of the font for the letters rBJ.
FIG. 2 is a diagram showing an example of printing in a conventional line thermal helad, FIGS. 3 and 4 are explanatory diagrams of an example of the driving time and driving method in one line driving of the present invention, and FIG. A circuit diagram of one embodiment, FIG. 6 is a timing chart showing the operation of the circuit in FIG. 5, and FIG. 7 is a timing chart showing the operation of the circuit in FIG.
A timing chart to explain the operation of the circuit shown in the figure,
FIG. 8 is a circuit diagram of another embodiment of the present invention, and FIG. 9 is a timing chart showing the operation of the circuit of FIG. T: Print processing time 1, , 12.13; Time slot tm + maximum drive time Patent applicant Oki Electric Industry Co., Ltd. Patent application agent Megumi Yamamoto -

Claims (1)

[Claims] In a method of driving a line thermal head in which a plurality of heating elements are arranged in a straight line and prints every dot line, 1
The maximum driving time of each heating element in line printing is divided into a plurality of time slots, and the current of each divided time slot is turned on or off depending on the driving state of the adjacent heating element for each heating element. A method of driving a line thermal head characterized by the following.