JPH02153756A - Line thermal head driving apparatus - Google Patents

Abstract

PURPOSE:To obtain a drive apparatus capable of more uniformizing the temp. characteristics of a line thermal head by controlling a voltage applying time corresponding to the data of the dot before one line of a dot to be printed and the data of the dots on both sides thereof. CONSTITUTION:When preheating data and printing data are prepared, the data of the line concerned to be recorded being 8-bit or 16-bit data is latched from a CPU 11 by a latch 10 and data from the CPU to be printed at the same position before one line is latched by a latch 9 and the respective latched data are transferred to a NAND gate 7 one at a time by shift registers 8. The data of the dots on the left and right sides of the latched dot concerned and the data of the dot before one line outputted from the shift register 8 are transferred to a NAND gate 3 to take NAND and transferred to an AND gate 6 to take AND along with the data of the dot concerned to prepare preheating data to perform temp. control. Since preheating data is prepared from the state of the data on the left and right sides of the dot concerned to be recorded and the data before one line to control voltage applying time, the temp. characteristics of a line thermal head can be made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal head driving device or temperature control device used in a thermal recording type device.

[Prior Art] Conventionally, in this type of thermal recording type device or heat-melting ink ribbon recording type device, such as a line type thermal printer, facsimile machine, barcode printer, etc., as is well known, a plurality of Using a thermal head equipped with recording electrodes made up of dot-shaped heating elements, a pulse voltage corresponding to an image signal is applied to each electrode to generate heat, and recording is performed on thermal recording paper placed in contact with the generated heat. Alternatively, the printer is configured to transfer and record heat-melting ink from a thermal transfer ink ribbon onto printing paper. Since the thermal response characteristics of the heating element are about several m8 for both rise and fall, image data is usually transferred to a shift register, latched in a latch circuit, temporarily stored, and then transferred in parallel to several hundred recording electrodes. Usually, a method is used in which a current is applied to the

According to the method described above, as the printing speed increases, the recording time for a line is extremely short, and due to the heat capacity of each heating element, continuous dots are shorter than independent dots. , the temperature is not completely cooled by the time of recording the next line, and the heat of the previous line is accumulated, and the temperature rises when recording the next line, and the chemical change in the heat-sensitive layer of the heat-sensitive recording paper is accelerated more than expected, or The disadvantage is that the thermal transfer ink and the ink in the ribbon melt too much, resulting in an increase in the density of the recorded dots and a scattering of dot sizes.

In order to compensate for these drawbacks, conventional thermal printers monitor the print data of one line before the previous line, and if there is print data before the -line, control is performed to reduce the pulse voltage application time. ζ was used to control the temperature of the thermal head.

[Problems to be Solved by the Invention] However, in the conventional method as described above, when printing is performed in one row or two rows in the vertical direction (column),
In addition to controlling the temperature by reducing the application time, the dots adjacent to the dot to be recorded do not generate heat, so the heat of the dot is diffused and the temperature rise is low. For this reason, in cases such as barcode printing in which K-rows or two rows in the vertical direction (columns) as shown in FIG. There have been problems in that the ink of the thermal transfer ink is not well melted and the density of the recorded dots becomes thinner or the size of the dots is reduced.

The present invention focuses on the problems of the conventional examples as described above.
The purpose of this invention is to provide a drive device that can make the temperature characteristics of a line-type thermal head more uniform using a simple logic circuit.

[Means for Solving the Problem] Therefore, in the present invention, the voltage application time is determined according to the data of the dot one line before the dot to be printed and the data of the dots on both sides of the dot. The drive device is configured with a logic circuit for control.

[Examples] The present invention will be described below based on Examples. Figure 1 shows
This is a diagram showing a timing chart of each signal for explaining the operating principle of the present invention, where D indicates a data string for a line to be transferred to a line type thermal head, and Dl in the first half indicates the left and right dots of the dot to be recorded. and shows the preheating data sequence depending on the presence or absence of dots in the previous line, and the latter half D2 is
The print data string of the said dot is shown. L indicates a trigger signal that causes the latch circuit to latch the preheating data and print data sent to the shift register. The preheating data of Dl latched by L is outputted to the heating element by the voltage application signal shown at 81 in the first half of the time chart of S. 'In the present invention, when all the dots on the left and right of the dot concerned and the dot one line before are printed, the preheating data of the dot concerned is data without preheating.

For other data, the preheating data is data with preheating. After the preheating data is output, print data is output to the heating element by the voltage application signal in S2. By repeating this process, each line is printed.

FIG. 2 shows a block diagram of a logic circuit diagram for creating the preheating data and printing data. 1 is a CPU 2 is a resistance heating element of each recording electrode, 6 is each NAND gate, 4 is a latching circuit, 5 is a shift register, 6 is an AND gate, 7
NAND gate 8 is two shift registers, 9 is a latching circuit for latching the print data of the previous line, and 10 is for latching the line to be recorded 7? A latching circuit is shown. The data of the line to be recorded in 10 with 8-bit or 16-bit data from the OPU is also recorded in 9.
- Latch the data to be printed at the same position before the line. Each latched data is transferred one bit at a time to seven NAND gates by eight shift registers.

At this time, the data of the said dot is latched by an external 2-bit shift register 11 as the dot data to be printed on either the left or right side and the said dot data. Then, NAND the data of the latched dots on the left and right of the dot concerned and the data of the dot one line before outputted from the shift register, and then AND with the data of the dot concerned to create preheating data and calculate the temperature. The feature is that it is controlled.

Print data can be created using the same circuit and procedure as above by setting all the data to be latched to 10 as data with printing. By doing this, the left and right and left and right sides of the dot to be recorded can be created. Since preheating data is created based on the state of data from the previous line and the voltage application timing is controlled according to the preheating data, the temperature characteristics of the line type thermal head can be made more uniform. All of these circuit configurations are used to realize the above operation.

Since this is performed using a known technique, detailed explanation will be omitted.

In this embodiment, when the voltage application time is controlled using the preheating data, the applied voltage level may be controlled instead of the application time control.

[Effects of the Invention] As explained above, according to the present invention, the drive of the thermal head is controlled using the dots to the left and right of the dot to be printed and the dot one line before by a simple circuit. Therefore, compared to the conventional example, the temperature characteristics of the thermal head can be made more even, and the density and dot size of the output print can be made more uniform.

[Brief explanation of the drawing]

Figure 1 is a timing chart of each signal, Figure 2 is
The circuit diagrams of the present invention shown in Fig. 1 and Fig. 6 are shown in the vertical direction (column) K.
- It is an explanatory view showing a print density change trend in a conventional example in barcode printing in which a row or two rows are printed.

Claims (1)

[Claims] In a thermal recording system that uses a line-type thermal head equipped with a recording electrode made up of a plurality of heating resistor elements in one line, and performs printing by applying a voltage to the electrode, the dots to be recorded are Each preheating data is created by a logic circuit based on the print data of one line before the print data and the print data on the left and right of the dot concerned, and the voltage application time is controlled in accordance with the preheating data at the dot concerned. A line type thermal head drive device characterized by: