JPH05208515A - Thermal head control device - Google Patents

Abstract

PURPOSE:To reduce the deviation of positions of respective data by dividing the printing time of thermal heads in which heat-generating sections to be generated by respective power sources of phase A and phase B are disposed on a straight line into one unit time, and printing respective data of phase A and phase B alternately in one line time. CONSTITUTION:In a thermal head, a data input line and a clock signal line and connected with a shift resistor 2, a latch signal line is connected with a latch 3, and a strobo signal line is connected with a driver 4 respectively, and the control for generating which of heat generating sections of a heat generating resister 1 is decided by means of a shift resistor 2 and a switch 7. In controlling the thermal head, printing time is divided into unit time for every T/2n hour (n is an integer of 2 or more). In the case printing on one line or more is performed, printing data of the line is divided into phase A and phase B data and retained thereon, and printing of phase A and phase B data is repeated alternately in N times to complete the printing of the line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head controller for controlling a thermal head.

[0002]

2. Description of the Related Art FIG. 2 is a connection diagram for explaining the operation of a thermal head. In the figure, 1 is a heating resistor, 2 is a shift register, 3 is a latch, 4 is a driver, 5 is a power supply, and 7 is a power supply.
Is a changeover switch, 70, 71, 72 are contacts of the switch 7, 8-1, 8-2, ... Are diodes for backflow prevention, 9-1, 9-2 ,. Patterns 10-1, 10-2, ... Show grounding side wiring patterns, respectively.

The shift register 2 has a data input line and a clock signal line, and the latch 3 has a load signal (latch signal).
2 and strobe signal lines are connected to the driver 4, respectively, but these control lines are omitted in FIG. Control of which heating section of the heating resistor generates heat is determined by the shift register 2 and the switch 7. For example, the shift register 2 is controlled via the latch 3 so that only D1 of the driver 4 is turned on, and the contacts 70 and 7
When 1 is connected, the current flows through the diode 8-1 and the power supply side wiring pattern 9-1 by the power supply from the power source 5, passes through the heat generation section R1, and the ground side wiring pattern 10-1.
It flows to the driver D1 and the heat generating section R1 generates heat. Also,
If the contacts 70 and 72 are connected while the D1 is in the ON state, the heat generating section R2 generates heat. The power supply connected to the contact 71 is tentatively called the A-phase power supply, and the power supply connected to the contact 72 is tentatively called the B-phase power supply.
The phase data and the data printed by the B-phase power supply will be temporarily referred to as B-phase data.

FIG. 3 is an operation time chart showing the conventional control. Reference numeral 31 shows the data in the shift register 2 and A
1, B1 are A phase data and B phase data on the same line, A
2 is A phase data one line after A1. Further, the data is steady in the section where the upper and lower two lines are parallel, and the data is updated while the two lines cross. A latch signal 32 is given to the latch 3, and the data of the shift register 2 at the time of this signal is latched by the latch 3. Reference numeral 33 is a strobe signal, and a current flows through the driver 4 at a position where the output of the latch 3 is "H" while the strobe signal is "H".

Since the paper feed is continuously performed even during the operation period shown in FIG. 3, the A-phase data in which printing is started at the time t1 and the B-phase data in which printing is started at the time t2 are accurate. In other words, the position in the X direction is different. However, when the time for printing one line, that is, the time for one line indicated by T in FIG. 3 does not exceed the predetermined limit, the paper feed is stopped within the time T, and the dot printed within the time T is Y.
It can be approximately regarded that they are arranged on one line parallel to the direction. 1 line time T is the paper feed speed,
It is determined by the design of how many lines are printed during the unit distance in the paper feed direction, and T cannot be made too small.

[0006]

However, the conventional thermal head control device as described above has a problem in that the printing unevenness due to the print position shift and the heat accumulated in the thermal head cannot be ignored. That is, since the 1-line time T cannot be made too small from the viewpoint of design, the conventional device has a problem as shown in FIG. For example, R in FIG.
When the four heating zones of 1, R2, R3 and R4 are made to generate heat and four dots are arranged on one line, the A phase data R1 and R3 are printed before the B phase data R2 and R4. However, since R2 and R4 are adjacent to each other, they are affected by the residual heat from R1 and R3, which had generated heat a short time ago, and the print dots become larger than those of R1 and R3 that are not affected by such heat. The print result is as shown in FIG.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a thermal head control device capable of reducing print position deviation and reducing the influence of heat accumulation.

[0008]

A thermal head controller according to the present invention divides a printing time T into unit times of T / 2n and prints A-phase data within the first unit time.
The B-phase data is printed within the next unit time, and the A-phase data is printed again within the next unit time, thus alternating the A-phase data and the B-phase data within one line time. Then, the printing of the line was completed by repeating n times. The case of n = 1 corresponds to the conventional device, and in the present invention, n
Is an integer of 2 or more, the time delay between the printing of the A-phase data and the printing of the B-phase data is shortened to 1 / n.
By alternately and repeatedly printing the phase data and the B phase data, the influence of the residual heat can be made uniform.

[0009]

【Example】

Example 1. FIG. 1 is an operation time chart showing an embodiment of the present invention. In the figure, 11 is data corresponding to 31 in FIG. 3, 12 is a latch signal, and 13 is a strobe signal. In the embodiment shown in FIG. 1, T / 2n
Represents the case of n = 2. That is, the A-phase data A1 and the B-phase data B1 on the same line are alternately printed and the same data is repeatedly printed twice. If the one-line time T is the same in the comparison between FIG. 1 and FIG.
3-t4 time delay is 1 of t1-t2 time delay of FIG.
It can be set to / 2, and the distance difference in the X direction between the printing of the A-phase data and the printing of the B-phase data on the same line can be halved.

Further, in FIG. 3, the data of A1 is B1.
However, in FIG. 1, since the data of A1 is printed after the data of B1, in the case of FIG. 1, the data of A1 is also affected by the same residual heat and can be made uniform. Although the embodiment shown in FIG. 1 is for n = 2, the above-mentioned effects can be improved as the value of n increases such that n = 3, n = 4 ,. However, as the value of n becomes larger, the unit time of T / 2n becomes shorter, but it is necessary to have a margin for data update within this unit time.

Embodiment 2. In the alternate multiple printing stage as shown in FIG. 1, the print density may change due to the heat accumulated in the thermal head. Therefore, in such a case, an apparatus that performs heat storage correction by considering the print history or the temperature of the thermal head may be used. FIG. 5 is an explanatory diagram showing an example of such heat storage correction. FIG. 5A is a diagram showing a control state when the A-phase data and the B-phase data are alternately printed with the heating time required for normal printing as t5 and the number of repetitions n = 3. .. When printing is continuously performed under the control as shown in FIG. 5A, heat may be accumulated in the thermal head, the temperature of the thermal head may rise, and the print density may become dark. In such a case, an appropriate print density can be obtained by detecting the temperature of the thermal head with a temperature detecting means such as a thermistor (not shown) and varying the heating time according to the detected temperature. .. In FIG. 5B, the heating time is t5.
It is a figure which shows the mode of control when it shortens from to t6.
By appropriately increasing or decreasing the heating time in this way, the effect of heat storage can be canceled out, and proper printing can be obtained even when the temperature of the thermal head rises. In this correction, the temperature of the thermal head or the heating time of several types of thermal heads should be stored in a storage means such as a ROM so that they can be selected according to the output level of the temperature detection means such as a thermistor. Good.

[0012]

As described above, the thermal head control device of the present invention can reduce the positional deviation between the A-phase data and the B-phase data on the same line, and uniformize the effect of heat storage.
Moreover, there is an effect that the correction can be easily performed.

[Brief description of drawings]

FIG. 1 is an operation time chart showing a first embodiment of the present invention.

FIG. 2 is a connection diagram for explaining the operation of the thermal head.

FIG. 3 is an operation time chart showing conventional control.

FIG. 4 is an explanatory diagram showing a problem of conventional control.

FIG. 5 is an explanatory diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 1 Heating Resistor 2 Shift Register 3 Latch 4 Driver 11 Data 12 Latch Signal 13 Strobe Signal A1 A Phase Data B1 B Phase Data

Claims (2)

[Claims] 1. A heat-generating section for generating heat from an A-phase power source and B
Using a thermal head in which the heat-generating sections heated by the phase power supply are arranged in a straight line, printing is performed line by line with a predetermined print time T on the recording paper transported in the direction perpendicular to the arrangement direction of the heat-generating sections. A thermal head control device for controlling the thermal head so as to sequentially create image patterns, a unit for dividing the printing time T into unit time every T / 2n (where n is an integer of 2 or more) time; A means for distinguishing and holding the print data of the line into the A-phase data to be printed by the A-phase power supply and the B-phase data to be printed by the B-phase power supply in performing the printing on the line. The A phase data is printed within the first unit time, the B phase data is printed within the next unit time, and the A phase data is printed again within the next unit time. phase The thermal head control apparatus characterized by comprising means to complete the printing of the line is repeated n times and over data alternately. 2. The thermal head control device according to claim 1, wherein printing with an appropriate density is obtained in consideration of the printing history of the thermal head or the temperature of the thermal head.
A thermal head control device comprising means for changing the heating time in the unit time.