JP2730473B2 - Driving device for thermal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-impact type printer, and more particularly to a thermal head drive for printing by applying thermal energy.

[0002]

2. Description of the Related Art Conventionally, in order to apply energy to heating elements arranged in a row, a wiring is extended from both ends of a thermal head and energy is supplied to each heating element. Color development tends to be light. In order to prevent this, sufficient energy was supplied to obtain the saturated density in the entire area of the heating element, and at the same time, the printing cycle was extended so that the printing on the current line was not affected by the printing on the previous line. . Further, in order to reduce the wiring resistance so as not to be affected by the wiring resistance, a wide wiring pattern is used, or a wiring material such as gold having a low resistance value is used.

A thermal head driving apparatus of this type has a plurality of heating resistors as described in Japanese Patent Application Laid-Open No. 3-82564, for example, and is configured to supply current to the heating resistors. Some of them enable printing. Further, as described in JP-A-3-121864, for example, the voltage of a driving pulse is controlled inside the thermal head according to the resistance value of the heating resistor in the thermal head and the temperature of the thermal head, and at the same time, the voltage is controlled externally. In some cases, the pulse width of the driving pulse is controlled according to other factors.

[0004]

In the conventional method, the thermal head becomes large in order to obtain a wide pattern, the production cost becomes high due to the use of a material having a low resistance value, and the saturation density of the medium is merely obtained. There is a problem in that the printing cycle must be long in order to supply energy, so that the printing speed is reduced. The present invention has been made in order to solve such a problem, and it is possible to reduce the size and the material cost by narrowing the pattern of the power supply wiring of the thermal head, or to shorten the printing cycle by eliminating waste of printing energy. It is an object of the present invention to obtain a driving device for a thermal head.

[0005]

According to the present invention, there is provided a driving apparatus for a thermal head, wherein the latch signal is inputted, and
Print position monitoring circuit that monitors which of the heating elements generated heat
Path and the monitoring result of this print position monitoring circuit,
Change the strobe data shift time for each heating element and print
Strobe data shift time change circuit that changes the cycle
And the printing cycle based on the monitoring result of the printing position monitoring circuit.
The first level from the beginning of the period to the specified number of print dots
Strobe data is output, and then the second level
Output strobe data
Path and strobe data shift time
A strobe data system that generates a lobe data shift signal
Shift signal generation circuit and the input first level switch.
Stores and retains the trobe data and
Output, and the above strobe data shift signal is input.
The first level stored in the memory
After shifting the lobe data sequentially,
And a strobe data shift register for outputting the data .

Therefore, in the present invention, the above-mentioned
The output signal of the strobe data shift register
And the print data latched by the latch circuit.
The heating element is energized according to
Is configured to do so.

With such a configuration, the present invention
Adjust the energy supplied according to the heating element
And the print density can be made uniform.

[0008]

According to the present invention, the printing density at the central portion is prevented from becoming lower than at both ends. In addition, the difference in coloring property between the printing portions of the thermal head is made uniform by adjusting the applied energy supplied to the heating element. Further, it is checked which heating element of the thermal head is turned on, and the energy application time is changed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a thermal head driving device according to the present invention. In FIG. 1, reference numeral 1 denotes a heating element of a thermal head, 2 denotes a driver for driving the heating element 1, 5 denotes a shift register for inputting print data d and a clock e, and 4 denotes an output of the shift register 5. The latch circuit 4 is configured so that a latch signal c is input and an output is supplied to the driver 2.

Reference numeral 6 denotes a strobe data generation circuit for generating strobe data a for determining the time for supplying a current to a dot to be printed and a heating element. Reference numeral 7 denotes a strobe data shift signal generation circuit for generating a strobe data shift signal b. The strobe data shift signal b from the strobe data shift signal generation circuit 7 and the strobe data a from the strobe data generation circuit 6 are input to the strobe data shift register 3, and the output of the strobe data shift register 3 is supplied to the driver 2. It is configured to:

Reference numeral 8 denotes a print position monitoring circuit for monitoring the print position by inputting the latch signal c, and constitutes a check means for checking which heating element of the thermal head is ON. Reference numeral 9 denotes a strobe data shift time changing circuit which changes the strobe data shift time by using the output of the print position monitoring circuit 8 and the output of the strobe data shift signal generating circuit 7 as input, and constitutes changing means for changing the energy application time. ing.

[0012] Then, the strobe data shift register 3 and Sutorobude capacitor onset production circuit 6 and the strobe data shift signal generating circuit 7 as well as the printing position monitoring circuit 8 and the strobe data shift time changing circuit 9, direct thermal printing and thermal transfer printing, etc. In a printing method that uses a thermal head, a drive unit that prevents the potential drop at the center of the printing element row from increasing due to the influence of wiring as the printing width increases and prevents the printing density at the center from becoming lower than at both ends doing. This driving means checks which heating element of the thermal head is turned on, and supplies a difference in the color development inside one thermal head caused by a structural influence such as wiring resistance of the thermal head to supply energy. It is configured to equalize by changing the amount.

FIG. 2 is a partial view showing a configuration example of the driver peripheral circuit in FIG. 2, the same reference numerals as those in FIG. 1 denote corresponding parts, and the print data in the latch circuit 4 is print data sent from the shift register 5 in FIG.

Next, a printing procedure which is an operation of the embodiment shown in FIG. 1 will be described. First, print data d is input to the shift register 5. After the data input for one line is completed, the print data d is transferred to the latch circuit 4 by the latch signal c. Next, input of strobe data a for determining a dot to be printed and a time for supplying a current to the heating element will be described. Here, as shown in FIG. 2, the printing is performed is determined whether the current to the heating element by the relation of the print data d and strobe data a, where effective towards both is (hereinafter, the effective time " H ", and the invalid time is referred to as" L ").

The strobe data "a" is composed of "H" and "L" signals smaller than the maximum number of simultaneously printable dots of the thermal head.
The number of “H” dots is appropriately determined according to the performance of the thermal head and printing conditions. Here, the number of simultaneously printable dots is 128, and the number of dots of the thermal head is 102.
It is assumed that four dots and each data is inputted from the dot “1” of the thermal head. First, “H” strobe data “a” is input from the strobe data generation circuit 6 to the strobe data shift register 3. Here, the initial value of each data of the strobe data shift register 3 is “L”. As a result, the print data of the dot “1” becomes “H”.
In the case of, the dot "1" is energized and printed.

After a predetermined time, a strobe data shift signal b is generated from the strobe data signal generation circuit 7, and the strobe data a is shifted to the next dot.
At the same time, new data is output from the strobe data generation circuit 6. The strobe data a output from the strobe data generation circuit 6 outputs "H" for a predetermined 128 dots from the beginning of the printing cycle, and thereafter outputs "L". Strobe data generation circuit 6 to 1
When the "H" data for 28 dots is output, as described above, the strobe data a for the next dot "1" becomes "L", and the energization of the dot "1" ends.

Furthermore, the number of dots 102 of the thermal head
Strobe data a for 4 dots is output, and dot 1
When the energization of 024 is completed, printing of one line is completed, and the operation moves to the printing cycle of the next line and the above operation is repeated.
The strobe data a is shifted during the printing cycle to energize each heating element, and the time to shift to the next dot is changed depending on the energized position to make printing uniform.

In this embodiment, assuming that the central portion of the thermal head has lower color development than the both ends, the "H" of the strobe data "a" is obtained from the information of the print position monitoring circuit 8.
As the data position approaches the center, the strobe data shift time change circuit 9 causes the strobe data shift signal generation circuit 7 to delay the generation cycle of the strobe data a by a time determined in advance according to the printing position. Furthermore, the shift time is shortened as the dot passes through the center and approaches the dot 1024.

[0019]

As described above, according to the present invention, the difference in the coloring properties of the printing portion of the thermal head is made uniform by adjusting the energy supplied to the coloring member, so that the power supply wiring of the thermal head is provided. This has the effect of enabling downsizing of the pattern by narrowing the pattern, reduction of material cost, and shortening of the printing cycle by eliminating waste of applied energy. Further, as the printing width increases, the potential drop at the center of the printing element array increases due to the influence of the wiring, and the printing density at the center can be prevented from becoming lower than at both ends.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a thermal head driving device according to the present invention.

FIG. 2 is a partial view showing a configuration example of a driver peripheral circuit in FIG. 1;

[Explanation of symbols]

 3 strobe data shift register 6 strobe data generation circuit 7 strobe data shift signal generation circuit 8 print position monitoring circuit 9 strobe data shift time change circuit

Claims (1)

(57) [Claims] 1. Heat generation of a plurality of dots arranged in a line
Body, driver for energizing each heating element, and one line
A shift register for storing print data of a plurality of dots of
The shift register according to an arbitrarily input latch signal.
Of multiple dots for one line, which is output from the data
A latch circuit for latching data.
A printer that prints by generating heat one dot at a time.
In the driving device for a thermal head, the latch signal is input and any one of the plurality of heating elements is turned on.
A print position monitoring circuit for monitoring whether or not the heating element is generated; and based on a monitoring result of the print position monitoring circuit, the heating element
Change the strobe data shift time for each
A variable strobe data shift time changing circuit, and a print cycle monitor based on the monitoring result of the print position monitoring circuit.
From the beginning until the specified number of print dots, the first level
Strobe data is output, and then the second-level strobe data is output.
Strobe data generation circuit that outputs trobe data
And a strobe based on the strobe data shift time.
Strobe data shift signal to generate data shift signal
Signal generating circuit, and stores the input first-level strobe data.
Hold and output to the driver, and
When the trobe data shift signal is input, the memory
The stored first-level strobe data is sequentially sequenced.
Strobe output to the driver after shifting
A data shift register, wherein the driver is the strobe data shift register.
Output signal and printing latched by the latch circuit
The heating element is energized according to the data and the print data
A driving device for a thermal head, wherein the printing is performed .