JPH037353A - Thermal head and video printer - Google Patents

Abstract

PURPOSE:To improve printing quality by storing a value regarding the resistance values of a plurality of dotlike heat generating resistors provided in a thermal head in a read-only memory even if the resistance values of the resistors provided in a thermal head are irregular, and regulating power energizing periods of the resistors based on the stored contents. CONSTITUTION:Signals A-C from a read-only memory 3, an image input data generator 6 and a correction data setter 8 are applied to a calculator 9. Data A of the memory 3 is multiplied by correction data B from the setter 8 by a multiplier 10, its output is applied to an adder 12 or a subtractor 13 through a changeover switch 11, further guided as gradation data D through a changeover switch 14, and applied to a gradation processor 15. The processor 15 sets power energizing periods of the resistors corresponding to the data D. Thus, irregular density can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of Application The present invention is used as an image printer! 3 thermal paper
The present invention relates to a thermal head device and a video printer for printing images.

BACKGROUND ART Such a thermal head device includes a thermal head configured by a plurality of dot-shaped heating resistors arranged in one line, and the dot-shaped heating resistors of the thermal head are arranged in the direction in which they are arranged. Thermal paper is conveyed in a direction perpendicular to the paper, and images are printed on the thermal paper.

In the prior art, the resistance value of a large number of heat generating resistors included in a thermal head is suppressed during the manufacturing process or manufactured so that the resistance value is almost constant to the extent that density unevenness during printing is not noticeable. Print on thermal paper using the printed thermal head with power (=f) to check the limit of density unevenness, and check that the resistance value of each heating resistor is within the allowable value where density unevenness is not a problem. Selected thermal heads are used.

Problems to be Solved by the Invention In such prior art, manufacturing must be performed accurately, resulting in poor productivity and poor manufacturing yield, resulting in an increase in the number of thermal heads per unit. , and such density unevenness is unacceptable! If you use a thermal head that falls within this value, the density unevenness will be further reduced. The object of the present invention is to improve productivity, improve manufacturing yield, and therefore to be realized at low cost, suppress density unevenness, and improve printing quality. It is an object of the present invention to provide a thermal head device and a video printer that can perform

J) Means for Solving the Problems The present invention provides a thermal l bed constructed by arranging a plurality of dot-shaped heating resistors in one line, and a value related to the resistance value of eight heating resistors for each heating resistor ( This thermal head device is characterized in that it includes a read-only memory having λ1-a for each a.

The present invention also includes a thermal head equipped with correction information for each resistance value of a plurality of dot-shaped heating elements, and a density correction circuit that sets a density correction amount according to the correction information and image information to be printed. With a video printer featuring the inclusion of +?
).

For example, regarding the thermal head's 8. heat resistor, values related to the resistance value of each heat generating resistor are stored in the read-only memory. By reading the stored contents and adjusting the power 1 standby time etc. of each heating resistor, you can check whether the resistance value of each heating resistor is thick, -), and the iM degree at the time of printing. It becomes possible to suppress unevenness. As a result, productivity is improved, and it is possible to reduce the number of v-rolls in manufacturing, thereby making it possible to realize cheaper alcoholic beverages and to improve the quality of printing.

Read-only memory (abbreviated as ROM) is the so-called E
P (EraServe Pro Bramable)
ROM and EEP (Electrical
Eraqert+le Progranable) R
It may be an OM or the like, and its stored contents are non-volatile.

Embodiment FIG. 1 shows a block diagram of one embodiment of the present invention. The thermal vent device 1 includes a thermal head 2 configured by a plurality of dot-shaped heating resistors arranged in a straight line, and a read-only memory 3. Thermal paper is conveyed perpendicularly (horizontal direction in Fig. 1) to the arrangement direction in which the heating resistors of the thermal head 2 are arranged in a line (1st I21g) vertical direction). Yo-
Printing is done at No.

The analog recall signal to be printed is i! It is applied to the analog/'digital conversion circuit n5 of the low call signal generation circuit 4 and converted into digital 1 (drying), and the image data (is applied to the electric input data generation port n6 for gradation printing). I was hit,
It is converted into a signal representing the gradation in proportion to the brightness.

The image input data of each Don't town obtained in this way is provided to the resistance value 7/density correction circuit 7. This image input data is indicated by 9 reference numeral C, and for convenience, the same reference numeral will represent the signal line. The image input data C is applied to a correction data setting circuit 8, whereby correction data B corresponding to the image input data C is obtained as shown in FIG.

The read-only memory 3 stores the variation rates AI and A corresponding to the plurality of 'PP heating resistors of the thermal head 2.
Data representing 2 is stored.

Here, the variation rate A1 of the first heating resistor placed at the end of one line of the thermal head 2 is as follows:
Define as in the first equation.

AI = + (R1-R,v,)/R,,,lX
100-(1) R1 is the resistance value of the first heating resistor, and R6vg is the average value found from the second equation.

Here, n is an integer and is the total number of dots in the heating resistor of the thermal head 2. The resistance value R4 of each heating resistor is determined by actual measurement, and the value R4 is calculated according to the second formula.
Find aV@.

Corresponding to the calculated variation rate A1, the data is stored in the read-only memory in a sort of ranked manner as integer data as shown by data 0 to 15 shown in Table 1.

In addition, this read-only memory 3 contains the variation rate A2 of the second heating resistor adjacent to the first heating resistor described above and the heating resistor following it by a third formula. As shown in the data 0 to 15 from the second person, corresponding to the variation rate A2, the data is stored as integer data in ranks, so to speak.

A2=+(R,-RJ,l)/R,,,l 〆100...(3) Thus, the variation rate A1. shown by the first and third equations. ．． Data from the memory 3 representing A2 will be represented by reference marks All and A12, respectively, and these data will be collectively represented by reference mark A.

Corresponding to the WR image input data row given from the image input data generation circuit 6, the correction data setting circuit 8 sets the 212th
The correction data B shown by is created and the correction data B is derived.

From the second eye, case 3 indicates that the image input data C is bright.
Since the influence of the adjacent resistance value V) is small, the correction data B should be set small, and when the video signal is dark, the correction data B should be set to a large value when the influence of the adjacent resistance value V) is large. .

When data A from the read-only memory 3 is expressed as a 4-bit binary number, the highest bit is the dispersion rate At, which represents the positive or negative of A2, and the remaining The lower three bits are +l data of the absolute values of the dispersion rates Al, A, and 2. The highest bit is j eclipse II ' I
It is negative when J, Theory 11! ! ' When OJ, it represents positive.

Signals AB and C from the read-only memory 3, the image input data generation circuit 6, and the correction data setting circuit 8 are applied to the calculation circuit n9. The specific configuration of this arithmetic circuit 9 is shown in No. 3I2I. In FIG. 3, data A in the read-only memory 3 and correction data B from the correction data setting circuit 8 are applied to a multiplication circuit n10 to be multiplied, and the output is passed through a changeover switch 11 to an addition circuit 12 or a subtraction circuit. 13, and the changeover switch 1
4, it is derived as gradation data D, and the tlV tone data is output! 815. In the gradation processing circuit 15, a waiting time is set for each heating resistor J1 power 1' corresponding to the gradation data D. Instead of adjusting the waiting time, this power may be used to adjust the load current flowing through the heating resistor.

Switches 11 and 14 are interlocked so that the highest bit of the output from read-only memory 3 is logic "1" and +? ) when
When the switching state shown in FIG. 3 is reached and therefore the subtraction circuit 13 is used and its most significant bit is a logic "0", the switching state deafness switches;
An adder circuit 12 is used. Image input data from the image input data generation circuit 6 is supplied to the addition circuit 12 and the subtraction circuit 13. Note that in FIG. 3, the numbers written on each signal line represent the number of parallel bit lines.

Regarding the 111th heating resistor located at the end of one line in the thermal head 2, the correction data corresponding to the image input data C is set as B1, and the read-only memory 3
11
When a is given, calculate the gradation correction IGI as shown in the fourth equation. This 1st '#g) Heating resistor G) Rose'
) Prison A1 is t? as shown in Table 1. The dispersion rate A2 of the remaining heating resistor is ranked at 5% as shown in Table 2. Lower 3 bits A of store content All that represents the resistance value of the first heating resistor
11it is doubled to match the correction amount G2 for the second and subsequent heating resistors.

Gl = 2 ・A11a-Bl = 1
4) 1!1 tone data of this first heating resistor [)1
teeth.

The print input data for the first heating resistor is C.
When it is 1, it is shown by the fifth equation.

D1=CI Gl...(5
) The gradation correction amount related to the second #th heating resistor adjacent to the first heating resistor and the subsequent jth heating resistor is as shown in the sixth formula ( j ≧ 2)
.

Gj = Aj Bj ・
(6) Here, Aj is the lower 3 bits of the stored content A21 of the read-only memory 3 [. Flj is correction data corresponding to image input data C.

This j1#th gradation data [)j is Dj=Cj+ (a+-t)MoQj・
(7) Such IPJ ilQ data D1 and Dj are given to the gradation processing circuit 15 as the gradation data D of the arithmetic circuit 9, as described above.

Although the stored contents of the read-only memory 3 may be read out every time the electric power of each heating resistor is read out at the time of printing, the stored contents of the read-only memory 3 may be read out every time the power of each heating resistor is turned on. , the stored contents of the read-only memory 3 are stored in the resistance value 2/density correction circuit 7 only once.
Alternatively, the data may be transferred to and stored in a random access memory provided separately, and the above-mentioned calculation may be performed based on the contents stored in the random access memory.

In the above embodiment, the read-only memory 3 stores the values corresponding to the variation rates Al and A2 of each heating resistor, but as an embodiment of the present invention, the read-only memory 3 stores The resistance values of each heating resistor of 2 may be stored, or data representing the difference between each resistance value and a predetermined reference value may be stored. 8- Other values related to the resistance value of each heating resistor may be stored, and if the read-only memory 3 stores data that allows knowing each resistance value of each heating resistor. good.

Effects of the Invention As described above, according to the present invention, even if the resistance values of each of the plurality of dot-shaped heating resistors provided in the thermal head vary, the values related to the resistance values can be maintained. Since it is stored in read-only memory, the power of each heating resistor can be adjusted depending on the variation in its resistance value by adjusting the time measurement etc. based on the contents stored in this read-only memory. It is possible to reduce the undesirable density unevenness caused by this, and to improve the printing quality, and as a result, such a thermal head can be used for M4 even if the resistance value of the heating resistor varies widely. This makes production easier and improves productivity, and also! By improving the retention, it becomes possible to achieve cheaper sake.

[Brief explanation of the drawing]

FIG. 1 is a diagram of one embodiment of the present invention, and FIG. 2 is a graph showing the configuration of the correction data setting circuit 8. FIG. 3 is an electric circuit diagram showing the specific configuration of the arithmetic circuit 9. 1... Thermal head device, 2... Thermal head,
3... Read only memory, 4... Image signal generator, 5... Analog 7/digital conversion circuit, 6 - Image input data generation circuit, 7... Resistor 1ia, /Density correction circuit, 8... ...Correction data setting circuit, 9... Arithmetic circuit, 15... Gradation processing circuit

Claims (2)

[Claims] (1) Includes a thermal head made up of a plurality of dot-shaped heating resistors arranged in one line, and a read-only memory that stores values related to the resistance values of each heating resistor for each heating resistance value. A thermal head device characterized by: (2) It is characterized by including a thermal head equipped with correction information for each resistance value of a plurality of dot-shaped heating elements, and a density correction circuit that sets a density correction amount according to the correction information and image information to be printed. video printer.