KR950005570Y1 - Thermal resistance gap treatment circuit in tph - Google Patents

Abstract

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Description

TPH thermal resistance error compensation circuit

1 is a TPH driving circuit diagram of a conventional color printer.

2A and 2B are characteristic diagrams of thermal resistance error.

4 is a thermal resistance error compensation circuit diagram of the TPH of the present invention.

5 is a detailed circuit diagram of FIG.

Fig. 6A to 6C and Fig. 5 each sub waveform diagram.

7 is a relationship between the TPH resistance error and the energization correction time in FIG.

* Explanation of symbols for main parts of the drawings

1: Data input part 2: TPH

3: TPH heating part 10: reference wave generating part

11 comparison unit 12 resistance detection unit

The present invention relates to the compensation of the thermal resistance error of the TPH (Thermal Printer Head), in particular, to compensate for the difference in calorific value due to the non-uniform thermal resistance value generated in the thermal printer and the color printer using the TPH. It relates to a thermal resistance error compensation circuit of TPH that is suitable.

1 is a configuration diagram of a TPH driver of a conventional color printer which is generally used. As shown therein, a data input unit 1 for inputting image data of a line to be printed, thermal resistance arrays R1-Rn, and a thermal resistance A TPH heat generating section (3) for melting and printing ribbons by heat in accordance with the image data, and the image data latched in the data history section (1). And a TPH driver 2 for outputting according to and conducting the resistors R1-Rn of the TPH heat generating unit 3.

Referring to the operation and problems with respect to the conventional circuit configured as described above in detail as follows.

First, the image data to be printed, that is, the data value of the portion with an image is "1", and the data value of the portion without an image is "0" and is applied to the data input unit 1 and stored in the internal register. After the input is completed, the strobe enable signal STB is applied to the strobe terminal of the TPH driver 2 during the heating time corresponding to one gradation.

The logic gate of the TPH driver 2 is enabled with the input signal while the strobe signal STB is present to conduct thermal resistances R1-Rn.

After the heat generation time (ton) is finished, it takes some cooling time and prepares for data input for taking the next gray level.

At this time, if a pixel is n gradation, it should be energized n times, and the above process is repeated by the maximum number of gradations.

However, in the above-described method, as shown in FIGS. 2 and 3, the resistance value (thermal low phase) of the TPH is unevenly distributed as shown in FIG. 2A, and here, as in the conventional apparatus of FIG. In the case of constant current regardless of the resistance value, the calorific value also appears unevenly as shown in FIG. 2b. In addition, as the number of gray scales increases, this error accumulates and increases.

On the other hand, Figure 3 shows a method of processing by software in order to compensate for the above error. In this case, since the distribution resistance value of TPH is different for each set, the distribution resistance value of TPH is measured for each set, and the resistance error It is difficult and cumbersome to obtain a table of the energization correction time DELTA ti that corresponds to the value DELTA Ri and store it in the memory (FIG. 3A).

In addition, taking the actual Kth pixel as an example, the current correction time Δtk is obtained from the table, and after several steps of calculation, it is finally corrected by the number of gradations, that is, the number of energizations. The following number of gray scales, i.e., the energization time between 0 and ton has a disadvantage of remaining as an error even when corrected.

Accordingly, the present invention is designed to detect the tph resistance value in consideration of the deficiencies of the conventional method as described above and to automatically adjust the energization time accordingly to obtain a constant amount of heat regardless of the resistance distribution. Same as

4 is a block diagram of the TPH driving unit according to the present invention, as shown therein, a reference wave generator 10 generating a reference wave while outputting a strobe signal STB, which is an output command signal, and outputting it to the next stage; By comparing the output voltages of the reference wave generator 10 and the resistance detector 12 with the resistance detector 12 that detects, converts, amplifies, and outputs a resistance error of each TPH, the TPH driving gate is checked. The comparator 11 includes a comparator 11 for enabling the signal.

Referring to the operation and effect of the circuit of the present invention configured as described above in detail as follows.

First, the basic operation is to adjust the TPH conduction time according to the resistance error as described above to make the amount of heat generated from TPH constant regardless of the distribution of the resistance error. The resistance error (ΔR) and the energization adjustment time (△ Derivation of the relationship with t) is as follows.

Since Q = P x T, that is, calories = power x time, if the average resistance value of TPH resistance error is O, Rav, this one-gradation energization time ton, the calorie value Q1, and the TPH applied voltage are V _H ,

In this case, when RTPH = Rav + ΔR, the energization time for Q2 to be Q1 is (ton + Δt),

On the other hand, from the formula (1) (2)

The equation is derived.

That is, the normal energization time should be proportional to the magnitude of the resistance error.

FIG. 5 is a detailed circuit diagram of FIG. 4 and shows the resistances R1 to Rn of the TPH heating unit 3 by applying the output of the reference wave generator 10 to the comparators CP10-CP12 as shown therein. And the outputs of the comparators CP10 to CP12 are inputted to the gates AD10 to AD12 of the TPH driver 2, and the output signals of the transistors Q1 to TPH are generated by the output signal. Qn) is configured to be controlled.

The detailed circuit of the present invention as described above is described in detail with the waveform diagram of FIG. 6 as follows.

First, when the strobe signal STB corresponding to about twice the ton signal is input while data is input, the reference wave generator 10 generates a voltage proportional to time, that is, a triangular wave, while the strobe signal STB is generated. When the resistance detector 12 operates to output an initial voltage to operate the comparators CP10 to CP12, the outputs of the gates AD10 to AD12 of the TPH driver 2 with data are made high to make the TPH resistor R1. -Rn) is energized.

In addition, the TPH resistance (R1~Rn) is energized when the voltage of the resistance detection unit (12) Vsi = A + B · △ R i - there is a (3), where △ R _i = R a _i -Rav R _i is It represents the first TPH resistance Rav is the average resistance R _i = a is detected when the voltage of the Rav and B is a proportional constant as a gain factor of the circuit.

On the other hand, the comparator CP10 to CP12 compares the triangular wave voltage with the output voltage of the resistance detector 21 (FIG. 6B). Vt If V _si , the outputs of the comparators CP10 to CP12 become high and are applied to the AND gates AD10 to AD12, and the outputs of the AND gates AD10 to AD12 also become high to turn off the N-MOS transistors Q10 to Qn. It keeps on and keeps TPH resistance (R1-Rn) energized.

However, if Vt If V _si , the output of the comparators CP10 to CP12 goes low, and accordingly, the output of the AND gates AD10 to AD12 falls low, thereby turning off the TPH resistors R1 to Rn to complete the current of one gradation. (Fig. 6C) The operation shows a characteristic in which the TPH energization correction time is proportional to the tPH resistance (R1-Rn) error.

On the other hand, this relationship will be described in detail.

That is, in FIG. 7, when t = t1, the voltage of the triangular plate vt and the voltage V _si of the resistance detector 12 coincide.

Vt (ti) = C. ti = C. (ton + △ t) ―― (4)

V _si = B + A. ΔRi — (5).

But when Ri = Rav, t = ton, so vt (ton) = C. ton = B and accordingly B / C = ton- (6).

Δt = ΔR / C- (7) can be obtained by combining equations (4), (5) and (6), and comparing this equation (7) with equation (3) A / C = ton / Rav and B / C = ton can be used to realize a circuit having a desired function.

As described above, the present invention detects an error of the TPH resistance and variably performs the TPH energization time, that is, the time of correction of the heating time, in proportion to this, thereby making it possible to obtain a substantially constant heating value irrespective of the error of the TPH resistance.

Claims (1)

The reference wave generator 10 generates a reference wave while outputting the strobe signal STB, which is an output command signal, and outputs the signal to the next stage. And a comparison unit (11) for enabling the TPH driving gate by comparing the output voltages of the reference wave generation unit (10) and the resistance detection unit (12). Resistance error compensation circuit.