JP2003341120A - Print controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a print controller performing print control of various print media accurately based on various control patterns each consisting of a power generation value and an integrated energy value. <P>SOLUTION: The print controller comprises a means for prestoring a plurality of target power generation values, a plurality of target driving time values or integrated heat generation energy values, a thermal head consisting of a collection of heaters each serving as a heating element and a temperature detecting element, a means for driving each heater to generate heat, a means for detecting instantaneous power generation of each heater, and a means for controlling the driving means to generate heat until one target power generation value is reached and performing control such that one target driving time or integrated energy generation value is reached when the target power generation value is reached while holding power generation of the heater at that power value and repeating that procedure for other target power generation value, target driving time or integrated heat generation energy value. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head printing for printing control of a printer apparatus for gradation-developing a medium according to the amount of heating energy, or for melting transfer or sublimation transfer of an intervening thermal transfer film. Regarding the control device.

[0002]

2. Description of the Related Art Conventionally, for example, in a thermal recording medium, a temperature of a fixed resistance heating element on a thermal head, which is generally called thermal history control, is estimated and calculated based on past print history information, and the thermal head is fixed on the thermal head. A general method is to control the amount of heat generated by the resistance element.

[0003]

In this conventional method, since the temperature change of the heating element in the thermal head cannot be measured and is estimated, the heat dissipation condition of the heat generated by the thermal head is limited in cold regions and tropical regions. Different and
Since the temperature on the paper surface of the medium may be different, there is a drawback that an error is likely to occur in control. That is, it is difficult to perform highly accurate and stable print control because the temperature that changes due to the heat generation power that changes from moment to moment cannot be detected and control is performed by estimating the temperature by predictive calculation. Also, if you print several sheets in succession, the thermal head will accumulate heat,
Another problem was that the head temperature gradually increased and the print density increased.

Further, in recent years, the paper medium used is, for example, in the category of thermosensitive recording paper, not only a monochromatic coloring paper but also a bicolor coloring paper and a paper having an erasing function. Among them, there is an emerging type that causes color development by switching every predetermined time, and in such paper media, accurate print density can be expressed by print control based on estimation control such as conventional history control. There wasn't. That is, according to one simple temperature control, for example, in the case of two color developing papers of black and red, the problem that the mixed color of these two colors is printed on the printing surface, There was a problem that parts that should have been erased remained.

For example, in the case of a two-color paper, as shown in FIG.
It is necessary to apply different heating profiles (heating patterns) for red and black colors as shown in FIGS. 2a and 2b, since the red and black colors have different coloring energies.
As for the red color, the thermal head accumulates heat when printing a large number of sheets, the temperature of the heating element rises, and the generated energy of the heating element of the thermal head shifts to the area of the broken line in FIG. 2b. There is a problem in that the mixed color of red and black is generated as a result of entering the energy range in the intermediate range between the black and red color ranges, resulting in a turbid red color.

Therefore, it is not affected by the difference in ambient temperature or the temperature rise after printing a large number of sheets, and as shown in FIGS. 2a and 2b,
It was necessary to generate different heating temperature profiles in a stable manner in the heating element. For this purpose, it is possible to detect in real time the heat generation power of the heating element of the thermal head that constantly causes the temperature change of the heat generation element, and as a result, the generated power of the heating element deviates from these heating power profiles momentarily. It is necessary to control the drive of the heating element so that it does not exist. For example, in order to realize the control according to the profile as shown in FIGS. 2a and 2b, it is necessary to control with a complex stepwise waveform as shown by the solid line in FIGS. 2c and 2d.
There has been no means for realizing this in the past.

[0007]

A print control apparatus according to the present invention includes a minute heating element (for example, Cr or Al, which also functions as a heating element whose resistance value changes depending on a heating temperature and a temperature detecting element.
A thermistor made of an alloy such as a linear head, a driving means for driving each heating element to generate heat, and a means for detecting the heating power value of the heating element 2c, the heating power value control is performed with a target waveform that is a stepwise waveform such as the solid line in FIG. 2d.
As a result, for example, it is possible to detect the actual power value of the heating element such as the stepwise waveforms shown by the solid lines in FIGS. 2e and 2f, and to control the driving of the heating element from ON and OFF from the detected value. Since the control waveforms shown in FIGS. 2e and 2f are combinations of a plurality of target heat generation powers and control times, the target heat generation powers and control time values are stored in advance in the control circuit or an external table as parameter information before printing. During printing, print control is performed with reference to this parameter table. In this way, the control of the heat generation power toward the target heat generation power value and the control of the time for generating energy is the case of the control according to the configuration of claim 1, and a plurality of target heat generation powers and control energy integrated values are calculated. The control as a parameter is the case of the control according to the configuration of claim 2. Details of both will be described in the following embodiments of the invention.

According to this structure, a plurality of types of parameter information tables for producing the above-mentioned control waveforms are prepared in advance inside or outside the control circuit, and selected and printed in accordance with the coloring characteristics of the medium used. Control can be performed. It is also within the scope of the present invention to prepare this table in a system controller or a higher-level device such as a memory device, receive the table from the higher-level device before printing, and use it for print control.

Further, the heat generation power of each heat generating element which is measured moment by moment is stored in a memory, and after printing is finished, it is plotted and expressed in a time series, so that the human being can visually see the state of change of the heat generating power of the heat generating element. It became possible to see, and it became possible to specifically pursue what is the optimum waveform of the medium used.
As an example, FIG. 3 shows a plot of the profile actually measured when the drive is controlled according to a certain temperature-time profile. Such storage and output of the heating power value is achieved by the third or fourth embodiment embodying the invention according to claim 3, and details thereof will be described later.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Before describing the embodiments of the present invention, while controlling the drive power for a target drive time while detecting the heat generation power value of each heating element on the thermal head, the heat generated by each heating element is controlled. The principle of the present invention, which enables the print medium to develop color at a desired density by energizing each heating element until the integrated amount of energy reaches a desired value, will be described in comparison with the conventional method. To do.

Examples of apparatuses to which the present invention is applied include a melt thermal transfer printer, a sublimation thermal transfer printer, and a thermal printer using a thermal recording medium. Although it is obvious to those skilled in the art of thermal printers that the present invention can be used for a melting thermal transfer printer or a sublimation thermal transfer printer, here, a thermal printer using this thermal recording medium will be described. An application example of is described. In fact, the effects when applied to a fusion thermal transfer printer or a sublimation thermal transfer printer have been confirmed.

As the thermal recording medium, so-called monochrome color thermal paper, two color thermal paper, and color color media such as thermo-autochrome paper (generally called TA medium) sold by Fuji Photo Film Co., Ltd. Etc.
A rewritable medium that can be repeatedly written and erased is used.

The color-developing characteristics of each color of these heat-sensitive media are, for example, as shown in FIG. 4, the color-developing density D during printing is the heat-generating energy (generated power) applied by the heat-generating elements on the thermal head. It shows that it is determined by the integrated value: E, and such a characteristic diagram is published for each paper by each thermal paper manufacturer.

It should be noted that the horizontal axis of this characteristic diagram is the integrated value of the heat energy of the thermal head,
That is, the integrated value of energy applied to the medium,
It is not a temperature value. Therefore, in order to set an arbitrary minute color-developing portion on the medium to the desired color-developing density: d1 in FIG. 4, the integrated value of the heat energy generated by the minute heating elements on the corresponding thermal head becomes e1. Control it. However, in the head using the heating element with a fixed resistance value mentioned in the section of the prior art, the integrated value of the generated energy is “estimated” by calculation based on the print history of the past printing results. When printing multiple media continuously, the thermal head accumulates heat and the temperature rises.Therefore, the thermal energy applied to the paper surface increases, and the color density of the paper surface increases as the number of printed sheets increases. There were times when it happened.
This is because in order to generate the integrated value of heat generation energy: e1 for achieving the above concentration: d1, an error occurs because the temperature of the head itself is currently determined by the estimation calculation. is doing. That is, in this conventional method, since the temperature value of the heating element before heating is unknown, the heating amount is determined by the estimation, and if the estimated value of the heating energy amount deviates from the true value, the color is generated. There is an error in the density.

As the number of continuously printed sheets increases, energy is accumulated in the head and the temperature rises, which exceeds the required heating energy. However, according to the present invention, the appropriate energy required for printing is always maintained. Since it is applied to the paper surface, there is an energy saving effect, and compared with the conventional control method, the applied energy can be about 1/3 to 1/4.

In the embodiment described below, the thermal head is, for example, 200 dots or 30 dots per inch.
An example of using a structure in which minute heating elements are arranged in a line with a density of 0 dots will be described.

When printing with this head, printing is performed while moving on the medium at a pitch of 1/200 inch if the head has a density of 200 dots / inch.

Printing is performed by simultaneously starting heating for each line by the heat generation of the heating elements whose resistance values arranged in a line on the thermal head change depending on the heating temperature. If the dot pitch of the thermal head is, for example, 300 dpi, the line pitch for sub-scanning, that is, simultaneous printing is also usually 300 dpi, and heating printing on the paper surface from the head is periodically repeated at this pitch. The present invention relates to control means in each line when heat generation is controlled for each line, and each line on the paper surface is sequentially controlled by the same control means. In this specification, the control of one element on the thermal head is described, but in reality, all the elements are independently controlled.
Printing is controlled by the same control means.

First, the first embodiment of the present invention will be described. In the following, when performing the printing operation for each line,
The thermal control operation when printing lines will be described. In the heat control according to the first embodiment, the driving time of the heating element is set to the target set in advance for each heating element while keeping the heating power of the heating element at the target heating power value set in advance for each heating element. Each heating element is driven and controlled until the driving time value is reached. Here, the target heating power value and the target drive time value are control target values for causing a target print medium to develop a color having a desired density, and values that can be preset as mutually related combinations. Is. However, the combination and the number of combinations can be freely designated by the host device, and can be set as a trial combination for determining a desired color forming characteristic, for example. Below, 6 combinations of 6 pieces of target power value data T1 to T6 and 6 pieces of target driving time values N1 to N6 are set (that is, (T1, N1) to (T6, N).
6 combinations of 6) are set).

FIG. 5a shows an example of the profile of the control target value according to one embodiment of the present invention when performing the control of the six combinations. In this way, the target power value T1 of each group is
One of the objects of the present invention is to arbitrarily set T6 and the target drive times N1 to N6 to determine a composite thermal control profile and perform thermal control of each dot of each line. Hereinafter, a case of two combinations, that is, a case of performing heat generation drive control in this order for the combination target value of (T1, N1) and (T2, N2) will be described. The pattern of this combined target value is shown in FIG. 5b. The actual power value change situation in this control is shown by the solid line in FIG. 5c. This embodiment focuses on the fact that it is possible to maintain the generated power of each heating element at a desired value with high accuracy by accurately detecting the heating power of each heating element itself, and Is maintained for a certain period of time to drive and control each heating element so that the energy generated by the heating element reaches a desired value.

Next, a configuration example of the print control device in the first embodiment will be described using the control circuit shown in FIG. 5e.

The heating element 500 is a resistor generally called a thermistor. Since the resistance value of the thermistor changes depending on the heat generation temperature, it also has a function as a temperature detecting element. The metal composition of this thermistor is selected such that the change in heat generation temperature and the change in resistance value, that is, the resistance-temperature characteristics have a good linear relationship as much as possible. As an example, an alloy of aluminum, chromium, boron or the like is used. An example of the characteristic diagram is shown in FIG. 5d.

The heating element 500 is a driving transistor 520.
Connected to the collector of the drive transistor is ON
Then, a current is applied and heat is generated. A 3-input AND gate 510 is connected to the base of the drive transistor 520, and the output of the AND gate becomes a logic high level signal (hereinafter, referred to as H signal), so that the drive transistor 520 is turned on. A current flows through the heating element 500. An inverted signal of the control signal a0 from a control device such as a system controller (hereinafter, referred to as a host device) is input to the first input of the 3-input AND gate 510 via the inverter 509. This signal a0 is a control signal for instructing switching between heat generation driving and detection of the generated power value. During heat generation driving, a logic low level signal (hereinafter,
It will be referred to as an L signal), and will become an H signal when the heating power value is detected. The output of a flip-flop 532 described below is connected to the second input of the 3-input AND gate 510, and the output of a flip-flop 518 described below is connected to the final third input. 3 at the start of driving
All the input signals of the input AND gate 510 are in the H signal state, and the transistor 520 is in the ON state. As a result, a current flows through the thermistor 500 and the temperature rises. On the other hand, the control signal a
When 0 becomes the H signal and the timing of power value detection comes, the output of the AND gate 510 becomes the L signal, so the drive transistor 520 is turned off. The collector of the drive transistor 520 is also connected to the collector of the power detection transistor 521. When the transistor 521 is turned on, the current flowing through the heating element 500 has a resistance value of 70Ω through the transistor 521. The current flows to the fixed resistance r1 for power detection. 2 of resistance r1
Each of the two ends is connected to an input of an amplifier (here, an operational amplifier or a linear amplifier) 511. Two
The control signal a is supplied to one input of the input AND gate 529.
0, and the output Q2 of the flip-flop 518 is connected to the other input. Therefore, the output of the gate 529 is when a0 is H, that is, when the power value is detected,
Further, when the output Q2 of the flip-flop 518 is H, it becomes H, and at this time, the power value detection transistor 521
Turns on. Here, as will be clear from the explanation below,
The output Q2 of the flip-flop 518 becomes H while the heat generation drive control for the current target control value is not yet completed. As described above, the transistor 520
The AND gate 510 on the base side of
Is inverted and input, and since a0 is input as it is to the input of the AND gate 529 on the base side of the transistor 521 without being inverted, only one of the transistors 520 and 521 is driven during the printing operation. However, they are not driven to the ON state at the same time. That is, the transistor 520 is turned on during heating driving, and the transistor 521 is turned on during power value measurement.

During power measurement, that is, the transistor 52
When 1 is ON, we can know the resistance value and heat generation energy (that is, heat generation power value) of the thermistor 500 by measuring the voltage generated across the fixed resistance r1. The reason for this will be described below. When the resistance value of the thermistor 500 is known, the temperature of the thermistor 500 at that time can be easily known from FIG. 5d.

Now, the power supply voltage applied to the terminals of the thermistor 500 is V, the flowing current is I, and the resistance value of the thermistor 500 is
R, the ON voltage of the transistor 500 is e, the power source (not shown) to the thermistor 500, and then the transistor 52.
1. Next, consider a circuit that flows into the fixed resistor r1 and then flows through the ground terminal. When the terminal voltage of the fixed resistor r1 is E, this E is expressed by the following equation.

E = r1 × I = r1 × (Ve) ÷ (r1 + R) Here, Ve = A (constant) is set, and normally R = 200.
Since r1 = 70Ω at about 0Ω, considering that R >> r1, E = r1 × A ÷ R can be obtained. Furthermore, considering that r1 is also a constant, r1
If × A = B (constant), E = B / R (1) That is, R = B / E and the voltage E across the fixed resistor r1 is known, and the resistance value R of the thermistor 500 is known. It turns out that you can.

On the other hand, the energy generated in the thermistor 500 will be calculated next. In the circuit from the power supply to the ground in the above circuit, V = Ri + e + r1 × i. Here, since i = (V−e) ÷ (R + r1), the energy W generated in the thermistor 500 is W = i ² × R = A ² × R ÷ (R + r1) ² = C × R ÷ (R + r1) ² and considering R >> r1 and assuming R + r1 = R, W = C × R ÷ R ² = C / R (2) Comparing the equations (1) and (2), it is found that both E and W are inversely proportional to R. When R is deleted from both equations, W = K × E (3) (where K is a proportional constant). From this, it is concluded that "when the voltage E across the fixed resistor r1 is known, the heat generation energy value (generated power value) of the thermistor resistance 500 as a heat generating element at that time can be known from the equation (3)." .

Therefore, it is possible to control the heating energy of the heating element of the thermal head to an optimum value by performing the following control in the control circuit of FIG. 5E.

That is, at the time of printing each line on the paper, the transistor 520 is turned on and the thermistor 500 is turned on.
About continuous heat generation. However, the transistor 520 is turned off only for about 75 ns in a cycle of 80 μs, the transistor 521 is turned on at that timing, and the voltage across the fixed resistor r1 is read only at that time, so that the thermistor 500, which is a heating element, at that time Generated energy
It is possible to know W at a cycle of 80 μs. That is, the control signal a0 is a signal having a cycle of 80 microseconds.

The processing of the voltage detected by the fixed resistor r1, in other words, the heat energy value generated in the thermistor 500 will be described below.

The amplifier 511 is an amplifier that amplifies the voltage across the terminals of the resistor r1, and the analog signal output from the amplifier 511 is input to an analog-digital converter (A / D converter) 512 and an 8-bit digital signal is input. Converted to a signal.

530 is a comparison circuit, which has two inputs A,
B has two outputs C and D. The input A is supplied with the output of the analog-digital converter (A / D converter), and the input B is supplied with the output of the multiplexer 536 described later. To be done. The comparison circuit 530 compares the magnitudes of the data values supplied to the inputs A and B, respectively, and the value supplied to A (hereinafter referred to as the value of A) is the value supplied to B (hereinafter referred to as B). Value), or equal to the value of B, the H signal is output to the output C and the L signal is output to the output D. On the other hand, when the value of A is smaller than the value of B, the L signal is output to the output C and the H signal is output to the output D.

The flip-flop 532 is an RS flip-flop, and the output C of the comparison circuit 530 is connected to the reset input (R input) and the output D of the comparison circuit 530 is connected to the set input (S input). Has been done. The output Q1 of the flip-flop 532 is connected to the second input of the 3-input AND gate 510 as described above.

The operation of the comparison circuit 517 is the same as that of the comparison circuit 530.
The same circuit as 530 can be adopted. The operation of the flip-flop 518 is similar to that of the flip-flop 532, and the same flip-flop as 532 can be used.

Reference numeral 534 is a table as a means for storing the target heating power value data. In this configuration example, this table is an 8-bit × 6 shift register (hereinafter referred to as an 8-bit × 6 shift register) in which six 8-bit registers are connected in series. , Register group). Of course, this table can also be configured as a data array in a memory such as a random access memory (RAM). In this configuration example, six pieces of target heating power value data T1 to T6, which are 8-bit data, are stored. These six pieces of target heating power value data are stored in the register group 534 via the data line D0.
Entered in. The number of pieces of target heating power value data can be set to a desired number by appropriately selecting the register configuration. Further, the input of the target heating power value data to the register group 534 may be supplied from a predetermined external device outside the printer device, or it may be provided inside the printer control device or outside the printer control device. May be supplied from the device.

The six inputs of multiplexer 536 are:
Each of the six 8-bit outputs of the register group 534 is connected. The multiplexer 536 has a register group 53
Among the target heating power value data stored in No. 4, one target heating power value is selected according to the control signal a3 composed of a plurality of signal lines, and is output to one input B of the comparison circuit 530.

The multiplexer 536 and the register group 5
34 can also be provided as an external component of the print control apparatus.

During measurement, the voltage detected by the fixed resistor r1 is DC-amplified by the operational amplifier 511, and then converted into a digital value by the A / D converter 512. This result is input to the A input terminal of the magnitude comparison circuit 530, and this is compared with the first value T1 set in the table 534. As a result, when the detected generated power value is smaller than the stored numerical value T1 of the table 534, the output Q1 of the flip-flop 532 remains the H signal, and therefore the output of the AND gate 510 remains the H signal,
The driving transistor 520 remains on and the heating state continues. However, as time goes by,
When the output of the A / D converter 512 becomes larger than the value of T1, the Q output of the flip-flop 532 becomes an L signal, which turns off the transistor 520 to stop the heating state and lower the heating element temperature. To do.

After that, when the output of the A / D converter 512 becomes smaller than the value T1, the flip-flop 53
The Q output of 2 becomes the H signal, the AND gate 510 becomes the H output again, and the transistor 520 is turned on again.
The power generated by the heating element increases. While repeating this, ON and OFF are repeated like a flat portion of the waveform shown in FIG. 3 (for example, the number of times of sensing on the horizontal axis is between 40 and 65), and as a result, a sawtooth-like change centered on the target generated power value is obtained. Becomes

As soon as the measurement is completed as described above, the pulse signal a0 is inverted, and as a result, the transistor 520 is turned off.
N, the transistor 521 is turned off, and the next 80 μs
Heating is driven during the progress, but as described above, the table 53
If the measured data exceeds the target heating power value T1 in 4 by comparing the magnitudes of the input terminals A and B of the comparison circuit 530, or if the driving time has passed a predetermined time, that is, a clock of 80 μs cycle is set. Count (see below)
The output of the time counter 542 is N in the table of 538.
The input terminal of the comparison circuit 517 has become larger than 1.
If it is found by comparing the values of A ′ and B ′ (that is, “value of A ′> value of B ′”), the output Q2 of the flip-flop 518 becomes L, and as a result, the output of the AND gate 510 becomes Since the signal is an L signal, the drive transistor 520 is O
It becomes FF. As a result, the heating drive of the heating element is stopped.
Further, since the output of the AND gate 529 also becomes the L signal,
After that, the transistor 521 is also turned off. As a result, the measurement of the generated power is stopped thereafter.

Here, the time counter 542 measures the total heating drive time by counting the drive time from the start of heating by counting the clock signal a0 indicating the power value detection timing input to the counter 542, and Output measurement data. A control signal a7 that becomes an H signal during the printing operation of each line is input to the enable input EN, and Q2 of the flip-flop 534 is input to the disable input DI.
The inverted signal of the output is connected. The counter 542 is
The pulse-shaped C that becomes H for a short time is input to the count clear input CL.
When the LR signal is input, it is set to the initial setting value (0 in this example), and then after the count enable signal a7 is input as the H signal during the printing operation,
The counting of the power value detection timing signal a0 is started. As described above, in the present configuration example, the generated power is measured about every 80 μs, and the a0 signal which becomes the H signal is counted each time. When the L signal is input to the disable input DI, the counter 542 stops the count operation while holding the count value at that time. At the start of heat generation driving, the enable input has a control signal a7 which is an H signal.
When the output Q2 of the flip-flop 534 becomes H because the count value has reached the target value because the heat generation drive is started, the L signal is input to the DI input and the count is stopped. To do. When the counting is stopped, a new target heating power value T2 is selected from the table 534, a drive time value N2 for setting a new drive time is selected from the table 540, and the same control as described above is repeated. As a result, the control shown in FIG. 5c is performed.

The combination of the target heat generation power value and the target drive time value and the number thereof are (T1, N1) to
Up to six (T6, N6) can be set, but if necessary, the same operation as described above can be performed in any order up to any combination of (T1, N1) to (T6, N6). It can be repeated. That is, according to this control method, the heat generation power of the heating element is always held at the target heat generation power value, and therefore, it is possible to perform control to heat to the required generated energy value without generating heat in excess of the required amount. It will be stably repeated and controlled with different profiles.

Next, a second embodiment of the present invention will be described with reference to FIG.
Write using. In the heat control according to the second embodiment, while maintaining the heat generation power of the heat generating element at the target heat generation power value set in advance for each heat generating element, the integrated value of the heat generation power value of the heat generating element is set in advance for each heat generating element. Each heating element is driven and controlled until the set target heating power integrated value is reached. Here, the target heat generation power value and the target heat generation power integrated value are control target values for causing a target print medium to develop a color having a desired density, and can be set in advance as a combination associated with each other. It is a value. However, the combination and the number of combinations can be freely designated by the host device, and can be set as a trial combination for determining a desired color forming characteristic, for example. In the following, six combinations of the six target power value data T1 to T6 and the six target heating power integrated values S1 to S6 are set (that is, (T1, S1) to (T6, S6). 6 combinations are set).

In FIG. 6, an amplifier circuit 611, an analog-digital converter 612, comparison circuits 617 and 630,
The operations of the flip-flops 618 and 632, the tables (here, configured as a register group) 634 and 638, and the multiplexers 636 and 640 are performed by the amplifier circuit 51 in FIG.
1, analog-digital converter 512, comparison circuit 51
7, 530, flip-flops 518, 532, tables 534, 538, multiplexers 536, 540, respectively, and the same ones as those in FIG. 5e can be adopted. Also, the timing and signal level of each of the signals b0 to b6 can be the same as each of the signals a0 to a6 of FIG. 5e.

The operation from the start of heating until the temperature of the heating element 600 rises and the operation of detecting the heating power value of the temperature rise of the heating element 600 are the same as those described above with reference to FIG. To do.

The heat generation power (that is, heat generation energy) sequentially detected by the fixed resistor r5 from the start of the first heating drive on the current print line is amplified by the amplification circuit (here, operational amplifier) 611, and then A / D
After being converted into a digital value by the converter 612, it is input to the adder 613 and integrated. Adder 61
3 operates so as to accumulate the measured electric power value for every fixed time (about 80 μs) and accumulate the total electric energy from the start of printing drive. The output of the adder 613 therefore corresponds to the total amount of energy generated in the heating element of the thermal head since the start of driving. The output of the adder 613 is the comparison circuit 617.
Input terminal A ', and another input terminal B'
The target heating power integrated value S1 stored in the table 638 is selected by the multiplexer 640 and input. As a result, as long as the output value of the adder 613 is smaller than the target value S1 selected by the multiplexer 640 (that is, "the value of A '<the value of B'"), it is A '.
The output Q2 of the RS flip-flop 618 connected to the B ′ magnitude comparison circuit 617 remains the H signal, and AN
The D gate 610 becomes H output, the transistor 620 remains ON, and heating of the thermistor 600 is continued.

During this overheating operation, the A / D converter 61
The output of 2 is also input to the input terminal A of the magnitude comparison circuit 630, and the other input terminal B of the comparison circuit 630 is
The target heating power value T1 stored in the target heating power value table 634 is selected by the multiplexer 636 and input, and the magnitudes of these values are compared. As a result, at the inputs A and B of the comparison circuit 630, “value of A <
The output of Q1 of the flip-flop 632 remains the H signal as long as the value of “B”, but the resistance r5 about every 80 μs.
The output of the comparison circuit 630 is inverted at the timing when the heat generation power value of the thermistor 600 detected by checking the voltage across both ends exceeds the target value T1 of the table 634, and the Q1 output of the flip-flop 632 becomes the L signal. , The output of the AND gate 610 becomes the L signal, the transistor 620 is turned off, the heating is stopped, and the temperature of the heating element gradually decreases due to heat radiation. In the process of lowering the temperature of the heating element, the signal b0 becomes H for about 75 ns after the next 80 μs, so that the output of the gate 629 becomes
It becomes an H signal, and the transistor 621 is turned on during that time.
At this time, as a result of measuring the amount of heat generated by the thermistor 600 with the fixed resistor r5, the comparison circuit 630 again determines that “A
If the value <value of B <value of B is detected, the flip-flop 632 is inverted again, and its output signal Q1 becomes the H signal, and AND
The output of the gate 610 becomes the H signal, the driving transistor 620 is turned on again, and the thermistor 600 is driven,
Exothermic power is generated. From the above, when the detected heat generation power value becomes larger than the target heat generation power value T1, the transistor 620 becomes
Is turned off, the heat generation of the thermistor is stopped, and the target heat power value T
When the detected heating power value becomes smaller than 1, the transistor 620 is turned on and the thermistor is reheated. As a result, as shown in FIG.
The OFF control will be performed. During this period, the output of the A / D converter 612, that is, the heating power value measured at intervals of 80 μs, is added to the adder 613 every 80 μs. As a result, the output of the adder 613 is compared with the comparison circuit 617.
Then, the target heating power amount value stored in the table 638
Although it is compared with S1, in the comparison circuit 617, “value of A ′>
When the “value of B ′”, that is, the integrated value of the measured heat generation power becomes larger than the target value, the output Q2 of the flip-flop 618 becomes the L signal as the necessary heat generation is completed, and the result gate 6
The output of 10 becomes an L signal and the drive transistor 620 becomes O.
It becomes FF, and the driving of the thermistor 600 is stopped.

The adder 613 is the A / D converter 61.
A signal obtained by delaying the b0 signal by the delay circuit 614 is used as the timing for fetching the output data of No. 2, but this is because the detection signal of the fixed resistor r5 detected by turning on the transistor 621 is the operational amplifier 611 or A / D. Since there is a delay in passing through converter 612, signal b0 is delayed to compensate for this delay.

Next, T2 is selected as the numerical value of the target heating power value table 634, and the target integrated heating power value table 6 is selected.
After the value S2 is selected from 38 and the adder 613 is reset, the same operation as described above is performed again as shown in FIG. After that, the numbers in the tables 634 and 638 are selected by the number of combinations designated by the host device, the same operation is performed, and then all the operations are completed. FIG. 7 shows a case where the number of this combination is three.

The combination of the target heat generation power value and the target integrated heat generation power amount value and the number thereof are (T1, S
Up to 6 of 1) to (T6, S6) can be set, but if necessary, the same operation as above can be performed up to any combination of (T1, S1) to (T6, S6). Can be repeated in this order. That is, according to this control method, the heat generation power of the heating element is always kept at the target heat generation power value, and therefore, the heat is not generated more than the required amount and the heat is heated to the required target integrated heat generation power value. The control to be performed is stably repeated and controlled with different profiles.

When the heat generation of all the heating elements with respect to the series of combinations of the target values is completed, the head position moves on the paper surface by one line, and the next color forming operation is started again all at once.

Next, a third embodiment of the present invention,
A configuration example of an embodiment embodying the invention according to claim 3 will be described with reference to FIG. The configuration shown in FIG. 8 is similar to that of FIG.
5a, which is similar to the configuration shown in FIG. 5a and has the same components and control signals as in FIG. Figure 5
The difference from the configuration shown in e is that a shift register 550 is added and is used as an auxiliary memory. This function is described below.

In the shift register 550, the detection timing a0 of the heat generation power is delayed by the delay circuit 514 and SH
It is input as a timing signal input to the IFT input terminal, and the output of the A / D converter 512 is stored at the timing of this input. That is, every time the detection timing a0 of the heat generation power is input, the transistor 521 is turned on, and a voltage proportional to the heat generation power is generated in the detection resistor r1. This detection voltage is transmitted through the amplification circuit 511 to the A / D converter 512. There is a delay from the output to the digital value. In order to compensate for this delay, the signal a0 is delayed by the delay circuit 514, and the 8-bit digital output of the A / D converter is sampled by the shift register 550 and shifted at the input timing of this delayed signal. .

Thus, the heat generation power detection timing a0
Is transmitted, the detected heating power value is shifted and stored in the shift register. Therefore, after the printing operation is completed, each time the shift pulse a8 is input, the shift pulse a8 is read and read by the upper device such as an external device.
Since the stored data of can be transmitted in 8-bit units, by expressing this in a graph, it is possible to easily know the change in the generated energy from the figure expressed in the plot. A memory such as a RAM may be used instead of the shift register as a storage unit for the heating power value, and the memory controller may control reading and writing of the heating power value from the memory.

Next, a fourth embodiment of the present invention will be described.
A configuration example of another embodiment embodying the invention according to claim 3 will be described with reference to FIG. The configuration shown in FIG. 9 is similar to the configuration shown in FIG. 6, and the same components and control signals as in FIG. 6 are given the same reference numerals.
The difference from the configuration shown in FIG. 6 is that a shift register 650 is added and is used as an auxiliary memory.
This function is described below.

In the shift register 650, the detection timing b0 of the heat generation power is delayed by the delay circuit 614 and SH
It is input as a timing signal input to the IFT input terminal, and the output of the A / D converter 612 is stored at the timing of this input. That is, every time the detection timing b0 of the heat generation power is input, the transistor 621 is turned on, and a voltage proportional to the heat generation power is generated in the detection resistor r5. This detection voltage is transmitted through the amplification circuit 611 to the A / D converter 612. There is a delay from the output to the digital value. In order to compensate for this delay, the signal b0 is delayed by the delay circuit 614, and at the input timing of this delayed signal, the 8-bit digital output of the A / D converter is sampled by the shift register 650 and shifted. To do.

As a result, the heat generation power detection timing b0
Is transmitted, the detected heating power value is shifted and stored in the shift register. Therefore, after the printing operation is completed, each time the shift pulse b8 is input, the shift pulse is read out, and the shift register 650 is read by the host device such as an external device.
Since the stored data of can be transmitted in 8-bit units, by expressing this in a graph, it is possible to easily know the change in the generated energy from the figure expressed in the plot. This graph allows us to see if the thermal control was done with the optimum profile for the media used. A memory such as a RAM may be used instead of the shift register as a storage unit for the heating power value, and the memory controller may control reading and writing of the heating power value from the memory.

[Brief description of drawings]

FIG. 1 is a characteristic diagram showing a relationship between thermal energy applied to a general thermal paper and a color development region.

FIGS. 2A and 2B are diagrams showing color development characteristics of a two-color print medium with a temperature-time pattern of the medium;
(A) shows a pattern for black color development, and (b) shows a pattern for red color development. (C) and (d) show examples of target patterns set to realize the patterns shown in (a) and (b), respectively. (E) and (f) are
Each of them schematically shows one example of the actual temperature-time pattern of the heating element with respect to the target pattern shown by the dotted line by the solid line.

FIG. 3 is a plot of actually measured patterns when drive control is performed according to the present invention with a certain temperature-time pattern as a target pattern.

FIG. 4 is a diagram showing color development characteristics of a general heat-sensitive medium in a relationship between heat generation energy and color development density.

FIG. 5a is a diagram showing a pattern composed of six combinations of a target heating power and a target driving time.

FIG. 5b is a diagram showing a pattern composed of two combinations of the target heat generation power and the target drive time, which are set in the first embodiment.

FIG. 5c is a diagram schematically showing an actual control pattern when the pattern shown in FIG. 5b is controlled as a target pattern.

FIG. 5d is a resistance of the heating element used in the embodiment of the present invention.
It is a graph which showed temperature characteristics roughly.

FIG. 5e is a circuit block diagram showing a configuration example of a print control apparatus according to the first embodiment of the present invention.

FIG. 6 is a circuit block diagram showing a configuration example of a print control device according to a second embodiment of the present invention.

FIG. 7 is a dotted line showing a combination pattern of the target heating power value and the target heating power integrated value actually set in the second embodiment of the present invention, and the heat actually detected by the control based on these setting patterns. The solid line indicates the combination pattern of the heat generation power value of the body and the heat generation power integrated value.

FIG. 8 is a circuit block diagram showing a configuration example of a third exemplary embodiment of the present invention.

FIG. 9 is a circuit block diagram showing a configuration example of a fourth exemplary embodiment of the present invention.

[Explanation of symbols]

500,600 heating element 509,609 inverter 511, 611 Operational amplifier 512,612 Analog-to-digital converter 517, 530, 617, 630 size comparison circuit 520 and 620 drive transistors 521, 621 Power detection transistor 613 adder 514 and 614 delay circuit 542 counter

Claims (3)

[Claims] 1. A target power value storage table for storing a plurality of target generated power values in advance prior to a printing operation, and a target drive time storage table for storing a plurality of target drive times in advance corresponding to the table, respectively. Is a thermal head composed of a set of heating elements which also function as heating elements and temperature detecting elements, driving means for driving each heating element to generate heat, means for detecting instantaneously generated power of each heating element, and the target power The driving means is driven to generate heat until the first target generated power value in the value storage table is reached, and when the target generated power value is reached, the target drive time is controlled while holding the generated power of the heating element at the same power value. Means for controlling to reach the first target time of the storage table, and the target generated power after reaching the first target time of the storage table,
The target generated power value is switched to the target generated power value, and the control operation of driving the heating element is performed until the second target time of the target drive time storage table is reached while maintaining the same target generated power value. The print control device, which is configured to be repeatedly executed until all the values of are used. 2. A target power storage table that stores a plurality of target heat generation power values in advance, a table that stores a plurality of target drive energy integrated values in advance corresponding to the table, and a heating element and a temperature detection element, respectively. A thermal head composed of a set of heating elements that also serves, a driving means for driving each heating element to generate heat, a means for detecting the generated power of each heating element that rises as a result of driving, and an addition for storing the detected powers. A circuit and heat generation drive by the driving means until the first target power value of the target power storage table is reached, and while controlling the generated power of the heating element to the same power value when reaching the same target power value, Heating control is performed until the value of the addition circuit reaches the first target energy integrated value of the target drive energy integrated value storage table, and after reaching the same energy value, After resetting the adder circuit, the drive target power is switched to the second target heating power value in the target power storage table, and the power value detected each time the power is measured while performing control to hold the same at the target heating power value. Is added to the adding circuit, the control operation is performed until the value of the adding circuit reaches the second driving energy integrated value of the target driving energy integrated value storage table. A print control device comprising a means for executing until used. 3. A storage memory for storing all detected temperature values during print control, a means for writing to the storage memory each time the temperature is detected, and a means for reading and outputting the contents of the storage memory after the printing operation is completed. The print control apparatus according to claim 1, further comprising: