JPS61208367A - Thermo sensing transfer gradation controller - Google Patents

Abstract

PURPOSE:To attain gradation recording with excellent linearity, to control gradation minutely and to widen the recording range of density by generating a pulse whose pulse width is changed depending on ambient temperature, kinds of recording paper and molten characteristic of ink. CONSTITUTION:A correction circuit 18 consists of a pulse generator 24, an analog signal generator 25 and an AND circuit 26. A pulse (timing pulse) (a) representing the end of count of 1-m gradations is fed to a signal generating section 27 via a terminal 23 from an address counter 11 is an analog signal generator 25. A thermister 28 and a resistor (r) whose one end is connected to common are connected to the signal generating section 27 and a switch circuit 29 is connected to the other end of the resistor (r). The switch circuit 29 divides a voltage Vcc to change the power supply voltage fed to the signal generating section 27 by changing over depending on the kind of recording paper 4, kind of ink film 1 of ink molten characteristic of the thermal molten ink 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thermal transfer gradation control device, which controls the size of printed dots by controlling the duration of a constant current flowing through a heating resistor of a thermal head. The present invention relates to a thermal transfer tone control device that controls tone.

Jurai's technology □ In addition to printers (hard copy devices) for terminals, such as wire, ear dot, shuttle, and inkjet types, thermal transfer type printing devices are also promising. For example, using an ink film in which heat-melting ink is applied to the m of a polyester film with a thickness of 5 to 6 μm, the front ink side of this ink film is brought into contact with recording paper, and the back side is applied with a heat-sensitive adhesive. A current is applied to the thermal head to heat it up, and the ink on the ink film at the position corresponding to the thermal head is melted and transferred onto the recording paper. This thermal head has a plurality of heat-generating resistors arranged in a row, and a current is sequentially applied to each heat-generating resistor.

The density, which determines the gradation of printed characters, figures, pictures, etc., is determined according to the area of each dot on the recording paper to which the molten ink has been transferred. The area of the molten ink dot is determined according to the current applied to each heating resistor. Generally, the larger the current value passed through the heating resistor, the larger the amount of heat generated, the larger the area of the molten ink dots, the larger the print density, and the closer the gradation is to the saturated density. Therefore, conventionally, to control the gradation of printing, the value of the current flowing through the heating resistor has been controlled. However, the current flowing through the heating resistor is generally 5 to 2 OA, which is a large current.

However, it is difficult to control such a large current with a high response speed, and the control device is large and expensive. Further, there are drawbacks such as the inability to increase the response speed when controlling the large current, and the printing speed cannot be increased.

Therefore, the present applicant previously proposed in Japanese Patent Application No. 57-216933 a device that controls the density of printing by controlling the size of printed dots by the duration of the current flowing through the heating resistor of a thermal head. did. This device converts, for example, an analog video signal into a digital signal (image data), sends it to a data storage device such as a semiconductor memory, determines and stores addresses for the required number of pixels, and then sends it from an address counter. The data is read out according to the address given and output to the grayscale data comparison circuit. This density data comparison circuit compares - standard density data (initially data indicating the minimum color density) sent from the data counter with image data of the same number as the number of heating resistors read out sequentially from the data storage device. After sequentially comparing, if the value of the image data is equal to or larger than the value of the reference density data, supplying, for example, a high level output signal to the gate circuit via the shift register circuit;
If it is smaller than the reference density data, a low level output signal is supplied to one input terminal of the gate circuit. The density data comparison circuit then compares the second standard density data from the one with the lowest coloring density with the image data of the same number as the heating resistors sequentially read out from the data storage device in the same manner as above. Then, in the same manner as above, a high level or low level signal is sent to one input terminal of the gate circuit. Thereafter, the above operation is repeated in the same manner as above until the reference density data reaches the maximum color density.

A heating pulse is applied to the other input terminal of the gate circuit, and the heating pulse passes through only the gate circuit to which the high-level signal is input to one input terminal, causing the corresponding heating resistor to generate heat.

In this way, a heating pulse is applied to the plurality of heating resistors for a time corresponding to the color density, and a pulsed current is caused to flow, thereby controlling the gradation.

Problems to be Solved by the Invention However, the relationship between the printing density in the thermal transfer printing device and the time for passing current through the heating resistor (recording time) is linear as shown by the solid line in FIG. 9(A). The problem was that it wasn't. That is, as shown in FIG. 9(B), the maximum density obtained at the maximum recording time [)a+ and FIG.
C), (D).

The relationship between the density obtained when recording time D+ and D2.03 shown in (E) is not linear, for example, when recording time f
A density difference of Δd occurs between the density obtained when il D 2 and the originally desired density shown by the dotted line in FIG. 9(A). Conventionally, in order to eliminate this density difference, there has been a method of connecting a correction circuit between the data storage device and the density data comparison circuit to correct the data from the data storage device, but in this case, for example, the number of gradations If is set to 64, the recording time will be controlled in increments of 1/64 of the maximum recording time [)m, but if the number of gradations is 32 and the corrected recording time is set to 32.5, the recording time will be either 32 or 33. There is a problem in that one has to select one or the other, resulting in density errors.

Furthermore, the conventional thermal transfer gradation control device described above does not take into account external conditions such as external ambient temperature, melting characteristics of ink, and types of recording paper and transfer paper, and therefore print density does not vary depending on the external conditions. There was also the problem of change.

Therefore, the present invention is based on the external temperature and the type of recording paper.

Another object of the present invention is to provide a thermal transfer gradation control device that solves the above problems by generating pulses whose pulse width changes depending on the melting characteristics of the ink and the like.

Means for Solving the Problems The thermal transfer gradation control device according to the present invention is composed of a density data generating means, an analog signal generator, a pulse generating means, and a means for passing a current through a heat generating resistor. ing. The density data generating means compares the data with the input data to be transferred, and generates density data indicating the time period of current flowing through the heating resistor for each unit of density. The analog signal generator generates an analog signal whose illll-to-level characteristics vary depending on external conditions such as ambient temperature, types of transfer paper and recording paper, and melting characteristics of ink.The pulse generating means includes:
The output analog signal of the analog signal generator and the signal of one gradation data time period are compared in level by a comparator to generate a pulse whose pulse width indicates the time of the current to be increased for each unit of density. The means for passing a current through the heat generating resistor is supplied with the output pulse of the pulse generating means and the concentration data, and causes the current to flow through the heat generating resistor for a time corresponding to the pulse width of the pulse.

Operation The analog signal generator described above provides analog signals responsive to external conditions such as ambient temperature, type of transfer paper and recording paper, and melting characteristics of ink. The pulse generating means generates and outputs a pulse whose pulse width changes according to the analog signal level, and performs recording by passing a current through the heating resistor for a time corresponding to the pulse width of the pulse.

Embodiment FIG. 1 shows a circuit diagram of an embodiment of a thermal transfer gradation control device according to the present invention. In the figure, the thermal head 6 includes n heating resistors R1 to Rn formed in a row on a ceramic substrate. The configuration of this thermal head 6 is the same as that of a conventional thermal transfer printing device, and extends in the width direction of the ink film 1, as shown in FIG. In FIG. 8, an ink film 1 serving as a transfer paper has a polyester film 2 coated with heat-melting ink 3 to a predetermined thickness on the surface thereof. The recording paper 4 is placed against the roller 5 with its recording surface facing the ink 3 surface of the ink film 1.
I/L, A1. ! ``Both arrow A direction 1 feed 0.

A thermal head 6 is provided opposite the roller 5 and is in contact with the back surface of the ink film 1.

The ink 3 of the ink film 1 corresponding to the energized heat generating resistor among the heat generating resistors R+-Rn of the thermal head 6 is melted 1 and transferred onto the recording paper 4. After the ink film 1 passes through the thermal head 6, it is guided to 0-57 and separated from the recording paper 4. - Winding spool (not shown) - Winding up the used ink film 1a. The transferred ink 3a remains on the printed recording paper 4a. For convenience of illustration, the transferred ink 3a is shown as having a large area, but it actually consists of a collection of small dots.

One dot is formed by a negative heat generating resistor, and the size of the negative dot is determined by the current value or energization time passed through the heat generating resistor. The shading, or gradation, of the printed figure is determined according to the size of each dot.

This Toshiaki is a gradation control device that can be applied to such a thermal transfer printing device, and to explain it again with reference to FIG.
The analog video signal supplied from the V signal generator M8 is A
The signal is converted into a digital signal by the /D converter 9 and sent to the data storage device W110 for storage. On the other hand, the address counter 11 is supplied with a reference clock signal from a terminal 12 and a start pulse from a terminal 13, and sends the first 7 addresses to the data storage device 10. The data storage device 10 stores first data (A
The first data of the image data from the /D conversion device 9 is sent to the grayscale data comparison circuit 14. At this time, the count of the data counter 15 is set to "1", for example, and the reference density data (hereinafter referred to as "second data") that increases sequentially according to this count number is sent from the data counter 15 for comparison of density data. The signal is supplied to the circuit 14. The gradation data comparison circuit 14 compares the first data with the second data r1J indicating the minimum color density, and if the first data is equal to or larger than the second data "1", the data is sent to the shift register 16. Control data "1" is sent, and if it is smaller, control data rOJ is sent to the shift register 16.

In this way, when the processing at the first address is completed, the address counter 11 is sequentially updated to 2°3, . . .
The n-th address is sent to the data storage device 10, and the data storage device 10 sequentially sends the first data corresponding to the 2nd to n-th addresses to the m-dark data comparison circuit 14 each time. Here, the first data from the 1st to nth addresses correspond to image data printed by each of the heating resistors R+ to Rn of the thermal head 6, respectively. The gray data comparison circuit 14 compares the first data and the second data "1" corresponding to the second to nth addresses, respectively, and transfers the control data rOJ or "1" to the shift register in the same manner as above. 1
Send to 6. The 0th stage shift register 16 sequentially takes in n-bit control data corresponding to the 1st to nth addresses supplied from the gray data comparison circuit 14 and sends it to the latch circuit 17.

When the address counter 11 completes the first to nth address cycles, it sends a data transfer pulse to the correction circuit 18 via the data counter 15, latch circuit 17, and terminal 19. At the same time as this data transfer pulse is sent, the data counter 15 sends a heating pulse to the correction circuit 18, the address counter 11, and the AND circuit 2 through the terminal 20.
At the same time, the second data, which had been "1", is increased to "2", which indicates the second smallest color density. On the other hand, a reference clock signal is supplied from the terminal 12 to one end of the AND circuit 21, and simultaneously with the input of the heating pulse, the pulse is output to the shift register 16, and the 1st to nth addresses of the address counter 11 are outputted. n bits of control data corresponding to the n bits are transferred from the shift register 16 to the latch circuit 17. When the data transfer pulse is received, the latch circuit 17 latches the control data supplied from the shift register 16 and sends it to one input terminal of each of the gate circuits G+ to Gn.

Next, the ° address counter 11 is reset by the input of the heating pulse, and sequentially counts addresses 1 to n again, and the first data of n pieces becomes the value "2".
The grayscale data comparison circuit 14 sequentially compares the data with the second data in the gray scale data comparison circuit 14. When the second data is "2", the data counter 15° shift register 16. Latch circuit 17
．． The AND circuit 21 and the like perform operations similar to those described above, and send latched control data to each of the gate circuits 01 to Gn. A heating pulse is applied to the other input terminal of each of the gate circuits 01 to Gn by a terminal 37 of a correction circuit 18, which will be described later, and each output signal is applied to the base of the corresponding NPN transistor T1 to Tn, which is used for switching. Control. Current flows only through the heating resistor connected to the collector side of the turned-on transistor among the transistors T1 to Tn, and heat is generated.

This embodiment is characterized in that a correction circuit 18 is provided in the gradation control device shown in FIG. 1, and one embodiment thereof will be described below. In FIG. 2, the correction circuit 18
is the pulse generator 24. Analog signal generator 25. and A
It is composed of an ND circuit 26. A pulse (timing pulse) a shown in FIG. 7 (A>) indicating the end of counting from 1 to Il1 gradation is sent from the analog signal generator 25 to the hair address counter 11 via the terminal 23 to the signal generator 27 shown in FIG. 3. A narmistor 28 and a resistor r whose one end is grounded are connected to this signal generating section 27.A switch circuit 29 is connected to the other end of this resistor r. Resistors r1 to ri each having a different resistance value are connected to the terminal S+-8i. By switching the switch, the voltage Vcc is divided and the power supply voltage supplied to the signal generator 27 is changed.The thermistor 28 detects the external temperature by changing its resistance value depending on the external temperature, and generates a signal. The signal is transmitted to the generator 27. As a result, the signal generator 27 generates an analog signal as shown in FIG.

The level of the analog signal S increases sequentially from the falling time of the pulse a, increases to VX at the time tx from the falling time of the pulse a to the next rising edge, and reaches zero at the rising time of the pulse a. Return to The above time tx corresponds to the maximum recording time of the current flowing through the heating resistor 6, and the time vs. level characteristics of the analog signal are shown in Fig. 4, for example.
As shown in ■, it changes in various ways depending on external conditions. Here, among the characteristics (1) to (2), I is the characteristic when the ambient temperature is the highest, for example, and has the highest level during the time within tx, thereby shortening the heating time.

As the ambient temperature decreases, the characteristics change from ■ to ■. In addition, as shown by ■ in Figure 4, analog signals @b
The magnitude relationship of the level vs. time characteristics may be changed.

First and second embodiments of pulse generator 24 are shown at 24a in FIG. 5 and 24b in FIG. 6, respectively. In FIG. 5, the pulse generator 24a is a counter 31a.

Comparator 32. and an A/D converter 33. The counter 31a receives a data transfer pulse C from the terminal 19.
A clock signal is supplied from the address counter 11 via the terminal 22, and each time the clock signal from the time when the data transfer pulse C arrives, the comparison data increases sequentially from, for example, "0". (hereinafter referred to as “3rd
data (referred to as "data") is generated and supplied to one end of the comparator 32.

Note that this third data is reset to "0" again when the next pulse of the data transfer pulse C arrives.

On the other hand, the analog signal @b input to the terminal 30 is converted into a digital signal by the A/D converter 33 and supplied to the other end of the comparator 32, and is digitally compared with the third data.

Comparator 32 compares the level of the analog signal (i.e., A
The value of the output digital signal of the /D converter 33) is compared with the third data every two pulse sections of the data transfer pulse C, and when the level of the analog signal is large, it is a high level, and when it is small, it is a low level. The pulse d shown in FIG. 7(D), which becomes the level, is output to the terminal 36. This pulse d is
As shown in FIG. 7(D), the pulse width gradually decreases, for example, in accordance with the slope of the analog signal.

The pulse generator 24b shown in FIG. 6 includes a counter 31b,
A/D converter 34. and a comparator 35.

This pulse generator 24b replaces the operation in which the comparator 32 of the pulse generator 24a shown in FIG. 5 compares digital signals with the operation in which the comparator 35 compares analog signals. The operation is the same as described above.

On the other hand, one end of the AND circuit 26 shown in FIG.
High level heating pulse (strobe signal) through 0
The pulse d supplied to the other end passes through the AND circuit 26 as it is and is output to the terminal 37.

Therefore, the pulse d is transmitted to the gate circuit G via the terminal 37.
A heating pulse is supplied to each of the other input terminals of I to Gn. Each of the gate circuits 01 to 3n supplies a gate signal obtained by gate processing this pulse d and control data supplied from the latch circuit 17 to the bases of each of the NPN transistors T1 to Tn.Transistor T
1 to Tn are the collectors of the transistors that are turned on among the heat generating resistors R1 to Rn by the voltage applied to the terminal 38 when the gate signal supplied to the base thereof is turned on while the gate signal is at a high level. The current flows only through the heat generating resistor connected to the .

In this way, a heating current whose conduction time varies depending on the coloring density is passed through some of the heating resistors R1 to Rn corresponding to the portion to be recorded, and recording is performed. It is done. Also, the data counter 15 is 1~
Each time one count (I is the value of maximum color density) is completed, one line is recorded on the recording paper 4, and after this one line recording is completed, the data counter again counts from 1 to 1. Start.

Note that the analog video signal supplied from the TV signal generator 8 may be an information signal of images such as other characters or figures. Furthermore, the analog signal is not limited to the curve shown in FIG. 7(B).

Effects of the Invention As described above, according to the present invention, there is a substantially linear relationship between the recording time and 1 degree, and it is possible to perform gradation recording with excellent linearity. It is possible to control the number of clocks sent during one line data transfer time. For example, if there are 2048 heat generating resistors, one gradation can be reduced to 1/20.
It has features such as being able to finely control the gradation in 48 units, widening the density recording range, and reproducing gradation corrections that correspond to external conditions without reducing the number of gradations in the recorded data. .

[Brief explanation of drawings]

1 is a circuit system diagram showing an embodiment of the thermal transfer gradation control device according to the present invention; FIG. 2 is a circuit system diagram showing an embodiment of the correction circuit in the circuit system shown in FIG. 1; The figure is a circuit system diagram showing an analog signal generator in the circuit system shown in Figure 2,
4 is an operational explanatory diagram of the circuit system shown in FIG. 3, FIGS. 5 and 6 are block diagrams showing the pulse generator in the circuit system shown in FIG. 2, and FIG. 7 is a diagram of the circuit system shown in FIG. A signal waveform diagram for explaining operation, FIG. 8 is a schematic perspective view of an example of a main part of a thermal transfer printing machine to which the thermal transfer gradation control device of the present invention can be applied, and FIG. 9 is a diagram of a conventional thermal transfer printing system. FIG. 3 is a diagram illustrating the density versus recording time characteristics of the control device. 1... Ink film, 1a... Used ink film, 2... Polyester film, 3, 3a...
Heat-melting ink, 4... Recording paper, 4a... Printed recording paper, 5.7... Roller, 6... Thermal head, 12... Reference clock signal input terminal, 13...
Start pulse signal input terminal, 18...correction circuit, 1
9...Data transfer pulse input terminal, 20...Heating pulse input terminal, 21.26...AND circuit, 22...
・Clock signal input terminal, 24...Pulse generator, 2
5... Analog signal generator, 27... Signal generation section,
28... Thermistor, 29... Switch circuit, 31
a, 31b...Counter, 32.35...Comparator, 33...A/D converter, 34...D/A converter,
37... Heating pulse output terminal, G1-G0... Gate circuit, R+-Rn... Heat generating resistor. Patent applicant: Victor Japan Co., Ltd. Figure 7 B? View Figure 8 Figure 9 - Ichinai

Claims (1)

[Claims] In a thermal transfer gradation control device that individually controls the time of each current flowing through a plurality of heat generating resistors arranged in a row according to the density, a comparison is made with the input data to be transferred, and the density is determined. Means for generating density data indicating the time of current flowing in a row of a plurality of heat generating resistors for each unit, and a means for generating density data in accordance with external conditions such as ambient temperature, types of transfer paper and recording paper, and melting characteristics of ink. An analog signal generator that generates an analog signal whose time vs. level characteristic changes; and a comparator that compares the output analog signal of the analog signal generator and the signal of one gradation data time period, and determines the pulse width according to the concentration. A pulse generating means generates a pulse indicating the time of the current to be passed for each unit, and the output pulse of the pulse generating means and the concentration data are supplied to the heating resistor for a time corresponding to the pulse width of the pulse. A thermal transfer gradation control device characterized by comprising a means for flowing an electric current.