JPS62279965A - Thermal transfer gradation controller - Google Patents

Abstract

PURPOSE:To contrive higher gradation characteristics in the range from an intermediate level to a black level and higher rise characteristics of density at a white level, by maintaining reference density data at a value indicating a minimum density and supplying an electric current to only those heat generating resistors for transferring input data higher than the value, during auxiliary heating period. CONSTITUTION:A control counter 9 counts the number of transfer pulses (b) generated by an address counter 5 based on a reference clock signal, while counting down from a count 'n' to '0'. During the period of time DELTAT for counting the pulses (b) in a number corresponding to an auxiliary heating preset value <'n'>, a low-level signal (c) is supplied to one input terminal of an AND circuit 20, and simultaneously when a high-level pulse is supplied from an m-level detector 16 to the other input terminal of the AND circuit 20, a low-level signal is supplied to a data counter 8 to stop an counting action of the counter. Accordingly, the value of reference density data supplied to a density data comparing circuit 7 is maintained at a value '0' indicative of a minimum density (white) during the period of time DELTAT (auxiliary heating period).

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Industrial Application Field) The present invention relates to a thermal transfer gradation control device, and in particular, the present invention relates to a thermal transfer gradation control device, and particularly to The present invention relates to a thermal transfer gradation control device that controls the size of printed dots and controls the gradation.

(Prior Art) As terminal printers (hard copy devices), in addition to wire dot type, shuttle type, inkjet type, etc., thermal transfer type printing devices have been developed as the most promising type. This thermal transfer printing device t, for example, has a thickness of 5 to 6 mm.
Using an ink film in which thermofusible ink is coated on one side of a μm polyester film, the front ink side of this ink film is brought into contact with recording paper, a thermal head is brought into contact with the back side, and a current is applied to this thermal head. The thermal head generates heat, melts the ink on the ink film at a position corresponding to the thermal head, and transfers the ink to 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 depending on the current applied to each heating resistor. In general, the larger the current value flowing through the heating resistor, the more heating holes there will be.
The area of the molten ink dots becomes large, the print density also becomes large, and the gradation approaches the saturated density.

1iil in the heat transfer type as mentioned above! In order to reduce the maximum power consumption of the apparatus as much as possible, the present applicant previously filed a patent application for a "thermal transfer gradation control apparatus" dated April 18, 1986 [Application No. 1].

This patent application by the present applicant uses standard concentration data corresponding to odd-numbered heating resistors among a plurality of heating resistors and standard concentration data corresponding to even-numbered heating resistors. The density data are separated so that they have a 1's complement relationship with each other, and these data are combined and output. Then, the base +*aa data value corresponding to the odd-numbered heating resistor is increased (or decreased), and the reference concentration data value corresponding to the even-numbered heating resistor is decreased (or increased). Then, this standard density data is compared with the input image data to be transferred at each intermediate density to generate density data, while current is applied to the heating resistor for a time corresponding to the value of the heating pulse. I am trying to apply it.

This makes it possible to use power effectively, smooth power, and significantly reduce maximum power consumption.
This makes it possible to reduce the cost of the power source.

(Problem to be solved by the invention) However, the above patent application filed by the applicant on April 18, 1986 [Application No. 1] has no significant effect in reducing maximum power consumption. However, when considering the accumulation of heat generated by the current flowing through the heat generating resistor, the relationship between print density and the time for which current is passed through the heat generating resistor (recording time) is actually an ideal straight line. The problem is that this results in a density error between the desired density and the desired density.

Therefore, in order to solve these problems, the present applicant previously filed a patent application for a "thermal transfer gradation control device" on May 8, 1986 [Application No. 21] Also, the above-mentioned book The applicant's patent application dated April 18, 1988 [Application No. 1] has some problems in the rise characteristics of the density at the white level, for example, when recording is performed at high speed.

Therefore, in order to solve these problems, the present applicant previously filed a patent application for a ``Thermal Transfer Gradation Control Device'' on May 20, 1986 [Application No. 3].

However, in the above patent application filed by the present applicant on May 8, 1988 [Application No. 2] and patent application dated May 20, 1986 [Application No. 3], the former has an intermediate level to a black level. The latter has a problem with its rJA tone characteristics, and the latter has a problem with its rising characteristics at the white level.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a thermal transfer gradation control device that solves the problems of the conventional techniques described above.

(Means for Solving the Problems) In order to achieve the above object, the present invention adjusts the time of each current applied to each heating resistor arranged in a row according to the concentration. In the thermal transfer gradation control device controlled by II+, there is a control counter [9] that generates and outputs a signal corresponding to a preset reheating time, and a control counter [9] that generates and outputs a signal corresponding to a preset reheating time. Means [8] for generating reference day and date data that holds a value indicating a minimum concentration and changes sequentially from the minimum concentration to a value indicating a maximum concentration in a short time after the reheating time elapses; and this reference concentration data generating means. The reference concentration data outputted from the plurality of heat generating resistors is such that the reference concentration data corresponding to the odd numbered heat generating resistor and the reference concentration data corresponding to the even number heat generating resistor among the plurality of heat generating resistors are mutually matched. A data selection means [15] that separates the data into one's complement data and synthesizes and outputs the data; and the reference density data outputted from this data selection means and the input image data to be transferred. Means [7] for generating gradation data indicating the time of current flowing through a row of the plural T11 heat generating resistors for each unit of concentration by comparing the density, and a reference concentration corresponding to the odd numbered heat generating resistors; A pulse generating means [16] that outputs a pulse when the data is supplied and the reference concentration data reaches a value indicating the maximum concentration, and the reference concentration data corresponding to the odd-numbered heating resistor are supplied, and the reference concentration data is supplied in advance. Correction data set so that the relationship between the stored concentration and the reference concentration data corresponding to the odd-numbered heating resistor becomes a straight line or a predetermined curve is applied to the input odd-numbered heating resistor. a first correction data generation circuit [11] that outputs according to reference density data corresponding to the body; and a first correction data generation circuit [11] that is supplied with reference density data corresponding to the even-numbered heat generating resistor, and which is supplied with the reference density data corresponding to the even-numbered heat generating resistor, and which is connected to a pre-stored storage density; Correction data set so that the relationship with the reference concentration data corresponding to the even-numbered heating resistors becomes a straight line or a predetermined curve,
a second correction data generating circuit [18] that outputs the input reference density data corresponding to the even-numbered heating resistor; The present invention provides a thermal transfer gradation control device characterized by comprising means [G+ to Gn, T+ to Tnl] for applying a current to a resistor for each density unit.

(Function) In the thermal transfer gradation control device configured as described above, the signal supplied from the control counter [9] causes the odd-numbered heating resistor to be activated during the heating time before main energization. The corresponding reference concentration data is the value indicating the minimum concentration, and during the reheating time before this main energization, input data with a value larger than the value indicating the minimum concentration corresponding to the odd-numbered heating resistor is transferred. Current is passed only through the heat generating resistor that is to be heated, and heat is replenished. In other words, the above reheating Jf! During this period, no current is passed through the heat generating resistor at the white pixel position and no heat is generated (heat supplementation), so that white background smear does not occur.

Next, after the reheating time before the main energization described above, the reference concentration data corresponding to the odd-numbered heating resistors increases (or decreases), and conversely, the reference concentration data corresponding to the even-numbered heating resistors increases (or decreases). The reference density data to be transferred decreases (or increases), and this reference density data is compared with the input image data to be transferred for each unit of density to generate gradation data. The first and second correction data generation circuits [17, 18] respectively set the relationship between the recording density and the grayscale data corresponding to the odd-numbered and even-numbered heating resistors so as to be a straight line or a predetermined curve. The corrected correction data is generated, and recording is performed by passing current through the odd-numbered and even-numbered heating resistors for a time based on the value of the correction data.

Then, during the reheating time after the end of main energization when the standard concentration data corresponding to the odd-numbered heating resistors reaches the value indicating the maximum concentration, the standard concentration data corresponding to the even-numbered heating resistors is the value indicating the minimum concentration, and during the reheating time after this main energization, input data with a value greater than the minimum concentration corresponding to even-numbered heating resistors is transferred only to the heating resistors to which the input data is to be transferred. Electric current is applied to replenish heat.

In this specification, thermal transfer recording refers to thermal recording in which recording is performed by chemically changing the recording paper itself due to heat generation, thermal recording using heat-melting transfer paper, and thermal sublimation using sublimation transfer paper. It shall include all types of thermosensitive recording that perform recording by applying geothermal heat.

(Embodiment) An embodiment of the thermal transfer gradation control device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block system diagram showing an embodiment of a thermal transfer gradation control device according to the present invention.

In FIG. 1, the thermal head R is mounted on a ceramic substrate.
1 liter (for example, n is about "16") heating resistor R
1 to Rn are formed in a row.

Also, TVs such as TV (television) cameras or VTRs
(Television) An analog video signal supplied from a signal generator 1 is converted into a digital signal by an A/D converter 2, and this digital signal is sent to a data storage device 3 such as a semiconductor memory, and is transferred to the required pixels. An address is determined and memorized for several minutes.

On the other hand, the address counter 5 is supplied with the reference clock signal from the terminal 6 and the start pulse from the terminal 4, and this start pulse is supplied to the data counter 8 and the AND circuit 1.
It is also supplied to one input terminal of 3. The start pulse mentioned above is a pulse as shown by a in FIG. 2(A).
and data counter 8 are reset, and the control counter 9 is supplied with a pulse at the same time as a high-level pulse is input to the other input terminal of the AND circuit 13 from the m level detector 16 (described later). is loaded with a preset reheating preset value (“n”) from the reheating preset source 10. This reheating preset value is the value that determines the reheating time, which will be described later.
It is determined by the period of the pulse b shown in FIG. 2(B), the voltage applied to the thermal head R, the pressing force between the thermal head R and the recording paper (not shown), the ambient temperature, etc. For example, r
8J and N6J are selected. Further, the heating time is selected to be a time during which pixel data for one line is read out repeatedly an integer number of times.

The control counter 9 subtracts the data transfer pulse b shown in FIG. 2(B) generated by the address counter 5 based on the reference clock from the counter value rnJ to "0".
During the time ΔT in which this pulse b is counted by the reheating preset value (rnJ), the low level signal C is connected to the AND circuit as shown in FIG. 2(C). 20, and this AND
An m level detector 1, which will be described later, is connected to the other input terminal of the circuit 20.
At the same time as a high level pulse is received from data counter 6, a low level signal (pulse) is supplied to data counter 8 to stop its counting operation. Therefore, the value of the reference density data supplied from the data counter 8 to the density data comparison circuit 7 is set to the reset value "O" during the above-mentioned time ΔT (this is the reheating time), that is, 1ift rO indicating the minimum density white.
It is held in J.

The period of the pulse b is selected to be shorter, for example, about 1/10, than the period of the output pulse of a conventional address counter.

The address counter 5 sends the first address to the data storage device 3 upon receipt of the start pulse a. The data storage device 3 sends the image data (the first data of the image data from the A/D converter 2) corresponding to this first address to the grayscale data comparison circuit 7. The gradation data comparison circuit 7 compares the image data with the reference density data "0" indicating the minimum density from the data counter 8, and if the image data is larger than the reference density data "0", the control data "0" is sent to the shift register 11. If it is smaller, control data "0" is sent to the shift register 11.

In this way, when the processing at the first address is completed, the 7 address counters 5 are sequentially 2°3, . . . -2n
The th address is sent to the data storage device 3, and the data storage device 3 sequentially sends image data corresponding to the 2nd to nth addresses to the grayscale data comparison circuit 7 each time. Here, the image data from the 1st to nth addresses correspond to the image data printed by each of the heating resistors R1 to Rn of the thermal head R, respectively. The grayscale data comparison circuit 7 compares the image data corresponding to the 2nd to nth addresses with the reference density data "1" and sends the control data rOJ or "1" to the shift register 11 in the same manner as above. . 11
The stage shift register 11 sequentially takes in n-bit control data corresponding to the 1st to nth addresses supplied from the grayscale data comparison circuit 7, and sends it to the latch circuit 12.

When the address counter 5 finishes counting the 1st to nth addresses, it sends a data transfer pulse to the data counter 8, latch circuit 12, and control counter 9.

The period Δt of this data transfer pulse is approximately 1/1 compared to the conventional one.
It has been shortened to about 10.

On the other hand, one input terminal of the AND circuit 21 is supplied with the reference clock signal from the terminal 6, and when the data transfer pulse b from the address counter 5 no longer enters the other input terminal, the pulse is transferred to the shift register 11. The control data corresponding to the first to nth addresses of the address counter 5 is transferred from the shift register 11 to the latch circuit 12.

The latch circuit 12 receives 1, l11 supplied from the shift register 11 at the time when the data transfer pulse b is received.
11 data is latched and sent to one input terminal of each of gate circuits G+ to Gn. Gate circuit G1~Gn
The other input terminals of the first and second input terminals are connected to the first and second input terminals as described later. A heating pulse is applied from the second correction circuit 17.18, and NPN transistors T1 to Tn corresponding to each output signal are applied.
is applied to the base of the circuit to control switching. 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.

On the other hand, the address counter 5 sequentially counts addresses from 1 to nWA, but during the reheating time ΔT, the address counter 5 repeatedly reads n image data of the same line from the data storage device 3. And criterion y:
Since the J degree data is held at "0", n pieces of image data for the same one line are repeatedly compared in magnitude with the reference density data having the value "0" in the gradation data comparison path 7.

Therefore, during the reheating time ΔT, a heating current is applied by the power supply voltage of 1 Vcc only to the heat generating resistor to be transferred when the image data is "1" or more, that is, the image data is reheated. For this reason, the white level image data is held as white and is not transferred, and by optimizing the heating preset layer for a density above white, it is possible to optimize the rise in transfer density.

After that, when the control counter 9 finishes counting pulses B by 31 times for the reheating preset l1llI (rnj) and the pulse C becomes high level at time t2, the data counter 8 starts counting operation. After performing the same operation as above once for one line of image data, pulse b is adjusted at time t3, and until then,
The image data (waveform d) shown in FIG. 2 (D) that was “O”
is increased to the value "1" indicating the second density from the smallest.

Thereby, the gradation data comparison circuit 7 sequentially compares the n pieces of image data for one line with the reference density data of the value "1". Even when the reference density data is "1", shift 1-register 11. Latch circuit 12. The AND circuit 21 etc. perform the same operation as above, and the gate circuits G1 to
The latched control data is sent to each of the transistors Gn to control switching of the transistors T1 to Tn. Therefore, a heating current is applied to the heating resistor to be transferred according to the image data, and the transfer is performed.

In this way, after time t2, the reference density data output from the data counter 8 is "0".

rlJ, r2J, ..., rmJ (where m is the value indicating the maximum density), and the density data comparison circuit 7
outputs control data "1" if the image data is greater than the reference density data, and outputs control data "0" if it is equal to or smaller than the reference density data. This rOJ or “
The energization time of the heating current flowing through the heat generating resistor changes in accordance with the control data of ``1'', and gradation recording of data for one line is performed.

Thereafter, when the next start pulse a comes in, the address counter 5 and data counter 8 are reset, and the data counter 8 again reads the reference density data as shown in FIG.
) are sequentially changed as shown after time t1, and the same operation as above is performed to record the gradation of the next line of image data.

By the way, as described above, the reference density data is supplied from the data counter 8 to the gradation data comparison circuit 7 and gradation recording is performed, but at that time, the base 1a degree data is In the data selection circuit 15, data (reference density data) obtained by alternately synthesizing data corresponding to odd-numbered heating resistors and data corresponding to even-numbered heating resistors is supplied to the grayscale data comparison circuit 7. be done.

This will be explained below.

The data (reference density data) output from the data counter 8 is supplied to the terminal A of the data selection circuit 15 via the inversion circuit 14, and the data outputted from the data selection circuit 15 as is.
It is divided into that which is supplied to the end 'FB.

Further, a switching signal for selectively controlling the data supplied to the terminals A and B, respectively, is supplied from the address counter 5 to the data selection circuit 15.

The data selection circuit 15 selects the data supplied to the terminals A and B, respectively, in response to the switching signal from the address counter 5, outputs it from the terminal Y, and supplies it to the grayscale data comparison circuit 7.

Further, among the above data (base Q, i11 degree data) output from the data counter 8, the same data as that supplied to the terminal B of the data selection circuit 15 is supplied to the first correction circuit 17 via the terminal 17a. be done. Further, the same data as that which is supplied to the terminal A of the data selection circuit 17 via the inverting circuit 14 is transferred to the second terminal via the terminal 18a.
is supplied to the correction circuit 18 of. Furthermore, the first correction circuit 1
7 terminal 17b and the terminal 18b of the second correction circuit 18
are supplied with the 1st to nth address data output from the address counter 8, respectively.

Also, 1st. As shown in FIG. 2, the second correction circuit 17.18 includes a correction table storage memory 22. and comparator 2
It is composed of 3.

Furthermore, the operation of the data selection circuit 15 will now be described.

First, when a start pulse (waveform a in Fig. 2 (A>)) is applied to the address counter 5 from the terminal 4, and a reference clock is applied from the terminal 6 to the address counter 5, the first address data is output from the address counter 5. The data corresponding to the address is read from the data storage device 3, and this data is sent to the grayscale data comparison circuit 7.
sent to.

At this time, the data counter 8 outputs the waveform d in FIG. 2(D).
is output, but as mentioned above, the value of this waveform d (reference concentration data) remains at the reset value "0" during the reheating time (6 units).
", that is, the value "0" indicating the minimum concentration is maintained.

Then, the waveform d outputted from the data counter 8 is passed through the inverting circuit 14 and becomes the waveform e in FIG. Supplied to the terminal. Further, the waveform d is supplied as is to the terminal B of the data selection circuit 15.

A switching signal is supplied from the address counter 5 to the data selection circuit 15;
This is a pulse that can clearly indicate the lowest address of , or the even or odd number of heating resistors. Then, this pulse (switching signal) causes terminals A and B of the data selection circuit 15 to
By switching the data (waveforms d and e in FIG. 2 (D) and (E)) respectively supplied to The resulting data (base r4 density data) is output and supplied to the grayscale data comparison circuit 7.

In the density data comparison circuit 7, if the data from the data storage device 3 is equal to or larger than the reference density data from the terminal Y of the data selection circuit 15, control data "1" is sent to the shift register 11; Send control data rOJ to.

At that time, for the data corresponding to the odd-numbered heating resistor among the n heating resistors R1 to Rn, the reference density data output from the terminal Y is the direct rOJ indicating no color development.
Maximum coloring ar! The density (value) is sequentially increased up to the value rmJ indicating 1, and each of these points and the image data read out from the data storage device @3 corresponding to the 1st to nth addresses are compared to the grayscale data comparison circuit. 7, the magnitude is compared, and as a result, control data is sent to the shift register 11. That is, energization from white (colorless) to black is controlled.

On the other hand, for the data corresponding to the even-numbered heat-generating resistor among the heat-generating resistors R1 to Rn of n#A, the reference concentration data output from terminal Y is Contrary to the case, the value rl indicating the maximum color density
The density (value) is sequentially decreased from 1 to 0, which indicates no color development, and each of these points and the image data read from the data storage device 3 corresponding to the 1st to nth addresses are The grayscale data comparison circuit 7 compares the data in terms of magnitude, and as a result, control data is sent to the shift register 11. That is, energization from black to white (colorless) is controlled.

By controlling energization in this way, the total power generated by energizing odd-numbered heating resistors and energizing even-numbered heating resistors can be smoothed, and therefore the conventional energization distribution can be smoothed. The maximum power consumption can be significantly reduced.

On the other hand, the reference concentration data (waveform d in FIG. 2(D)) outputted from the data counter 8 is supplied to one input terminal 16a of the m level detector 16. Further, the value of rm-IJ is supplied to the other input terminal 16a of the m level detector 16 (where m is data indicating a gradation, for example, "6
4).

This m level detector 16 is composed of a comparator, and the value supplied to one input terminal 16a is equal to the value supplied to the other input terminal P16.
A high-level pulse is sent from the output terminal IGc only to the platform larger (>) than the value (rm-1J) supplied to b, that is, only when the reference concentration data reaches the value "m" indicating a maximum of 1 degree. This is a pulse generator that outputs . Further, the pulse output from the output terminal 16c of the m-level detector 16 is supplied to the other input terminal of the AND circuit 13, and the other input terminal of the AND circuit 20. That is, the m level detector 16 detects that the reference density data corresponding to the odd-numbered heating resistor has reached the value rmJ indicating the maximum density.

Next, let's move on to the first point mentioned above. The operation of the second correction circuits 17 and 18 will be explained. In FIG. 2, the correction table storage memory 22 is connected to a terminal 17a by the data counter 8.
Alternatively, the reference concentration data is supplied via the terminal 17a (however, the waveform d in FIG. 3(D) is supplied to the terminal 17a, and the waveform e in FIG. 3(E) is supplied to the terminal 18a). Of this reference density data, data that is in a one's complement relationship with the data supplied to the terminal 18a via the inversion circuit 14 is supplied to the terminal 17a. Then, the correction table storage memory 2
2 corrects the supplied reference density data using a correction table in which correction data is stored in advance so that there is a linear relationship between recording time and density, and outputs the data to one input terminal of the comparator 23. be done.

The comparator 23 is cleared at the beginning of one gradation data time by the address data input from the terminal 17b or 181), and is also supplied with an O-check signal, and is cleared by the input address data and correction data. A pulse (waveform f, 0 in FIG. 3 (F), (G)) that rises at the falling time of the data pulse and has a pulse width that changes depending on the content of the correction data is generated, and output terminal 17c or 18c is generated. (However, waveform f is output to output terminal 17G, and output terminal i8
The waveforms are output to c).

The device constituted by the output terminal 17c or 18c is supplied as a heating pulse to each other input terminal of the gate circuits G1 to Gn.

Each of the gate circuits G1 to Gn applies a gate signal obtained by gate processing the heating pulse and the υItll data supplied from the latch circuit 10 to the NPN transistors T1 to Gn.
Supplied to each base of Tn. Transistor T1-T
n is the collector of the transistor whose heating current is turned on among the heating resistors R1 to Rn by the voltage applied to the voltage input terminal 19 when the gate signal supplied to its base 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 changes depending on the coloring density is passed through some of the heating resistors R1 to Rn corresponding to the page portion to be recorded, and recording is performed. will be carried out. Also, the data counter 8 is 1 to m.
Each time the count of times (m is the value of the maximum color density) is completed, one line is recorded on the recording paper, and after the recording of this one line is completed, the data counter starts counting again from 1 to m times. .

Then, as described above, it is detected that the reference concentration data corresponding to the odd-numbered heating resistor has reached the value rmJ indicating the maximum concentration, that is, after the main energization is completed, the even-numbered heating resistor The value of the reference concentration data corresponding to the body is calculated as follows: The value of the reference concentration data corresponding to 1ift r OJ, which indicates the minimum density white, during the thermal time).

Therefore, in the same way as above, the reheating time ΔT after main energization
Inside, a heating current is supplied by the power supply voltage +Vcc only to the heating resistor to be transferred when the image data is "1" or more, that is, according to the image data, and heat is recuperated.

As described above, according to the signal supplied from the control counter 9, during the reheating time before main energization, the reference concentration data corresponding to the odd-numbered heating resistor is set to the value rOJ indicating the minimum concentration, During this reheating time ΔT before main energization,
A current is applied to only the heat generating resistors to which input data having a value larger than the value representing the minimum density corresponding to the odd numbered heat generating resistors is to be transferred, thereby reheating the heat generating resistors. In other words, during the reheating period ΔT, no current is passed through the heat generating resistor at the white pixel position and no heat is generated (heat replenishment), so that white background staining does not occur. Furthermore, after the reheating time of the above-mentioned main energization hall,
The reference concentration data corresponding to odd-numbered heating resistors increases (or decreases), and conversely, the reference concentration data corresponding to even-numbered heating resistors decreases (or increases). The reference density data and the input image data to be transferred are compared for each unit of density to generate density data. Correction data is set by the first and second correction circuits 17 and 18 so that the relationship between the recording density and the density data corresponding to the odd-numbered and even-numbered heating resistors, respectively, becomes a straight line or a predetermined curve. are generated, and recording is performed by passing current through the heating resistors of the odd and even numbers for a time based on the value of the correction data. Then, during the reheating time ΔT after the end of main energization when the reference concentration data corresponding to the odd-numbered heating resistor reaches the value rmJ indicating the maximum concentration, the reference concentration data corresponding to the even-numbered heating resistor The concentration data is the value "0" indicating the minimum concentration
During the reheating time ΔT after this main energization, current is applied only to the heating resistors to which input data with a value larger than the minimum concentration rOJ corresponding to the even-numbered heating resistors is to be transferred. , reheated.

Therefore, both the odd-numbered blocks made up of odd-numbered heat-generating resistors among the plurality of heat-generating resistors and the even-numbered blocks made up of even-numbered heat-generating resistors can conduct electricity in a well-balanced manner. In particular, the gradation characteristics from the intermediate level to the black level can be improved, and the rising characteristics at the white level can also be improved.

Moreover, since the reheating time is divided into two periods, one before and after the main energization, when paying particular attention to the reheating time, the maximum power consumption during this time can be significantly reduced.

Note that the analog video signal supplied from the TV signal generator 1 may be an information signal of an image of another character or figure. In addition, although the above embodiment has been described in the case where the relationship between the recording density and the density data is a straight line, the relationship between the recording i degree and the density data may be a predetermined curve.

(Application example) In the above embodiment, the image quality is improved and stabilized, but for example, the a-degree distribution of one line of the image is centered around the intermediate level, as shown in FIG. Maximum power consumption can be reduced for images whose levels are distributed from white level to black level. However, as shown in Figure 5, for an image where only the black level is distributed, there is no difference at all from the maximum power consumption under normal energization; in this case,
Maximum power consumption cannot be reduced. That is, in the above-described embodiment, the maximum power consumption can be reduced only for the image shown in FIG.

Therefore, as shown in Figure 5, the maximum 8! An application example that makes it possible to reduce I-cost power will be described below.

FIG. 6 is a block system diagram showing this application example, and the figure shows an example of the thermal transfer gradation control device according to the present invention shown in FIG. It shows only the part.

In the figure, the address data from the address counter 5 is supplied to the terminal 18b of the second correction circuit 18, and the inverting circuit 24 is connected to the terminal 18b of the second correction circuit 18.
is connected, and the inverted address data is supplied to the terminal 1111b via this inversion circuit 24. Then, the second correction circuit 18 generates a pulse (waveform h) as shown in FIG. 3(H) and outputs it from the output terminal 18G. This pulse (waveform h) is outputted from the terminal 17G of the first correction circuit 17 as shown in FIG. 3(F) only during the low level of this waveform f. , the waveform is at a high level.

Therefore, the first. Terminal 17c of second correction circuit 17.18
, 18c, respectively (waveform f).

h) are respectively supplied as heating pulses to the other input terminals of the gate circuits G1 to Gn, and each of the gate circuits G1 to Gn gate-processes the heating pulses and the control data supplied from the latch circuit 12. The current flow to the heating resistors R1 to Rn is controlled by the gate signal, but for example, for an image like the one shown in FIG. 5, all the thermal heads are energized as data. Also, 1st. The output pulses (waveforms f, h) of the terminals 17c and 18c of the second correction circuit 17.18 have the relationship shown in FIG. Since the waveform is at a high level only in the inside, the current consumption (heating current) from the voltage input terminal 19 is less than ÷ during normal energization.

In short, in the above application example, the heating resistors G1 to G
The first correction circuit 17 is installed in the "odd block" consisting of heat generating resistors corresponding to the odd gate circuits among n.
A heating pulse output from the terminal 17c is supplied to control the energization of the odd-numbered heating resistors (odd-numbered blocks), and also correspond to the even-numbered gate circuits among the heating resistors G1 to Gn. The heating pulse output from the end 18c of the second correction circuit 18 is supplied to the "even blocks" made up of heat generating resistors, and the energization of the even numbered heat generating resistors (even blocks) is controlled. However, when recording one gradation level, the heating pulse (output pulse of the first correction circuit 17) that controls the odd-numbered blocks is 11! ! J
The energization time is determined according to the gradation level starting from the beginning of the 1st gradation level, and the heating pulse (output pulse of the second correction circuit 18) for υItIl of the even numbered block starts after the 1st gradation level. The pulse is designed to determine the energization time in accordance with the gradation level in the direction.

Therefore, according to the configuration of the application example described above, it is possible to reduce the maximum power consumption even for an image where only the black level is distributed as shown in FIG.

(Effects of the Invention) As described above, according to the thermal transfer gradation control device of the present invention, recording time and density have a substantially linear relationship, and gradation recording with excellent linearity can be performed. In particular, it can improve the gradation characteristics from intermediate level to black level,
Furthermore, if the density rise characteristic at the white level can be improved, the maximum power consumption can be significantly reduced, and the cost of the power supply can therefore be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block system diagram showing an embodiment of the thermal transfer gradation control device according to the present invention, and FIG. A block system diagram showing an embodiment of the second correction circuit, FIGS. 3(A) to 3(1-1) are waveform diagrams of each part of FIGS. 1 and 6, and FIGS. 4 and 5. is image 1
FIG. 6, which is a diagram showing each line density distribution, is a block system diagram showing the main part of an application example related to the thermal transfer gradation fI+11tl apparatus according to the present invention. 1...TV signal generator, 2...A/D conversion device,
3...Data storage device, 4, 6.16a, 1flib, 17a, 17b. 18a, 18b...input terminal, 5...address counter, 7...gradation data comparison circuit, 8...data counter, 9...control counter, 10.
・・Heating preset source, 11 ・・Shift register, 1
2... Latch circuit, 13.20.21... AND circuit, 14, 24... Inverting circuit, 15... Data selection circuit, 16... m level detector, 16c, 17c, 18c. ...Output terminal, 17...
-First correction circuit, 18...Second correction circuit, 19.
... Voltage input terminal, 22... Correction table storage memory, 23... Comparator, G1 to Gn... Gate circuit, R... Thermal head,
R1-Rn...Resistor for heat generation. T1 to Tn...NPN type transistors. Masutokishi 5 times

Claims (1)

[Claims] In a thermal transfer gradation control device that individually controls the time of each current applied to a plurality of heat generating resistors arranged in a line according to the concentration, a control counter that generates and outputs a signal corresponding to the time; and a value indicating the minimum concentration during the reheating time is maintained according to the signal supplied from the control counter, and after the elapse of the reheating time, the value is increased from the minimum concentration to the maximum concentration. means for generating reference concentration data that sequentially changes in a short period of time up to a value indicating the concentration; Data selection means for separating the reference concentration data corresponding to the resistor and the reference concentration data corresponding to the even-numbered heating resistors so that they are in a 1's complement relationship, and synthesizing and outputting these data. The reference density data outputted from this data selection means is compared with the input image data to be transferred, and gradation data indicating the time period of current flowing through a plurality of rows of the heating resistors for each unit of density is obtained. pulse generating means that is supplied with reference concentration data corresponding to the odd-numbered heating resistor and outputs a pulse when the reference concentration data reaches a value indicating a maximum concentration; The reference date data corresponding to the heating resistor is supplied, and the relationship between the pre-stored memory density and the reference density data corresponding to the odd-numbered heating resistor is set to be a straight line or a predetermined curve. a first correction data generating circuit that outputs the corrected correction data according to the inputted reference concentration data corresponding to the odd-numbered heating resistor; and The data is supplied, and correction data set so that the relationship between the pre-stored storage density and the reference density data corresponding to the even-numbered heating resistor becomes a straight line or a predetermined curve is applied to the input data. a second correction data generation circuit that outputs according to reference concentration data corresponding to even-numbered heating resistors; A thermal transfer gradation control device characterized by comprising: means for applying current in units.