JPS62179276A - Thermosensible transfer gradation controller - Google Patents

Abstract

PURPOSE:To obtain a high speed and stable and faithful gradation representation by reducing the influence applied to the present line recording by the residual quantity of heat within a concurrent heating time. CONSTITUTION:According to the residual quantity of the respective heating resistors through preceding line recording data, the time for concurrently heating the respective heating resistors in the present line recording time is controlled. Namely when the recording of the second line is carried out, the heating resistor is not energized from the time tc to the time td after the time DELTAt' required for cooling the residual quantity of heat of the preceding line elapses but cooled. Thereafter, from the time td, according to a predetermined recording density, the heating resistor is energized, as a result, it is heated to a predetermined temperature Tc. Thus, the correct gradation representation can be obtained.

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 applying a constant current to a heating resistor of a thermal head, and The present invention relates to a thermal transfer tone control device that controls tone.

As conventional printers (hard copy devices) for terminals, thermal transfer printing devices have been developed as the most promising printers for wire dot and inkjet printers. This thermal transfer printing device uses an ink film in which heat-melting ink is coated on one side of a polyester film with a thickness of 5 to 6 μm, for example, the front ink side of the ink film is brought into contact with recording paper, and the back side is placed with a thermal head. A current is applied to the thermal head to generate heat, thereby melting the ink on the ink film at the position corresponding to the thermal head and transferring it 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 duration of the current applied to each heating resistor.

However, in the thermal response of the heating resistor in the thermal transfer printing device, in order to express one gradation, it is necessary to
Since the IUS interval is required, there is a problem in that the printing time cannot be increased.

Therefore, the present applicant previously proposed in Japanese Patent Application No. 1179'16/1983 to reheat only the heating resistor to be transferred, and to reduce the print density by 100%.
We proposed a thermal transfer gradation control II device that controls the energization time of each heating resistor for each unit. Such a thermal transfer gradation control device is, for example, Ana [! The video signal 8 is converted into a digital signal (
image data) and outputs it to the grayscale data comparison circuit. This density data comparison circuit uses - standard density data sent from the data counter (data that maintains the minimum density during the reheating time, and then increases sequentially) and the above-mentioned image data of the same number as the heating resistors. If the value of this image data is equal to or larger than the value of the reference density data, a high level output signal is supplied to one input terminal of the gate circuit, and if it is smaller than the rl density data, a low level output signal is supplied. The output signal of the gate circuit is supplied to one input terminal of the gate circuit.

Thereafter, the above operation is repeated in the same manner as above until the reference 83 degree data reaches the maximum density.

On the other hand, a heating pulse is supplied 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, and the heating pulse is applied to the corresponding heat generating resistor. cause the body to heat up. In this way, a heating pulse is applied to the plurality of heating resistors for a time corresponding to the concentration, and a pulsed current is caused to flow, thereby controlling the gradation.

However, in the conventional thermal transfer gradation control device described above, there is no consideration of the temperature state of the heating resistor due to the previous line recording data that has already been recorded, and the general temperature of the heating resistor is focused only on the current line recording data. Since the dead time was controlled by υ, the heating resistor was heated more than necessary due to heat accumulation.
Therefore, there was a problem that stable gradation expression could not be obtained.

Therefore, the present applicant previously proposed in Japanese Patent Application No. 60-279687 a thermal transfer gradation control device that corrects the current line recorded data according to the amount of residual heat in each heating resistor based on the previous line recorded data. .

Such a thermal transfer gradation control device corresponds to the amount of residual heat in each heat generating resistor due to the second recorded data of the previous line from the number of gradations of the first recorded data (corresponding to the image data) of the current line. A conversion table that subtracts the number of gradations and outputs the obtained kma number as third recorded data, and stores the third recorded data from the conversion table, and converts the third recorded data to the second recorded data of the previous line. and a memory for supplying the conversion table to the conversion table, and is configured to control the time of each current flowing through the heating resistor according to the third recorded data from the conversion table.

In addition, in the above conversion table, the number of gradations of the second recording data of the previous line is p (however, p is an integer of p≧0), the thermal fall time constant of the heating resistor is α, and the printing period of one line is When is t, the l'ia number q(
However, it is configured to output the third data q' obtained by calculating q (an integer with q≧O) using the variable formula %.

Problems to be Solved by the Invention However, in the above thermal transfer gradation control device proposed by the present applicant, the value of the reference density data is held at the value "0" indicating the minimum density during the reheating time. Therefore, if you adjust the system by setting the value of the previous line recorded data to "0" (white level), for example, the value of the previous line recorded data will become r6.
3J (black level), high-density data is recorded on the current line due to the residual heat m of the previous line, and when the system is adjusted by setting the value of the previous line recorded data to ``63'', the previous line recorded When the data value is "0", the recording density of the current line will decrease.

In addition, in the above-mentioned conventional device, for example, human image data (first
When the value of the recorded data (recorded data) is "40" and the conversion calculation value of the conversion table becomes "44.5J", this data value must be replaced with "45" or "44", which is output from the conversion table. The third recorded data contained errors with respect to the input image data, and there was a problem in the fidelity of gradation expression. Furthermore, the conversion formula is 1 line printing period ti+
tg) Since it is a gII number, it is not easy to change the recording time of the system, and when changing the recording time, it is necessary to convert the entire table.

Therefore, the present invention solves the above problems by controlling the time for reheating each heating resistor during current line recording according to the amount of residual heat in each heating resistor based on the previous line recording data. The purpose is to provide a thermal transfer gradation control device.

Means for Solving the Problems The thermal transfer gradation control device according to the present invention includes means for compressing previous line recorded data and converting it into previous line compressed data;
The apparatus includes means for generating reference density data, and means for generating control data in accordance with a comparison result of the reference density data and the recording data consisting of the previous line compressed data and the current line recording data.

The previous line recorded data of action x (where X is an integer of 2 or more) bits is converted to the previous line compressed data of y (where y is an integer such that 0<y<x) bits.

On the other hand, the reference density data is 2xm during the reheating time set at the beginning of the 1-line recording time (where m indicates the maximum number of gradations, and m = 2.2, O≦2≦2y-1). (integer) changes sequentially from the maximum value to the minimum value in a predetermined order, and the minimum m
The number of gradations changes sequentially in a predetermined order from the degree to the number of gradations indicating the maximum density.

Next, the previous line compressed data of y bits is bound to the upper bit, and the recorded data of total (X 10 V) bits, including the current line recorded data of X bits as the lower bit, is compared with the reference density data. , control data is generated according to the comparison result. Thereafter, the time of each current flowing through each heating resistor is controlled according to this control data.

Embodiment FIG. 1 shows a block system diagram of an embodiment of a thermal transfer gradation control device according to the present invention. In the figure, a thermal head 6 includes n heating resistors R+ 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. 6, for example. Fourth
In the figure, 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 conveyed along with the ink film 1 in the direction of the arrow by the roller 5, with its recording surface facing the ink 3 surface of the ink film 1. 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 R+''Rn of the thermal head 6 is melted and transferred onto the recording paper 4.The ink film 1 passes through the thermal head 6. After that, it is guided by the roller 7 and separated from the recording paper 4, and then the take-up spool (not shown)
The ink film is wound up as a 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 - heating resistor, and each dot has a size of 1 to 1 and the current flowing through the heating resistor is
Determined by value or energization time. The shading, or gradation, of the printed figure is determined according to the size of each dot.

The present invention is a gradation control device that can be applied to such a thermal transfer printing device.
The analog video signal supplied from the V signal generator 8 is Δ
The data is converted into a digital signal with a quantization bit count of 6 bits, for example, by a /D conversion device, and sent to the data storage store 10 and stored therein.

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. The above-mentioned start pulse is a pulse as shown by a in FIG.
6 etc., address counter 11 and data counter 1
5 is largely reset, and the control counter 1
4 is loaded with a preset reheating preset value from the reheating preset source 16. This reheating preset value is used to determine the reheating time, which will be described later, and includes the period of pulse b shown in FIG. 2(B), the voltage applied to the thermal head 6, and the pressing force between the thermal head 6 and the recording M4. , further determined by the ambient temperature, etc. 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 14 generates 'i' based on the reference clock signal supplied from the address counter 11.
82. Pulse b shown in FIG.
During the reheating time Δt of 3, as shown in FIG. 2(C),
A signal C which becomes a low level and then a high level is supplied to the data counter 15 and the previous line compressor 17, respectively.

The address counter 11 sends the first address to the data storage device 10 upon receipt of the start pulse a.

The data storage device 10 supplies, for example, 6-bit recording data (the first data of the image data from the A/D converter 9) according to this first address to the previous line compression device 17 and the grayscale data comparison circuit 18, respectively. do.

The front line compression device 17 stores the 6-bit previous line recording data and then compresses the heat generating resistor R) by recording the previous line.
This is for converting into, for example, 2-bit previous line compressed data according to the residual heat amount of Rn, and reading this to the grayscale data comparison circuit 18 when recording the current line. In this case, if the time vs. residual heat characteristic is linear, the upper two bits of the 6-bit previous line recording data can be inverted and used as the previous line compressed data, but if it is non-linear, the 6-bit previous line recording data can be used as the previous line compressed data. Recorded data is non-linearly compressed into 2-bit previous line compressed data. After that, the front line compression device 17
During current line recording, the 2-bit previous line compressed data is repeatedly read during the reheating time when the signal C is at a low level.

On the other hand, the data counter 15 receives the start pulse a,
Pulse b and signal C are supplied, respectively, to generate, for example, 6-bit reference density data as shown in FIG. During the period, the value indicating the minimum density white (white level value) is held at "O", and during the period from time t3 to t6 when the signal C becomes high level, the value changes from the value "0" to the value indicating the maximum density black. The value is increased by 1 until (black level value) rm-14 (where m indicates the maximum number of gradations).

The data counter 15 outputs this reference density data to the density data comparison circuit 18 and the correction table storage memory 19, respectively. In this case, since the reference aa data is 6 bits, the maximum number of gradations is m=26=64. Therefore, the value of the reference temperature data changes from "0" to "63".

In the correction table storage memory 19, the address value when the signal C is at a low level from the control [call counter 14] is input, and accordingly, as shown in FIG. The values are r3J, r2J, rlJ
.

The gray data comparison circuit 18 uses the 6-bit current line recorded data from the data storage neck 10 as the upper bits, and the 2-bit previous line compressed data from the previous line compressor 17 as the upper bits, of a total of 8 bits. 1 data and 6-bit lt from data counter 15.
A total of 8 bits of second data is generated, with the \density data as the lower bits and the 2-bit data from the correction table storage memory 19 as the upper bits.

As shown in FIG. 2(D) (or FIG. 3(C)), the values of the second data d are r3mJ, r2mJ, and rmJ for the reheating time Δ from time t1 to t3.

It gradually decreases to "0". Here, one gradation or one step recording time (that is, the period of pulse b) is expressed as ts, and when t is set to Urate time as Δ1=10ts, for example, the above-mentioned r3mJ.

The data periods for r2mJ, l-ml, and rOJ are ts, respectively.
, 2ts, 3ts, 4ts.

After that, the values of the second data d are changed from time t3 to time t6 to rob, rlJ, r2J, ..., 1m-2J, 1-
It increases by 1 for each step recording time ts like m-IJ.

On the other hand, the value of the previous line compressed data is i (however, i is 0≦i
≦3) and the value of the current line recording data is k, the grayscale data comparison circuit 18 includes the data storage device 1
0 to the current line recording data of 6 bits as shown in FIG.
3 to t6, the 2-bit previous line compressed data held at the value r01 is supplied, respectively. Therefore, the first
The value of the data is from time t1 to t as shown in FIG. 4(C).
3, it is held at the value "i-m+k", and from time t3 to t6, it is held at the value rkJ.

The gray data comparison circuit 18 compares the first and second data that change as described above, and if the first data is greater than or equal to the second data d, it outputs control data "1" to the shift register 20. Send, if small, shift register 2
Send 1IIIll data 10 to 0.

Therefore, when performing the process of inputting data to the first address from the address counter 11, if the value of the previous line compressed data at the first address is i, then the first
The data “11 ・m+kJ” and the second data “3m” are compared in the grayscale data comparison circuit 18, and ri+
When −m+kJ≧3m, control data “1” is sent out, and when [11·m×kJ<r3mJ”, control data “0” is sent out.

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 bag N10 sequentially sends the recording data corresponding to the 2nd to n-th addresses to the previous line compression device 17 and the grayscale data comparison circuit 18 each time. Here, the recording data from the 1st to nth addresses correspond to image data printed by the heating resistors R1 to Rn of the thermal head 6, respectively. In this case, if the values of the previous line compressed data at the 2nd to nth addresses are respectively 12 to in, then 2 to n
First data ri2 −m+k at the second address
J~[in-m+kJ and the second data "3m" are compared in the gray data comparison circuit 18, and in the same way as above, a
1 control data “0” or “1” is sent to the shift register 20.

On the other hand, when the address counter 11 finishes counting the 1st to nth addresses, it sends a data transfer pulse b shown in FIG. 2(B) to the control counter 14, data counter 15, and latch circuit 21, respectively. data counter 1
5 supplies a heating pulse to the address counter 11 and one input terminal of each of the AND circuits 22 and 23 at the same time as this data transfer pulse b is sent.

A reference clock signal is supplied from the terminal 12 to the other input terminal of the AND circuit 22, and the data counter 1
At the same time as the heating pulse from No. 5 is input, the pulse is output to the shift register 20 to transfer n-bit control data corresponding to the 1st to nth addresses of the address counter 11 from the shift register 20 to the latch circuit 21. When the data transfer pulse b is received, the latch circuit 21 latches the control data supplied from the shift register 20 and sends it to one input terminal of each of the gate circuits G+'' and Qn.

On the other hand, the address counter 11 is reset by the arrival of the heating pulse and sequentially counts 1 to n addresses again.

Such an operation is repeated, and the control data is sequentially changed to 1 according to the comparison result between the first data and the second data d.
The signal is sent from the one-light data comparison circuit 18 to one input terminal of each of the gate circuits 01 to Gn via the shift register 20 and latch circuit 21.

In this case, for example, when the value 11 of the previous line compressed data in the heat generating resistor R1 is "0" and the value of the current line recorded data is k, the value of the first data is at time 1.
-1. The control signal f (control data) supplied to one input terminal of the gate circuit G1 is held at "0" between times t3 and t6, and is held at rkJ between times t3 and t6, as shown in FIG. 2(F). As shown, the low level (control data value rOJ) is between time t1 and t2, and the high level (control data value rOJ) is between time t2 and t5.
The control data value [11] is at a low level between times t5 and t6.

On the other hand, the correction table storage memory 1 generates pulses of data corrected using a correction table in which correction data is stored in advance so that the reference density data has a linear relationship between the recording time and the ci degree. It is sent to the device 24. The pulse generator 324 is at a high level during a predetermined period including the reheating time Δt according to the incoming correction data, and after this period, generates a pulse signal whose pulse width gradually changes to reduce the AN.
It is output to the other input terminal of the D circuit 23. AND circuit 2
3 generates a pulse e shown in FIG. 2(F) by the incoming heating pulse and the pulse signal, and outputs the gate circuit
1 to Gn to each other input terminal.

As shown in FIG.
The period (up to t4) has a predetermined pulse width, and after this period, the pulse width gradually decreases, for example, depending on the data content of the correction data sent from the correction table storage memory 19.

The gate circuits G1 to Qn respectively gate the pulse e and the n-bit control data supplied from the latch circuit 21 to apply gate signals to the NPN transistors T1 to T.
n to each base and control switching of these. 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.

In this case, for example, for the heating resistor R1, a gate signal Q as shown in FIG. Therefore, the heating resistor R1 is heated during the period from time t2 to t5 when the pulse signal e is at a high level.

In this way, vA tone recording for one line is performed.

When the next start pulse a arrives, the address counter 11, data counter 15, etc. are reset, and the data counter 15 and correction table storage memory 19 store the second data d as shown in FIG. 2(D). Time 1
．． -1. As shown in FIG. 2, the tone is changed sequentially, and the same operation as above is performed to record the gradation of the first data for the next line.

In this way, according to the present embodiment, the correction table storage memory 19 etc. can perform approximately linear density control from the white level to the black level, and the previous line compression device 17 etc. Since the 'CJC system is performed when recording the current line in consideration of the influence of heat T on the temperature distribution of the heating resistor, accurate +i tone expression is possible.

In addition, the data structure used in this embodiment is mainly 8 bits, and even in the case of 6 bits, 6 bits out of 8 bits are used for data processing.
The current line recording data, etc. is assumed to be 6 bits, and the data is changed from 8 bits to 6 bits.
By subtracting one bit and using the remaining two bits to reduce the influence of the residual heat section of the previous line, there is an advantage that no major changes are required to the existing system.

Note that the number of bits of various types of recording data according to the present invention is not limited to this embodiment, and the number of bits of 6-bit current line recording data and reference density data is
It is sufficient that the 2-bit previous line compressed data and the output data of the correction table storage memory 19 are each y (where y is Q<y<x
It suffices if it is an integer) bit data.

At this time, the value of the second data is l during the reheating time.
xm (where 2 is an integer satisfying O≦2≦2y−1) changes sequentially from the maximum value to the minimum value in a predetermined order.

Next, the humidity characteristics of the heat generating resistor in the apparatus of the present invention will be explained with reference to FIG. Here, ■ indicates the temperature characteristic of the conventional device, and ■ indicates the temperature characteristic of the device of the present invention. Now, when recording the first line, the heat-generating resistor is reheated for a reheating time Δ from time ta, and then circulated according to the recording temperature to generate heat up to the required temperature Ta at time tb. Forced. Thereafter, the heat generating resistor is cooled (that is, energization of the heat generating resistor is stopped) from time ta until time tc after one line recording time tL has elapsed. Here, one line recording time tL is one step recording time t
s, the maximum number of gradations m, and the number of reheating stages I before gradation expression S (
However, S is an integer greater than or equal to O and F, and in this example, 5=10
), it is expressed as tL = (m+5)ts.

Next, when performing recording on the second line, in the conventional apparatus, the heating resistor is energized for the required energization time including the reheating time Δt to reach the target temperature f! Heat is generated up to a temperature Tb higher than ITc. For this reason, with the conventional device, accurate LFI tone expression could not be obtained.

On the other hand, in the device of the present invention, the time Δt' required to cool down the amount of residual heat in the previous line from time tc (where Δt'≦Δt) is not energized to the heating resistor until time td after R'lA. not carried out (i.e. not reheated),
Allowed to cool. Thereafter, from time td, the heating resistor is energized according to the required recording density, and as a result, heat is generated up to the required temperature TC. In this way,
With the device of the present invention, accurate gradation expression can be obtained.

Note that the interval between each data If1 in the reheating time Δ of the second data d is not limited to the present embodiment shown in FIG. 2(D), and may be set arbitrarily. . Further, this data period is not limited by the one-step recording time ts, and does not need to be set to the same period.

Further, it goes without saying that the analog video signal supplied from the TV signal generator 8 may be an information signal of an image of another character or figure.

Effects of the Invention Song As described above, according to the present invention, the time for reheating each heat generating resistor in the current line arrangement is controlled according to the residual heat amount of each heat generating resistor based on the previous line recorded data. As a result, the influence of the residual heat amount on the current line record can be reduced within the reheating time.
It is possible to obtain stable and faithful gradation expression, and
For example, in the data structure of the current 8-bit system, the remaining 2 bits that are not used for 6-bit recording data are used as pre-line compressed data that indicates the amount of residual heat, making a major change to the current system. The present invention has the advantage that the device of the present invention can be realized without any trouble, and the circuit configuration is easy.

[Brief explanation of drawings]

FIG. 1 is a block system diagram showing an embodiment of the thermal transfer gradation 1+1J system according to the present invention, and FIGS. 2 to 4 are signal waveform diagrams for explaining the operation of the block system shown in FIG. FIG. 5 is a temperature characteristic diagram of an example of the apparatus of the present invention, and FIG. 6 is a schematic perspective view of an example of the main part of a thermal transfer type printing apparatus to which the apparatus of the present invention can be applied. 6...Thermal head, 10...Data storage device, 11
...Address counter, 12...Reference clock signal input terminal, 13...Start pulse signal input terminal, 1
4... Control counter, 15... Data counter, 16... Reheating preset source, 17... Front line compression device, 18... Grayness data comparison circuit, 19...
- Correction table storage memory, 20... Shift register, 21... Latch circuit, 22.23... AND circuit, 24... Pulse generation circuit, 01-Gn... Gate circuit, R1-Rn.・Heating resistor, T1~l'-n・
...Transistor. Patent applicant: Victor Company of Japan Co., Ltd. 6, 2, same patent attorney: Kaneyuki Matsuura

Claims (2)

[Claims] (1) In a thermal transfer gradation control device that individually controls the time of each current flowing through a plurality of heating resistors arranged in a row according to the density, x (where x is an integer of 2 or more) bits means for converting the previous line recorded data into previous line compressed data of y bits (where y is an integer such that 0<y<x) corresponding to the amount of residual heat of each heating resistor, and outputting the same, and one line recording time. lxm (however, m indicates the maximum number of gradations, m = 2^x, e is 0≦l≦
2^y-1 (integer)) changes in a predetermined order from the maximum value to the minimum value, and from the end of the reheating time until the end of the one line recording time, the gradation shows the minimum density to the maximum density. means for generating reference density data that sequentially changes in a predetermined order up to a predetermined order; and recording a total of (x+y) bits in which y bits of the previous line compressed data are the upper bits and x bits of the current line recording data are the lower bits. and means for generating control data according to a comparison result between the recording data and the reference density data, and controlling each current to be applied to the heating resistor to be transferred according to the control data. A thermal transfer gradation control device characterized by being configured to control time. (2) The thermal transfer gradation control device according to claim 1, wherein the x bits are 6 bits and the y bits are 2 bits.