JPS63166559A - Thermal-type multigradation recorder - Google Patents

Abstract

PURPOSE:To enable recording to be perform without any effects of variations in the temperature of a heat-sensitive body, by selecting a gradation level representing the level of recorded density according to an image signal, determining an energization time corresponding to the gradation level, and energizing for the energization time corresponding to the gradation level from the time of start of color forming in response to the temperature of the heat-sensitive body. CONSTITUTION:A data selector 7 first transfers digital image data DB to a thermal head 15 according to a control input from a line counter 9, and setting an STR 1a of a STB selector 31 to a high level according to a control input from the line counter 9, whereby printing for the first segment is started. A thermistor 17 detects the temperature of a substrate of a thermal head 15, and outputs a resistance value to an energizing pulse generating circuit 19. An energization time selector 29 selects the energizing pulse generating circuit 19, and the thermal head 15 is energized for the energization time tB according to the resistance value sent from the thermistor 17. The operation is similarly repeated for four segments, thereby completing printing in one line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a thermal multi-gradation recording device that generates color by applying electricity to a heat sensitive member in accordance with an image signal.

(Prior Art) As a method for recording image signals in a printer or the like, there is a thermal recording method using a thermal head which has a simple mechanism, low noise, and high reliability. Conventionally, a thermal multi-gradation recording device using this thermal recording method applies electricity to a recording electrode made up of a heating element of a thermal head, and controls the duration of the electricity to print on a thermal paper placed in contact with the recording electrode. the color i
! ! It is printed in different shades of light.

A specific example of this is disclosed in Japanese Patent Publication No. 54-659. This Japanese Patent Publication No. 54-659 provides an energizing pulse width generating circuit with the same number of different pulse widths as the so-called gradation level, which indicates the shading of the color of the image data when image data is input.C1 corresponds to this gradation level. A multi-gradation recorded image is obtained by selecting the energizing pulse width generating circuit to control the energizing time of the thermal head. In this device, it was necessary to provide an energizing pulse width generating circuit depending on the gradation level.

(Problems to be Solved by the Invention) Conventional apparatuses select an energizing pulse width generating circuit in response to multiple gradation levels of image data, and control the energizing time of the thermal head.

However, in order to control the energization time of the thermal head, a control circuit must be provided to control the energization time, which has the disadvantage that the circuit becomes complicated. As a countermeasure against this problem, Japanese Patent Application Laid-Open No. 61-64466 is disclosed. This Japanese Patent Application Laid-Open No. 61-64466 discloses that data representing the energization time of the thermal head corresponding to the gradation level when the temperature of the thermal head is used as a parameter is stored in a ROM in advance, and the temperature of the thermal head detected by a temperature detection means is Voltage application time data corresponding to the temperature is read from the ROM, and the current application time of the thermal head is controlled using this voltage application time data. However, this Japanese Patent Application Publication No. 61-644
66 requires a large number of ROMs by storing a large number of voltage application time data in the ROM in order to obtain a clear image, and since the price of this ROM is expensive, the price of the device increases. Therefore, a countermeasure was desperately needed.

This invention has been made in view of the above, and its purpose is to provide a thermal multi-gradation recording device that is capable of recording without complicating the circuitry and being unaffected by changes in temperature of the thermal sensitive body. It is about providing.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides an apparatus for recording by energizing a heating element of a heat sensitive body to develop color according to an input image signal. a gradation level selection means for selecting a gradation level indicating a level of recording density according to the image signal; and an energization time determining means for determining an energization time corresponding to the gradation level of the gradation level selection means. , a coloring start means for detecting the temperature of the heat sensitive body and outputting a coloring start time in response to this temperature; and a energizing time corresponding to the gradation level of the energizing time determining means from the coloring start time of the coloring starting means. The gist of the present invention is to have an energization control means for energizing and coloring.

(Function) When the thermal multi-gradation recording apparatus having the above configuration performs recording, a gradation level indicating a recording density level corresponding to an image signal is selected by the li-level selection means, and this lj
! Determine the energization time corresponding to the iWA level and start coloring in response to the temperature of the heat sensitive element.

Since the current is applied for a period of time corresponding to the gradation level between the two and the color is developed, recording can be performed without being affected by changes in the temperature of the thermosensitive member.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a thermal multi-gradation recording apparatus of the present invention.

The configuration of this embodiment consists of an analog-to-digital conversion circuit 1. OR gate 3, 1 line memory 5. Data selector 7, line counter 9, 1 line memory WRCK generation circuit 11
．． Print GK generation circuit 13, thermal head 15. It has a thermistor 170, energization pulse generation circuits 19-272, energization time selector 29, STR selector 31, and AND gates 33-39.

An analog-to-digital conversion circuit (hereinafter referred to as A/D conversion circuit) 1 receives an analog image signal from an input terminal Ain, converts it into digital image data, and sends it to an output terminal D.
This is to output from the BO-DB 3 to the 1-line memory 5.

The OR gate 3 performs the logical sum of the digital image signals output from the A/D conversion circuit 1, gives a coefficient corresponding to each bit, so-called weight, and outputs the data DB of the one-line memory 5.

The one-line memory 5 stores one line of digital image data input from the input terminals DIO to DI4, and outputs the digital image data to the data selector 7 from the output terminals D00 to D004.

The data selector 7 outputs digital image data inputted from the one-line memory 5 to the data input terminal DI of the thermal head 15 under control input from the line counter 9.

The line counter 9 counts the image data input to the one line memory 5 when drive signals from the one line memory WRCK generation circuit 11 and the print GK generation circuit 13 are input, and controls the data selector 7 and the thermal head 15. It outputs an LA latch signal to the LA latch terminal.

The 1-line memory WRCK generation port 11 outputs a clock signal that instructs the line counter 9 to count when an analog image signal is input to the A/D conversion circuit 1.

The print GK generation circuit 13 outputs a clock signal to the line counter 9 and the CK (clock) terminal of the thermal head 15 in response to a pulse input from an energization time selector 29, which will be described later.

The thermal head 15 has a data input terminal DI.

Data latch signal input terminal LA, clock terminal GK,
Has 5TR1 to 5TR4 input terminals, 1 line is 102
The CK generating circuit 1 prints digital image data input from the data selector 7 to the data input terminal DI using a line thermal head that prints 4 dots divided into 4 parts.
It is input in synchronization with the clock signal input from 3. 1
When the digital image data for a line is input, the thermal head 15 latches the digital image data for one line by the LA Shintan input to the LA terminal, and then divides the digital image data into four lines to be printed. By setting the 5TR1 terminal to the 5TR4 terminal to a high level in this order, the heating element is energized for the energization time corresponding to this high level, and printing is performed on thermal paper.

The thermistor 17 detects the temperature of the thermal head 15 and outputs a resistance value to the energization pulse generation circuit 19.

The energization pulse generation circuits 19 to 27 are activated at 11t when energized by a signal indicating the counter value inputted from the line counter 9.
Pulse energization time selector 29 corresponding to B-t 3
This is what is output to. Here, the energizing pulse generation circuit 1
Reference numeral 9 generates a pulse indicating the energization time tB at which the thermal head 15 starts coloring the thermal paper.

The energization time selector 29 is connected to the print OK generation circuit 13 and the AND gates 33 to 39, and selects the pulse input from the energization pulse generation circuits 19 to 27.
It is output to AND gates 33-39.

The STR selector 31 is controlled by a control signal input from the line counter 9, and sequentially selects 5TR1.
Enable 5TR4a from a and AND gate 33~
39.

AND gates 33 to 39 control the thermal head 1 by the AND of the STR selector 31 and the energization time selector 29.
This is to set the input terminals of 5TR1 to 5TR4 of No. 5 to a high level.

FIG. 2 is a time chart showing the operation of this embodiment. Digital image data D8 to D3 are sequentially input from the data selector 7 to the DI input terminal of the thermal head 15, and the line counter 9 controls the STR selector 31 to set the input terminals of the AND gates 33 to 39 at high level to output the thermal signal. When the 5TR1 to 5TR4 input terminals of the head 15 become high level, the thermal head 15 causes the heating element to generate heat based on this high level, and prints one line on the thermal paper by dividing it into four.

FIG. 3 is a time chart showing the operation of the thermal head 15. Digital image data 10 is sent from the data selector 7 to the DI terminal in synchronization with the 0 clock signal at the CK terminal.
24 dots (one line) are transferred, and when the LA[ signal is input and the transfer of one line of digital image data is completed, the second line of digital image data is transferred to the DI terminal. At the same time, the STR selector 31
The pulse width of the R terminal becomes ton and 5TR4 becomes ton.
As a result, after the first line is printed in four parts, the thermal paper is fed and the data of the third line is transferred, and the second line is printed. Processing is performed by repeating the above operations.

FIG. 4 shows w! of digital image data and logical OR data. FIG. 4 is a diagram illustrating the head energization time for starting the fourth level.

Digital image data DO to D3 output from the A/D conversion circuit 1 and this digital image data DO to D3
The combination of logical sum data DB is expressed in 16 gradation levels, and indicates the head energization time corresponding to this 1611i gradation level. Here, digital image data Do
When D3 becomes "1", the head energization time becomes the sum of tB and 10 to t3, resulting in the maximum recording density.

FIG. 5 is a diagram showing the recording density of printing on thermal paper with respect to the head energization time of the thermal head 15.

[8] indicates the coloring start time of the thermal head 15, which is determined by the temperature of the thermal head 15, which will be described later. After this tB elapses, in response to the gradation levels 1 to 15 shown in FIG.
5a is determined and when this head is turned off, 1mtB ~ t15a
Accordingly, the recording density becomes dO to d15.

FIG. 6 is a diagram showing recording density versus head current supply time when substrate temperatures T1 to T3 of the thermal head 15 are used as parameters.

That is, the substrate temperature of the thermal head 15 changes from T1 to T.
When the temperature drops to 3, the color development start time changes from tBl to tB3.
will be late. As a result, the color development start time is determined in accordance with the substrate temperature of the thermal head 15, so that a recorded image with uniform recording density can be obtained without being affected by temperature.

Next, the operation of this embodiment will be explained.

First, after turning on the power to the printer, the analog image signal is
/D conversion circuit 1. When input, the A/D conversion circuit 1 converts the analog image signal input from the 1-line memory GK generation circuit 11 into digital image data and outputs it to the OR gate 3 and the 1-line memory 5. The OR gate 3 performs the logical sum of the digital image data and outputs the image data to the 010 terminal of the 1-line memory 5. 1
The line memory 5 stores input image data, the print GK generation circuit 13 outputs a clock signal to the line counter 9, the line counter 9 performs counting, and outputs digital image data to the data selector 7. Data selector 7 is line counter 9! II'
First, from the a large input, digital image data DB is transferred to the thermal head 15, and 5TR1a of the STR selector 31 is set to high level by the w4m input of the line counter 9, and printing of the first division is started. Further, the thermistor 17 detects the substrate temperature of the thermal head 15 and outputs a resistance value to the energization pulse generation circuit 19.

On the other hand, the 51 energization time selector 29 selects the energization pulse generation circuit 19, and energizes the thermal head 15 during the energization time tB according to the resistance value from the thermistor 17.

Then, after the energization time 11at B has elapsed and one line of digital image data Do has been transferred to the thermal head 15, the energization time selector 29 selects the energization pulse generation circuit 21 and operates the AND gate 33 for a time 10. is set to a high level, a pulse signal is output to the print GK generation circuit 13, a control input is performed from the line counter 9 to the data selector 7, and the digital image data D1 is transferred to the DI terminal of the thermal head 15. After repeating this operation and printing up to the digital image data D3, the line counter 9 inputs a control signal to the STR selector 31 to set 5TR2a to a high level, which causes the 5TR21 of the thermal head 15 to go to a high level and print the second division. It is done. Similarly, this operation is repeated up to four divisions to complete the printing of one line. Furthermore, by repeating the above operations, printing on the second and subsequent lines is performed.

By this, one part of the digital image data is transferred to the thermal paper.
Since line printing is continued for each division into four divisions, printing can be performed efficiently and at high speed.

Furthermore, since this embodiment can be used without complicating the circuit, the device can be kept from becoming expensive.

[Effects of the Invention] As explained above, according to the present invention, a gradation level indicating the level of recording density according to an image signal is selected, a current application time corresponding to this gradation level is determined, and a thermosensitive Since the current is applied for a time corresponding to the gradation level from the color development start time in response to body temperature, recording can be performed without complicating the circuit and being unaffected by temperature changes of the heat sensitive body.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the thermal multi-gradation recording device of the present invention, FIG. 2 is a time chart showing the operation of the present invention, and FIG. 3 is a time chart showing the driving of the thermal head. FIG. 4 is a diagram showing the head energization time for digital image data, FIG. 5 is a diagram showing the recording density versus the head energization time, and FIG. 6 is a diagram showing the recording density versus the head energization Fft using the thermal head substrate temperature as a parameter. 1... A/D conversion circuit 3... OR gate 5...
・1 line memory 7...data selector 9...
Line counter 11...1 line memory WRCK generation circuit 13...
Print CK generation circuit 15...Thermal head 17...Thermistor 19
．． 21, 23.25.27... Energization pulse generation circuit 29... Energization time selector 31... STR selector (data transfer) Fig. 4, 5r; IJ Fig. 6

Claims (1)

[Scope of Claims] In an apparatus for recording by energizing a heating element of a heat sensitive body to develop color according to an input image signal, there is provided a gradation for selecting a gradation level indicating a level of recording density according to the image signal. tone level selection means; energization time determining means for determining the energization time corresponding to the gradation level of the gradation level selection means;
a coloring start means for detecting the temperature of the heat sensitive body and outputting a coloring start time in response to this temperature; and a energizing time period corresponding to the gradation level of the energizing time determining means from the coloring start time of the coloring starting means. What is claimed is: 1. A thermal multi-gradation recording device comprising: energization control means for color development.