JP3028671B2 - Thermal recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal recording apparatus, and more particularly to an improvement in a recording operation at the time of solid black recording in an apparatus for coloring recording of the magnitude of a waveform on thermal recording paper.

[0002]

2. Description of the Related Art As a recorder for recording the magnitude of a waveform, a plurality of heating elements arranged at regular intervals so as to constitute a line thermal head are selectively driven according to the magnitude of the waveform to generate heat. There is a type in which a thermosensitive recording paper is colored and recorded based on the heat generation.

FIG. 13 is a block diagram showing an example of such a conventional apparatus, and FIG. 14 is a timing chart showing an example of the operation of the circuit of FIG. In the shift register 1,
Data of m dots for one line shown in (a) is sequentially stored in accordance with m clocks CLK shown in (b). When one line of data is stored in the shift register 1, the data is latched by the latch 2 by the latch pulse LAT shown in FIG. The output data of these latches 2 is applied to one input terminal of each NAND gate 3. An enable signal EN ′ shown in FIG. 3D is commonly applied to the other input terminals of the NAND gates 3 via the inverter 16. Note that a dash “′” indicates that the operation is performed by negative logic. The output terminal of the NAND gate 3 is connected to one end of a heating element 5 constituting a thermal head, and the other end of the heating element 5 is connected to a DC power supply 6.
Are connected in common.

In such a configuration, as the recording data of each line, for example, the maximum value and the minimum value of the measurement value in each measurement period are recorded in a line form, and the heating element corresponding to the maximum value corresponds to the minimum value. The interpolated data is added so as to simultaneously drive a plurality of continuous heating elements in the arrangement direction up to the heating element. Thus, the enable signal EN' is between t ₀ which is the L level, the recording based on the recording data of 1 line driving current flows through the heating element 5 from the DC power supply 6 is carried out. The recording paper (not shown) is fed one line at a time every time the recording operation of one line is completed.

By the way, in performing the waveform recording by such a thermal recording apparatus, when a high-frequency waveform is continuously input, solid black recording in which the waveform is recorded at a high density continues. In solid black recording, it is impossible to read the frequency component of the input signal from the recording result, and only the peak value is important. That is, in the case of solid black recording, the recording density of the contour is more important than the recording density of the inside.

[0006]

However, since solid black recording imposes a heavy load on the power supply of the thermal recording apparatus, a power supply having a considerably larger capacity is required as compared with ordinary line waveform recording alone. In addition, the line thermal head also causes abnormal overheating.

As a countermeasure, it has been proposed to extract a contour portion of a solid black recording portion and record the contour portion deeply and lightly inside, however, a digital signal processor and a data processing circuit are required, and the circuit configuration is required. However, there is a problem that the circuit size is complicated and the circuit scale becomes large. The present invention
Focusing on such a point, the purpose is to provide a thermosensitive recording apparatus capable of lowering the recording density of a solid black recording portion in the case of a solid black recording state, and recording a phenomenon with a large change in a dark state. Is to do.

[0008]

According to the present invention, which solves such a problem, a plurality of heating elements arranged at regular intervals so as to constitute a line thermal head are selectively driven in accordance with the magnitude of a waveform. In a thermal recording apparatus that records the magnitude of a waveform on thermal recording paper based on the generated heat, thermal storage temperature data related to the recording operation of the heating element is stored in advance, and the current thermal storage temperature data and recording are performed. A first memory for reading the next heat storage temperature data with the presence or absence as an address, a second memory for temporarily storing the heat storage temperature data read from the first memory, and a heat storage temperature temporarily stored in the second memory A comparator for comparing the data with a preset set temperature; and a switch element for controlling a recording operation of the heating element according to the comparison result. Trap data for forming a minor loop for driving the heating element so as to reduce the color density, characterized in that stored in the case of continuously driven by the same heating element.

Further, the first memory stores trap data for forming a minor loop for driving the heating element so as to increase the coloring density when the same heating element is continuously driven at a low coloring density. A second data group storing a data group, a trap data forming a minor loop for driving the heating element so as to lower the color density when the same heating element is continuously driven, and a trap forming the minor loop. It is also characterized in that a third data group containing no data is stored, and a desired data group is selected according to the feed speed of the thermal recording paper.

[0010]

When the same heating element is driven continuously, trap data stored so as to form a minor loop is read out as heat storage temperature data, and the heating element is driven so as to lower the color density and the power is stored. Make a save.
Further, when the high-speed feed speed is selected and set as the feed speed of the thermal recording paper, power saving is realized by selecting the second data group and reducing the recording density, and the medium-speed feed speed is selected and set. In this case, the third data group is selected and the special correction of the recording density is not performed. When the low feed rate is selected and set, the first data group is selected to improve the reduction of the recording density.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, reference numeral A denotes a digital one-shot unit for generating print data for driving a heating element,
Is a heat history control unit for controlling the heat generation temperature of the heat generating element.

[0012] In the digital one-shot unit A, the input data d _i to be recorded is added as a selection signal to the data selector 7. This data selector 7 receives input data d
_The predetermined data P selected according to "1" or "0" of _i
i-1 is output to the data converter 8 and to the subtractor 9. When the data P _i-1 added from the data selector 7 is other than “0”, the data conversion unit 8 supplies the data d _i ′ of “1” to one input terminal of the AND gate 18 constituting the thermal history control unit B. For example, an OR gate is used. The subtractor 9 calculates P _i = P for the input data P _i-1 .
Subtract _i-1 -1. However, the subtractor 9 performs subtraction only to the natural number, for example, when P _i-1 is 0 and outputs the 0 directly as P _i. The operation result _Pi is temporarily stored in the dual port memory 11 via the latch 10. Output data P _i-1 of the dual port memory 11 is applied to the data selector 7 via the latch 12.

In the heat history control section B, the memory 13 previously stores heat storage temperature data relating to the recording operation of a plurality of heating elements constituting the thermal head 19. The heat storage temperature data includes a first data group storing trap data for forming a minor loop for driving the heating element so as to increase the coloring density when the same heating element is continuously driven at a low coloring density, and the same heating element. And a second data group in which trap data forming a minor loop for driving the heating element so as to reduce the color density by saving power when the is continuously driven, and trap data forming these minor loops are included. The third data group is divided and stored in three banks, and a data group of a desired bank is selected according to the feed speed of the thermal recording paper 21. That is, the first data group is selected so as to increase the color density at the time of low-speed feeding, the second data group is selected so as to decrease the color density at the time of high-speed feeding, and the color density correction is not performed at the time of medium-speed feeding. A third data group is selected. The trap data is temperature data
It is stored in advance corresponding to SD.

The heat storage temperature data stored in each bank of the memory 13 is obtained from a predetermined bank corresponding to the feed speed of the thermal recording paper 21 from the temperature around the thermal head 19 measured by a temperature sensor 20 such as a thermistor. In response to the,
The output data of a predetermined current heat storage temperature data R _i-1 and recording the AND gate 18 associated with the presence of the address is read out as the next thermal storage temperature data R _i. The heat storage temperature data R _i to be read from the memory 13 is temporarily stored in the dual port memory 15 via the latch 14. Then, the heat storage temperature data R _i temporarily stored in the memory 15 is read out as the above-described current heat storage temperature data R _i−1 , added to the memory 13 via the latch 16 as an address, and supplied to one of the comparators 17. Input terminal. The preset input temperature data SD is applied to the other input terminal of the comparator 17. The output signal of the comparator 17 is applied to the other input terminal of the AND gate 18. The output data O _{i of the} AND gate 18
Is applied as an address to the memory 13 as described above, and is also applied as a drive signal to the heating element of the thermal head 19. Reference numeral 21 denotes a heat-sensitive recording sheet on which color recording is performed by heat generated by a plurality of heating elements constituting the thermal head 19, and is fed at a predetermined speed by a motor 22. A timing control circuit 23 outputs a control signal for controlling the operation of each unit. Note that the thermal head 19 can be configured similarly to FIG.

Tables 1.1 and 1.2 are specific examples of the first data group, Tables 2.1 and 2.2 are specific examples of the second data group, and Tables 3.1 and 3.2 are the third data group. Table 1.1, Table 2.1 and Table 3.1 are read out when the temperature is lowered, and Tables 1.2, 2.2 and 3.2 are read out when the temperature is raised. These heat storage temperature data are sequentially stored from the top data to the lower address from the top data, such as the first data at address 0, the next data 0 at address 1, and the subsequent data 1 at address 2.
The trap data is underlined.

[0016] (Table 1.1) 000,000,001,002,003,004,005,006 007,008,008,009,010,011,012,012 013,014,015,016,016,017,018,019 020,021,021,022,023,024,025,026 026,027,028,029,030,031,031,032 033,034,035,036,036,037,038,039 040,041,042,042,043,044,045,046 047,047,048,049,050,051,052,053 053,054,055,056,057,058,059,059 060,061,062,063,064,065,065,066 067,068,069,070,071,071,072,073 074,075,076,077,077,078,079,080 081,082,083,083,084,085,086,087 088,089,090,090,091,092,093,094 095,096,096,097,098,099,100,101 102,102,103,104,105,106,107,108 109,109,110,111,112,113,114,115 115,116,117,118,119,120,120,121 122,123,124,125,125,126,127,128 129,130,130,131,132,133,134,134 135,136,137,137,138,139,140,140 141,142,142,143,144,144,145,146 147,147,148,148,149,150,150,151 151,152,153,153,154,154,155,155 156,156,157,157,158,158,159,159 160,160,161,161,162,162,163,163 163,164,164,165,165,165,166,166 167,167,167,168,168,168,169,169 169,170,170,170,171,171,171,172 172,172,173,173,173,174,174,174 174,17 5,175,175,176,176,176,176 177, 177, 120, 177,178,178,178,179 (1.2 Table) 111,111,112,112,112,112,113,113 113,114,114,114,114,115,115,115 116,116,116,117,117,117,118,118 119,119,119,121,121,121,121,121 122,122,122,123,123,124,124,124 125,125,126,126,126,127,127,128 128,129,129,129,130,130,131,131 132,132,133,133,134,134,135,135 136,136,137,137,138,138,139,139 140,140,141,141,142,142,143,143 144,144,145,145,146,146,147,148 148,149,149,150,150,151,151,152 153,153,154,154,155,155,156,157 157,158,158,159,160,160,161,161 162,162,163,164,164,165,166,166 250, 167,168,169,169,170,170,171 172,172,173,174,174,175,175,176 177,177,178,179,179,180,180,181 182,182,183,184,184,185,185,186 187,187,188,189,189,190,190,191 192,192,193,193,194,194,195,196 196,197,197,198,198,199,199,200 200,201,201,202,202,203,203,204 204,205,205,206,206,207,207,208 208,208,209,209,210,210,210,211 211,212,212,212,213,213,213,214 214,214,215,215,215,216,216,216 217,217,217,218,218,218,218,219 219,219,219,220,220,220,221 , 221 221,221,222,222,222,222,223,223 223,223,223,224,224,224,224,225 225,225,225,226,226,226,226,226 (2.1 Table) 000,000,001,002,003,004,005,006 007,008,009,010,011,012,013,014 015,016,017,018,019,020,021,022 023,024,025,026,027,028,029,030 031,032,033,034,035,036,037,038 039,040,041,042,043,044,045,046 046,047,048,049,050,051,052,053 054,055,056,057,058,059,060,061 062,063,064,065,066,067,068,069 070,071,072,073,074,075,075,076 077,078,079,080,081,082,083,084 085,086,087,088,089,090,091,092 093,094,095,096,097,098,099,100 101,102,103,104,105,105,106,107 108,109,110,111,112,113,114,115 116,117,118,119,120,121,122,123 124,125,126,127,128,129,130,131 132,133,134,134,135,136,137,138 139,140,141,142,143,144,145,146 147,148,149,150,151,152,153,154 155,155,156,157,158,159,160,161 162,163,164,165,166,167,168,168 169,170,171,172,173,174,175,175 176,177,178,179,180,181,182,182 183,184,185,186,186,187,188,189 190,190,191,192,193,194,194,195 196,198, 197, 198,199,200,200,201 202,203,203,204,2 05,205,206,207 207,208,209,210,210,211,212,212 213,214,214,215,216,216,217,218 218,219,220,220,221,221,222,223 223,224,225,225,226,227,227,228 (2.2 Table) 115,115,115,115,115,116,116,116 116,116,117,117,117,117,118,118 118,118,119,119,119,119,120,120 120,121,121,121,122,122,122,123 123,123,124,124,125,125,125,126 126,127,127,127,128,128,129,129 129,130,130,131,131,132,132,133 133,134,134,135,135,136,136,137 137,138,138,139,139,140,140,141 141,142,142,143,144,144,145,145 146,146,147,148,148,149,149,150 151,151,152,152,153,154,154,155 156,156,157,157,158,159,159,160 161,161,162,163,163,164,165,165 166,167,167,168,169,169,170,171 171,172,173,173,174,175,176,176 177,178,178,179,180,181,181,182 183,183,184,185,186,186,187,188 189,189,190,191,192,192,193,194 195,195,196,197,198,198,199,200 201,201,202,203,204,204,205,206 207,207,208,209,209,210,211,212 212,213,214,215,215,216,217,218 218,219,220,220,221,222,222,223 224,225,225,226,227, 254, 228 and 229 229,230,231,231,232, 254, 254, 234 235 , 235,236,236,237,238,238,239 240,240,241,241,242,243,242,244 244,245,246,246,247,248,248,249 249,250,250,251,252,252,253,253 254,254,255,255,255,255,255,255 255,255,255,255,255,255,255,255 (3.1 Table) 000,000,001,002,003,004,005,006 007,008,009,010,011,012,013,014 015,016,017,018,019,020,021,022 023,024,025,026,027,028,029,030 031,032,033,034,035,036,037,038 039,040,041,042,043,044,045,046 046,047,048,049,050,051,052,053 054,055,056,057,058,059,060,061 062,063,064,065,066,067,068,069 070,071,072,073,074,075,075,076 077,078,079,080,081,082,083,084 085,086,087,088,089,090,091,092 093,094,095,096,097,098,099,100 101,102,103,104,105,105,106,107 108,109,110,111,112,113,114,115 116,117,118,119,120,121,122,123 124,125,126,127,128,129,130,131 132,133,134,134,135,136,137,138 139,140,141,142,143,144,145,146 147,148,149,150,151,152,153,154 155,155,156,157,158,159,160,161 162,163,164,165,166,167,168,168 169,170,171,172,173,174,175,175 176,177,178,179,180,181,182,182 183,184,185,186,186,187,188 , 189 190,190,191,192,193,194,194,195 196,197,197,198,199,200,200,201 202,203,203,204,205,205,206,207 207,208,209,210,210,211,212,212 213,214,214,215,216,216,217,218 218,219,220,220,221,221,222,223 223,224,225,225,226,227,227,228 (Chapter 3.2 Table) 115,115,115,115,115,116,116,116 116,116,117,117,117,117,118,118 118,118,119,119,119,119,120,120 120,121,121,121,122,122,122,123 123,123,124,124,125,125,125,126 126,127,127,127,128,128,129,129 129,130,130,131,131,132,132,133 133,134,134,135,135,136,136,137 137,138,138,139,139,140,140,141 141,142,142,143,144,144,145,145 146,146,147,148,148,149,149,150 151,151,152,152,153,154,154,155 156,156,157,157,158,159,159,160 161,161,162,163,163,164,165,165 166,167,167,168,169,169,170,171 171,172,173,173,174,175,176,176 177,178,178,179,180,181,181,182 183,183,184,185,186,186,187,188 189,189,190,191,192,192,193,194 195,195,196,197,198,198,199,200 201,201,202,203,204,204,205,206 207,207,208,209,209,210,211,212 212,213,214,215,215,216,217,218 218,219,220,220,221 Will be described with reference to 222,222,223 224,225,225,226,227,227,228,229 229,230,231,231,232,233,233,234 235,235,236,236,237,238,238,239 240,240,241,241,242,243,242,244 244,245,246,246,247,248,248,249 249,250,250,251,252,252,253,253 254,254,255,255,255,255,255,255 255,255,255,255,255,255,255,255 timing chart of FIG. 2 the operation of the apparatus configured as shown in FIG.

In FIG. 2, the data DATA of m dots is transferred to the thermal head 20 four times, and the recording of one line is performed by applying the enable signal EN 'four times. Here, the pulse width t ₀ of the enable signal EN '' is 1/4 of the pulse width t ₀ in FIG. 14. That is, the energy applied to the heating element 5 in one drive is 1/4 of that in FIG.
The recording of one line is performed by sending the data DATA and the enable signal EN 'twice. It should be noted that the feeding of the recording paper 21 is also divided into quarter steps in FIG.

In such a driving method, since the pulse width t ₀ ′ of the enable signal EN ′ is constant, for example, the recording condition of the recording sequence of the line up to the data d ₄ starting from the data d ₁ and the data d Data d ₅ starting with ₂
The recording conditions of the recording sequence of the lines up to are the same. Thus, the feeding speed of the recording paper 21 are equal, that is, when the data transfer period d _n of FIG. 2 is 1/4 of the data transfer period FIG. 14, according to the driving method of FIG. 2, along the time axis resolution Is four times the driving method of FIG.

FIG. 3 shows a recording example by such a recording method.
FIG. The recording paper has a pitch P in FIG.
Sent by 1/4. The heating element 5 is provided as shown in a to c.
It is driven four times in synchronization with the paper feed pitch. a is
Heating element 5_FourB indicates the heating element 5_FiveDrive
Indicates a state, and c indicates a heating element 5₆Shows the driving state of
You. Heating element 5_FourRecording pattern PTa at time t₁In de
Input data d to the data selector 7_i"1" is added
Is recorded by four consecutive drives by
5_FiveThe recording pattern PTb at time t_TwoWith data selector
Input data d in 7 _iContinuation by adding "1"
It is recorded by the four times of driving, and the heating element 5₆Note by
Recording pattern PTc is time t_ThreeInput data to the data selector 7.
Data d_i4 consecutive times by adding “1”
Recorded by driving. Similarly, each recording pattern is
The corresponding heating elements are divided into 4 times in synchronization with the paper feed pitch
It is recorded by continuous driving. In addition, during driving
The input data d is again input to the data selector 7 of the heating element.
_iWhen “1” is added, drive is performed four times again from that point
Is executed, and the recording pattern is long.
You.

As is clear from the recording result of FIG. 3,
Since the resolution of the paper feed pitch is higher than the conventional recording result, the maximum height of the stepped portion caused by the paper feed pitch when the paper is fed at the same speed becomes smaller than before,
Waveform curve recording results are smooth. Since the input data is taken in synchronism with the paper feed timing, a signal waveform having a higher frequency than in the related art can be faithfully recorded.

FIG. 4 is a timing chart for explaining the operation of the digital one-shot section A. The memory 11 stores trigger data corresponding to each dot. For example, the address Al stores trigger data P _i−1 , _l corresponding to the m−1-th dot. By adding an address A _l in the l-th clock of the internal clock CLK as shown from the timing control circuit 23 (a), the memory 11
To (b), the trigger data P _i−1 , _l corresponding to the (m−1) -th dot is read out. The trigger data read from the memory 11 is latched by the latch 12 at the rising edge of the (l + 1) -th clock as shown in FIG. Data selector 7, the input data d _{i, l} is "0" in the case of directly outputting the input data P _{i-1, l,} input data d _i, the input in the case of _l is "1" data P _{i -1} and _l are output to the data CD which is set in the data selector 7 in advance. In this embodiment, 1
"4" is output because the line equivalent is recorded four times. The output data of the data selector 7 is applied to a data converter 8 and a subtractor 9. The data converter 8 sets the data d _i ′ to “1” when the data P _i−1 , _l added from the data selector 7 is other than “0”, and adds the data d _i ′ to the AND gate 18 of the thermal history controller B. The subtractor 9 calculates P
_{The operation of i-1} and _l-1 is performed, and the operation result P _i and _l is output to the latch 10 as shown in (d). The latch 10 calculates the operation result P _i , _l of the subtractor 9 at the rise of the (l + 2) th clock.
Is latched as shown in (e), and the data P _i , _l are output to the memory 11 as the address A _l during the clock cycle.

Such a series of operations is repeated m times for each data d _{1 to} d ₅ interval in FIG. Next, a description will be given of how the data at a certain address _{Al in} the memory 11 changes in accordance with the repetition of the interval cycle. FIG. 5 shows a data change of each part when a certain address _Al of the memory 11 is fixed.

In the interval k shown in FIG.
Data d input to selector 7_i, _lAs shown in (c)
Is "1". At this time, the data selector 7
"4" is set as the output data of
It is. On the other hand, the output data of the data
(E) because the output data of the
Becomes "1", and gives the record data to the history control unit B.
You. In the following interval k + 1, k + 2, k + 3, the data
The subtracter 9 subtracts “1” at a time as shown in (f).
You.

According to such a process, the input of "1" of the data d _i , _l of the interval k as a trigger triggers the recording data from the data conversion unit 8 to the history control unit B four times from the interval k to k + 3. Will be added. Such a series of operations is the same even when “1” is input as the data d _i , _{l at} intervals k + 5 and k + 8, and the digital one-shot unit A is as if it were a retriggerable monostable multi-unit. It operates as a vibrator, the data conversion unit 8 will output the recording data to the history control unit B in the four intervals that the top interval data d _i, is "1" as _l entered.

That is, the digital one-shot section A
Input data d _i, it operates to stretch the predetermined interval times arguments set the input data by the data selector 7 _l as a trigger. Next, the operation of the heat history control unit B will be described. For example, during the interval k + 5 to k + 10 in FIG. 5, the recording data d _i ′ output from the data converter 8
It becomes the continuous "1" will flow continuously driving current to the heating element corresponding to the transfer of such recording data d _i 'as it is to the thermal head 19. As a result, the temperature of the heating element rises remarkably so that uniform recording quality cannot be maintained, and in the worst case, the heating element may be burned.

Therefore, the heat history control unit B performs data processing such as thinning out the recording data d _i ′ based on the heat storage temperature data previously stored in the memory 13 as described above, and then records the recording data on the thermal head 19. Transfer O _i . By performing one-line recording by four data transfers as in the present embodiment, the pattern of the drive pulse applied to the heating element 5 according to the manner of taking the data d _{1 to} d ₄ each time is 15 as shown in FIG. Street (2 ⁴ -1 = 15). That is, the driving of the heating element 5 is controlled according to the heat storage temperature, and as a result, the heating element 5 is driven according to any one of these 15 patterns.

In FIG. 2, it is described that one line is recorded by sending the data DATA and the enable signal EN 'four times. However, the recording is not limited to four times, and may be performed n times (n is 2 or more). ). In the case of n times, there are 2 ⁿ -1 driving patterns. Details of such heat storage control will be described. At the address Ax of the memory 15, the heat storage temperature data corresponding to the mxth heating element in the main scanning direction to be recorded is stored as shown in FIG. The timing control circuit 23 corresponds to (a) of the timing chart of FIG.
The address _Al is sent to the memory 15 which temporarily stores the heat storage temperature data at the 1st clock of the internal clock CLK shown in FIG. As a result, the memory 15 stores the heat storage temperature data R _i−1 , corresponding to the (m−1) -th heating element, as shown in FIG.
Output _l .

In the cycle of l + 1 of the internal clock CLK
Then, at the rising edge of the clock CLK, the latch 16
As shown in (c) of FIG._i-1,_lLatch
You. Thermal storage temperature data R latched by latch 16_i-1,_l
Is the temperature data which has been added to the comparator 17 and initialized.
Compared to the SD. These heat storage temperature data
R_i-1,_lAnd temperature data SD are quantized to multiple s bits
Have been. The comparator 17 stores, for example, the temperature data SD of 200
℃ and the heat storage temperature data R_i-1,_lAt 100 ° C
If so, “1” is output to the AND gate 18 and the
Temperature data SD is set to 200 ° C and heat storage temperature data R
_i-1,_lIf the temperature is 250 ° C, “0” is AND gated
18 is output. In this l + 1 clock cycle, the data
From the data converter 8_i,_lBut And Gate 18
And the output data of the comparator 17 as shown in FIG.
AND with the data. The exit of this AND gate 18
Force data O _lThermal data as data to be actually recorded
It is applied to the heating element 5 of the head 19. That is,
The fact that the heating element 5 of the multiple head 19 is in the recording state is described below.
Recording data d '_i,_lIs “1” and the heat storage temperature data R_i-1,_lBut
Only when it is lower than the temperature data SD.

In the l + 1 cycle, the following control is performed simultaneously with the above-described process. That is, the heat storage temperature data R
The output data O _l of _{i-1, l} and the AND gate 18 inputs the address to the memory 13. Here, the comparator 17
And so AND gate 18 may be composed of a high speed gate elements, settling of the output data O _l of the AND gate 18 becomes about several 10 ns, the number 100ns clock cycle
Thus, data reading from the memory 13 can be completed within one clock.

The memory 13 stores addresses R _i−1 , _l and O
_The next heat storage temperature data R _i , _l is output as shown in FIG. For example, when the heat storage temperature data R _i−1 , _l is 100 ° C., if _Ol is 1, the heat storage temperature data R _i , _l is 180.
Outputs ° C.-bit data, O _l outputs a 50 ° C.-bit data as a heat storage temperature data R _{i, l} if 0. l +
In two cycles, the latch 14 latches the heat storage temperature data R _i , _l output from the memory 13 at the rise of the clock CLK of l + 2 cycles as shown in (e). Moreover, the data latched in the latch 14 are written is applied to the other port of the memory 15 to the address A _l.

These series of operations are performed in parallel in a pipeline manner, and the heat storage temperature data R _i−1 , _{l + 1} is read from the memory 15 in the clock cycle of _{l + 1} . By performing such an operation m times, the thermal head 19
Receive the record data. Timing control circuit 23
After the m data transfer, the latch pulse LAT is activated as shown in FIG. 2C, and the enable signal EN ′ is activated once for the time t ′ as shown in FIG. 5 is supplied with a drive current. The transfer of the m data, the transmission of the latch pulse LAT, and the transmission of the enable signal EN 'are repeated a plurality of times. FIG. 2 shows an example of repeating four times.

Next, the setting of the heat storage temperature data of the memory 13 will be described. Temperature change of the heating elements 5 of the thermal head 19 can be simulated by the amplitude and pulse width of the drive pulses to the initial temperature T ₀ as a reference. That is, the structure of the thermal head 19 is known, and the physical constants of each part are also known. From these, thermal head 1
9 can be modeled and described using the heat conduction equation. By giving the initial temperature to the heat conduction equation as an initial condition and the amplitude and pulse width of the drive pulse as input energy to the system, the temperature of the heating element 5 of the thermal head 19 at each time can be simulated by numerical calculation. Since the heat conduction equation is nonlinear, a numerical operation is performed by a computer using a one-dimensional finite element method, and the temperature state after data transfer is predicted by simulation, and is stored in a table in the memory 13.

In the configuration shown in FIG.
Transfer cycle of m-dot data and enable signal
Since the pulse width of EN ′ is constant, the temperature after data transfer can be predicted by simulation if the initial temperature T ₀ is known. 9A and 9B are explanatory diagrams of such a simulation state. FIG. 9A shows a temperature change state when a drive pulse is applied for a time t ′, and FIG. 9B shows a temperature change state when no drive pulse is applied. ing.

In the memory 13, using the initial temperature T ₀ as a parameter, the temperature T ′ after the transfer cycle when the drive pulse is applied and when the drive pulse is not applied is tabulated as data in advance. That is, the heat storage temperature data R _i−1 , _l is _converted to the initial temperature T
_The memory 13 outputs the temperature T ′ after the transfer cycle as bit data R _i , _l by setting the output signal O _l of the AND gate 18 to ₀ as an ON / OFF signal of the drive pulse to the address of the memory 13. Will be.

By storing such data in the memory 13, the heat storage temperature is sequentially calculated. And
The comparator 17 compares the heat storage temperature data with the set temperature one by one. As a result, a pulse train matching the past heat storage temperature data is selected from the plurality of pulse trains in FIG. History control is performed. In the above description, the temperature control is in an open loop.
Further, an error occurs in the simulation data depending on the ambient temperature. Therefore, the temperature of the heat radiating plate of the thermal head 19 is measured by the temperature sensor 20, and the measured data TD is added to the memory 13 as an address, and the data in the memory 13 is switched. If the temperature of the heat radiating plate of the thermal head 19 is too high, the driving pulse is cut to control the temperature so that the temperature does not rise any more.

The pulse width of the driving pulse may be variable in order to improve the recording quality according to changes in the chart feed speed and the ambient temperature. In this case, the data read from the memory 13 may be changed by switching the address of the memory 13 according to the chart feed speed or the ambient temperature. According to such a configuration, the application pattern of the driving pulse of the thermal head can be finely set basically by a simple combination of one read-only memory and a comparator, and the recording quality can be improved.

FIG. 10 is a block diagram showing a modification of the present invention, in which two types of recording lines are used, and the portions common to FIG. 1 correspond to the types of recording lines.
_The same reference numerals to which the subscripts _{1 and 2} are added are attached. That is, in FIG. 10, the digital one-shot portion A has a subscript
_The data selector 7, data conversion unit 8,
Two digital one-shot loops including a subtractor 9, latches 10, 12 and a memory 11 are provided. On the other hand, the heat history control unit B is provided with two comparators 17 and two AND gates 18 for processing data output from each digital one-shot loop system, and these two systems of AND gates 18 ₁ and 18 _2. Is applied to the thermal head 19 via the OR gate 24.

In such a configuration, recording with different types of lines is performed as follows. Note that the one of the data selector 7 ₁ is "4" is set as the set value CD _1, the other of the data selector 7 _2, "6" is set as the set value CD _2. FIG. 11 is a timing chart for explaining the operation, which corresponds to FIG. 5 described above, and shows a change in data corresponding to one arbitrary dot during a transfer interval by focusing on one dot. .

In the interval k shown in (a), the data selector 7 _{1 of one} system of the digital one-shot section A.
When the data d _1i inputted to the data selector ₁ becomes “1” as shown in FIG. 7C, the value “4” of CD ₁ is set as the output data of the data selector 71 as shown in FIG. Data converter 8 ₁
Since the output data d' _1i of the data selector 7 is "4", it becomes "1" as shown in FIG.
To one input terminal of the AND gate 18 ₁ of the history control unit B applies a recording data. The following interval k + 1, k +
In 2, k + 3, the data is decremented by "1" as shown by the subtractor 9 ₁ (f). By this process, the recording data in the history control unit B from the data converting unit ₈₁ over four data d _1i of inputted to the data selector 7 ₁ "1" from the interval k in the trigger in the interval k to k + 3 Will be added.

Such a series of operations is performed at intervals k
In +7 and k + 9 comprising the same when "1" as the data d _1i is input, the digital one-shot unit A is operated as if re triggerable monostable multivibrator, the data conversion unit ₈₁ is data d _In the four intervals starting from the interval in which “1” is input as _1i , the AND gate 1 of the history control unit B is used.
8 ₁ will output the recording data.

Such an operation is also performed in the other system with the subscript ₂ shown in (g) to (k). However, since the data selector 7 ₂ "6" is set as a data CD _2, the data selector 7 at the interval k
₂ recording data to the AND gate 18 ₂ of the history control unit B data d _2i from the data converter ₈₂ six times of a trigger from the interval k to k + 5 "1" is input will be added to.

The same applies to the case where "1" is input as data d _{2i at} intervals k + 7 and k + 8.
Digital one-shot unit A is operated as if re triggerable monostable multivibrator, the data conversion unit ₈₂ is history control unit in six intervals that the head interval entered is "1" as the data d _2i thereby outputting recording data to the aND gate 18 ₂ B.

That is, the digital one-shot section A
Input data d _1i, d _2i operates to stretch the predetermined interval times arguments set the input data by the data selector 7 _1, 7 ₂ of the set data CD _1, CD ₂ as a trigger, set data CD _1, CD _{In this case} , the recording line width is varied depending on the number ( ₂₎ . The comparators 17 ₁ and 17 _{2 of the} heat history control unit B
The temperature data SD ₁ and SD ₂ set the recording densities of the data d ′ _1i and d ′ _2i output from each system of the digital one-shot unit A individually. Temperature data SD ₁ example of the comparator 17 ₁
There when it is set to 0.99 ° C., the comparator 17 ₁ outputs "1" only when the temperature data R _i-1 applied from the latch 16 is lower than 0.99 ° C. AND gate 18 _1.
The logical product of the AND gate 18 ₁ and the comparator 17 _first output data and the output data of the data converter 8 ₁ OR gate 2
Will be output to 4, the heat storage temperature of the heating element will be suppressed to a value of the temperature data SD ₁ neighborhood. Here, the level of the heat storage temperature is related to the level of the recording temperature,
As the heat storage temperature increases, the recording density increases. That is,
The recording density can be set individually by the temperature data SD ₁ and SD ₂ of the comparators 17 ₁ and 17 ₂ .

As described above, according to the configuration of FIG. 10, the recording line width can be set by the data CD ₁ and CD ₂ of the data selectors 7 ₁ and 7 ₂ , and the data SD ₁ and SD of the comparators 17 ₁ and 17 ₂ can be set. ₂ allows you to set the recording density. Therefore, for example, CD ₁ = 4, CD ₂ = 6,
By setting SD ₁ = 200 ° C. and SD ₂ = 150 ° C., the system of the input data d _1i can be recorded with a thin and dark line, and the system of the input data d _2i can be recorded with a thick and thin line.
In the portion where the two types of lines intersect, the OR gate 24
The dark line is preferentially recorded by the action of.

Although two types of recording lines have been described with reference to FIG. 10, three or more types of recording lines can be simultaneously recorded by adding a digital one-shot section system and a thermal history control section system as necessary. . Also, the memories 11 ₁ and 11 ₂
May be assigned to a plurality of upper bits and a plurality of lower bits of one memory, respectively.

Further, the type of recording lines such as continuous lines, broken lines, and chain lines can be further increased by controlling the intermittent recording lines. In this case, the data input to the AND gate 18 system and the data input from the outside to the data selector 7 system may be ON / OFF controlled by the gate.
Next, each density correction operation when recording a waveform will be described.

First, in the configuration of FIG.
The density correction operation when a linear waveform is recorded will be described. Me
The data in Table 1.1 stored in memory 13
24 output data O_iIs "0", the 1.2th
The data in the table is the output data O of the OR gate 24. _iIs "1"
Is selected at the time. Input data d_1iAs straight line image data
Data has been entered. That is, liners
“1” is input to a certain heating element of the multiple head 19.
Data conversion unit 8₁Output data d '_1iIs also "1"
You.

[0048] and has been set to "203" in order to set the dark lines as, for example, temperature data SD ₁ of the comparator 17 _1. It is assumed that the data in the memory 15 has been cleared to “0”. The operation state of the heat history control unit B at this time is described in Section 4.1.
It is shown in the table. Here, A represents the order of the processing loop, i represents an output data _d'1i of the data conversion section _81, c represents the heat storage temperature data R _i-1, d is the output data O _i of the OR gate 24オ indicates heat storage temperature data R _i .

(Table 4.1) Air 1 1 0 1 111 2 1 111 1 162 3 1 161 1 192 4 1 192 1 208 5 1 208 0 163 6 1 163 1 193 7 1 193 1 208 8 1 208 0 163 9 1 163 1 193 10 1 193 1 208 11 1 208 0 163 - - - - - - - - - - i.e., in the loop 1, the heat storage for the temperature data SD ₁ of the comparator 17 ₁ "203" temperature data R _i-1 is "0", the output of the comparator 17 ₁ applied to one input terminal of the aND gate 18 ₁ becomes "1". Output data _d'1i of the data conversion unit ₈₁ applied to the other input terminal of the AND gate 18 ₁ is also "1", output data O _i of the OR gate 24 to be added as an address of the memory 13 to "1" Become. As a result, Table 1.2 described above is selected. Since the heat storage temperature data _Ri-1 input as an address of the memory 13 is "0",
The heat storage temperature data “111” at address 0 in the table is output as the heat storage temperature data R _i . In the subsequent loop 2, the heat storage temperature data “111” read out in loop 1 is used as the heat storage temperature data R _i−1 , and the heat storage temperature data “161” of the 111 address in Table 1.2 is used as the heat storage temperature data R _i. Is output. The same procedure is repeated in and after the loop 3, and the output data O _i applied to the thermal head 19 from the OR gate 24 when the linear image data is recorded as a dark line is output from the loop 4.
Up to "1", and thereafter become a continuous and repeated output of "011011 ...".

Next, when performing light line recording, the comparator 1
7₁Temperature data SD₁Lower than the setting for dark line recording
The value is set to, for example, “140”. Heat history control unit B at this time
Table 4.2 shows the operating states of the. Allocation of data
Are the same as in Table 4.1. (Table 4.2) Air 1 1 0 1 111 2 1 111 1 161 3 1 161 0 136 4 1 136 1 177 5 1 177 0 147 6 1 147 0 125 7 1 125 1 170 8 1 170 0 142 9 1 142 0 120 10 1 120 1 250 11 1 250 0 120 12 1 120 1 250 13 1 250 0 120 14 1 120 1 250 15 1 250 0 120 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ n 0 250 0 120 n + 1 0 120 0 102 n + 2 0 102 0 86----------
Output data O applied to the thermal head 19 from the
_iIs "1" for loops 1 and 2, and "0" for loop 3.
After that, it becomes “100100” until the loop 9. loop
10 is output data O _iBecomes “1” and the ad shown in Table 1.2
Temperature data 250 stored in the trap 120
Is read out, and the output data O_iIs "1"
The traffic stored at address 250 in Table 1.1.
The heat storage temperature data 120 is read out,
Output data O_iIs a repetition of "101010 ...". this
As a result, the voltage is applied to the thermal head 19 after the loop 10.
Energy from Loop 3 to Loop 9
0 "and larger than" 110110 ... "for dark line recording
And the density of the light-line recording becomes too light.
Can be prevented.

Next, the operation of the heat history control unit B when the second data group provided with the minor loop is selected will be described with reference to FIG. Table 4.3 shows the operating state at this time. Here, it is assumed that “210” is set as the temperature data SD of the comparator 17 and the data in the memory 15 is cleared to “0”. Also in Table 4.3, a indicates the order of the processing loop, and b indicates the output data d of the data conversion unit 8.
Indicates' _i, c denotes the heat storage temperature data R _i-1, d represents the output data O _i of the AND gate 18, o denotes the thermal storage temperature data R _i.

(Table 4.3) Air 1 1 0 1 115 2 1 115 1 168 3 1 168 1 207 4 1 207 1 234 5 1 234 0 214 6 1 214 0 200 7 1 200 1 229 8 1 229 0 211 9 1 211 0 198 10 1 198 1 228 11 1 228 0 210 12 1 210 0 197 13 1 197 1 254 14 1 254 0 227 15 1 227 0 210 16 1 210 0 197 17 1 197 1 254 18 1 254 0 227 19 1 227 0 210 20 1 210 0 197 21 1 197 1 254 22 1 254 0 227 23 1 227 0 210 24 1 210 0 197 That is, in the loop 1, the temperature data of the comparator 17
The heat storage temperature data _Ri-1 is "0" for SD "210", and the output of the comparator 17 applied to one input terminal of the AND gate 18 becomes "1". The output data d ′ _i of the data converter 8 applied to the other input terminal of the AND gate 18 is also “1”, and the output data O _i of the AND gate 18 applied as an address of the memory 13 is also “1”.
become. As a result, Table 2.2 described above is selected. Then, since the heat storage temperature data R _i-1 input as the address of the memory 13 is “0”, “0” in Table 2.2
The heat storage temperature data “115” of the address is the heat storage temperature data R _i
Is output as In the subsequent loop 2, the heat storage temperature data “115” read out in loop 1 is replaced with the heat storage temperature data R _i−1.
And the heat storage temperature data “168” at address 115 in Table 2.2 is output as the heat storage temperature data R _i . The same procedure is repeated after the loop 3, and the output data O _i applied from the AND gate 18 to the thermal head 19 becomes “1” until the loop 4, and thereafter “001001. become. Loop 13
2.2 Trap heat storage temperature data "254" at 197 addresses in the table
Is read out, and in the loop 14, the output data O _i is “0”
become. Thus, the heat storage temperature data "227" in the 254 address of the 2.1 Table In the loop 14 is output as a heat storage temperature data R _i, output data O _i of the loop 15 becomes "0". In the loop 15, the heat storage temperature data “210” of the 227 address in Table 2.1 is output as the heat storage temperature data R _i , and the output data O _i of the loop 16 becomes “0”. In the loop 16, the heat storage temperature data “197” of the 210 address in Table 2.1 is output as the heat storage temperature data R _i , and the output data O _i of the loop 17 becomes “1”. In loop 17 again, Table 2.2
Trap heat storage temperature data “254” at 197 addresses is read out, and in loop 18 the output data O _i becomes “0”.
In other words, after the loop 14, a minor loop based on the trap data is entered, and the output becomes "00010001 ..." repeatedly. Note that when the output data d' _i becomes "0", it is possible to escape from the minor loop.

When there is a minor loop like this,
When the recording data continues, the energy applied to the thermal head 19 becomes smaller than "001001...", And the recording density is reduced by the power save driving. As a result, FIG.
In the case of recording a waveform as shown in FIG. 2, the recording density of a solid black portion becomes light because the recording data is continuous, but the protruding portion is recorded darker because the recording data is not continuous. Will be.

Further, the operation when the third data group in which the minor loop is not incorporated is selected will be described with reference to FIG. Also in this case, the temperature data SD of the comparator 17
Is set to “210”, and the data in the memory 15 is cleared to “0”. The operation state of the heat history control unit B at this time is shown in Table 4.4. Here, A also indicates the order of the processing loop, A indicates the output data d' _i of the data converter 8, C indicates the heat storage temperature data R _i-1 ,
D represents the output data O _i of the AND gate 18, o denotes the thermal storage temperature data R _i.

(Table 4.4) Iio 1 1 0 1 115 2 1 115 1 168 3 1 168 1 207 4 1 207 1 234 5 1 234 0 214 6 1 214 0 200 7 1 200 1 229 8 1 229 0 211 9 1 211 0 198 10 1 198 1 228 11 1 228 0 210 12 1 210 0 197 13 1 197 1 227 14 1 227 0 210 15 1 210 0 197 16 1 197 1 227 17 1 227 0 210 18 1 210 0 197 19 1 197 1 227 20 1 227 0 210 21 1 210 0 197 22 1 197 1 227 23 1 227 0 210 24 1 210 0 197 ・ ・ ・ ・ ・ ・ In other words, the temperature data of the comparator 17 in the loop 1
The heat storage temperature data _Ri-1 is "0" for SD "210", and the output of the comparator 17 applied to one input terminal of the AND gate 18 becomes "1". The output data d ′ _i of the data converter 8 applied to the other input terminal of the AND gate 18 is also “1”, and the output data O _i of the AND gate 18 applied as an address of the memory 13 is also “1”.
become. As a result, Table 2.2 described above is selected. Then, since the heat storage temperature data R _i-1 input as the address of the memory 13 is “0”, “0” in Table 2.2
The heat storage temperature data “115” of the address is the heat storage temperature data R _i
Is output as In the subsequent loop 2, the heat storage temperature data “115” read out in loop 1 is replaced with the heat storage temperature data R _i−1.
And the heat storage temperature data “168” at address 115 in Table 2.2 is output as the heat storage temperature data R _i . Same procedure is repeated loop 3 or later, output data O _i applied from the AND gate 18 to the thermal head 19 until the loop 4 becomes "1", thereafter the output data d'
Until _i becomes “0”, “001001...” is continuously and repeatedly output.

[0056]

As described above, according to the present invention,
In the case of a solid black recording state, the recording density of the solid black recording portion is reduced, so that a thermal recording apparatus capable of recording a phenomenon with a large change in a dark state can be realized. As a result, the load in solid black recording can be reduced, and the effect of reducing the size of the power supply can be obtained.

When a high-speed feed speed is selected and set as the feed speed of the thermal recording paper, power saving can be realized by lowering the recording density, and when a medium-speed feed speed is selected and set, special recording is performed. When the low-speed feed speed is selected and set without performing the density correction, the decrease in the recording density can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a timing chart illustrating the operation of FIG.

FIG. 3 is a diagram illustrating an example of recording by the apparatus of FIG. 1;

FIG. 4 is a timing chart for explaining the operation of the digital one-shot unit in FIG. 1;

FIG. 5 is an explanatory diagram of a change in data in the digital one-shot section of FIG. 1;

FIG. 6 is an example of a drive pulse pattern according to the timing chart of FIG. 2;

FIG. 7 is a perspective view of a main part of FIG. 1;

FIG. 8 is a timing chart illustrating the operation of the heat history control unit in FIG. 1;

FIG. 9 is an explanatory diagram of simulation data used in the present invention.

FIG. 10 is a block diagram showing an application example of the present invention.

11 is an explanatory diagram of data change in the digital one-shot section of FIG.

FIG. 12 is a recording example diagram of solid black.

FIG. 13 is a circuit diagram of an example of a conventional thermal recording apparatus.

FIG. 14 is a timing chart illustrating the operation of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shift register 2, 10, 12, 14, 16 Latch 3 NAND gate 4 Inverter 5 Heating element 7 Data selector 8 Data converter 9 Subtractor 11, 15 Memory (dual port RAM) 13 ROM 17 Comparator 18 AND gate 19 Thermal head Reference Signs List 20 temperature sensor 21 recording paper 22 motor 23 timing control circuit 24 OR gate

Claims (2)

(57) [Claims] A plurality of heating elements arranged at regular intervals so as to constitute a line thermal head are selectively driven in accordance with the size of a waveform to generate heat, and a waveform is formed on a thermosensitive recording paper based on the generated heat. A first memory for storing heat storage temperature data relating to a recording operation of a heating element in advance, and reading out the next heat storage temperature data using the current heat storage temperature data and the presence or absence of recording as an address. A second memory for temporarily storing heat storage temperature data read from the first memory; and a comparator for comparing the heat storage temperature data temporarily stored in the second memory with a preset set temperature. A switch element for controlling the recording operation of the heating element according to the comparison result, wherein the color density is reduced when the same heating element is continuously driven in the first memory. Thermal recording apparatus characterized by trap data forming the minor loop is stored for driving the heating element so as to. 2. A plurality of heating elements arranged at regular intervals so as to constitute a line thermal head are selectively driven in accordance with the size of a waveform to generate heat, and a waveform is formed on a thermosensitive recording paper based on the generated heat. A first memory for storing heat storage temperature data relating to a recording operation of a heating element in advance, and reading out the next heat storage temperature data using the current heat storage temperature data and the presence or absence of recording as an address. A second memory for temporarily storing heat storage temperature data read from the first memory; and a comparator for comparing the heat storage temperature data temporarily stored in the second memory with a preset set temperature. A switch element for controlling the recording operation of the heating element according to the comparison result, wherein the same heating element is continuously driven at a light color density in the first memory; A first data group in which trap data forming a minor loop for driving the heating element to increase the color density is stored, and the heating element is driven to reduce the color density when the same heating element is continuously driven. A second data group storing trap data forming a minor loop and a third data group not including the trap data forming these minor loops are stored, and a desired data group is stored in accordance with the feed speed of the thermal recording paper. A thermal recording device, wherein