JPS637070B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording method in which recording is performed in accordance with an image signal by energizing heating elements arranged in a row in accordance with the image signal in a facsimile device or the like. .

In this type of thermal recording method, electricity is applied to the heating element to be printed, and the generated heat is transmitted to the thermal recording paper, and the part of the recording paper corresponding to the heating element is chemically Printing is performed by causing a change, and the print density can be said to be in a proportional relationship with the temperature of the heating element within the recordable temperature range.

Therefore, the thermal responsiveness of the heating element greatly affects printing quality. In other words, assuming that the energization time for each printing to the heating element is a fixed time, when focusing on one heating element, the interval from energization once to the next energization is It is good if it is longer than the heat dissipation time until the temperature drops below a certain level, but if it is shorter, the next energization will be performed with the influence of the previous energization remaining, and if this is repeated, heat accumulation will occur. As a result, inconvenient phenomena such as blurring of printed characters gradually occur.

For this reason, when the heating element is energized for a fixed time each time as described above, it is not possible to shorten the time from one printing to the next printing. This has been one of the factors hindering the speeding up of thermal recording.

Now, as can be inferred from the above explanation to capacity, when energizing is carried out while the influence of the previous energization remains, the energization is shorter than when energizing is carried out after the influence of the previous energization has disappeared. Sufficient print density can be obtained in a short amount of time. Moreover, the heat dissipation time becomes shorter as the energization time becomes shorter. Therefore,
If the next energization is performed while the influence of the previous energization remains, and the energization time takes into consideration the energization interval from the previous energization, it is possible to shorten the energization time and speed up recording. It is possible to prevent deterioration of printing quality due to the influence of heat accumulation.

However, in facsimile devices and the like that receive a band-compressed signal and record the expanded signal, the expanded signal is obtained at an undefined speed, so conventionally, the recording period has also been undefined. . Therefore, conventionally, in this type of facsimile device, as mentioned above, ``the next energization is performed while the influence of the previous energization remains, and the energization time is taken into account the energization interval from the previous energization.'' In order to achieve this, the recording cycle must be taken into consideration, which is difficult to achieve.

The present invention has been made in view of the above circumstances, and even when the image signal to be recorded is input at an irregular speed, it is possible to maintain the recording speed without causing blurring, density unevenness, blurring, etc. of the print. The purpose of this invention is to provide a thermal recording method that can speed up the process.

The present invention achieves the above objects in the following manner.

(I) The image signal input at an undefined speed is temporarily stored in a memory, and then the image signal is read out from this memory every N (N3) lines at a constant speed, and based on this read out image signal, By controlling the energization to each heating element, the recording cycle is kept constant within the section for every N lines.

As a result, in printing every N lines, without considering the recording cycle sequentially, as mentioned above, "while the influence of the previous energization remains on each heating element, The next energization is performed at an energization time that takes into account the current energization interval.'' This reduces the energization time, thereby increasing the recording speed, and at the same time, it is possible to prevent deterioration of print quality due to the effects of heat accumulation.

Furthermore, in the printing every N lines, it is possible to eliminate the unevenness of printing density caused by a change in the recording cycle, which conventionally occurs.

() When printing every N lines, the specific method of "carrying out the next energization at a time that takes into account the energization interval from the previous energization" is to change the energization time to the heating element that printed in the previous line. In the line, the energization time is shorter than that of a heating element that does not perform printing.

() Since the interval between prints for each of the N lines is indefinite, the operations described in (I) and () above alone will result in uneven print density for each of the N lines.

Also, if a long time elapses between the end of printing the previous N line and the start of printing the next N line, each heating element will cool down to a certain temperature or higher, so the next N line will be printed. The first printing performed by each heating element tends to be blurred.

Therefore, in printing every N lines, the time for energizing the heating element that prints for the first time is longer if the time from the end of printing of the previous N line to the start of printing of the N line is long, and if it is short By making the length shorter than 1, it is possible to prevent density unevenness between printings for every N lines and blurring of printing for the first time.

Hereinafter, the present invention will be explained in more detail based on embodiments shown in the drawings.

FIG. 1 shows an embodiment of the invention. In the figure, a facsimile signal P transmitted through a telephone line is input to a demodulator 2 through an input terminal 1, and is demodulated by the demodulator 2. The demodulated signal output from the demodulation section 2 is input to the data expansion section 4 via the buffer memory section 3.

Here, the buffer memory section 3 is inserted between the demodulation section 2 and the data decompression section 4 because the facsimile signal P is input to the input terminal 1 from the telephone line at a constant speed. Since the processing after the decompression unit 4 is performed at an undefined speed, the purpose is to make adjustments during that time. Therefore, the capacity of the buffer memory section 3 is set so as not to cause an overflow even when input to the buffer memory section 3 continues and the processing after the data decompression section 4 is at its slowest speed.

The data expansion unit 4 decodes the image signal in the demodulated signal input from the buffer memory unit 3,
The data is transferred to the line memory section 5. This line memory section 5 has a capacity for (N+1) lines,
Under the control of the signal A input from the recording section 6, the decoded image signal is further transferred from the same line memory section 5 to the recording section 6 at a constant speed every N lines (B is this (shows the image signal transferred from the line memory section 5 to the recording section 6).

FIG. 2 shows details of the recording section 6. As shown in FIG. In the figure, 7 is a control section which outputs the signal A to the line memory section 5 through the output terminal 25, and also outputs the signal A to the line memory section 5 through the output terminal 25.
It controls each part of the recording section 6.

Reference numeral 8 designates an image signal input terminal to which the image signal B transferred from the line memory section 5 is input, and 9 a clock input terminal to which the clock signal C is input. Reference numeral 10 denotes an n-bit serial input/parallel output shift register, into which the image signal B is inputted using a clock signal C. Here, n is the total number of dots (total number of heating elements) in one line. A latch circuit 11 latches the output of the register 10 in response to a latch signal D output from the control section 7.

12 is also a latch circuit, which latches the outputs K ₁ to Kn of each bit of the latch circuit 11 in response to a latch signal H output from the control section 7. 13 is also a latch circuit, and n two-input OR gates 14 (1) to 14 are connected by a latch signal H common to the latch circuit 12
14(n) is latched. Here, the said
One input of the OR gates 14(1) to 14(n) is the output ₀₁ to On of each bit of the latch circuit 13, and the other input is the output K1 to _Kn of the latch circuit 11.

Note that the latch circuits 12 and 13 are cleared by clear signals G and J output from the control section 7, respectively.

15(1) to 15(n) are 2-input ANDs in which the outputs K ₁ to Kn of each bit of the latch circuit 11 are used as one input, respectively, and the energization signal E output from the control unit 7 is commonly used as the other input. It is a gate. 1
6(1) to 16(n) are inverters whose input is the output of each bit of the latch circuit 12, and 17(1) to
17(n) is the inverter 16(1) to 16(n)
The outputs of the latch circuit 1 are each taken as one input, and the latch circuit 1
This is a 3-input AND gate in which the outputs K ₁ to Kn of 1 are each used as other inputs, and the energization signal F outputted from the control unit 7 is commonly used as another input.

18(1) to 18(n) are inverters whose inputs are the outputs O ₁ to On of the latch circuit 13; 19(1)
-19(n) are inverters 18(1)-18
The outputs of (n) are each used as one input, the outputs K ₁ to Kn of the latch circuit 11 are each used as other inputs, and the energization signal I output from the control unit 7 is commonly used as another input. It is an input AND gate.

Here, the energization signals E, F, and I are signals that are turned on for times T ₁ , T ₂ , and T _{3 ,} respectively, according to timings described later.

20(1) to 20(n) take outputs L ₁ to Ln of AND gates 15(1) to 15(n) as one input, respectively, and AND gates 17(1) to 17(n)
It is a 3-input OR gate which takes outputs M ₁ to Mn of AND gates 19(1) to 19(n) as other inputs, and outputs Q ₁ to Qn of AND gates 19(1) to 19(n) as another input, and these OR gates 20 The outputs of (1) to 20(n) are connected to heating elements 22(1) to 22(n) via amplifier circuits 21(1) to 21(n).

Next, the operation of the recording section 6 shown in FIG. 2 will be explained together with the signal timing diagram shown in FIG. 3.

First, from the line memory section 5 to the image signal input terminal 8
Before the image signal B of the first line of one page is transferred to the shift register 10, the latch circuits 12 and 13 are cleared by clear signals G and J, respectively.

Then, the image signals for the first N lines of the one page are decoded by the data decompression unit 4, and when the control unit 7 turns on the signal A, the line memory unit 5
The image signal B of the first line of the page starts to be transferred to the shift register 10 through the image signal input terminal 8. When the signal A is started, the signal A is turned off). When the transfer of the picture signal B of the first line to the shift register 10 is completed, the latch signal D is turned on, and the picture signal B of the first line is latched in the latch circuit 11. When this latch is completed, the signal A is turned on again, and the transfer of the image signal B of the second line of the one page to the shift register 10 is started.

Next, the energization signal E is turned on for a time _T1 , and this
During T ₁ , among the AND gates 15(1) to 15(n), the outputs K1 to Kn of the corresponding latch circuits ₁₁ are black signals (logical level "1"), and the AND gates are The heating elements 22 corresponding to those gates 15 are connected to the amplifier circuits 21(1) to 2.
1(n).

When the energization signal E is turned off, the energization signal F is then turned off.
is on for time T ₂ . Then, in this case, since the outputs of all the bits of the latch circuit 12 are white signals, the AND gate 1 is turned off during the time _T2 .
7(1) to 17(n), the outputs _K1 to Kn of the corresponding latch circuits 11 are black signals, and the AND is established, and the heating elements 22 corresponding to those gates 17 are energized. be exposed.

When the energization signal F is turned off, the energization signal I is then turned off.
is on for time T ₃ . Then, in this case, since all outputs O ₁ to On of the latch circuit 13 are white signals, the AND gates 19 ( ₁ ) to
19(n), the outputs K ₁ to Kn of the corresponding latch circuits 11 are black signals, and the AND is established, and the heating elements 22 corresponding to those gates 19 are energized.

As a result of the above, printing is performed on the black signal of the first line of the page, but in this case, the energization time to each heating element 22 is T ₁ +T ₂ +T ₃ .

Next, when the energization signal I turns off, the latch signal H turns on. Then, the latch circuit 12 latches the outputs K ₁ to Kn of the latch circuit 11, that is, the image signal of the first line. Also, at the same time,
Output K ₁ ~ Kn of latch circuit 11 to latch circuit 13
and the outputs O ₁ -On (all white signals) of the latch circuit 13 itself, that is, the image signal of the first line is latched.

Subsequently, after the transfer of the second line image signal B from the line memory section 5 to the shift register 10 is completed, the latch signal D is turned on, and the second line image signal B is turned on.
The picture signal of the th line is latched by the latch circuit 11. When this latch is completed, the signal A is turned on in the same manner as described above, and the transfer of the image signal of the third line of the one page from the line memory unit 5 to the shift register 10 is started. Next, the energization signal E is turned on for a time _T1 , and in the same manner as described above, during this time _T1 , the energization signal E is turned on, and during this time T1 corresponds to the black signal in the image signal of the second line, which is latched in the latch circuit 11. The heating element 22 is energized.

When the energization signal E is turned off, the energization signal F is then turned off.
is on for time T ₂ . Then, during this T ₂ ,
Among the AND gates 17(1) to 17(n), an AND is established between the gates in which the outputs K1 to Kn of the corresponding latch circuits ₁₁ are black signals and the outputs of the corresponding latch circuits 12 are white signals. Therefore,
During the time _T2 , the heating element 22 whose corresponding signal in the image signal of the first line is a white signal and whose corresponding signal in the image signal of the second line is a black signal is energized. will be held.

When the energization signal F is turned off, the energization signal I is then turned off.
is on for time T ₃ . Then, during this T ₃ ,
The outputs K ₁ to Kn of the corresponding latch circuits are black signals,
The AND of the gate 17 is established in which the outputs O ₁ to On of the corresponding latch circuits 13 are white signals.
Therefore, during the time _T3 , the corresponding signal in the picture signal of the first line is a white signal, and the corresponding signal in the picture signal of the second line is a black signal. The body 22 is energized.

As a result of the above, printing is performed for the black signal on the second line, but in this case, (a) the corresponding image signal is a white signal on the first line, and is not printed on the second line for the first time. The energization time for the heating element 22 that has become a black signal, that is, the heating element 22 that prints for the first time in the second line, is T ₁ + T ₂ + T ₃ (b) When the corresponding image signal is a black signal in the first line, The energization time for the hot heating element 22, that is, the heating element 22 that also printed in the previous line, is _T1 .

Energization signal I for printing the second line
When the latch signal H turns off, the latch signal H turns on, and the latch circuit 12 latches the outputs K ₁ to Kn of the latch circuit 11, that is, the image signal of the second line, and the latch circuit 13 latches the output of the latch circuit 11. output
K ₁ ~ Kn and the output of the same latch circuit 13 itself O ₁ ~ On
The signal obtained by ORing the image signal of the first line and the signal of the second line.
The signal that is ORed is latched.

Next, from the line memory section 5 to the shift register 1
After the transfer of the picture signal B of the third line to 0 is completed, the latch signal D is turned on, and the picture signal of the third line is latched in the latch circuit 11.

Thereafter, by repeating the same operation as described above, during the next time _T1 when the energization signal E is turned on,
The heating element 22 whose corresponding image signal is a black signal in the third line is energized. Also, during the time _T2 when the energization signal F is turned on next,
Current is applied to the heating element 22 whose corresponding image signal is a white signal in the second line and a black signal in the third line. moreover,
Next, during time _T3 when the energization signal I is turned on, the corresponding image signal is a white signal in the first line and the second line, and becomes a black signal for the first time in the third line. heating element 22
energization is performed.

As a result of the above, printing is performed on the third line, but in this case, (a) the corresponding image signal becomes a black signal for the first time in the third line, that is, the heating element 22, that is, the third line. The energization time for the heating element 22 that prints for the first time in a line is T ₁ +T ₂ +T ₃ (b) The corresponding image signals are a black signal in the first line, a white signal in the second line, and a white signal in the third line. In the th line, the energization time for the heating element 22 which became a black signal is T ₁ +
T ₂ (c) The energization time for the heating element 22 whose corresponding image signal was a black signal also in the second line, that is, the heating element 22 that printed in the previous line, is T ₁ .

Thereafter, by repeating the same operation as described above, the latch circuit 11 receives the current line, the latch circuit 12 receives the previous line, and the latch circuit 13 receives the image signal from the first line to the previous line.
Each ORed signal is latched. (a) During the time _T1 when the energizing signal E is on,
The heating element 22 whose corresponding image signal is a black signal in the current line is energized, and (b) during the time T ₂ during which the energization signal F is on,
The corresponding image signal is a white signal on the previous line,
In the current line, the heating element 22 which is the black signal is energized, and (c) during the time _T3 when the energization signal I is turned on, the corresponding image signal continues to be white from the first line to the previous line. This is a signal, and the heating element 22 that has become a black signal for the first time in the current line is energized.

As a result, printing is performed on the current line, and the energization time for each heating element 22 during printing on this current line is as follows: (a) The heating element 22 whose corresponding image signal becomes a black signal for the first time in the current line; That is, for the heating element 22 that prints for the first time on the current line, T ₁ + T ₂ + T ₃ (b) Although the corresponding image signal has become a black signal at least once from the first line to the previous line. , T ₁ + T ₂ (c) for the heating element 22 that was a white signal in the previous line, that is, the heating element 22 that printed at least once, but did not print in the previous line. For the heating element 22 whose image signal was a black signal in the previous line, that is, the heating element 22 which also printed in the previous line,
It becomes T ₁ .

In this way, when all of the image signals B for the first N lines of one page have been transferred from the line memory unit 5 to the shift register 10, decoding for the next N lines is completed in the data decompression unit 4. Before this, the clear signal J is turned on and the latch circuit 13 is cleared (the clear signal J is turned on every N lines thereafter).

Thereafter, when the decoding of the image signals for the next N lines is completed in the data decompression unit 4 and the signal A is turned on, the image signal B of the (N+1)th line is transferred to the shift register 10. .

Thereafter, the same operation as described above is repeated, so that the image signal of the (N+1)th line is latched in the latch circuit 11, and after that, (a) During the time T ₁ when the energization signal E is turned on, The corresponding image signal is a black signal in the (N+1)th line, and the heating element 22 is energized, and (b) during the time T ₂ when the energization signal F is turned on, the corresponding image signal is latched. The heating element 22 is energized with a white signal on the Nth line latched in the circuit 12 and a black signal on the (N+1)th line, (c) Time T during which the energization signal I is turned on. ₃ , the heating element 22 whose corresponding image signal is a black signal in the (N+1)th line is energized.

As a result, printing is performed on the (N+1)th line, that is, the first line of the new N lines. In this case, the energization time for each heating element 22 is as follows: (a) The corresponding image signal is For the heating element 22 that was a white signal in the Nth line, that is, the heating element 22 that was not printing in the last line of the previous N line, T ₁ + T ₂ + T ₃ (b) corresponds to The heating element 22 whose image signal was a black signal in the Nth line, that is, the previous N
For the heating element 22 that also printed on the last line, T ₁ +T ₃ is obtained.

Thereafter, the (N+1)th to 2Nth lines are printed in the same manner as the second to Nth lines.

Also, the lines after the (2N+1)th
Printing is carried out by repeating the same operation for each line. However, if the image signals decoded and stored in the line memory section 5 at the end of one page are less than N lines, the image signal of the last line of one page has finished being stored in the line memory section 5. At this point, the signal A is turned on, and the transfer of the image signal B from the line memory section 5 to the shift register 10 of the recording section 6 is started.

The control unit 7 sets the time _T3 during which the energization signal I is turned on to be longer if the time from the end of printing of the previous N line to the start of printing of the N line is long, and to be short if it is short. do. Therefore, N
In printing for each line, the energization time for the heating element that prints for the first time is longer if the time from the end of printing of the previous N line to the start of printing of the N line is long, and short if it is short.

Further, in this embodiment, in addition to the above-mentioned control, the control unit 7 also controls the time T ₁ , during which the energization signals E, F, and I are turned on, depending on the ambient temperature of the heating element 22 .
Controls T ₂ and T ₃ .

In addition, if there is an interval of more than a certain period of time between the end of printing the previous N line and the start of printing the next N line, the latch circuit 12 is also cleared, since the influence of the previous N line printing disappears. , the same condition as when printing the first line of the first page, and the next N lines are printed regardless of the printing of the previous N lines.
Line printing may also be performed.

Furthermore, in this embodiment, one line is printed at the same time, but the heating elements arranged in one row may be divided into several blocks, and the heating elements may be energized for each block. Needless to say.

As described above, the thermal recording method according to the present invention can be used even when the image signal to be recorded is input at an undefined speed.
This provides an excellent effect of increasing the recording speed without causing blurring, density unevenness, blurring, etc. of printed characters.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a thermal recording system according to an embodiment of the present invention, FIG. 2 is a circuit configuration diagram showing details of the recording section 6 of FIG. 1, and FIG. 3 is a timing diagram of signals in the recording section 6. It is. 5... Line memory section, 6... Recording section, 10...
...shift register, 11,12,13...latch circuit, 21(1) to 21(n)...amplifier circuit, 2
2(1) to 22(n)...Heating elements.

Claims (1)

[Claims] 1. Temporarily store the image signal input at an undefined speed in a memory, and transfer the image signal from this memory to N (N≧3)
Each line is read out at a constant speed, and based on the read image signal, energization to each heating element is controlled, and in printing every N lines, the energization time to the heating element that prints for the first time is determined. If the printing interval from the end of printing for the previous N lines to the start of printing for the relevant N lines is long, the printing interval is lengthened, and if it is short, the printing interval is shortened.
A thermal recording method in which the time for energizing a heating element that printed in the previous line between each line within a line is shorter than the time for energizing for a heating element that did not print in the previous line.