JPH02178065A - Thermal recording device - Google Patents

Abstract

PURPOSE:To obtain a recorded image without 'blank space' and 'black streak', even if a highly blackish line and a less blackish line appear alternately and restrict noise by using N pieces of pulse for feeding recording paper for subscan to the frequency of divided recordings by a thermal head, allowing a pulse generating device to synchronize the drive of recording blocks with the timing of subscan, estimating the recording cycle of a single line and making a pulse output interval constant. CONSTITUTION:A recording cycle estimating section 21 estimates the cycle of a line to be recorded based on the frequency of divided recordings of a single line and time for block selection for each divided recording. In addition, a subscan feed calculation section 22 calculates data by dividing a cycle which is output from the recording cycle estimating section 21 by the number N of paper feeds for subscan, and determines the interval of pulses. In addition, a comparison circuit 25 compares the content of an ENB output frequency counter 11 with that of a subscan feed counter 24. A subscan feed pulse generating device 23 receives the comparison results and determines the cycle of application pulse and subscan feed pulse to each block. At the same time, the device 23 controls both pulses so that they do not become excessive or short.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a thermal recording device used in facsimile.

[Conventional technology]

FIG. 3 is a block connection diagram showing a conventional thermal recording device disclosed in, for example, Japanese Unexamined Patent Publication No. 61-50464. In the figure, 1 is a transfer lock (hereinafter referred to as TCK) for transferring image signals. 2 is a signal input terminal for inputting an image signal (hereinafter abbreviated as PIX); 3 is a signal input terminal for inputting an image signal (hereinafter abbreviated as PIX);
4 is a signal input terminal for inputting a 1-line recording cycle signal (hereinafter abbreviated as LINE), and 4 is an 1-line recording end signal (
(Hereinafter abbreviated as FIN), 5 is a signal output terminal that outputs P
During the transfer of IX, for example, high level rH. 6 is a black pixel counter as a black pixel counting means for counting the number of black pixels on one line of PIX, and 7 is the number of transferred PIXOs on one line. a transfer pixel counter as a pixel counting means for counting; 8 a batch recording block detection unit as a dividing method determining means for determining a dividing method for one line; 9
is a recording block selection section for selecting a block to be recorded, 1
゜ is the division number counter as a means of division number 21, 11
12 is an applied pulse width generating section; 13 is a strobe generating section for latching PIX into the latch circuit of the thermal head; 14 is an AND gate; It is a thermal head. Next, the operation will be explained while looking at the timing chart of the signals of each part of the block in FIG. First, in synchronization with the rise of the line, PIX, TCK, T
NSO is input. Here, it is assumed that the corresponding black pixels are distributed such that the first line of PIX does not need to be divided, the second line needs to be divided into two, and the third line needs to be divided into three. When the above PIX and TCK are input, the black pixel counter 6
, the transfer pixel counter 7 starts counting black pixels and transfer pixels, respectively, and the black pixel counter 6 outputs (n-1) divided signals OVR when it is necessary to divide l line into n and record them. . -Batch recording block detection unit 8
Now, the division method for one line is determined from this division signal OVR and the transfer pixel counter 7. At the same time, the division number power rank 10 which receives this division signal OVR outputs a division number signal BDT indicating the number of divisions, for example, 1, 2.3, . . . . The ENB output number counter 11 that receives this division number signal BDT presets the number of divisions and generates a trigger signal TRIG that causes the applied pulse width generation section 12 to output the pulse width signal ENB. Further, the applied pulse width generating section 12 which receives this division number signal BDT determines the pulse width according to the number of divisions, and
A pulse width signal ENB is output in synchronization with the trigger signal TRIG. The pulse width of this pulse width signal ENB is the fourth
As shown in the figure, as the number of divisions increases, such as T A < T s < T c, the width is increased. Next, the recording block selection unit 9 decodes the data of the blocks to be recorded in batches, and inputs the decoded data to each block of the thermal head 15 via the AND gate 14. In addition, the ENB output number counter 11 which manually inputs this pulse width signal ENg has a preset value (
Each time the pulse width signal ENB is output, a number of pulses (trigger signal T
RIG) is output. When the preset value and the number of outputs of the pulse width signal ENB match, a line recording end signal FIN is output. The strobe generator 13 receives the 1-line recording end signal F.
A strobe signal S is sent from IN and TNSO to launch the next PIX to be recorded into the latch circuit of the thermal head 15.
Output TB. On the other hand, the recording paper is fed in the sub-scanning direction by generating a predetermined drive current by a stepping motor driver (not shown) in synchronization with the rise of a line, and rotating the stepping motor. The above operations are repeated in sequence to complete recording of one page.

[Problem to be solved by the invention]

Since the conventional thermal recording device is configured as described above,
When lines with more black and lines with less black appear alternately, the recording cycle of one line changes greatly depending on the number of divisions, but since the timing of sub-scanning of the recording paper is fixed at the rising edge of the line, each block The recording interval of the image changes greatly from line to line, causing "white spots" and "black streaks" in the sub-scanning direction, resulting in a significant decrease in the quality of the recorded image, and the feeding speed of the stepping motor changes significantly. There were problems such as increased noise. This invention was made to solve the above-mentioned problems, and allows for high-quality recording that does not cause "white spots" or "black streaks" even when lines with a lot of black and lines with a little black appear alternately. It is an object of the present invention to obtain a thermal recording device that can obtain a high surface area and suppress noise to a low level.

[Means to solve the problem]

The thermal recording device according to the present invention has a timing for sub-scanning the recording paper with N pulses and driving the recording blocks of the thermal head by the sub-scanning feed pulse generating means for the number of divided recordings of the thermal head. , the timing of sub-scan feeding is synchronized, the recording cycle of one line is predicted, and the output interval of the N pulses is set to a constant value.

[Effect]

The sub-scan feed pulse generating means in this invention refers to the division information of one line and the recording cycle information, selects a block to be recorded based on this data, and also generates a paper feed pulse for sub-scan feed of the recording paper. occurs.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, reference numeral 21 denotes a recording cycle predicting section as a recording cycle predicting means, which predicts the cycle of a line to be recorded based on the number of times one line is divided and the block selection time per time. Reference numeral 22 denotes a sub-scanning feed calculating section which performs calculations such as dividing the cycle output from the recording cycle predicting section 21 by the number N of sub-scanning feed pulses of the recording paper to determine the interval of sub-scanning feed pulses. 23 is sub-scanning feed pulse generation means for block driving and sub-scanning feed pulse generation;
An application pulse to each block and a sub-scanning feed pulse synchronized with this application pulse are generated from the number of divided recordings of one line outputted from 0 and the output of a comparison circuit 25 to be described later. A sub-scan feed counter 24 counts the number of sub-scan feed pulses. A comparison circuit 25 compares the contents of the ENB output number counter 11 and the sub-scanning feed counter 24. In response to this result, the sub-scanning feed pulse generating means 23
Then, the pulses applied to each block and the sub-scanning feed pulses are synchronized, and control is performed so that both pulses are output in just the right amount. 26 is a stepping motor driver, 2
7 is a stepping motor. Note that 1 to 13 are the same as those in the conventional example, and a redundant explanation thereof will be omitted. FIG. 2 is a timing chart for explaining the operation of the block connection diagram in FIG. This figure shows the case where four pulses are used. In other words, in the case of a G3 standard facsimile, the paper feed pitch for one line is 1 line per pulse, but in this embodiment, the paper feed pitch is -1 x 1 line per pulse at 7.7.
4 shall be carried out. ENB 1 to ENB 4 are PMDR signals indicating the drive timing of each block of the thermal head.
V is a signal indicating a sub-scanning paper feed pulse composed of pulses 31 to 39, and as described above, therefore, pulses 31 to 39
Paper feed for the first line with 4 pulses of 34, pulses 35 to 3
The second line of paper is fed by four pulses of 8. Next, the present invention will be explained in detail. 1st line PI
When X and TCK are respectively input from the signal input terminal 2゜l, the block recording block detection section 8 detects the black pixel counter 6,
Upon receiving the signal from the transfer pixel counter 7, the division method for one line is determined in the same manner as in the conventional method. Further, the division number counter 10 outputs a division number signal BDT indicating the number of divisions of the l line. The recording cycle predicting unit 21 calculates the number of divisions of one line and the sub-scanning feed pulse generating means 23, which will be described later.
With reference to the applied pulse width per time output from
The recording time per line, and therefore the LINE cycle, is also predicted (in FIG. 2, the first cycle is indicated by tl, and the second cycle is indicated by t2). The sub-scan feed calculating section 22 calculates the period τ of the sub-scan feed pulse from the result of the above-mentioned period, for example, as τ, tl. The sub-scanning feed pulse generating means 23 generates the division number signal B.
DT, each signal of ENB1 to ENB4 that drives the recording block of the thermal head 15 and a signal PMDR that drives the stepping motor driver 26 in response to signals from the sub-scanning feed calculation unit 22 and the ENB output number counter 1.
V is output by the method described below. First, the signal PMDR
After outputting a pulse 31 at V, the signals ENBI and ENB2 are simultaneously selectively driven for a period of T1 in synchronization with this timing. Here, the number of heating elements selectively driven by the signals ENBI and ENB2 is set to a predetermined value or less that does not exceed the power supply capacity. After T1, pulse 32 is output, but T,
> T1, the signals ENB 1 and ENB
2 is selected. Note that the signal ENB and the signal PMDRV are accumulated by the ENB output number counter 11 and the sub-scanning feed counter 24, respectively, and are compared in the comparator circuit 25, and controlled so that pulses with no excess or deficiency are output. Ru. That is, when pulse 33 is output in signal PMDRV, the cumulative value of pulses in signal PMDRV is "3".
On the other hand, since the cumulative value of ENB pulses is "2°", at this timing, the signal ENB3. ENB
4 is selectively driven for T,. Furthermore, at the timing when pulse 34 is obtained, the cumulative value of ENB pulses is “4°°,
Since the cumulative number of pulses in signal PMDRV is "3",
Only pulse 34 is output. Note that when the recording of the ■ line is completed, the ENB output number counter 11 and the sub-scan feed counter 24 are returned to their initial values of 0. Now, in the second line, the period of LINE is predicted to be t2, so the period of signal PMDRV is determined so that τ2LiT-, and after outputting pulse 35, signals ENBI, ENB
2 is selectively driven during T2. Here, the cumulative value of the ENB pulse is "2"', and the signal PMD
Since the cumulative value of pulses at RV is "1'°, the signal P
In MDRV, only pulse 35 is output, and ENB is not driven. Also, at pulses 35 and 36, the signal PMD
The recording of the second line is completed by respectively driving RV and signal ENB. In this way, the above operations are repeated to complete recording of one page. In addition, in the above embodiment, the number of recording blocks of the thermal head 15 was explained as "4°", and the sub-scanning feed pulse of the (1) line was "4", but each value may be 11211 or more, and the same as in the above embodiment. It has the effect of

【Effect of the invention】

As described above, according to the present invention, the sub-scanning feed of the recording paper is performed with a predetermined number of pulses for the number of divided recordings of the thermal head, and the timing of driving the recording block of the thermal head and the timing of the sub-scanning feeding. At the same time, the recording cycle of one line is predicted, and the output interval of the N pulses is configured to be a constant value, making it possible to obtain high-quality recorded images as well as ones with little noise. effective.

[Brief explanation of the drawing]

FIG. 1 is a block connection diagram showing a thermal recording device according to an embodiment of the present invention, FIG. 2 is a timing chart of signals of each part of the block showing the operation of the present invention, and FIG. 3 is a block diagram showing a conventional thermal recording device. The connection diagram and FIG. 4 are timing charts of signals of each part of the block showing the operation of the conventional example. 6 is a black pixel counting means (black pixel counter), 7 is a pixel counting means (transfer pixel counter), and 8 is a division method determining means (-
10 is a dividing number determining means (dividing number counter), 21 is a recording cycle predicting means (recording cycle predicting unit), 23 is a sub-scanning feed pulse generating means, 26 is a stepping motor driver, and 27 is a stepping motor. motor. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. NB STB Figure 4T^ c c -

Claims (1)

[Claims] A pixel counting means for counting the number of pixels input to the thermal head, a black pixel counting means for counting the number of black pixels among the number of pixels, and a dividing method determination for determining a dividing method for one line based on the counted number of black pixels. means, division number determining means for determining the number of divisions of one line, recording cycle prediction means for predicting the cycle of a line to be recorded from the number of divisions of one line and the block selection time per time; a sub-scanning feed pulse generating means for generating a sub-scanning feed pulse synchronized with the applied pulse according to the number of divisions of one line, the applied pulse to each block, and the pulse interval obtained from the period; and a stepping motor driver that drives a stepping motor.