JPS6150464A - Thermosensing recorder - Google Patents

Abstract

PURPOSE:To obtain a recording picture without uneven density by changing a drive time of a recording element in response to the number of divisions of one line in the constant bit recording system. CONSTITUTION:When a detected black picture element number exceeds a prescribed value, a black picture element counter 6 outputs a pulse signal (OVR). A total recording block detection section 8 inputs the OVR to detect data from a picture element counter 7 to decide the method of division of one line of the transmitted picture signal (PIX) and a division number counter 10 outputs a (BDT). Then an application pulse width signal (ENB) output number counter 11 presets its division number to generate a TRIG outputting the ENG from a print pulse width generating section 12. Further, the section 12 decides the pulse width in response to the number of divisions and outputs the ENB in synchronization with the TRIG. The pulse width of the ENB is increased as the number of divisions is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thermal recording device used in facsimile machines and the like.

Conventional Structure and Problems Recently, facsimile machines that transmit images and the like using lines have been installed not only in workplaces but also in ordinary homes. A low-noise, high-reliability thermal recording device using a thermal head that is excellent in high speed and high resolution is widely used to record images received by this facsimile machine.

Various recording methods are used in this thermal recording device.

Among these methods, the method in which one line is recorded on recording paper in one drive is the fastest. However, in a thermal recording device using this method, one line is recorded in one drive, so if all the pixels of one line are black pixels, the driving current for all the recording elements of one line is applied at the same time. In other words, a power source with a very large capacity is required. However, the proportion of black pixels in most lines of a transmitted original is less than ten percent, and there are cases in which the number of black pixels in a line is extremely small. Therefore, using a power source with a large capacity is extremely uneconomical, and also increases the cost of the device itself.

Therefore, if the number of black pixels included in one transmitted line is less than a certain value, one line is recorded at a time,
If the number of black pixels exceeds a certain value K, one line is divided so that the number is equal to or less than the number of A black pixels, and the data is recorded by dividing it into the divided number of times. A so-called constant bit recording method has been proposed.

However, in a thermal recording device using the above-mentioned constant bit recording method, the recording time for one line varies depending on the number of black pixels, that is, the driving time of each recording element (heating element) is the same, but Since the driving timing of the printing elements differs depending on the number of lines, the larger the number of times one line is divided, the greater the difference in heat storage between the individual printing elements. Therefore, this is a problem that causes density differences in the recorded black pixel portions due to differences in heat storage in individual recording elements, and particularly, the greater the number of line divisions, the more significant density differences occur.In other words, this problem causes unevenness in the entire recorded image. was there.

) E#Joc+h The present invention solves the above-mentioned conventional problems, and when driving and recording using a constant bit recording method, the recording element is driven according to the number of divisions of one line without requiring complicated circuits or controls. It is an object of the present invention to provide a thermal recording device capable of obtaining a recorded image without density unevenness by changing the time.

Structure of the Invention The thermal recording device of the present invention includes a recording element corresponding to the number of pixels for one line, a storage circuit for storing an image signal for one line, and a recording element corresponding to the number of black pixels of the stored image signal. A recording device comprising: a drive circuit for selectively driving the recording element; and means for detecting the number of black pixels of the image signal stored in the storage circuit; and means for determining a driving time for driving the recording element according to the determined number of divided recordings, and means for determining a driving time for driving the recording element according to the determined number of divided recordings and the driving time. The Eel□1□IJ through the circuit
M L Me M t Z + Yo. , it is one thing. The present invention having such a configuration detects the number of black pixels of one line, determines the number of divided recordings of one line based on the number of black pixels, and increases the driving time of the recording element by a predetermined time as the number of divided recordings increases. By doing so, the above purpose can be achieved.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a thermal recording apparatus according to an embodiment of the present invention. In the figure, 1 is a transfer lock (hereinafter abbreviated 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 a one-line recording cycle signal (hereinafter abbreviated as I, INK); 4 6 is a signal output terminal that outputs a 1-line recording end signal (hereinafter abbreviated as FIN), and 6 is a signal output terminal that outputs a signal that reaches level 5 during PIX transfer (hereinafter TNS).
6 is PIX1
A black pixel counter 7, which counts the number of black pixels in a line and generates a pulse, for example, a carry (hereinafter abbreviated as OVR) every time this number exceeds a predetermined value, is transferred. Transfer pixel counter that counts the number of PIX in one line, 8 is OV from black pixel counter 6
A batch recording block detection unit inputs R and information on the number of PIX transferred from the transfer pixel counter 7 and determines the division method necessary to record one line. 10 is a recording block selection unit that decodes 1 line division information) and selects a block to be recorded based on this data; 10 is an OV from a black pixel counter;
A dividing number determining means for counting R and recording one line, that is, a dividing number counter (hereinafter abbreviated as BDT);
11 records one line by BDT, so it counts the number of outputs of an applied pulse width signal (hereinafter referred to as NEB), which will be described later, and compares this number with the BDT. If the results do not match, a trigger signal (hereinafter referred to as TRIG) is output, and if there is a discrepancy, a one-line recording end signal (hereinafter FIN) is output.
ENB output number counter 12 that outputs
is variable according to the BDT from the division number counter 10,
The driving time determining means, that is, the applied pulse width generating section 13 outputs KNB synchronized with TRIG from the KNB output number counter 11, furthermore, when Tl5O is low level - L1, that is, the image signal is not being transferred, FIN A strobe generator 14 generates a strobe signal (hereinafter abbreviated as STB) for latching the PIX temporarily stored in the shift register of the thermal head unit 16 to the launch circuit at the output timing of the thermal head unit 16, which will be described later. At this point, E is selected by the signal from the recording block selection unit 9 and ENB.
An AND gate selects NB1 to ENBN, and 16 is a thermal head section equipped with a shift register, a latch circuit, an AND gate, a driver, and the like.

Next, the operation of the thermal recording apparatus of the present invention will be explained based on the timing chart of FIG. First, LINE (7)
Rini Synchronization City, PIX, TGK, and TNSO will be providing human resources. Here, the first line of PIx does not need to be divided, the second line needs to be divided into two, 3
Black pixels corresponding to each line are distributed so that it is necessary to divide the line into three. When this PIX is transferred to the thermal head section 16, the previous line that has already been transferred to the shift register is latched by the launch circuit, and recording is started at the rising edge of LINE of the next line.

At this time, with the data already detected by the black pixel counter 6 and the transfer pixel counter 7, the batch recording block detection unit 8
Calculate the data of the recording block that records the previous line all at once. The black pixel counter 6 outputs a pulse signal (hereinafter abbreviated as OVR) every time the number of black pixels, which is the detected data, exceeds a preset value. In other words, if one line needs to be divided into n and recorded, n -1(
OVR of 1@ is output. Then, the batch recording block detection unit 8 inputs this OVR and calculates the pixel counter 7.
Detects data from and determines how to divide the transferred PIX1 line. Also, at the same time, 0°v” & A, f
J l-t oII @ % h'y > 1107
5") +i, IBDT (in this example, data in which the number of divisions is 0.1.2.3, etc.) is output. The KNB output number counter 11 that inputs this BDT presets the number of divisions and applies Pulse width generator 1
2 generates TRIG that outputs ENB. In addition, the applied pulse width generating section 12 that manually generates this BDT determines the pulse width according to the number of divisions, and generates the EN signal in synchronization with TRIG.
Output B. The pulse width of this ENB increases as the number of divisions increases. Therefore, in this example ENB
The pulse width of is T, 〈TB <T.

The relationship is In other words, the applied pulse width can be varied according to the number of times one line is divided. At this time, the bundled recording block detection unit 8 that has input this ENB
determines the division method for one line, and outputs the data of the block to be recorded all at once to the recording block selection section 9. Here, the data of the block is decoded by the recording block selection section 9, and the ENB is selected by the thermal head section 16 as the selected ENB1 to ENBN through the AND gate 14.
is applied to At this time, the greater the number of divisions, the more the KNB becomes a pulse width (T, , T, , To) sufficient to correct the degree of heat accumulation between recording elements. In addition, the ENB output count counter 11 to which this KNB is input will count the number of times each ENB output ends until it matches the preset value (BDT).
Continuously TRI(.

Output. In other words, the number of pulses corresponding to the number of divisions is output. Then, when the preset value and the number of END outputs match and the one-line recording end signal FIN is output, the strobe generator 13 detects this FIN and the low level of TNSO from the outside and outputs the next line to be recorded to the thermal head. The STB to be launched to the latch circuit of section 15 is output. One page is recorded by sequentially repeating the above operations.

In addition, LINE does a handshake with FIN.
After detecting the output of FIN, it is input to the signal input terminal 3. That is, a high level signal is input to this input terminal f-3. Also, this second
Although the timing chart shown in the figure shows cases in which one line is driven simultaneously, divided into two, and divided into three, the recording operation can be performed at the same timing as described above even when the number of divisions of one line increases.

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 rising edge of LINE, and rotating the stainless steel and ping motors.

Effects of the Invention According to the present invention, the driving time (current supply time to the recording element) can be adjusted according to the number of divided recordings of one line without using complicated circuits or controls so as to eliminate the influence of heat storage difference between the recording elements. ) can be varied, so even in the constant bit recording method, density unevenness does not occur in the recorded image, and a high quality image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a thermal recording apparatus showing an embodiment of the present invention, and FIG. 2 is an operation timing chart of the thermal recording apparatus shown in FIG. 1...TCK signal input terminal, 2...P4X signal input terminal, 3...LINK signal input terminal, 4...L
F I N I″I′lj″ eaves・b゛゛°
4 N S O @ On 1 child, 6-... Black pixel counter (
black pixel number detection means), 7...transfer pixel counter, 8...batch recording block detection unit, 9...
- Recording block selection section, 10... Division number counter (divided recording number determining means), 11... KNB output number counter, 12... Applied pulse width generation section (driving time determining means) , j3... Strobe generation section, 14... AND gate, 16... Thermal head section. Name of agent: Patent attorney Toshio Nakao (1 person)

Claims (1)

[Claims] A recording element corresponding to the number of pixels for one line, a storage circuit for storing an image signal for one line, and a drive circuit for selectively driving the recording element according to the number of black pixels of the stored image signal. A recording device comprising: means for detecting the number of black pixels of the image signal stored in the storage circuit; means for determining the number of divided recordings of one line based on the detected number of black pixels; means for determining a driving time for driving the recording element according to the determined number of divided recordings, and driving the recording element via the drive circuit according to the number of divided recordings and the driving time, A thermal recording device characterized by recording on recording paper.