JP2669952B2 - Fax machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a facsimile apparatus having a thermal printing unit such as a thermal head, and more particularly to a facsimile apparatus which eliminates uneven print density by smoothing print control.

[0002]

2. Description of the Related Art Conventionally, as a technique of this kind of field, there is one as shown in FIG. The configuration will be described below with reference to the drawings.

FIG. 2 is a block diagram showing a configuration example of a conventional facsimile apparatus.

This facsimile apparatus has a data bus 1, which is provided with a central processing unit (hereinafter referred to as CPU) 2 for controlling the operation of the entire apparatus and a circuit for controlling connection of lines. And the image data storage area 4 for storing the image data received from the communication control unit 3.
An image data decoding device 5 for decoding the encoded received image data line by line and transmitting the decoded image data,
A motor driving device 6 for printing and a thermal head printing device 7 that prints the decoded image data on a line-by-line basis by driving the motor driving device 6 are connected to each other.

Next, the operation will be described.

When the image data received from the facsimile machine on the transmission side of the other party is received, the image data is received by the communication control unit 3.
Is stored in the image data storage area 4 via the. The accumulated received image data is decoded by the image data decoding device 5 in units of one line by the image data decoding device 5 according to the notification from the central processing unit 2.

When the decoding of one line is completed, the CPU 2
The motor driving device 6 is driven through the same, and at the same time, one line of image data is transferred to the thermal head printing device 7. The motor drive device 6 prints on a line-by-line basis, but since it is synchronized with the decoded image data, the printing speed is directly proportional to the transmission time of one line.

For example, when the transmission speed is 9600 BPS, when the transmission time is T when the decoded image data of one line is 1 KB, T = 1024B / (9600/8) = about 853 ms. Therefore, the printing speed is about 853 ms, and the printing is performed. However, this printing speed is the printing movement time for one line, and the time for actually applying thermal energy to the thermal paper is a certain time.

[0009]

However, in the facsimile apparatus having the above-mentioned structure, the printing time is directly proportional to the transmission time of one line in units of line. Therefore, if the transmission time is long, the time required for printing becomes long. The shorter the transmission time, the shorter the time required for printing. In the case of the thermal recording type, thermal energy is applied to the heating element of the thermal head for a certain period of time, which is a unit of one line, and printing is performed on the thermal paper.

The longer the time required to print one line, the longer the waiting time for starting the printing of the next line, so that the heating element of the thermal head gets stuck and the print density of the next line is hard to appear. . On the contrary, the shorter the time required for printing one line is, the shorter the printing time interval with the next line is. Therefore, the heating element of the thermal head is printed without being pinched, and the density is easily generated. As described above, since the printing time depends on the transmission time, there is a problem in that the density may be improved or may be difficult to output.

The present invention provides a facsimile apparatus which solves the problem that the print density unevenness occurs as a problem of the above-mentioned prior art.

[0012]

In order to solve the above problems, a first invention is an image data decoding unit for decoding received image data in units of one line and transmitting the decoded image data,
A facsimile apparatus provided with a printing unit for printing the decoded image data line by line in a thermal recording system is provided with the following means. That is, a one-line transmission time conversion table that stores transmission time data for one line of the received image data, and a decoded image data memory that stores a plurality of lines of less than one screen in the decoded image data as sample lines. And an average print control unit for calculating the average print time of each sample line with reference to the transmission time data for one line and controlling the print time for each line of the printing unit based on the calculation result. And are provided.

A second invention is the same as the first invention,
An inter-line threshold value control means for controlling the variation amount of the average printing time between the sample lines with a predetermined threshold value is provided.

A third invention is the same as the second invention,
Correction control means for correcting an error between each control result of the inter-line threshold value control means and the transmission time of each sample line is provided.

[0015]

According to the first aspect of the present invention, since the facsimile apparatus is configured as described above, the average print control means refers to the transmission time data for one line in the one-line transmission time conversion table. The average printing time of each of the plurality of sample lines stored in the decoded image data memory is calculated, and the printing time for each line is controlled by the average printing time. This eliminates density unevenness caused by variations in printing time between lines.

According to the second aspect of the invention, the inter-line threshold value control means sets a certain threshold value and controls so that the inter-line threshold value control means does not fluctuate greatly when the average print time difference between lines is large.

According to the third invention, the correction control means allows
The error between the actual transmission time and the printing time caused by the second invention is corrected.

Therefore, the above problem can be solved.

[0019]

1 is a block diagram showing the configuration of a facsimile apparatus according to an embodiment of the present invention.

In this facsimile apparatus, a control unit 51 for controlling the operation of the entire apparatus, a communication control unit 52 for performing communication control such as line connection control, a storage unit 53 for storing received image data, and received image data An image data decoding unit 54 that decodes in units of lines and sends decoded image data, a decoded image data memory 55 that stores a plurality of lines of less than one screen in the decoded image data as sample lines, and a decoding unit. A printing unit 56 for printing the decoded image data from the image data memory 55 on a line-by-line basis (main scanning direction) is provided, and these are connected to each other via a data bus 57. The control unit 51 is composed of a microprocessor or the like, and the communication control unit 52 includes a modem 52a for converting analog image reception image data into a digital signal, and a fill control device 5 for synchronizing with a facsimile machine on the other side.
2b and a multi-protocol serial controller 52c for controlling serial data communication,
I have it. The storage unit 53 is composed of a RAM (random access memory), and has an image data memory 53a for storing the received image data from the communication control unit 52 and one line for storing the transmission time data for one line of the received image data. And a transmission time conversion table 53b.

Here, the 1-line transmission time conversion table 5
The transmission time data for one line in 3b is identification data EOL (CCI indicating that it is the last data of one line.
The time between TT recommendations) is calculated by the transmission rate and configured. The storage format of the 1-line transmission time conversion table 53b is shown in FIG. In the figure, reference numeral 11 represents the first line, t1 represents the transmission time of the first line, and similarly, reference numerals 12 and 13 represent the second line and the third line, respectively.
2 and t3 represent the transmission time of the second line and the third line.

Further, the printing section 56 comprises a motor driving device 56a for printing, a thermal head printing device 56b for printing the decoded image data line by line by driving the motor driving device 56a, and a recording paper moving mechanism. Has been done.

The control unit 51 also refers to the transmission time data for one line in the one-line transmission time conversion table 53b to calculate the average printing time of each sample line in the decoded image data memory 55. An average print control unit 51a that controls the print time of each line of the printing unit 56 based on the calculation result, and an interline threshold control unit that corrects the variation amount of the average print time between each sample line with a predetermined threshold value. 51b and correction control means 51c for correcting the deviation between the calculated average print time and the actual transmission time caused by the difference between the average print times being corrected by the interline threshold control means 51b.

The operation of the facsimile apparatus configured as described above will be described. Before describing the operation, an outline of the print control methods (A), (B), and (C) of the present invention will be described.

(A) The number of sample lines is determined, and the average print control means 51a calculates the average print time from the following equation. FIG. 4 shows the control state of the average print control means 51a.
In the figure, reference numerals 11, 12, 13, ... Represent 1 line, 2 lines, 3 lines, respectively, t1, t2, t3 ...
Represents the transmission time of 1 line, 2 lines, 3 lines, and Mt1, Mt2, Mt3, ... Represent the respective average printing times obtained by the following equation. Here, assuming that the number of sample lines is three, for example, the average printing time Mt1 to Mt of the first line to the third line
t3 is as follows. Mt1 = (t1 + t2 + t3) / 3 Mt2 = (t2 + t3 + t4) / 3 (however, no correction) Mt3 = (t3 + t4 + t5) / 3 (however, no correction) (B) If it is large, density unevenness occurs, so the average printing time is corrected with a certain threshold value S as in the following equation. S ≦ | Mt2-Mt1 | (2) However, Mt1; average printing time of the first line Mt2; average printing time of the second line When the above equation (2) is satisfied, the average printing time after correction M
t2a is Mt2a = Mt1 ± S (+ increases, − decreases).

(C) When the above equation (2) is satisfied, the deviation between the actual transmission time and the calculated average printing time is corrected by the following equation. d = Mt2-Mt2a (d; correction value of real number) (3) The correction value d is added to the above equation (1) of the next line to obtain the average printing time. As a general formula, the average printing time Mtn of n lines is expressed by the following formula. Mtn = (tn + tn + 1 + tn + 2 + d) / 3 (4) Next, the operation of the facsimile apparatus of the embodiment shown in FIG. 1 will be described.

The image data received from the facsimile apparatus on the other side is analog-digital converted by the modem 52a, and the fill control device 52b removes the fills other than the image data signal. Further, the received image data that has passed through the fill controller 52b is put on the data bus 57 via the multi-protocol serial controller 52c and stored in the image data memory 53a.

Thereafter, the received image data stored in the image data memory 53a is decoded by the image data decoding unit 54 under the control of the control unit 51 by decoding the encoded received image data in units of one line. The image data is sent to the decoded image data memory 55 via the data bus 57.

Now, assuming that the number of sample lines stored in the decoded image data memory 55 is three, the flow of the print control of this embodiment will be described with reference to FIG. In addition,
FIG. 5 is a flowchart showing the print control of FIG.

First, the transmission time for the first three lines is obtained as follows (step S60). By referring to the transmission time data for one line in the one-line transmission time conversion table 53b, the transmission times of the first first line, the second line, and the third line are obtained. Further, the initial value of the line is set to 1 with n = 1 (step S61).

In step S62, the presence or absence of correction is determined. The method of obtaining the average printing time differs depending on whether or not there is a correction. When it is determined in step S62 that the correction is performed, the average printing time Mtn of the nth line to which the correction value d is added is obtained by the average printing time calculation formula of the above formula (4) (step S63). Correction is necessary for the following reasons. That is,
When the above equation (2) is established, the printing time for n lines is
Generally, the average print time of n-1 is obtained by adding or subtracting the threshold value S. As a characteristic of the received image data of one page, when the data amount gradually increases or decreases conversely, the memory capacity of the image data memory 53a and the decoded image data memory 55 is limited. If the correction is not made, a waiting time for the memory control is added, and smooth print control becomes impossible.

If there is no correction, the process proceeds to step S64, and the average printing time of the nth line is calculated. Step S
63 or step S64, a time difference is obtained from the obtained average printing time, and it is determined whether or not the absolute amount is larger than a certain threshold value S. If it is larger, step S6
6, the process proceeds to step S67 if the allowable value, Mt
Print the nth line in n hours. When the difference between the line Mtn and the line Mtn + 1 line is large, this threshold value S makes it difficult to eliminate the print density unevenness that is the object of the present invention. Therefore, printing is performed with an allowable time that does not cause density unevenness. It is provided for.

Originally, the average printing time Mtn is printed. If the difference exceeds the allowable range, the printing time of n lines is (Mtna = Mtn-1 ± S) (step S66). . In the subsequent step S68, the correction value d is obtained. As shown in FIG. 6, the correction value d becomes positive if the inclination of the data amount of the correction value d is rising to the right, and is negative if it is falling to the right. The difference between the actual transmission time Mtn + 1 and the transmission time Mtn is as indicated by the symbol V in FIG. 6, but the printing time is Mtn + 1 and the error amount d occurs.

Succeedingly, in a step S69, printing of the nth line is carried out in the printing time Mtna. That is, printing is performed within the corrected average printing time obtained in step S66. Further, the data of n is updated to obtain the average printing time of the next line (step S70), and the transmission time of the (n + 2) th line is obtained (step S71). As the formula for calculating the average time, the transmission time of the nth, n + 1th, and n + 2th line must be obtained as a condition for obtaining the average time of the nth line. Since the (n + 1) th line has already been obtained, it is necessary to obtain new data of the (n + 2) th line. In step S72, it is determined whether n is the last line. When n is the last line, it becomes impossible to obtain the transmission time of the n + 1 and n + 2 lines, and different control is required. The control method is shown in step S73. If n is not the last line, the process moves to step S62 and is repeated until the last line.

Next, in step S73, the last 3
The line prints at a certain time. The remaining 3 lines are printed in the minimum printing time declared by the communication with the partner device.

The present invention is not limited to the illustrated embodiment, and various modifications can be made. For example, the average print control means 51a, the interline threshold control means 51, and the correction control means 51c are individual circuits. Or may be executed under program control.

[0037]

As described in detail above, according to the first aspect of the invention, the average printing time is obtained from the number of lines for any sample, and the printing time for each line is controlled by the average printing time. Therefore, it has the following effects.

(1) It is possible to eliminate the density unevenness caused by the variation in the printing time between the lines, and it is possible to improve the printing accuracy.

(2) Since the load on the printing motor provided in the printing unit is reduced, smooth printing can be performed and the noise of the motor can be suppressed to a low level.

According to the second invention, when the difference in the average printing time between the lines is large, a certain threshold value is provided so that the difference does not fluctuate greatly. Therefore, the effect of the first invention is further enhanced. , Become noticeable.

According to the third invention, since the error between the actual transmission time and the printing time caused by the second invention is corrected, the effect of the first invention is clarified more clearly than the second invention. can do.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a facsimile apparatus showing an embodiment of the present invention.

FIG. 2 is a configuration block diagram showing a configuration example of a conventional facsimile apparatus.

FIG. 3 is a diagram showing a storage format of a 1-line transmission time conversion table in FIG.

FIG. 4 is a diagram showing a control state of an average print control unit in FIG.

5 is a flowchart showing the print control of FIG.

FIG. 6 is a diagram showing a control state of interline threshold control means in FIG. 1.

[Explanation of symbols]

 51 control unit 51a average printing control unit 51b inter-line threshold value control unit 51c correction control unit 53b 1 line transmission time conversion table 54 image data decoding unit 55 decoded image data memory 56 printing unit

Claims (3)

(57) [Claims] 1. A picture data decoding section for decoding received picture data line by line and sending the decoded picture data, and a printing section for printing the decoded picture data line by line in a thermal recording system. In a facsimile device provided with, the transmission time data for one line of the received image data is stored 1
A line transmission time conversion table, a decoded image data memory that stores a plurality of lines of less than one screen in the decoded image data as sample lines, and the transmission time data for one line is referred to for each sample. A facsimile apparatus, comprising: an average print control unit that calculates the average print time of each line and controls the print time of each line of the printing unit based on the calculation result. 2. The facsimile apparatus according to claim 1, further comprising an inter-line threshold value control means for controlling a variation amount of the average printing time between the sample lines with a predetermined threshold value. 3. The facsimile apparatus according to claim 2, further comprising correction control means for correcting an error between each control result of the inter-line threshold value control means and the transmission time of each sample line.