JP2756203B2 - Printing 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 printing apparatus suitable for use in a line printer for recording a received image in a facsimile apparatus.

[0002]

2. Description of the Related Art Conventionally, in a facsimile apparatus, a line printer is used for printing a received image. In particular, a thermal printer is often used for the purpose of downsizing and simplifying the apparatus. Specifically, the image data received via the modem is stored in the data buffer line by line, a synchronous timer interrupt for one line printing is generated, and the interrupt signal is synchronized as a print command signal, The data for one line is transferred to the print head and printed. In the sub-scanning direction, one line is fed by rotating the platen roller in synchronization with the data transfer to the print head.

[0003]

Assuming that normal printing is performed, the dot arrangement in the sub-scanning direction is neatly arranged as shown in FIG. 6, and each is printed at an equal interval. .

However, the amount of data for one line of image data greatly changes depending on the image pattern, and the data buffer does not always have one line of data when an interrupt signal as a print command signal is generated. . In other words, there are a state where data is aligned and a state where data is not aligned within the interrupt signal generation cycle. Therefore, while waiting until one line of data is collected in the data buffer, the motor for recording paper feeding is repeatedly started and stopped to operate. Therefore, the dot position in the sub-scanning direction may change between when the operation of the motor is performed continuously and when the motor temporarily stops. That is, as shown in FIG. 8, when the data waiting period has elapsed from the state where the motor rotation command pulse is continuous, no head print command pulse is generated. Then, the motor stops and the recording paper feed is stopped, but the printing operation is started again due to the lack of mechanical rigidity of the printing device or the backlash of the gear coupling part of the reduction gear. In this case, the print line is not at the same interval as the past line, and the line print is performed at a slightly shifted position. This state is shown in FIG. 7, in which the dot interval in the sub-scanning direction fluctuates, thereby generating a white line.

As described above, in the type in which print data for one line is stored in the data buffer and the print head is operated when the print data for one line is collected in the data buffer, a recording paper feed mechanism or the like is used. A white line as shown in FIG. 7 is generated due to insufficient mechanical rigidity or play of an adjustment portion necessary for power transmission.

[0006]

A print commanding means for generating a synchronization signal for one-line printing, a line data detecting means for detecting whether or not print data for one line are arranged in a data buffer; Transfer means for transferring one line of data to the print head on condition that the data buffer has one line of data, and recording paper feeding means for driving a motor to feed one line of recording paper in accordance with the data transfer A printing means for generating a print pulse on the print head after the recording paper is fed, and a first time when one line of data is not aligned in the data buffer when a synchronization signal is generated from the print command means. A printing device was formed by the same data double hitting means for transferring the previous line data to the print head and printing it on condition that the signal was a synchronous signal.

[0007]

If the print data for one line is in the data buffer within the period of the synchronization signal by the print command means, the operation of feeding the recording paper by one line and generating a print pulse in the print head to perform printing is performed. The printing operation is performed continuously, whereby the printing operation is performed at an even dot interval in the sub-scanning direction. On the other hand, if the print data for one line is not aligned in the data buffer within the period of the synchronization signal by the print command unit, the recording paper feed is stopped until the alignment is completed, so that the recording paper feed pitch is not correct. However, since the previous line data is transferred to the print head and printed by the same data double hitting means, even if a white line is generated, the previous print data is printed on that part, thereby Above is one in which no white line occurs.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. First, a roll-shaped platen roller 1 is provided, and a thermal head 2 as a print head is pressed against the platen roller 1 by being urged by a pressing spring 3. A thermal paper 4 as a recording paper is inserted between the platen roller 1 and the thermal head 2. The platen roller 1 is connected to a motor 6 constituting a recording paper feed mechanism with a speed reduction mechanism 5 including a plurality of gears interposed.

Next, a modem 7 connected to an external telephone line is provided, and the modem 7 is connected to a central processing unit 8 (hereinafter, referred to as a CPU). This CPU 8
Is connected to a ROM 9 storing a processing program and a RAM 10 acting as a temporary storage device. An I / O device 11 is connected to the CPU 8, and the thermal head 2 and the motor 6 are connected to the I / O device 11.

In such a configuration, during a printing operation, a synchronization timer interrupt for one-line printing is generated, that is, a synchronization signal is generated, for example, every 10 ms by the print command unit. When this synchronization signal is generated, the line data detecting means detects whether or not print data for one line is ready in a data buffer provided in the RAM 10.

If one line of print data is present in the data buffer within the period of the synchronization signal, new data for one line is transferred to the thermal head 2 by the transfer means. Next, the motor 6 serving as a recording paper feed mechanism is rotated by a motor rotation command pulse shown in FIG. 5 based on the above-mentioned synchronization signal, and the platen roller 1 is driven via the speed reduction mechanism 5 so that the heat-sensitive paper 4 is moved for one line. send. After that, the thermal head 2 is printed by the printing means.
A pulse is generated based on the data transferred to the thermal paper 4 to form dots. Such an operation is similarly performed continuously as long as the motor rotation command pulse is generated periodically.

Next, if one line of print data is not ready in the data buffer within the period of the synchronization signal,
As shown in FIG. 5, only one motor rotation command pulse is generated at a timing corresponding to the first synchronization signal.
The same data double hitting means operates by this motor rotation command pulse to transfer the previous line data to the thermal head 2. Then, the previous line data is printed by the thermal head 2 without driving the motor 6 as shown in FIG. That is, two hits are performed. Of course, if one line of print data is not yet in the data buffer at the time of the next synchronization signal and thereafter, the print data driven by the motor 6 is not transferred to the thermal head 2 at this time. , Completely dormant.

When one line of print data is arranged in the data buffer when a synchronization signal is generated thereafter, new data for one line is transferred to the thermal head 2 by the transfer means as described above. Next, the motor 6 serving as a recording paper feed mechanism is rotated by a motor rotation command pulse shown in FIG. 5 based on the above-mentioned synchronization signal, and the platen roller 1 is driven via the speed reduction mechanism 5 so that the heat-sensitive paper 4 is moved for one line. send. After that, a pulse is generated based on the data transferred to the thermal head 2 by the printing means, and a dot is formed on the thermal paper 4.

By hitting the previous line data twice only once during the idle period in this way, the rigidity of the mechanical path from the motor 6 to the platen roller 1 is insufficient, and there is gear backlash and the like. Therefore, even if the thermal paper 4 is discontinued, there is a dot that has been hit twice at the white line position, which has conventionally occurred, so that the appearance of an apparent white line is prevented. .

[0015]

As described above, the present invention provides a print command means for generating a synchronization signal for one-line printing, and a line data detecting means for detecting whether or not print data for one line is arranged in a data buffer. Means, transfer means for transferring the data to the print head on condition that the data buffer has one line of data, and driving the motor to feed the recording paper by one line with the data transfer. Recording paper feeding means, printing means for generating a print pulse in the print head after the recording paper feeding, and when one line of data is not aligned in the data buffer when a synchronization signal is generated from the print command means. A printing device is formed by means of the same data double-strike means for transferring the previous line data to the print head and printing it on condition that it is the first synchronization signal. If the print data for one line is in the data buffer within the period of the synchronization signal by the print command means, the operation of feeding the recording paper by one line and generating a print pulse in the print head to perform printing is continuous. In this manner, the printing operation is performed with a uniform dot interval in the sub-scanning direction. On the other hand, if the print data for one line is not aligned in the data buffer within the period of the synchronization signal by the print command unit, the recording paper feed is stopped until the alignment is completed, so that the recording paper feed pitch is not correct. However, since the previous line data is transferred to the print head and printed by the same data double hitting means, even if a white line is generated, the previous print data is printed on that part, thereby The upper part has an effect that a white line based on discontinuity of the print timing does not occur.

[Brief description of the drawings]

FIG. 1 is a flowchart of a print interruption operation according to an embodiment of the present invention.

FIG. 2 is a side view schematically showing the structure of the printing apparatus.

FIG. 3 is a block diagram showing an electrical connection.

FIG. 4 is a plan view showing an example of the arrangement of printed dots.

FIG. 5 is a timing chart showing a relationship between a motor rotation command pulse and a head print command pulse.

FIG. 6 is a plan view showing an example of an arrangement of dots in a state where continuous normal printing is performed.

FIG. 7 is a plan view showing an example of dot arrangement in a state where a white line has occurred.

FIG. 8 is a timing chart showing the relationship between a conventional motor rotation command pulse and a head print command pulse.

[Explanation of symbols]

Claims (1)

(57) [Claims] 1. A print command means for generating a synchronization signal for one-line printing, a line data detecting means for detecting whether or not print data for one line is arranged in a data buffer, Transfer means for transferring the data to the print head on condition that the data for the lines are prepared; recording paper feed means for driving a motor to feed the recording paper by one line with the data transfer; A printing means for generating a print pulse in a print head after paper feeding; and a first synchronization signal when data for one line is not aligned in the data buffer when a synchronization signal is generated from the print command means. A printing apparatus, characterized in that the printing apparatus comprises the same data double-strike means for transferring the preceding line data to the printing head and printing the data.