JPS6239264A - Platen controller in printer - Google Patents

Abstract

PURPOSE:To prevent deterioration of recording quality to be caused by irregularities in rotation to be encountered when the driving condition is changed, by a method wherein a motor is so controlled as to be driven under the same driving condition as that during recording operation, beginning two or more lines in advance of the record-start position. CONSTITUTION:When a recording is started after a recording paper is set in a printer, a recording paper 2 is automatically wound around a platen 1. A motor 24 is driven by an constant-speed pulse, asynchronous to a video signal 6, so that the platen 1 is fed toward the record-start position at constant-speed. When the recording paper 2 faces a recording head 3 at a position thereon which is two or more lines up to record-start position, the constant-speed feed is switched to the intermittent feed. Upon completion of the intermittent feed of the predetermined number of lines, a control signal 20 from a line signal generating circuit 32 goes to an H-level, which permits the operation of an A/D converter 30, and the video signal 6 is output to a head drive circuit 11 as a density signal for one-line 10 and therein converted in a recording signal 12 which enables a recording head 3 to perform recording. In this manner, a printing record of good image quality can be obtained by electrical control processing alone.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a platen control device for a printer that prints and records characters, images, and the like.

(Background of the Invention) Conventionally, in printers that print and record information such as characters and still images on recording paper, as shown in FIG.
is transported by a transport mechanism (not shown) to just below the fixing member 4 on the platen 1 to fix one end of the recording paper 2, and then the platen 1 is continuously rotated under the control of a drive motor to wrap the recording paper 2 around it. Next, the recording head 3 is raised and brought into pressure contact with the recording paper 2 of the platen 1, and in this state, the recording head 3 is
is rotated and set at the recording start position shown in the figure, and from this recording start position, the platen 1 is intermittently advanced by a predetermined line pitch in synchronization with the line scanning of the recording head 3.

FIG. 5 shows a conventional device used for such platen control, and FIG. 6 shows signal waveforms and time charts of each part.

In FIG. 5, a video signal 6 to be recorded is input to an A/D converter 9 and a sync separation circuit 18.
separates the synchronizing signal 13 and outputs it to the line signal generating circuit 19.

When the recording paper 2 reaches the recording start position shown in FIG. 4, the control circuit 16 outputs a start signal 17 to the line signal generation circuit 19 and the A/D converter 9 to start the recording operation. That is, the A/D converter 9 that received the start signal 17
The head drive circuit 11 converts the two-yield video signal of either the even or odd fields of the video signal 6 into digital form and outputs it as a density signal 10 for one line.
Output to. The head drive circuit 11 receives the density signal 1'1 for one line, converts it into a recording signal @12 for driving the recording head 3, and records data for one line by scanning the recording head 3 in a line. Let's do it.

When the recording head 3 finishes recording data for one line, the line signal generation circuit 19 outputs a line signal @22 to the control circuit 16 in synchronization with the video synchronization signal 13, indicating that the recording operation for one line has been completed. And this line signal 2
2, the control circuit 16 outputs a motor control signal 26 to the motor drive circuit 14. This motor control signal @26 is a signal for rotating the platen so as to advance the recording paper by a predetermined line pitch after one line of recording is completed, and in the time chart of FIG. 6, three pulses are output.

Therefore, the motor drive circuit 1 receiving the motor drive signal 26
4 outputs a drive signal 15 to rotationally drive the motor 24;
The recording paper 2 is rotated by a predetermined pitch, and the driving control of the platen 1 is repeated in the same manner to intermittently feed the recording paper in synchronization with the completion of line recording scanning by the recording head 3.

In contrast to such intermittent platen feed control during recording, the platen drive control when setting the recording paper 2 at the recording start position is performed using, as is clear from the drive signal @15 in FIG. 6, in order to shorten the operation time. Drives at a constant speed (continuous drive) at high speed without synchronizing with video signal @6, and switches to intermittent drive synchronized with video signal 6 during recording operation after recording paper 2 reaches the recording start position. Sleep.

(Problems to be Solved by the Invention) However, in such a conventional platen control device, when the drive state changes from constant speed drive to intermittent drive after the recording start position, the platen does not move at the boundary point. Uneven rotation occurs. This means, for example, that motor power is transferred to platen 1.
One possible cause is the backlash of the gears inside the transmission filter structure that transmits the speed. This rotational unevenness causes variation in the feed line pitch of the platen 1 immediately after the start of recording, causing unnecessary white lines to appear in the recording result and deteriorating the recording quality. There was a problem in that it was very difficult to remove the unevenness.

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems. Another object of the present invention is to provide a platen control device that can accurately feed recording paper intermittently at a predetermined line pitch from a recording start position without being affected by rotational unevenness.

(Summary of the Invention) In order to achieve this object, the present invention uses the same driving conditions as during the recording operation, that is, the platen is moved intermittently at a predetermined line pitch in synchronization with the video signal, starting from several lines before the recording start position. The drive is controlled under the drive condition of rotationally driving, and recording quality is prevented from deteriorating due to uneven rotation when the drive state changes.

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention.
The same parts as those of the conventional device shown in FIG. 5 are denoted by the same reference numerals.

First, to explain the configuration, numeral 30 is an A/D converter that receives the input of the video signal 6, and the A/D converter 30 receives the input of the video signal 6.
The start and stop of the conversion operation can be controlled. Specifically, the A/D conversion operation is stopped when at least one of the start signal 17 and the A/D control signal 20 is at the L level, and when both are at the H level. When the level is reached, A/D conversion starts.

Further, the A/D converter 30 A/D converts both the even and odd field signals of the video signal 6 and outputs the resultant signal as a density signal 10 for one line. Furthermore, since the operating speed of the recording head 3 is slow relative to the video signal 6, the A/D converter 30 has a built-in memory for temporarily storing the A/D converted density signal 10 for one frame period. The density signal 10 stored in this memory is output in synchronization with the line scanning of the recording head 3.

The density signal 10 output from the A/D converter 30 is given to the head drive circuit 11, and the head drive circuit 11 converts it into a recording signal 12 for causing the recording head 3 to perform a recording operation and outputs it.

Reference numeral 18 denotes a synchronization separation circuit into which the video signal @6 is input, which separates the video synchronization signal 13 included in the video signal 6 and outputs it to the line signal generation circuit 32.

Reference numeral 34 denotes a control circuit for controlling platen drive in the present invention, which controls the recording paper 2 for the platen 1 shown in FIG.
The automatic winding of the recording paper 2 and the winding of the recording paper 2 command the subsequent feeding control to the printing start position, and furthermore, the intermittent feeding control of the platen in synchronization with the line scanning of the recording head 3 after printing is started.

To explain in more detail, as is clear from the time chart of signal waveforms at various parts shown in FIG. The drive signal 15 outputs equally spaced drive pulses for driving the motor 24 at a constant speed asynchronously with the drive signal 15, and while driving the motor 24 at a constant speed, the A/D
The start signal 17 for the converter 30 and line signal generation circuit 32 is fixed at L level. The line signal generation circuit 32 receives the L level output of the start signal 17.
is the A/D control signal 2 to the A/D converter 30 at the same time.
0 is fixed at L level.

While the motor 24 is driving at a constant speed, the control circuit 34 moves the recording paper to a predetermined position several lines before the recording start position.
It monitors whether the feeding position of the recording paper 2 has been reached, and when the recording paper 2 reaches a set position before the recording start position, the start signal 17 is set to H level. This start signal 17
When the line signal generation circuit 32 is at H level, the control circuit 34
On the other hand, a line signal 22 for intermittently driving the platen in synchronization with the video synchronization signal 13 from the previous constant speed drive.
Output. In response to this line signal 22, the control circuit 34
outputs a 3-pulse signal shown intermittently in FIG. 2 as a motor control signal 26 to the motor drive circuit 14,
Therefore, the motor 24 intermittently moves the platen 1 by a predetermined pitch in synchronization with the video synchronizing signal 13 for one frame period, as in the recording operation.

During this intermittent drive before the recording start position, the start signal 1
7 becomes H level, the A/D control signal 20 from the line signal generating circuit 32 is fixed at the L level, so the recording head 3 does not perform a recording operation.

During such intermittent driving of the platen 1 before the recording start position, the line signal generation circuit 32 uses a built-in counter etc. to calculate the number of generated line signals 22 synchronized with the video synchronization signal 13, that is, the intermittent feeding of the platen 1. The number of times is counted, and when it is determined that the preset multi-line intermittent feeding is performed, that is, when it is determined that the recording paper 2 has reached the recording start position, the A/D control signal 20 is set to H level and the A/D converter 30 A/D conversion operations are allowed, and thereafter the platen is moved intermittently in synchronization with the recording operation of one line by the recording head 3.

Next, the operation of the embodiment shown in FIG. 1 will be explained with reference to the flowchart shown in FIG.

First, when recording paper is set in the printer and the recording operation is started by operating a switch or the like, the recording paper 2 is conveyed to just below the fixing member 4 of the platen 1 in block 40, one end of the recording paper 2 is fixed, and then The platen is continuously rotated and wound, and an initial operation is performed in which the recording paper 2 is automatically wound around the platen 1 as shown in FIG.

When the winding of the recording paper 2 around the platen 1 is completed, the process proceeds to the next block 50, in which the motor 24 is driven by constant velocity pulses asynchronously with the video signal 6, and the platen is fed at a constant velocity toward the recording start position. The position of the recording head 3 relative to the recording paper 2 during this constant speed feeding is monitored by a determination block 44, and when it reaches a predetermined position several lines before the recording start position, a block 46 Switch to intermittent feed as shown in . During this intermittent feeding, even if the start signal 17 from the control circuit 34 becomes H level, the A/D control signal 2 from the line signal generation circuit 32
0 is at the L level, the recording operation by the recording head 3 is placed in a paused state.

The position of the recording paper relative to the recording head 3 due to the intermittent feeding of the block 46 is monitored by the determination block 48.
When the intermittent feeding of a predetermined number of lines is completed, it is determined that the recording start position has been reached, and the recording operation from block 50 onwards is started. That is, when it is determined that the recording start position has been reached, the A/D control signal 20 from the line signal generation circuit 32 becomes H level, and since the start signal 17 is already at H level at this time, the A/D converter 30 A/D conversion operations are allowed, and the A/D converted video signal 6 is output to the head drive circuit 11 as a density signal 10 for one line, and is converted into a recording signal 12 by the head drive circuit 11, and then recorded. One line recording operation is performed by the head 3 in block 52. The recording operation of one line is monitored by the discrimination block 54, and when the recording operation of one line is completed, the next block 5 is monitored.
At step 6, it is checked whether it is the last line or not, and if it is not the last line, the process advances to block 5B to perform intermittent feeding to achieve a predetermined line pitch, and returns to block 52 again to record one line of the video signal 6 of the next frame. When the last line is recorded, the series of control processing ends.

In this way, in the platen control of the present invention, since the platen is intermittently fed several lines before the recording start position in the same manner as during the recording operation, backlash etc. are caused in the power transmission mechanism from the motor to the platen. Even if there is some movement unevenness, since multiple intermittent feeds have already been performed when the recording start position is reached, variations in platen feed due to rotational unevenness caused by backlash etc. during the intermittent feed before recording starts. This eliminates this problem, and when the recording operation starts, it is possible to always advance the line pitch at a constant line pitch, and it is possible to reliably prevent unnecessary white lines, etc. from appearing on the recording line immediately after the recording operation is started. .

Wear.

In the above embodiment, the A/D converter 30 is controlled during intermittent feeding before the start of print recording to prevent the recording head from performing the recording operation, but other embodiments may be used. The head drive circuit 11 may be controlled, and furthermore, the control circuit 34 may directly control the print data for the print head 3.

Further, as is clear from the flowchart in FIG. 3, it is clear that the control circuit 34 can be realized by program control by a microcomputer.

(Effects of the Invention) As described above, according to the present invention, the platen is intermittently fed at a predetermined pitch in synchronization with the platen drive condition during recording operation, that is, the video signal, starting from several lines before the recording start position. Since the drive is controlled based on the drive conditions,
It is possible to reliably prevent uneven recording paper feeding and uneven recording caused by backlash, etc. that occurred when the platen was switched from constant-velocity drive to intermittent drive after the recording start position.
Print records of high-quality images can be obtained using only electrical control processing without requiring mechanical processing to eliminate uneven rotation of the platen.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a time chart showing signal waveforms of each part in Fig. 1, Fig. 3 is an operation flowchart of Fig. 1, and Fig. 4 is a platen FIG. 5 is a block diagram of a conventional device, and FIG. 6 is a time chart showing signal waveforms of the conventional device. 1 Nibraten 2: Recording paper 3: Recording head 11: Head drive circuit 14: Motor drive circuit 18: Synchronous separation circuit 24: Motor 30: A/D converter 32 Niline signal generation circuit 34: Control circuit

Claims (1)

[Claims] Wrap the recording paper around the outer periphery of the platen by continuously rotating the platen with at least one end of the recording paper fixed;
In a platen control device of a printer that intermittently rotates the platen wrapped with recording paper at a predetermined line pitch in synchronization with line scanning of a recording head from a printing start position after the winding, from a plurality of lines before the recording start position. A platen control device for a printer, comprising means for controlling the intermittent rotational drive of the platen under the same drive conditions as the platen drive conditions during a printing operation.