JPH0393558A - Heat-sensitive recording device - Google Patents

Abstract

PURPOSE:To reduce the unevenness in feeding of a head-sensitive recording paper at the rising time of a driving motor, and prevent white stripes from generating in a recording image, which are accompanied with an intermittent recording motion by a method wherein at the time of resuming recording after a temporary stop, a subsidiary scanning of a driving motor for a first line is performed, being divided into a designated number of times, and at the same time, recording is done for the designated number of times. CONSTITUTION:When a recording motion is resumed after a temporary stop, 1-2 phase excitation driving is performed, and one subsidiary scanning pitch is divided in two, and a half pitch each is carried, and the same image data is printed twice. When the driving of a driving motor 10 is performed in this way, a delay in the rotation to the excitation condition at the rising time becomes smaller comparing to the case when 2-phase excitation is done, and vibration accompanying with the later corrective motion also becomes less. Therefore, paper feeding becomes stable, and further since a first line in which the printing dot size becomes smaller, is printed twice, being divided into two sections, white stripes in the main scanning direction of a heat- sensitive recording paper 4 can be prevented from generating Therefore, white stripes in a recording image on the heatsensitive recording paper 4 during an intermittent recording motion can be prevented from generating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording device, and more particularly, to a thermal recording device that prevents white streaks from appearing on a recorded image due to a temporary stop of a drive motor during image recording. (Prior Art) In recent years, thermal recording devices have been widely used as recording devices because they are easy to miniaturize and are excellent in immediacy and simplicity of recording.

Generally, a thermal recording device includes a thermal head and a platen roller, and a plurality of heating elements are arranged in a row in the main scanning direction in the thermal head. A driving pulse is supplied to the heating element based on the image data, and the heating element selectively generates heat according to the image data. A thermal recording paper is supplied between the thermal head and the platen roller, and the thermal recording paper is heated by the heat of the thermal head. When heat-sensitive recording paper is heated, the coloring agent applied to the recording surface of the paper melts and develops color to perform recording. In this case, the thermal recording device supplies a sub-scanning pulse to a drive motor that rotationally drives a platen roller at the same time that the thermal head records one line, thereby sub-scanning the thermal recording paper line by line. Normally, 1-line recording and sub-scanning are performed continuously, and the sub-scanning of the thermal recording paper is performed continuously due to the inertial force of the platen roller or other sub-scanning.

(Problem to be Solved by the Invention) However, in such a conventional thermal recording device, when the thermal recording device is applied as a recording section of a facsimile machine, the transmission time of encoded image information is shortened. The recording speed of the thermal head may be slower than the recording speed of the thermal head. In this case, intermittent recording occurs, causing heat accumulation in the thermal head and uneven feeding of the thermal recording paper, resulting in white spots in the main scanning direction on the recorded image. Streaks appear.

The reason for the occurrence of white streaks will be described in detail below.

In a recorded image, white stripes extending in the main scanning direction occur when the relationship shown below is met.

(Length of one pixel in the sub-scanning direction) <(Feed amount of recording paper in each line)...(1) In other words, when the recording operation is restarted from a paused state, the heating temperature of the heating element is As shown in FIG. 3, it is relatively low for the first line of printing, slightly higher for the second line, and gradually increases from the third line onwards up to the level of 10 lines.

This is due to heat storage in the heating element, and the coloring area of the thermosensitive recording paper changes as the temperature of the heating element changes.

In particular, up to several lines after restarting recording, the coloring area is quite small compared to the continuous printing state, and the left side of the above condition (1) has a small value.

Further, FIG. 4(a) shows the feeding state of the thermal recording paper before and after the recording operation is temporarily stopped when a two-phase excitation type drive motor (step motor) is used.

In Fig. 4(a), the broken line part of the chart paper feed shows the ideal paper feed, and the actual paper feed is as shown in the solid line. The start of paper feed is delayed due to the delay in the rise of the current and the inertial load and frictional load of the conveyance system, and then a movement is made to correct this delay. That is, the feed amount is relatively small in the A section of FIG. 4(a), and the feed amount is large in the B section, so that the right side of the above condition (1) becomes a large value. As a result of the above recording operation, the above condition (1) is met in the first few lines of the recording operation from a pause.
This tends to cause white streaks to appear as shown in FIG. 4(b).

Note that FIG. 4(c) shows the heating element driving pulse, and FIG. 4(d) shows the heating element driving pulse.
) is the drive pulse of the drive motor in the sub-scanning direction, Fig. 4 (e
) indicates the terminal voltages supplied to the drive motor, and the drive motor is excited by these supply voltages and rotates by one sub-scanning pitch.

(Object of the Invention) Therefore, the present invention divides the sub-scanning of the first line of the drive motor into a predetermined number of times when resuming recording after a pause, and records only the predetermined number of times. Reduces uneven feeding of thermal recording paper at startup, 1
The purpose of this method is to make the recording pixels of the line denser to prevent the occurrence of white streaks in the recorded image due to intermittent recording operations.

(Structure of the Invention!) In order to achieve the above object, the present invention includes a drive motor that is driven in steps at a predetermined speed, a plurality of conveyance rollers that are driven by the drive motor and conveys thermal recording paper in the sub-scanning direction. a thermal head in which heating elements are arranged in rows in the main scanning direction, and the heating elements generate heat according to input image information to record an image on thermal recording paper that is sub-scanned every l line. In a thermal recording device, when the drive motor is temporarily stopped due to a delay in inputting image information or the like during the image recording, and when the image recording is restarted after the pause, the sub-scanning of the first line by the drive motor is performed in a predetermined manner. This method is characterized in that the image information for one line is repeatedly recorded a predetermined number of times.

Hereinafter, the present invention will be specifically explained based on examples.

1 and 2 are diagrams showing an embodiment of the present invention.

FIG. 1 is a diagram showing the main part structure of a thermal recording apparatus 1. In FIG. 1, 2 is a thermal head. thermal hesode 2
A platen roller (transport roller) 3 is disposed opposite to the thermal head 2 and the platen roller 3 are pressed against each other by a biasing means (not shown), such as a spring.
In the thermal head 2, a plurality of heating elements are arranged in one line in the axial direction of the platen roller 3, that is, in the main scanning direction. For example, it is divided into four blocks. Drive pulses are selectively supplied to the heating elements based on image data for each block, and the heating elements sequentially generate heat starting from the first block. A thermal recording head 4 is supplied between the thermal head 2 and the platen roller 3, and the thermal recording apparatus 1 heats the thermal recording head 2 while the thermal recording head 4 is conveyed by the platen roller 3. A coloring agent is applied to the heat-sensitive recording layer 4, and when the heat-sensitive recording layer 4 is heated by the thermal head 2, the coloring agent melts and develops color.

A platen pulley 5 is attached to the platen roller 3, and a timing belt 6 is attached to the platen pulley 5.
is engaged. Timing belt 6 is intermediate booley 7
The timing belt 8 is further engaged with the intermediate pulley 1-7. This timing belt 8 is engaged with a motor pulley 9, and the motor pulley
9 is attached to the shaft 10a of the drive motor 10. Therefore, the platen roller 3 is driven by the drive motor lO
The thermosensitive recording paper 4 is rotated by and conveyed in the sub-scanning direction. As the drive motor 10, a two-phase PM type stomping motor with bipolar connection is used, and when the drive motor 10 is energized in two phases, it rotates by one sub-scanning pitch.
When the 1-2 phase is excited, it rotates by half of one sub-scanning pinch.

Next, the effect will be explained.

When there is at least one line of image data in a buffer memory (not shown), the thermal recording device 1 outputs a drive pulse as shown in FIG. Then, it receives image data from the bathophore memory and outputs a drive pulse (FIG. 2(b)) to the thermal head 2 based on the image data. When a driving pulse is input to the thermal head 2, a heating element selectively generates heat, melting the color forming agent of the thermosensitive recording medium 4 and causing color development. When image data is stored in the bathophone memory, recording for each line is performed continuously, and the conveyance of the thermal recording paper 4 is also performed continuously due to the inertia of the conveyance system such as the platen roller 3 and the thermal recording paper 4. be exposed.

However, when the thermal recording device 1 is used as a recording section of a facsimile machine, the image data reception speed may be slower than the recording speed of the thermal recording device 1. In such a case, there is no more image data in the buffer memory, and the control section temporarily stops recording by the thermal head 2 and transporting the thermal recording head 4 by the drive motor 10. However, when the conveyance of the thermal recorder 4 is stopped,
As described above, uneven feeding of the drive motor 10 occurs, and white streaks occur in the recorded image of the thermal recording paper 4.

Therefore, in this embodiment, when restarting the recording operation after a temporary stop (portion A in FIG. 2(a)), 1-2 phase excitation drive is performed as shown in FIG. 2(d), and one sub-scanning is performed. The pitch is divided into two times and the same image data is transported by half a pitch each time.
It is printed twice (as shown in FIGS. 2(a) to 2(c) and (e)). When the drive motor 10 is driven in this manner, the delay in rotation with respect to the excitation state at startup is reduced compared to the case of two-phase excitation as shown in FIG. 4(a) (see FIG. 2(a)).
(Part A), vibrations associated with subsequent correction operations are also reduced. In other words, since the state of the B part shown in FIG. 4(a) is reduced, paper feeding is stabilized, and furthermore, the lth line, where the print dot size is smaller, is divided into two parts and printed twice. The generation of white streaks in the main scanning direction of the thermal recording paper 4 can be prevented. Therefore, it is possible to prevent white streaks from occurring in the recorded image of the thermal recording medium 4 during intermittent recording operations.

(Effects) According to the present invention, when resuming recording after a pause, the sub-scanning of the first line of the drive motor is divided into a predetermined number of times, and recording is performed only for the predetermined number of times, so that the drive motor starts up. It is possible to reduce the uneven feeding of the thermal recording paper during printing, make the recording pixels of the l-th line denser, and prevent the occurrence of white streaks in the recorded image due to intermittent recording operations.

[Brief explanation of drawings]

1 and 2 are diagrams showing an embodiment of the thermal recording device according to the present invention, and FIG. 1 is a diagram of the main parts of the thermal recording device, and FIGS. C), (d), and (e) are the recording paper feed amount (Fig. 2 (a)), the drive pulse of the thermal head (Fig. 2 (b)), and the drive pulse of the drive motor in the sub-scanning direction (Fig. 2 (b)). 2 (C)”), the terminal voltage of the drive motor (Fig. 2 (d)) and the state of the printed dots (Fig. 2 (D)).
It is a figure which shows the relationship of e>). 3 and 4 are diagrams showing an example of a conventional heat-sensitive recording device. FIG. 3 is a diagram showing the temperature rise characteristics of the thermal head of the heat-sensitive recording device, and FIGS. ), (d
), (e) shows the recording paper feed amount (Fig. 4 (a)), the state of printed dots (Fig. 4 (b)), the drive pulse of the thermal head (Fig. 4 (c)), and the drive motor. It is a diagram showing the relationship between the drive pulse in the sub-scanning direction (FIG. 4(d)) and the terminal voltage of the drive motor (FIG. 4(e)). l...Thermal recording device, 2.・・・・・・To thermal・7・３・・・・・・Platen roller (lm feed roller>4・・・・
...Thermal recording paper, 5...Platen pulley 6...Timing belt, 7...Intermediate pulley 8...Timing belt, 9... -... Motor pulley, 10... Drive motor. Agent Patent Attorney Agagun

Claims (1)

[Claims] A drive motor that drives in steps at a predetermined speed, a conveyance roller that is driven by the drive motor and conveys thermal recording paper in the sub-scanning direction, and a thermal head in which a plurality of heating elements are arranged in a row in the main-scanning direction. In a thermal recording device that records an image on a thermal recording paper that performs sub-scanning for each line by causing the heating element to generate heat according to input image information,
When the drive motor is temporarily stopped due to a delay in inputting image information or the like during the image recording, and when the image recording is restarted after the pause, sub-scanning of the first line by the drive motor is divided into a predetermined number of times. , A thermal recording apparatus characterized in that image information for one line is repeatedly recorded the predetermined number of times.