JPH04294180A - Line thermal printer - Google Patents

Abstract

PURPOSE:To set the driving torque of a platen roller to be low and make the life of a line thermal head longer in a line thermal printer wherein recording is performed on thermal papers or plain papers by the line thermal head. CONSTITUTION:At starting of conveyance of a cut sheet 30, a cam 35 abuts against a locating pin 14 from down side and a line thermal head 12 separates from a platen roller 13. The cut sheet 30 is taken in by a pair of supply rollers 31 and 32. When a tip of the sheet is detected by a paper detecting switch 33, the cut sheet 30 stops after lapse of a predetermined time taken for reaching between the line thermal head 12 and the platen roller 13, and the cam 35 is driven such that the line thermal head 12 presses the platen roller 13. Then, paper feeding of the cut sheet 30 is restarted. When the paper detecting switch 33 detects the rear end of the cut sheet 30, the cut sheet 30 stops after lapse of a predetermined time that the rear end reaches between the line thermal head 12 and the platen roller 13. Thereafter, after the cam 35 is driven such that the line thermal head 12 separates from the platen roller 13, the cut sheet 30 is discharged.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line thermal printer that records on thermal paper or plain paper using a line thermal head.

0002

[Prior Art] As a type of printer, cut-shaped, roll-shaped
There is a line thermal printer that performs recording using a line thermal head that is capable of printing and recording images on recording paper such as plain paper such as a roll or thermal paper. This type of line thermal printer is used, for example, as an output device for word processors, personal computers, facsimile machines, and the like.

FIG. 7 shows an example of a line thermal printer that records on thermal roll paper as a first conventional example.

In the figure, the thermal roll paper 10 is
The paper is conveyed horizontally from the right to the left in the figure, along the paper guide 11 between the line thermal head 12 and the platen roller.
It is guided to the recording position between the lines 13 and recording is performed here. The line thermal head 12 is attached to a mounting plate 15 so as to face the platen roller 13 perpendicularly, and is urged by a positioning pin 14 so as to press the platen roller 13 in the direction of the arrow shown in the figure. The mounting plate 15 also includes a line thermal head 12.
A positioning guide 16 is attached to the shaft of the platen roller 13 so that the positioning guide 16 faces the platen roller 13 perpendicularly.

[0005] In this type of printer, the thermal roller
Thermal cut paper can also be used instead of the paper 10. In this case, the line thermal head 12, positioning pin 14, mounting plate 15, and positioning guide 16 constitute a head unit, and this head unit is configured to be freely attachable to and detachable from the platen roller 13 in the vertical direction.

FIG. 8 shows, as a second conventional example, an example of a line thermal printer that records on cut sheets of plain paper.

In the figure, a line thermal head 12
The head unit, which is composed of the positioning pin 14, the mounting plate 15, and the positioning guide 16, can be attached to and detached from the platen roller 13 in the vertical direction, as in the case of using thermal cut paper in the first conventional example described above. Can be configured freely. The cut sheets 20 are set in a bundle in advance, and the uppermost cut sheet is conveyed horizontally from right to left in the figure by a sheet feed roller 21, and is then transported along the paper guide 11 to the line thermal head 12 and the platen roller. The recording position is guided to the recording position between the lines 13 and 13. Also, the supply side roll of the roll ribbon 22
A roll 23 and a take-up roll 24 are arranged upstream and downstream of the head unit, respectively, and the ribbon 22 is guided to a recording position between the line thermal head 12, the cut paper 20, and the platen roller 13, where it is recorded. will be held.

FIG. 9 shows a state in which the head unit is removed from the platen roller 13 in the conventional example as described above.

In the figure, a line thermal head 12
, a head unit composed of a positioning pin 14, a mounting plate 15, and a positioning guide 16 is attached to the upper frame 2.
The paper guide 11 and platen roller 13 are attached to the lower frame 26. upper frame
The frame 25 is connected to the lower frame 26 by, for example, a service (not shown).
It is rotatable around a rotating shaft 27 formed at one end of the set position side of the cut sheet 20 of round cut paper or plain paper,
Therefore, by opening and closing the upper frame 25 with respect to the lower frame 26, the head unit can be attached to the platen roller 1.
3, it can be attached and detached in the vertical direction, and the service
Cut paper 20 such as maru-cut paper or plain paper is placed in the lower frame 26.
can be set to .

0010

[Problems to be Solved by the Invention] In general, in line thermal printers, by reducing the driving force required for recording, it is possible to reduce power consumption and downsize the drive mechanism and the entire device, and to use a line thermal head, which is a type of consumable item. It is desired to extend the lifespan of

However, the conventional line service mentioned above
In a multi-purpose printer, when thermal cut paper or plain cut paper is used, the leading edge of the cut paper passes through this point before it reaches the recording position between the line thermal head 12 and the platen roller 13, and the trailing edge passes through this point. After that, the line thermal head 12 and the platen roller 13 come into direct contact, so in order to ensure stable driving of the platen roller 13, it is necessary to set the driving torque of the platen roller 13 to a large value. Further, there is a problem that such direct contact shortens the life of the line thermal head 12.

The present invention has been made in view of the above-mentioned conventional problems, and provides a line thermal printer in which the driving torque of the platen roller can be set to a small value and the life of the line thermal head can be extended. The challenge is to provide the following.

[0013]

[Means for Solving the Problems] In order to achieve the above-mentioned problems, the present invention includes a platen roller and a support that is movable between a first position in contact with the platen roller and a second position spaced apart from the platen roller. - a thermal head, a drive means for moving the thermal head to the first and second positions, a conveyance means for conveying the cut paper via a conveyance path to a recording position between the thermal head and the platen roller; A detection means is provided at a predetermined position on the transport path to detect the presence or absence of a cut sheet at the recording position, and a thermal head is activated when it is determined that the cut sheet is at the recording position based on the detection by the detection means. The first position is provided with a control means for controlling the drive means to move the thermal head to the second position when it is determined that the cut sheet is not at the recording position based on the detection by the detection means. Features.

[0014]

[Operation] According to the present invention, the thermal head is configured to be movable between a first position in contact with the platen roller and a second position away from the platen roller. is moved to the second position. Further, the detection means is provided at a predetermined position on the conveyance path to detect the presence or absence of the cut sheet being conveyed at the recording position.

Therefore, when the conveyance means starts conveying the cut paper, the detection means detects that the cut paper is not at the recording position, and based on this, the control means separates the thermal head from the platen roller. Since the driving means is controlled to move the cut paper to the second position, the thermal head does not come into contact with the platen roller until the cut paper reaches the recording position. Therefore, stable driving of the platen roller is ensured with a relatively small driving torque, and in this state, no load is placed on the line thermal head.

Next, when the cut paper is conveyed, the detection means detects when the leading edge of the cut paper reaches the recording position. Based on this detection, the control means controls the drive means to move the thermal head to the first position. Therefore, after the leading edge of the cut paper reaches the recording position, the
The multihead can press the cut paper against the platen roller, that is, can perform recording.

Next, at the end of the recording that has been continuously executed in this state, the detection means detects that the trailing edge of the cut sheet passes through the recording position. The control means controls the drive means to move the thermal head to the second position based on the detection by the detection means. Therefore, after the trailing edge of the cut sheet reaches the recording position, the thermal head does not come into contact with the platen roller. Therefore, stable driving of the platen roller is ensured with a relatively small driving torque, and in this state, no load is placed on the line thermal head.

As a result of the above, the thermal head is pressed against the platen roller through the cut paper only when the cut paper is at the recording position, so that good recording can be performed. Since the thermal head and the platen roller do not come into direct contact with each other during the period from the start of conveyance of the cut sheet to the ejection of the cut sheet after recording is completed, the driving torque of the platen roller can be set to a small value. Furthermore, the life of the line thermal head can be extended.

The following examples of the present invention will make these effects of the present invention clearer, and other effects of the present invention will become clearer.

[0020]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic side view showing a state in which the head is pressing the platen roller in an embodiment of the line thermal printer according to the present invention, and FIG. 2 is a schematic side view of the line thermal printer of FIG. A schematic side view showing a state in which the head is separated from the platen roller, FIG. 3 is similar to FIG.
4 is a perspective view of the main part showing the detailed structure of the head unit in FIG. 2, FIG. 4 is a perspective view of the main part showing the state in which the mounting plate is removed in FIG. 3, and FIG. A block diagram showing the control circuit of the printer, FIG.
3 is a flowchart for explaining the operation of the control circuit of FIG. In these drawings, the same reference numerals are given to the same components as those shown in FIGS. 7 to 9.

In FIGS. 1 and 2, thermal cut paper 30 is taken diagonally downward from the outside of the casing by a pair of paper feed rollers 31 and 32 constituting an example of a conveyance means, and its tip and the trailing edge are detected by a paper detection switch 33 that constitutes an example of a detection means. This thermal cut paper 30 is conveyed horizontally from right to left in the figure.
Recording is performed while being guided to a recording position between a line thermal head 12 and a platen roller 13 along a paper guide 11 constituting an example of a conveyance path. Paper feed roller pair 31
, 32 and the platen roller 13 are driven by a motor 34.

The line thermal head 12 is attached to a mounting plate 15 so as to face the platen roller 13 perpendicularly, and is attached to the platen roller 13 by a positioning pin 14.
is energized so as to be pressed in the direction of the arrow shown in the figure. Further, a platen roller is mounted on the mounting plate 15 so that the line thermal head 12 is perpendicularly opposed to the platen roller 13.
A positioning guide 16 that fits into the collar 13 is attached.

These line thermal head 12, positioning pin 14, mounting plate 15 and positioning guide 16
As shown in detail in FIGS. 3 and 4, this head unit includes a device for separating the line thermal head 12 from the platen roller 13 against the urging force of the line thermal head 12. A cam 35 is attached to the positioning pin 14 from below. The cam 35 is driven by a camshaft 36, and the camshaft 36 is rotated by a motor 45 (described later). In this way, an example of a driving means for moving the thermal head 12 from the cam 35 and the cam shaft 36 to the first position in contact with the platen roller 13 and the second position away from the platen roller 13 is constructed. Next, the configuration of the control circuit of the line thermal printer will be explained with reference to FIG.

In the figure, a control circuit constituting an example of the control means controls the printing of the line thermal head 12, and also controls the cam 35 as shown in FIG.
A PU (central processing unit) 41 and a ROM (read only memory) 4 in which programs for the CPU 41 are stored in advance.
2 and a RAM (random access memory) 43 having a work area for the CPU 41, etc.
The detection signal of the paper detection switch 33 shown in is taken into the CPU 41.

This control circuit also includes a head drive circuit 4 for driving the thermal head 12 shown in FIGS. 1 and 2.
4, and head up/down (UP/DOWN) for rotating the cam 35 to move the head 12 up and down.
It has a head up-down motor drive circuit 46 for driving the motor 45 and a paper feed motor drive circuit 47 for driving the paper feed motor 34, and these drive circuits 44, 46, 47 is controlled by the CPU 41. still,
The head up-down motor 45 may also be used as the paper feed motor 34, in which case the head up-down motor
The cam 35 can be driven by providing a clutch mechanism or the like instead of the motor drive circuit 46.

Next, the operation of the line thermal printer configured as described above will be explained with reference to FIGS. 1 to 6. When the CPU 41 starts carrying in the cut paper 30, first, as shown in FIG.
The head up/down motor drive circuit 46 is controlled so as to move away from the head up/down motor drive circuit 46.

When the paper feed motor 34 is started to be driven via the paper feed motor drive circuit 47 in this state, the cut paper 30 is taken in by the pair of paper feed rollers 31 and 32 in step S1 shown in FIG. When the leading edge of the paper is detected by the paper detection switch 33 in the subsequent step S2, the process proceeds to step S3. In step S3, after the leading edge of the cut paper 30 is detected by the paper detection switch 33, the line thermal head 12 and the platen roller 13
The paper feed motor 34 is controlled via the paper feed motor drive circuit 47 so that the cut paper 30 stops after a predetermined time (x seconds) has elapsed to reach the recording position between. In the subsequent step S4, the cam 35 is controlled via the head up/down motor drive circuit 46 so that the line thermal head 12 comes into contact with the platen roller 13 as shown in FIG.

Next, in step S5, paper feeding of the cut paper 30 is restarted and the thermal head 12 is restarted.
The head drive circuit 44 performs recording on the cut paper 30.
control operation continues. Then, the paper detection switch 33
detects the trailing edge of the cut paper 30 (step S6),
The cut sheet 30 is controlled to stop after the elapse of x seconds (step S7). Next, the line thermal head 12 is connected to the platen roller 13.
The cam 35 is driven to move away from the cam 35 (step S8).
, the cut paper 30 is discharged (step S9).

Therefore, as shown in FIG.
While the line thermal head 12 is not at the recording position between the line thermal head 12 and the platen roller 13, the line thermal head 12 does not press the platen roller 13 and they do not come into contact with each other, so the driving torque of the platen roller 13 is set to a small value. In addition, the life of the line thermal head 12 can be extended.

[0031]

As described in detail above, according to the present invention, the thermal head is configured to be movable between a first position in contact with the platen roller and a second position away from the platen roller. and is moved to these first and second positions by a driving means. Further, the detection means is provided at a predetermined position on the conveyance path to detect the presence or absence of the cut sheet being conveyed at the recording position. Here, the control means sets the thermal head to the first position when it is determined that the cut sheet is at the recording position based on the detection by the detection means, and sets the thermal head to the first position when the cut sheet is determined to be at the recording position based on the detection by the detection means. When this occurs, the driving means is controlled to move the thermal heads to the second positions. Therefore, the thermal head is pressed against the platen roller through the cut paper only when the cut paper is at the recording position, so that good recording can be performed. Since the thermal head and the platen roller do not come into direct contact from the start of conveyance of the cut sheet to the ejection of the cut sheet after recording, the driving torque of the platen roller can be set to a small value. , the life of the line thermal head can be extended.

As a result, according to the present invention, it is possible to realize a line thermal printer in which the drive mechanism and the entire device can be made smaller, the power consumption can be reduced, and the life of the head is longer.

[Brief explanation of drawings]

FIG. 1 is a schematic side view showing a state in which a head is pressing a platen roller in an embodiment of a line thermal printer according to the present invention.

2 is a schematic side view showing a state in which the head is separated from a platen roller in the line thermal printer of FIG. 1; FIG.

FIG. 3 is a perspective view of essential parts showing the detailed configuration of the head unit shown in FIGS. 1 and 2. FIG.

FIG. 4 is a perspective view of the main parts of FIG. 3 with the mounting plate removed.

FIG. 5 is a block diagram showing a control circuit of the line thermal printer of FIGS. 1 to 4. FIG.

[Fig. 6] Flowchart for explaining the operation of the control circuit shown in Fig. 5.
It is a chart.

FIG. 7 is a schematic side view showing a line thermal printer that records on thermal roll paper.

FIG. 8 is a schematic side view showing a conventional line thermal printer that records on cut sheets of plain paper.

FIG. 9 is a side view showing a state in which the head unit is removed from the platen roller in a conventional printer using cut paper.

[Explanation of symbols]

12 Thermal head 13 Platen roller 30 Cut paper 31, 32 Paper feed roller 33 Switch 35 Cam 41 CPU (central processing unit)

Claims (1)

[Claims] 1. A platen roller, a thermal head movable between a first position in contact with the platen roller and a second position spaced apart from the platen roller; a driving means for moving the object to the second position;
a conveyance means for conveying a cut sheet to a recording position between the thermal head and the platen roller via a conveyance path; and a predetermined position on the conveyance path for detecting the presence or absence of the conveyed cut sheet at the recording position. and a detection means provided at the detection means, and when it is determined that the cut sheet is at the recording position based on the detection by the detection means, the thermal head is placed in the first position, based on the detection by the detection means. and a control means for controlling the drive means to move the thermal head to the second position when the cut paper is not at the recording position. printer.