JP2682698B2 - Thermal head pressure contact control method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head pressure contact control method, and more particularly to a thermal printer that performs printing in a state in which the thermal head is pressed against the platen via a sheet at a constant pressure. Relates to a method for controlling pressure contact of a thermal head.

[Conventional technology]

Conventionally, JP-A-63-77750 and JP-A-63-1
As disclosed in Japanese Patent No. 73655, the thermal head mounted on the carriage is pressed against the platen through the ink ribbon and the paper to perform printing in a head-down state, and when the printing is not performed, the above pressure is applied. A thermal head printer having an up / down mechanism of a thermal head that is released to drive a carriage in a head-up state is often used.

In such a conventional thermal printer, the fourth
As shown in the figure, in a head-down state in which the thermal head 1 is pressed against the printer via the ink ribbon and the paper 2, the carriage is moved along the platen, and the carriage is gradually accelerated beyond the through-up area. When a certain speed is reached, each heating element of the thermal head 1 is driven to generate heat based on a desired print signal, and desired printing is performed on a desired sheet 2.

Then, when printing for one line is completed, the carriage
It enters the slow down area where it gradually decelerates and stops while slowing down. After that, the thermal head 1
Separated from the platen, the head is up. In this head-up state, the carriage is returned to the original position, the paper 2 is fed by a predetermined amount, and then the printing of the next line is started.

[Problems to be solved by the invention]

However, in the conventional thermal printer, since the thermal head 1 is always pressed with a large printing pressure required for printing when the head is down, a predetermined printing is performed even in the through-up area and the through-down area of the carriage. When the carriage is stopped, the pressure contact force of the thermal head 1 concentrates on one point, so that both sides of the paper 2 that are not printed, At both ends of the moving range of the carriage, the head-down pressure of the thermal head 1 causes pressure contact marks 3 to be formed on the paper 2, which causes a problem that the print finish of the paper 2 is not clean.

The present invention has been made in view of these points, and an object thereof is to provide a thermal head pressure contact control method capable of performing extremely high-quality printing or the like without forming a pressure contact trace of the thermal head. To do.

[Means for solving the problem]

In order to achieve the above object, the thermal head pressure contact control method according to the present invention is a print head down in which a thermal head mounted on a carriage is pressure contacted with a platen via an ink ribbon and paper at a pressure necessary for printing. In the pressure contact control method for the thermal head, the print head is positioned in a state, a standby head-down state in which the platen is pressed against the platen with a pressure that does not cause the ink ribbon to slide, and a head-up state in which the platen is separated from the platen when printing is not performed. At the start, the thermal head is set to the standby head down state, and then, in the through-up area of the carriage, the thermal head is changed from the standby head down state to the print head down state, and printing is performed in this print head down state. And then the key In the through-down area of the ridge, the thermal head is changed from the print head down state to the standby head down state, and the thermal head is brought to the head up state after the movement of the carriage is stopped. .

(Operation)

According to the present invention, the head of the thermal head is moved down with an ink ribbon holding pressure smaller than the printing pressure required for printing when the carriage is stopped, and the pressure contact force of the thermal head is increased to the printing pressure in the through-up area of the carriage. , In the slew down area, the pressure is reduced to the ink ribbon holding pressure.
Even if the thermal head is in a head-down state when the carriage is stopped, the pressure contact mark of the thermal head is not formed on the paper, and the print finish of the paper can be maintained neatly.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 and FIG. 2 show an embodiment of a thermal printer to which the thermal head pressure contact control method according to the present invention is applied. The body frame 4 is provided with a flat platen platen 5 extending in the left-right direction. A guide shaft 6 extending in parallel with the platen 5 is provided on the front side of the platen 5 of the main body frame 4. A carriage 7 is slidably attached to front end edges of the guide shaft 6 and the main body frame 4 in the axial direction of the guide shaft 6.
Is mounted with a thermal head 1 having a plurality of heating elements (not shown) arranged on the surface facing the platen 5. Further, on the upper surface of the carriage 7, a pair of take-up bobbins 8 and 8 for taking up and driving an ink ribbon housed in a ribbon cassette (not shown) are provided.
A rack 9 for driving the carriage 7 is formed inside the front edge of the main body frame 4 in parallel with the guide shaft 6.

Further, as shown in FIG. 2, the fixing member 10 of the thermal head 1 is provided on the swing shaft of the carriage 7 on the platen 5 side.
It is mounted so as to be swingable about 11, and the thermal head 1 is mounted on the tip of this fixing member 10.

Further, a carriage driving motor 12 is provided inside the carriage 7, and an output pinion 13 of the carriage driving motor 12 is meshed with a driving gear 14 meshed with the rack 9 of the body frame 4. Has been done.

Further, an up / down motor 15 for the thermal head 1 is disposed inside the carriage 7, and an output pinion 16 of the up / down motor 15 is provided with an outer circumference of a cam member 18 via a transmission gear 17. The cam gear 19 formed integrally with the gear meshes with the gear. An endless cam groove 20 is formed on the upper surface of the cam member 18.
Includes a tip portion 22a which is rotatable about a rotation shaft 21.
A base end portion 22b of a bell-shaped cam follower 22 that is in contact with the fixing member 10 of the thermal head 1 is slidably engaged. Then, by driving the up / down motor 15, the cam member 18 is rotated through the output pinion 16 and the transmission gear 17, and the cam follower 22 is rotated to swing the fixing member 10, The thermal head 1 is operated so as to freely move toward and away from the platen 5. In this case, in the present embodiment, due to the shape of the cam groove 20, the pressure contact force of the thermal head 1 changes from the pressure contact force 0 when the thermal head 1 is separated from the paper 2 and the ink ribbon to the ink ribbon. It is possible to increase / decrease for a while until the standby head-down state in which the contact pressure is such that the sheet does not slip and the print head-down state in which the printing pressure required for printing is performed.

Below the platen 5 of the body frame 4, a paper feed roller 23 and a small roller 24 pressed against the paper feed roller 23.
Is rotatably supported. Behind the paper feed roller 23 and the small roller 24, there is a paper insertion opening 25 for inserting paper.
Are formed. In addition, the one paper feed roller 23
Is connected to a paper feed motor 27 via a reduction gear group 26 disposed on one side surface of the main body frame 4, and by rotating the paper feed motor 27 by the rotation of the paper feed motor 27, The sheet inserted through the sheet insertion port 25 is conveyed between the platen 5 and the thermal head 1 while being sandwiched between the small roller 24 and the sheet.

Next, the operation of this embodiment will be described with reference to FIG.

First, a predetermined paper 2 is inserted from the paper insertion opening 25 of the main body frame 1, and the paper feed motor 27 is driven to rotate the paper feed roller 23 via the reduction gear group 26, thereby the paper 2 is platen. 5 and the thermal head 1.

Then, the up / down motor 15 is driven to drive the cam member through the output pinion 16 and the transmission gear 17, respectively.
By rotating 18, the cam follower 22 moves to the second
The cam follower 22 is rotated clockwise in the drawing, and the tip end 22a of the cam follower 22 presses the fixing member 10 toward the platen 5 by the rotation of the cam follower 22. The head is pressed down to the extent that the ink ribbon does not slip.

Then, by driving the carriage driving motor 12 to rotate the driving gear 14 via the output pinion 13, the driving gear 14 moves with respect to the rack 9, and the carriage 7 moves along the guide shaft 6. Then, the movement to the right in FIG. 3 is started. At the same time, by driving the up / down motor 15, the carriage 7 is pressurized to a print head down state of a print pressure required for printing in a through-up area until the carriage 7 reaches a predetermined speed immediately before the print range. It

Then, after the carriage 7 reaches a constant speed, the carriage moves to the print range, and each heating element of the thermal head 1 is driven based on a desired print signal,
The desired printing is performed on the paper 2.

When the printing of the printing range for one line is completed, the carriage 7 is stopped while decelerating the carriage drive motor 12 and gradually stopping the carriage 7. As the carriage driving motor 12 stops, the up / down motor 15
By rotating the cam member 18 by driving the cam member 18, the cam follower 22 is rotated counterclockwise in FIG. 2, and the fixing member 10 is gradually moved in a direction away from the platen 5, and the thermal head In No. 1, the pressure is gradually reduced from the print head down state to the standby head down state. Then, when the carriage 7 is completely stopped, the up / down motor 15 is further driven to bring the thermal head 1 into a completely head-up state, and then the carriage driving motor 12 is reversely rotated.
The carriage 7 is returned to the original position, the paper feed motor 27 feeds the paper 2 by a predetermined amount, and then the printing operation is repeated to start printing of the next line.

Therefore, in this embodiment, when the carriage 7 that is the start point of the slew-up area and the end point of the slew-down area is stopped, the thermal head 1 is moved down with an ink ribbon holding pressure smaller than the pressure required for printing. Since the pressure contact force of the thermal head 1 is increased to the printing pressure in the slew-up area of the carriage 7 and is decreased to the ink ribbon holding pressure in the slew-down area, the thermal head 1 is operated by the head when the carriage 7 is stopped. Even in the down state, the pressure contact mark of the thermal head 1 is not formed on the paper 2, and the print finish of the paper 2 can be held neatly.

The present invention is not limited to the above-described embodiment, and can be variously modified as needed.

〔The invention's effect〕

As described above, the thermal head pressure contact control method according to the present invention performs the head down of the thermal head with the ink ribbon holding pressure smaller than the printing pressure when the carriage is stopped, and the thermal head pressure contact is performed only during the printing operation of the thermal head. Since the force is used as the printing pressure,
Even if the thermal head is in a head-down state when the carriage is stopped, it is possible to prevent the pressure contact trace of the thermal head from being formed on the paper, and it is possible to remarkably improve the printing finish of the paper. Play.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a thermal printer to which a thermal head pressure contact control method of the present invention is applied, and FIG. 2 is a plan view of a carriage portion shown in FIG. FIG. 4 is an explanatory view showing the pressure contact state of the thermal head and the moving state of the carriage of the present invention, and FIG. 4 is an explanatory view showing the pressure contact state of the conventional thermal head and the moving state of the carriage. 1 ... Thermal head, 2 ... Paper, 4 ... Main body frame, 5 ... Platen, 7 ... Carriage, 12 ... Carriage drive motor, 14 ... Drive gear, 15 ... Up / down motor, 17 ...... Transmission gear, 18 …… Cam member, 20 ……
Cam groove, 22 …… Cam follower, 23 …… Paper feed roller, 27
...... Paper feed motor.

Claims (1)

(57) [Claims] 1. A print head down state in which a thermal head mounted on a carriage is brought into pressure contact with a platen via an ink ribbon and paper at a pressure required for printing, and a pressure at which the ink ribbon does not slip. In a standby head-down state in which the platen is brought into pressure contact with each other, and a thermal head pressure-contact control method in which each is positioned in a head-up state in which it is separated from the platen when printing is not performed, the thermal head is set to the standby head-down state at the start of printing, In the subsequent through-up area of the carriage, the thermal head is changed from the standby head-down state to the print head-down state, and printing is performed in this print head-down state.
After that, in the through-down area of the carriage,
A thermal head pressure contact control method, wherein the thermal head is changed from the print head down state to the standby head down state, and after the movement of the carriage is stopped, the thermal head is brought to the head up state.