JPS6154972A - Thermal printer - Google Patents

Abstract

PURPOSE:To permit high-speed printing to be performed at low cost by effectuating the mechanical basic actions of a thermal printer by a common drive source. CONSTITUTION:A thermal head is provided with a platen 1, a carriage 4 with a thermal head 5 moving reciprocally in parallel with the platen 1, a driver to reciprocally move the carriage 4, and a switcher to switch power transmission from the driver in conformity to the reciprocal movement of the driver. The thermal head 5 is pressed on the platen 2 according to the movement to one direction of the carriage, and papers are fed by utilizing the movement to other directions of the carriage 4. Since necessary mechanical basic actions of thermal printer can be effectuated by only one drive source, the number of parts to be used can be lessened and small-size, low-cost, and light-weight thermal printers can be obtained.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a thermal printer, and more particularly, to pressing and releasing a thermal head toward a platen side, feeding paper,
The present invention relates to a thermal printer in which the carriage 2 can be moved using one power source.

[Prior Art] In a thermal printer, a thermal head is installed on a carriage that moves in parallel along a platen, and serial printing is performed by pressing and releasing heat-sensitive recording paper or recording paper via an ink ribbon. The basic operations include reciprocating the carriage, pressing the thermal head toward the platen, releasing the pressure, and feeding the paper.

Further, in a thermal transfer printer, there is an operation for feeding an ink ribbon.

In conventional thermal printers, the above-mentioned basic mechanical operations are performed using dedicated motors and solenoids, resulting in a large number of parts and high costs.

On the other hand, a method has been proposed in which the ink ribbon is fed by using the carriage feed operation, and a method in which the paper is fed when the carriage moves outside the printing area by using the carriage feed operation.

However, if the paper feed operation is performed using a carriage feed operation, apart from the ink ribbon feed, a mechanical sequence is performed at the position where the carriage moves outside the printing area, so the amount of paper feed by one paper feed operation is reduced. Since this method is fixed, it has the disadvantage that minute paper feeding is not possible and it takes a long time to feed the paper.

Furthermore, when printing a printing range specified on the left or right side of the printing range, each time a line is printed, the carriage must be moved to the paper-feeding range to perform the paper-feeding operation. Compared to printers using motors or solenoids, the disadvantage is that it takes longer to print.

[Purpose] The present invention was made to eliminate the above-mentioned conventional drawbacks, and it configures the basic mechanical operations of a thermal printer so that it can be operated by one common driving source, and achieves low cost. The purpose is to provide a thermal printer that can perform high-speed printing at low cost.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

Figure 1 and the following diagrams explain one embodiment of the present invention.
The figure shows a plan view of the main parts.

In the figure, the symbol l is a platen that also serves as a paper feed roller.
It is rotatably supported between frames 2 and 2 of the printer.

A guide shaft 3 is arranged parallel to the platen 1, one end of a carriage 4 is slidably supported on the guide shaft 3, and a thermal head 5 is attached to the carriage 4.

Further, a pressing lever 6 is arranged parallel to the guide shaft 3.

Both ends of the pressing lever 6 are connected to the guide shaft 3 via arms 6a, 6a.
The bearing is mounted on the shaft.

A U-shaped protrusion 4a protruding from the front side of the carriage 4 is slidably fitted into the pressing lever 6.

On the other hand, a pulse motor 7 is provided outside the frame 2.

A drive gear 8 is fixed to the output shaft of the pulse motor 7, and the drive gear 8 meshes with a large diameter gear 9.

A pulley 10 is fixed coaxially with the gear 9, and another pulley 11 is arranged on the opposite side, facing the pulley lO, and an endless timing belt 12 is stretched between the two. .

A carriage 4 is fixed in the middle of this timing belt 12.

Reference numeral 13 indicates a switching lever, and a shaft 9a of a gear 9 is slidably fitted into an elongated hole 13a formed at one end of the switching lever.

Further, an intermediate gear 14 is rotatably supported on the thin end of the switching gear 8-13.

The above-mentioned switching lever 13 is connected to the elongated hole 1 by a leaf spring 19.
The end portion on the side where 3a is formed is pressed, and the pressing force is kept in the right direction as indicated by the arrow in the figure.

A head pressing gear 15 is rotatably supported below the intermediate gear 14 .

This head pressing gear 15 is a partially toothed gear, and a gear portion 15a that meshes with the intermediate gear 14 only over approximately 180'' is formed on its circumferential surface. On the upper surface, a cam 15b is formed over approximately 180' or more with a 180° phase shift so that the gear portion 15a faces the cam 15b.

The cam 15b is lower on the left end side in FIG. 1 and becomes higher toward the right end side.

Further, the head pressing gear 15 is given a rotational force in the counterclockwise direction indicated by an arrow 15c by a spring (not shown).

Note that a one-way spring clutch 15d is coaxially provided on the lower surface of the head pressing gear 15.

By the way, above the cam 15b is the pressing lever 6.
A protruding piece 6b formed at one end of the plate is exposed.

This protruding piece 6b is caused by the weight of the entire pressing lever 6 to cause the cam 15 to
It is always in contact with the top of b.

By the way, a gear 16 is rotatably supported on the opposite side of the head pressing gear 15 with the intermediate gear 14 interposed therebetween.

This gear 16 has a worm gear 16a, and this worm gear 16a meshes with a worm wheel 1b fixed to one end of the carriage 1a of the platen 1.

By the way, a control solenoid 17 is provided on the side of the end of the switching lever 13 on the side where the intermediate gear 14 is provided.

This control solenoid 17 has an actuator 17a at the tip of its rod for actuating the switching lever 13, and an actuating piece 17b for turning on and off the spring clutch 15d is provided integrally with this actuator 17a.

What is indicated by the reference numeral 18 is a recording paper (thermal recording paper).

Next, the operation of this embodiment configured as above will be explained.

Before printing starts, the carriage 4 is at the home position, the solenoid 17 is not energized, and the actuator 17a is moved to the switching lever 13 as shown by the dotted line.
located away from one end of the

In this state, the recording paper 18 is set along the platen 1.

Subsequently, when print data is prepared in a control circuit (not shown), the motor 7 is first rotated counterclockwise as shown by the arrow in FIG.

Then, the gear 9 is rotated clockwise, the timing bell 12 also starts moving clockwise, and the carriage 4 starts moving toward the right from the left end in FIG.

At the same time as operating the motor 7, the control solenoid 1
When 7 is also energized, the actuator 17a comes into contact with the free end side of the switching lever 13 and presses it to the left in the figure.

Then, the switching lever 13 is pushed by the force of the spring 19,
The one where the intermediate gear 14 was located away from the gear 9,
It will mesh with gear 9.

When the intermediate gear 14 meshes with the gear 9, the intermediate gear 14 is rotated counterclockwise in FIG.

Due to the frictional force at this time, the intermediate gear 14 is rotated clockwise in FIG. ff11 in the clockwise direction in the figure.

Then, the cam 15b also rotates in the same direction.

Since the gear portion 15a is formed only over approximately 180°, the intermediate gear 14 will eventually come to face the portion other than the gear portion 15a, and the rotation of the head pressing gear 15 will stop.

At this time, the actuating piece 17b integrated with the actuator 17a acts as a stopper and moves the spring clutch 15d for preventing reverse rotation to the operating state 7.
g, the return of the head pressing gear 15 in the direction of the arrow 15c is restricted, and the head pressing gear 15 is stopped at the same position &4.

During this time, the protruding piece 6b of the pressing lever 6 reaches the highest position of the cam 15b, and as shown in FIG. 3, the pressing lever 6 is raised via the protruding piece 6b.

As a result, the carriage 4 is rotated clockwise in FIG. 2, and the thermal head 5 is pressed against the recording paper 18.

Even if the head pressing operation is completed in this way.

The motor 7 continues to rotate counterclockwise, and the carrying 4 moves to the right in FIG. 1 to perform printing in accordance with a printing signal from a control device (not shown).

When one line of printing operation is completed, the control solenoid 17
1, the actuator 17a returns to its original position shown by the dotted line in FIG.
9, the actuating piece 17b also returns with the return of the actuator 17a, and the head pressing gear 1
Release the restraint on the one-way spring clutch 15d of 5,
To make this free, the head pressing gear 15 returns to its original position by the return force of the spring.

As a result, the protruding piece 6b of the pressing lever 6 also returns from the highest position to the lowest position of the cam 15b, and the pressing lever 6 is lowered, so that the protruding piece 4a side of the carriage 4 is lowered, and the thermal head 5 is moved from the platen 18 to the recording Move away from paper 18.

In this way, the pressure release operation of the thermal head is completed.
Once completed, the motor 7 is reversed and the return operation of the carriage 4 is started.

On the other hand, when the control solenoid 17 is energized during the return operation of the carry-on position, the medium-thin gear 14 again engages with the gear 9 via the switching lever 13, but at this time, the motor 7 is reversed so that the gear 9 is being rotated counterclockwise, the intermediate gear 14 moves in the direction of the gear 16 together with the switching lever 13 and starts meshing therewith.

As a result, the worm gear 16a is also rotated, and the platen shaft 1a and the platen 1 feed the recording paper 18 via the worm wheel lb.

The amount of paper feed can be arbitrarily selected depending on the time period during which the solenoid 17 is energized.

When the energization to the solenoid 17 is stopped, the actuator 17a returns, the switching lever 13 also returns, and the intermediate gear 1
4 and the gear 9 are disengaged, the paper feeding operation is completed, and the carriage 4 is returned to the print head position of the next line, completing the printing of one line.

By the way, if the desired paper feed amount cannot be obtained with only one return operation of the carriage 4 as described above, the solenoid 17. Without energizing the thermal head 5, the carriage 4 is moved rightward in FIG. 1 by the required amount, and from that point on, the solenoid 17 is energized to return the carriage.

Although the above-described embodiment has been described only in the case where the recording paper 18 is thermal paper, it is of course applicable to a thermal transfer type printer using a thermal transfer ink ribbon.

By the way, the pressing force of the thermal head is related to printing quality and requires a pressing force of about 100 to 500 g. Therefore, in thermal printers that press the head with a solenoid as in the past, a large, high-power, expensive solenoid is required. 2 In the present invention, the only solenoid is the control solenoid 17, and this solenoid does not require a force to directly press the thermal head, so a small, low-power, lightweight, and inexpensive solenoid can be used. Can be done.

[Effects] As is clear from the above explanation, according to the present invention, the number of parts per unit is reduced because a structure is adopted in which basic mechanical operations required by a thermal printer can be performed with one drive source. It is possible to obtain a thermal printer that is small, inexpensive, and lightweight.

[Brief explanation of the drawing]

The drawings are for explaining one embodiment of the present invention, and FIG. 1 is a plan view, and FIG. 2 is a cross-sectional view taken along the line A--A in FIG. 1. FIG. 3 is a side view for explaining the operation of the pressing lever. 1...Platen ib...Worm wheel 4...Carriage 5...Thermal head 6.
...Press lever 7...Motor 13...Switching lever 14...Intermediate gear 15...Head press gear 15a...Gear part 15b...Cam 15d...
・One-way spring clutch 16... Gear 1B &... Worm gear 1
7... Solenoid 17a... Actuator 1
7b... Actuation piece

Claims (1)

[Claims] A platen, a carriage that reciprocates parallel to the platen and is provided with a thermal head, a drive means for reciprocating the carriage, and power transmission from the drive means in response to the reciprocation of the drive means. The switching means is configured to cause the thermal head to press the platen according to the movement of the carriage in one direction, and to feed the paper using the movement of the carriage in the other direction. A thermal printer characterized by: