JPS6334174A - Thermal printer - Google Patents

Abstract

PURPOSE:To enhance the pressure contact force of an ink film with a thermal head by imparting predetermined tension to said film to enhance heat transfer efficiency, by positively driving a film supply reel so as to rotate the same in the direction reverse to a film supply direction. CONSTITUTION:Compression spring 19, 20 are inserted between gears B, D and reels 6, 7 and when force of predetermined torque or more is applied to an ink film 5, sliding is generated between the reels and the compression springs, the gear B, D, race to protect the ink film from damage. A film take-up driving part 15 is constituted so that the drive shaft of a pulse motor can be easily connected to the shaft of the drive roller 9 is film cassette when a film cassette is set to a carriage. The speed of the pulse motor is synchronous to the moving speed of the carriage during printing and control is performed so that the relative speed of the ink film to a platen always becomes zero even when the moving speed of the carriage is changed to a slow speed. At the time of non- printing, the pulse motor is stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal printer, and particularly to a serial type thermal printer that performs printing while moving a thermal head in the main scanning direction.

When rough paper is used as the recording paper in the Fox-Rai-Q-Fu-Giu thermal printer, printing quality defects such as discontinuous printing are likely to occur. This is because the rough paper surface is highly uneven, which reduces the degree of adhesion between the thermal head, the ink film, and the recording paper, which lowers the heat transfer efficiency and impedes ink melting and transfer. Possible countermeasures to this problem include increasing the pressing force of the thermal head against the platen and increasing the energy applied to the thermal head, but each of these methods has a limit to its effectiveness, and under excessive conditions it may adversely affect printing. There is a problem in that it causes a loss of dignity.

In order to solve the fundamental problem, that is, to print even on rough paper without quality loss, we must wait for the quality of ink to be improved, but according to the knowledge of the present inventors, even if current ink films are used, It has been found that by increasing the heat transfer efficiency during printing while preventing large pressure from being applied to the molten ink, it is possible to print on rough paper without major quality loss. In order to make this possible, the pressing force between the thermal head and the ink film must be increased as much as possible while keeping the pressing force of the thermal head against the platen as small as necessary for the molten ink to transfer to the recording paper. There is a need to. This is because by increasing the contact force between the thermal head and the ink film, the ink can be melted with good heat transfer efficiency without increasing the energy applied to the thermal head. And to achieve this,
It is necessary to establish a technique that can increase the pressing force between the thermal head and the ink film independently of the pressing force of the thermal head against the platen.

Conventionally, such a technology does not exist, but a spring is simply pressed against the ink film supply reel, and the friction force generated by the elastic restoring force of the spring applies back tension to the ink film being wound onto the take-up reel. There is something given. According to this conventional means, the ink film is brought into pressure contact with the thermal contact in proportion to the back tension applied to the ink film.

Problems that IN is trying to solve However, with the above conventional means, although the pressure force between the thermal head and the ink film is somewhat higher than the pressing force of the thermal head against the platen, it does not improve the efficiency of heat transfer from the thermal head to the ink film. Therefore, it was not possible to expect an improvement in the quality of printing on rough paper.

In view of these problems, an object of the present invention is to provide a useful means that can increase the contact force between the thermal head and the ink film to a required pressure independently of the pressing force of the thermal head against the platen. There is.

In order to achieve the above object of solving the problem, the thermal printer of the present invention has an ink film take-up reel in the film cassette mounted on a carriage that moves in the main scanning direction and is provided with a film cassette. a first drive unit that drives the ink film supply reel in the film cassette in a direction opposite to the ink film supply direction, and a second drive unit that applies tension to the ink film; It is characterized by comprising a film winding drive unit that drives the ink film between the take-up reels in the winding direction at a speed synchronized with the moving speed of the carriage.

The point of applying tension to the ink film to increase the pressure contact force with the thermal head is similar to the conventional means of applying bank tension to the ink film by pressing a spring on the ink film supply reel. However, in the present invention, since the ink film supply reel is actively rotated in the opposite direction to the ink film supply direction to apply tension to the ink film, the pressure contact force necessary to improve the heat transfer efficiency from the thermal head to the ink film is required. Therefore, it is possible to perform high-quality printing on rough paper.

Figure 1 is a side sectional view showing the main parts of a thermal printer as an embodiment of the present invention, Figure 2 is a plan sectional view showing the inside of a film cassette, and Figure 3 shows the structure of the carriage. The plan view shown in FIG. 4 is a partially sectional view taken along the arrow E in FIG. 3.

In the figure, 1 is a platen, 2 is a recording paper wound around the platen 1, such as rough paper, and 3 is a film cassette mounted on a carriage, in which a supply reel 6 of an ink film 5 and a take-up reel are placed in a cassette case 4. 7, a roller 8 for winding the ink film 5 along a predetermined path, a winding drive roller 9 for winding and driving the ink film 5, and a pressing roller 1o for pressing the ink film 5 against the winding drive roller 9. The circumferential surface of the drive roller 9 is covered with a material having a high coefficient of friction to ensure the feeding of the ink film. Further, an opening 12 is formed in the center of the front surface of the cassette case 4 to allow the rad 11 to enter the thermal.

The carriage exists below the film cassette 3, and is mounted on a base (not shown) for rotating the take-up reel 7 in the film cassette 3 in the winding direction (direction of arrow a in the figure). 1 drive unit 13, a second drive unit 14 for rotationally driving the supply reel 6 in the direction opposite to the a direction, and the ink fills 1 and 5 in the a direction at a speed synchronized with the moving speed of the carriage. The film winding drive unit 15 includes a film winding drive unit 15 and a thermal head 11. This carriage is reciprocated in the main scanning direction (in the direction indicated by the arrow) by a timing belt rotated by a pulse motor (not shown). When the carriage moves forward, printing is performed on the recording paper 2 with the thermal head 11 in pressure contact with the platen 1, and when the carriage moves backward, the thermal head 11 is separated from the platen 1 and no printing is performed.

In this embodiment, the first drive section 13 is composed of a gear A and a gear B that meshes with the gear A. On the other hand, the second drive section 14 includes a gear A that is shared with the first drive section 13, a gear C that meshes with the gear A, and a gear D that meshes with the gear C. The gear A has two upper and lower gear parts At, A
2, and serrated engagement portions al and a2 are formed on opposite surfaces of both Al and A2, and a spring 16 is inserted inside as shown in FIG. The upper gear portion Al meshes with a rack 17 disposed behind the carriage along the main scanning direction of the carriage, and the lower gear portion A2 meshes with gears B and C. Also,
The lower gear portion A2 has a thermal head 11 attached and fixed at its tip, and an L-shaped interlocking lever 18 having a rotation center O is connected to an appropriate position near the base end, as shown in FIG. 5(A). When the thermal head 11 is in pressure contact with the platen 1 (during printing), it is moved upward by the interlocking lever 18 and is integrally connected to the upper gear portion A1 via the engaging portions a1 and A2. As a result, from the rack 17 to the gear B,
All gears up to D are in mesh, and rotational force is generated in gears B and D as the carriage moves. In this case, the rotational direction of gear B is the same as the ink film winding direction a, as shown in FIG. 1.3, and the rotational direction of gear D is opposite thereto. Gear B.

D is connected to the take-up reel 7 and the supply reel 6 in the film cassette through a structure described later, so that the ink film being printed is applied with tension by the gear D and the take-up drive roller 9. It is wound up by the rotation of B. On the other hand, as shown in FIG. 5(B), when the thermal head 11 is away from the platen 9 (when not printing), the upper and lower gear parts At and A2 are separated by the elastic restoring force of the spring 16, Gear part Al, A
Rotational force cannot be transmitted between the two. Therefore, even if the carriage moves, gears B and D do not rotate. At this time, when the winding drive unit 15 stops driving, no tension is applied to the ink film during non-printing, and the ink film is not wound up either. In this way, it is advantageous to wind up the ink film only during printing, and not to wind it up during non-printing, as this eliminates wasted use of the ink film. In addition, in order to prevent rotational force from being transmitted from the upper gear portion A1 to the lower gear portion A2 via the spring 16 during non-printing, the spring 1
It is desirable to provide sliding members on the upper and lower surfaces of 6.

The gears B and D are connected to the take-up reel 7 and the supply reel 6, as shown in FIG. 1.4.
It has a structure in which a compression spring 19.20 is inserted between 7,
When a force exceeding a predetermined torque is applied to the ink film, the reel 6.7 and the compression spring 19.20 slip, causing the gears B and D to idle, thereby protecting the ink film from damage.

The film winding drive section 15 uses a pulse motor M in this embodiment. The drive shaft of this motor M and the shaft of the drive roller 9 in the film cassette are appropriately configured so that they can be easily connected when the film cassette is set on the carriage.

The speed of the pulse motor M is synchronized with the moving speed of the carriage during printing, and is controlled so that the relative speed between the ink film and the platen is always zero even if the moving speed of the carriage changes slowly. On the other hand, during non-printing, the pulse motor M is stopped.

According to the above configuration, during printing, the supply reel 6 is rotationally driven in the opposite direction to the film supply direction a to apply a predetermined tension to the ink film, and in this state, the film winding drive section 15 is used to speed up the carriage movement. It is wound up in synchronization with the winding reel 7. Since a predetermined tension is applied to the ink film by the 60 revolutions of the supply reel, the pressure contact force between the thermal head 11 and the ink film can be maintained at the required level, which increases the heat transfer efficiency between the two and ink with low energy. This means that melting can be performed.

In addition, the pressure contact force between the thermal head 11 and the platen 1 is
Since the pressure contact force between the thermal head 11 and the ink film can be adjusted independently, high-quality printing on rough paper is possible.

In addition, the pressure contact force between the thermal head and the ink film is 20
It is desirable to use a strong one of about 0 to 500 g/aJ. Further, it is desirable that the coefficient of friction between the winding drive roller 9 and the ink film 5 is 1 μ or more.

Next, FIGS. 6(a) and 6(b) show another embodiment of the present invention. The point of applying tension to the ink film is the same as in the above embodiment, but this embodiment is devised so that the film cassette 3 can be easily attached and detached. That is, a core 22 having a plurality of protrusions 22a, . A fitting member 23 having a hole into which the core 22 is fitted is provided at the center of the reel 7 and the supply reel 6. A compression spring 20 is provided between the core 22 and gear B (D).
(19) is inserted, so the drive is transmitted via this spring. Note that the core 2 is attached to the tip of the shaft 21.
An E-ring 24 is attached to prevent No. 2 from coming off.

7 and 8 show still another embodiment of the present invention. In the embodiment shown in FIGS. However, in this embodiment, the driving force is obtained from the film winding motor M. Therefore, pulleys 27 and 28 are provided on the drive shaft 25 of the motor M and the shaft 26 of the film take-up reel 7, respectively, and a gear meshing with the gear D connected to the film supply reel 6 via a compression spring 19 is provided. A pulley 29 is provided on the shaft of E, and a belt 30 is passed between these three pulleys 27, 28, and 29.

This configuration has the advantage that a predetermined tension can be applied to the ink film, and that the configuration for driving the take-up reel 7 and the supply reel 6 is simplified.

Difference 1 and Kanri The thermal printer according to the present invention actively rotates the film supply reel in the opposite direction to the film supply direction as described above, so that a predetermined tension is applied to the ink film and the ink film is brought into pressure contact with the thermal head. Therefore, even if the pressing force of the thermal head against the platen is reduced, the heat transfer efficiency from the thermal head to the ink film can be maintained high, and printing without quality loss can be achieved even on rough paper. It becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing the main parts of a thermal printer as an embodiment of the present invention, FIG. 2 is a plan sectional view of a film cassette, FIG. 3 is a plan view of a carriage, and FIG.
A partially cross-sectional view taken along the arrow E in the figure, FIG. 5 (A) is a diagram showing the power transmission state during printing, FIG. Figure (a)
7 is a plan view showing another embodiment of the present invention, FIG. 7 is a side view of the carriage, FIG. It is a diagram. 3... Film cassette, 5... Ink film,
6... Supply reel, 7... Take-up reel, 13...
1st drive section, 14... second drive section, 15... film winding drive section. Patent distributor Minolta Camera Co., Ltd. Fig. 1 Fig. 3 Fig. 4 Fig. 5 (B) Fig. 6 (A) (B) Fig. 7 Fig. 8 Fig. ) 1. Indication of the case Patent Application No. 92505 filed in 1985 2. Name of the invention Thermal Blink 3. Relationship with the case by the person making the amendment Name of the patent applicant Minolta Camera Co., Ltd. Specification, page 14, line 5 r (12) Correct "J" to "r".

Claims (1)

[Claims] (1) A first drive unit that drives an ink film take-up reel in the film cassette in the film winding direction, and an ink film supply reel in the film cassette, on a carriage that moves in the main scanning direction and is provided with a film cassette. a second drive unit that applies tension to the ink film by driving the ink film in a direction opposite to the ink film supply direction; A thermal printer characterized by comprising a film winding drive unit that drives in the direction.