JP2519344Y2 - Serial printer cooling structure - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a print head cooling fan in a serial printer.

[0002]

2. Description of the Related Art A wire dot print head is mounted on a carriage inside a printer, and an arbitrary actuator inside the print head is driven in association with the left and right spacing of the carriage to eject the print wire from the tip of the print head. In a serial dot printer that transfers ink from an ink ribbon placed between a print head and a medium to a medium for printing, the print head generates heat by performing printing.

When the print head is heated to a high temperature due to heat generation, the coil inside the print head is burned and the parts of the actuator are deteriorated or destroyed. In order to prevent deterioration and destruction of the print head due to high temperature, a temperature sensor such as a thermistor is installed inside the print head, and when the print head becomes hot, the function to detect it and temporarily stop the printing operation is provided. Comes with many printers.

However, in order to increase the printing speed in the printer, a means for forcibly radiating or cooling the print head without stopping the printing operation is required. FIG. 5 is a perspective view showing a main part of a printer having a conventional cooling means. In the figure, 31 is a print head, and 32 is a carriage that supports the print head 31.

A carriage shaft 33 supports the carriage 32. The carriage 32 is spaced along the carriage shaft 33. 34 is a ribbon cassette holder that supports an ink ribbon cassette (not shown), and 35 is a gear group (not shown) that drives a ribbon drive shaft 36 that rotates to feed the ink ribbon in the ink ribbon cassette (not shown) supported by the ribbon cassette holder 34. The ribbon cassette holder 34 and the gear case 35 are integrated with the carriage 32.

A space rack 37 is provided in parallel with the carriage shaft 33.
7 and a gear fixed to a shaft on one end side of a space motor (not shown) provided in the lower part of the gear case 35 mesh with each other, and the space motor alternately rotates in both directions, so that the carriage 32 slides left and right along the carriage shaft 33. Pacing.

The above-mentioned ribbon drive shaft 36 is attached to the shaft on the other end side of the space motor (not shown).
Gears for driving the are attached. In the gear case 35, the gears attached to the shaft on the other end side of the space motor are attached to the ribbon drive shaft 36.
In order to transmit the driving force to, a ribbon feed mechanism consisting of a plurality of gear groups is built in, and since this ribbon feed mechanism has a planetary gear whose meshing destination changes according to the rotation direction of the space motor, The ribbon drive shaft 36 is used when the carriage 32 is spaced left and right by rotating the space motor alternately in both directions.
Rotates in a fixed direction regardless of the spacing direction.

The print head 31 is mounted on the carriage 32 so as to face a platen (not shown). Then, an ink ribbon and a medium (not shown) pass between the print head 31 and the platen, and the print head 31 is driven in conjunction with the left and right spacing of the carriage 32 to transfer the ink of the ink ribbon to the medium. To print. Fins 38 for improving heat dissipation of the print head 1 are formed on the outer peripheral portion of the print head 31.

Further, in order to forcibly cool the print head 31, the carriage 32 is equipped with a micro fan 39. The temperature rise of the print head 31 due to printing is detected by an internal thermistor, and when the temperature of the print head 31 becomes higher than a certain temperature, the micro fan 39 is energized to forcibly cool the print head 31.

[0010]

However, the micro fan provided for forcibly cooling the print head is expensive, and a circuit for driving and controlling the micro fan is also required. Such a forced cooling means has a problem that it can be installed only in some high-end models.

The present invention has been made in order to solve the problems that the forced cooling method for a print head using a micro fan increases the cost and complicates the electric system as described above. It is an object of the present invention to provide a cooling structure for a serial printer, which enables inexpensive forced cooling.

[0012]

A first invention for achieving this object is a carriage for mounting a print head and a ribbon cassette holder for accommodating an ink ribbon, and a carriage for supporting the carriage so as to be horizontally movable. A shaft, a space rack parallel to the carriage shaft, a space motor fixed to the carriage, a pinion gear attached to the shaft of the space motor and engaged with the space rack, and a ribbon gear attached to the shaft of the space motor, A ribbon drive shaft that feeds the ink ribbon, a first drive force transmission path from the ribbon gear to the ribbon drive shaft, and a ribbon gear to the ribbon drive shaft, and an odd number of gears from the first drive force transmission path. The second drive force transmission path with increased According to the rotation direction of the motor, the ribbon feed mechanism has a planetary gear that switches the transmission destination of the driving force from the ribbon gear to the first driving force transmission path or the second driving force transmission path. ，
In the cooling structure of a serial printer, in which the ribbon drive shaft rotates in a certain direction and the ink ribbon is fed in one direction while the carriage is spaced left and right along the carriage shaft by counterclockwise rotation, the ribbon feed In the mechanism, the carriage is provided with a fan that receives a driving force from a gear that rotates in a fixed direction regardless of the rotation direction of the space motor, constantly rotates in a fixed direction, and blows the print head.

A second invention for achieving the above object is that the driving force is transmitted from a gear that rotates in a fixed direction in the ribbon feed mechanism regardless of the rotation direction of the space motor, so that the ribbon feed mechanism always moves in a fixed direction. The carriage is provided with a fan that rotates and blows air to the print head, and the drive force is transmitted to the fan when the rotation speed on the side driving the fan is low in the drive force transmission path from the ribbon feed mechanism to the fan. It is characterized in that a clutch is provided for cutting off the transmission of the driving force to the fan when the rotation speed on the driving side is high.

[0014]

In the first device having the above-mentioned structure, the space is rotated left and right by rotating the space motor clockwise and counterclockwise. At this time, the ribbon drive shaft always rotates in a fixed direction by the ribbon feed mechanism to feed the ink ribbon.

At the same time, the fan is always rotated in a fixed direction by receiving a driving force from a gear that rotates in a fixed direction in the ribbon feed mechanism regardless of the rotation direction of the space motor, so that the fan stabilizes the print head. It can blow the air. Further, according to the second invention, by providing a clutch that transmits the driving force when the rotation speed of the fan on the drive side is low and cuts off the transmission of the drive force when the rotation speed on the drive side is high, a high pixel density is achieved. When the carriage spacing is low, the fan rotates and prints with a coarse pixel density, so the print head does not generate too much heat. The carriage spacing is high. When it is, the fan does not rotate. Accordingly, when the spacing of the carriage is low, it is possible to set the fan to rotate at a high rotation speed that is optimal for cooling the print head.

[0016]

Embodiments Embodiments will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of the first device.
1A is a plan sectional view, and FIG. 1B is a front sectional view.
FIG. 2 is an overall perspective view of this embodiment. In the figure, reference numeral 1 denotes a print head, and a fin 2 for improving heat dissipation of the print head 1 is formed on an outer peripheral portion of the print head 1.

Reference numeral 3 denotes a carriage that supports the print head 1, and reference numeral 4 denotes a carriage shaft that supports the carriage 3 so as to be movable in the horizontal direction. The carriage 3 is spaced along the carriage shaft 4. Reference numeral 5 is a ribbon cassette holder that supports an ink ribbon cassette that stores an ink ribbon (not shown), 6 is a ribbon drive shaft 7 that is rotated to feed the ink ribbon in the ink ribbon cassette (not shown) that is supported by the ribbon cassette holder 5, The ribbon cassette holder 5 and the gear case 6 are integrated with the carriage 3.

Reference numeral 8 denotes a space motor which is attached to the lower side of the gear case 6 and has a shaft protruding from both upper and lower ends. 9
Is a pinion gear fixed to a shaft protruding below the space motor 8, and 10 is a space rack which meshes with the pinion gear 9 and is provided in parallel with the carriage shaft 4. The pinion gear 9 and the space rack 10 are connected to each other. Due to the meshing, the space motor 8 is rotated clockwise or counterclockwise so that the carriage 3 is spaced laterally along the carriage shaft 4.

Reference numeral 11 is a ribbon gear fixed to a shaft protruding above the space motor 8. Reference numeral 12 is a planetary gear that meshes with the ribbon gear 11. Reference numeral 13 denotes a bearing of the planetary gear 12, which has a long hole shape that draws an arc about the axis of the ribbon gear 11.
Even if the shaft 12a of the planetary gear 12 moves in the bearing 13, the meshing state between the ribbon gear 11 and the planetary gear 12 is always maintained.

Here, when the ribbon gear 11 rotates clockwise, the planetary gear 12 rotates counterclockwise about the shaft 12a, and the shaft 12a has an elongated hole shape that draws an arc about the axis of the ribbon gear 11. Since the planet gear 12 itself is supported by the bearing 13, the shaft 12a of the planet gear 12 itself moves along the bearing 13 in the same clockwise direction as the rotation direction of the ribbon gear 11.

On the contrary, when the ribbon gear 11 rotates counterclockwise, the planetary gear 12 rotates clockwise around the shaft 12a, and the planetary gear 12 itself has the shaft 12a along the bearing 13 in the rotational direction of the ribbon gear 11. Move in the same counterclockwise direction as. Reference numeral 14 denotes a first idle gear, which meshes with the first idle gear 14 when the ribbon gear 11 rotates clockwise and the planet gear 12 moves clockwise.

Numeral 15 is a second idle gear, which when the ribbon gear 11 rotates counterclockwise and the planetary gear 12 moves counterclockwise, the second idle gear 15 and the planetary gear 12 are separated from each other. Mesh with each other. Here, when the first idle gear 14 and the planetary gear 12 are engaged with each other, the second idle gear 15 and the planetary gear 12 are not engaged with each other and the second idle gear 15 and the planetary gear 12 are not engaged with each other.
When the idle gear 15 and the planetary gear 12 are meshed with each other, the gap between the first idle gear 14 and the second idle gear 15 is set so that the first idle gear 14 and the planetary gear 12 do not mesh with each other. It is taken.

The bearing 13 has a structure in which the shaft 12a of the planetary gear 12 moves within the bearing 13 so that the planetary gear 1
The shaft 12 necessary and sufficient for the gear 2 to engage with the first idle gear 14 or the second idle gear 15.
It has a movement range of a. Reference numeral 16 is a third idle gear that meshes with the first idle gear 14. 17 is the second idle gear and the third idle gear 16
A ribbon drive gear which meshes with the ribbon drive shaft 17 is mounted coaxially with the ribbon drive gear 17. When the ribbon drive shaft 7 rotates, it feeds an ink ribbon contained in an ink ribbon cassette (not shown) supported by the ribbon cassette holder 5.

Here, from the ribbon gear 11 to the planetary gear 1
2, the gear ratio from the first idle gear 14 and the third idle gear 16 to the ribbon drive gear 17, and the gear ratio from the ribbon gear 11 to the planet gear 12 and the second idle gear 15 to the ribbon drive gear 17. Up to the same gear ratio. With the above configuration, the first drive force transmission path including the second idle gear 15 and the first drive force transmission path including the first idle gear 15 are provided in the gear case 6 as the drive force transmission path from the ribbon gear 11 to the ribbon drive gear 17 having the ribbon drive shaft 7. The idle gear 14 and the third idle gear 16, and has a second driving force transmission path in which the number of gears is an odd number (here, one) larger than that of the first driving force transmission path. To the first driving force transmission path or the second driving force transmission path, the planetary gear 12 that switches the transmission destination of the driving force is formed.

Here, the space motor 8 rotates alternately in both clockwise and counterclockwise directions for spacing the carriage 3 left and right. When the space motor 8 rotates clockwise, the pinion gear 9 and the space rack 10 mesh with each other, so that the carriage 3 is spaced to the left side in FIG. At this time, as described above, the ribbon gear 1
1 rotates in the clockwise direction, so the planet gear 12 has a shaft 12a.
While rotating counterclockwise around the
The whole moves clockwise along the bearing 13, and the planetary gear 1
2 and the first idle gear 14 mesh with each other.

As a result, the first idle gear 14 rotates clockwise. Since the first idle gear 14 and the third idle gear 16 mesh with each other,
Idle gear 16 rotates counterclockwise. And
Since the third idle gear 16 and the ribbon drive gear 17 mesh with each other, the ribbon drive gear 17 rotates clockwise, and the ribbon drive shaft 7 mounted coaxially with the ribbon drive gear 17 also rotates clockwise. Then, an ink ribbon (not shown) is fed. At this time, since the planetary gear 12 and the second idle gear 15 are not meshed with each other, the driving force is not transmitted from the second idle gear 15 side to the ribbon drive gear 17.

Contrary to the above operation, when spacing the carriage 3 to the right in FIG. 1, the space motor 8 is rotated counterclockwise. At this time, since the ribbon gear 11 rotates counterclockwise, the planetary gear 12 rotates clockwise around the shaft 12a, and the entire planetary gear 12 moves counterclockwise along the bearing 13 to cause the planetary gear 11 to rotate. And the second idle gear 15 mesh with each other.

As a result, the second idle gear 15 rotates counterclockwise. Then, the second idle gear 15
Since the ribbon drive gear 17 and the ribbon drive gear 17 are engaged with each other, the ribbon drive gear 17 rotates clockwise, and the ribbon drive shaft 7 mounted coaxially with the ribbon drive gear 17 also rotates clockwise, and an ink ribbon (not shown) is shown. Is sent. At this time, the planetary gear 12
Since it does not mesh with the first idle gear 14,
Ribbon drive gear 1 from the side of the first idle gear 14
No drive force is transmitted to 7.

As described above, the ribbon drive shaft 7 is always rotated clockwise by the planet gear 11 even if the space motor 8 is repeatedly rotated clockwise and counterclockwise for spacing the carriage 3 left and right. It is like this. Reference numeral 18 is a fourth idle gear that meshes with the third idle gear 16, and 19 is a fifth idle gear that meshes with the fourth idle gear 18, and the fourth idle gear 18 and the fifth idle gear 19 are also included. It is built in the gear case 6.

Reference numeral 20 denotes a fan for sending air to the print head 1. Below the fan 20, a final gear 21 which meshes with the fifth idle gear 19 is coaxially provided. Reference numeral 22 denotes an air blowing path for sending air to the print head 1 by the fan 20, and this air blowing path 22 is used for the print head 1.
The sides are bifurcated so that the entire print head 1 is blown with air.

Reference numeral 23 is a cover for closing the upper portion of the ribbon cassette holder 5, and a hole 24 for intake by the fan 20 is formed at a position of the cover 23 facing the fan 20. Although not shown, when the ink ribbon cassette is set in the ribbon cassette holder 5, the holes 24 are not closed so as not to obstruct the intake of air by the fan 20.

Here, the fourth idle gear 18 and the fifth idle gear 19 are for increasing the speed of the fan 20.
It is a two-stage gear in which a large gear and a small gear are provided coaxially, the small gear of the fourth idle gear 18 meshes with the third idle gear 16, and the large gear of the fourth idle gear 18 is the fifth gear. Of the idle gear 19 and the large gear of the fifth idle gear 19 mesh with the final gear 21.

When the space motor 8 rotates clockwise, the planetary gear 11 meshes with the first idle gear 14, and the first idle gear 14 rotates clockwise. Accordingly, the third idle gear 16 receives the driving force from the first idle gear 14 side and rotates counterclockwise. When the space motor 8 rotates counterclockwise, the planet gear 11 meshes with the second idle gear 15 and the ribbon drive gear 17 rotates clockwise as described above. At this time, the planetary gear 11 and the first idle gear 14 are not meshed with each other, so the third idle gear 1
6 receives a driving force from the ribbon drive gear 17 side and also rotates counterclockwise.

As described above, the third idle gear 16 is
Regardless of the rotation direction of the space motor 8, the space motor 8 always rotates in the counterclockwise direction, so that the fan 20 always rotates in the clockwise direction regardless of the left or right spacing of the carriage 3. When the fan 20 rotates in a certain direction, during the spacing of the carriage 3, the air is sucked from the holes 24 of the cover 23 and is blown to the print head 1 through the air passage 22 to perform forced air cooling of the print head 1.

The gear ratio from the ribbon gear 11 to the third idle gear 16 via the planet gear 12 and the first idle gear 14 and the ribbon gear 11 to the planet gear 12, the second idle gear 15 and the ribbon drive. The gear ratios from the gear 17 to the third idle gear 16 are set to be the same (for example, the number of teeth of the first idle gear 14 and the number of teeth of the second idle gear 15 are the same). The number of teeth of the third idle gear 16 and the number of teeth of the ribbon drive gear 17 are the same.) Therefore, in the spacing direction of the carriage 3, the fan 20
The rotation speed of is not changed.

FIG. 3 is an explanatory view showing an embodiment of the second invention, FIG. 3 (a) is an overall perspective view, and FIGS. 3 (b) and 3 (c) are main part explanatory views. It should be noted that the mechanism for spacing the carriage 3 by the space motor 8 described in the first invention and the planetary gear 11 are used to move the ribbon drive shaft 7 in a constant direction regardless of the spacing direction of the carriage 3. Since the mechanism for rotating and the third idle gear 16 to the fifth idle gear 19 which always rotate in a constant direction have the same configuration in this second invention, a detailed description thereof will be given here. The second device will be described with reference to FIG. 1 as needed for those components that are not visible in FIG.

Reference numeral 25 is a fan for sending air to the print head 1.
A fan gear 26 is provided on the lower surface of the fan 25 coaxially with the fan 25. Reference numeral 27 is a clutch rotatably incorporated in the rotary shaft 25a of the fan 25. The clutch 27 is a gear coaxial with the fan 25 that meshes with the large gear of the fifth idle gear 19 described in FIG. 1 of the first invention. The portion 27a and one end thereof are integrally fixed to the gear portion 27a, respectively, and the tip end side thereof is the fan gear 26 of the fan 25.
2 in the shape of an arc made of an elastic body surrounding the
It is composed of a book arm portion 27b and a rack portion 27c which is fixed to the tip of each arm portion 27b and meshes with the fan gear 26 of the fan 25.

FIG. 4 is a diagram for explaining the operation of the essential parts of an embodiment of the second invention, and the operation of the clutch 27 described above will be described below. Here, the cycle of driving the print wire (not shown) of the print head 1 to print each pixel is fixed and determined by the performance of the print head 1. In a serial printer that performs printing using the print head 1 as described above, when printing characters with coarse pixel density, the spacing speed of the carriage 3 is set high, and when printing graphics with high pixel density. , Set the spacing speed of the carriage 3 to be slow. Further, the heat generation of the print head 1 is small when printing a character having a coarse pixel density, and is large when printing a graphic having a high pixel density.

As described above, in order to perform printing with a high pixel density, the carriage 3 is moved at a low speed. At this time, since the rotation speed of the space motor 8 described in the first invention is suppressed, the rotation speed of the clutch 27 is low and the centrifugal force acting on the rack portion 27c is small. Rack 27
When the centrifugal force acting on c is small, the elastic arm portion 27b is hardly deformed to the outside, and the rack portion 27c and the fan gear 26 of the fan 25 are kept in mesh with each other. As a result, the driving force is transmitted to the fan 25, and the fan 25 always rotates in a fixed direction regardless of the spacing direction of the carriage 3 to forcibly cool the print head 1 as in the first invention.

When printing with a coarse pixel density, the carriage 3 is spaced at high speed. At this time, since the rotation speed of the space motor 8 is increased, the clutch 27
Is also high, and the centrifugal force acting on the rack portion 27c becomes large. When the centrifugal force acting on the rack portion 27c becomes large, the arm portions 27b are deformed outward with one end side, which is respectively integrated with the gear portion 27a, as a fulcrum, and the rack portion 27b.
The engagement between c and the fan gear 26 of the fan 25 is released. As a result, when spacing the carriage 3 at high speed, the driving force is not transmitted to the fan 25, and the load on the space motor 8 by the fan 25 is eliminated.

As described above, when the carriage 3 is spaced at high speed, the driving force is not transmitted to the fan 25. Therefore, when the carriage 3 in which the print head 1 generates a large amount of heat is spaced at low speed, the fan 25 is operated. A gear ratio that allows high rotation can be set, and the performance of the fan 25 can be sufficiently exhibited.

[0042]

As described above, according to the first invention, the carriage on which the print head and the ribbon cassette holder for accommodating the ink ribbon are mounted, the carriage shaft for movably supporting the carriage, and the carriage. A space rack that is parallel to the shaft, a space motor that is fixed to the carriage, a pinion gear that is attached to the shaft of the space motor and that meshes with the space rack, and a ribbon that feeds the ink ribbon regardless of the rotation direction of the space motor. It has a ribbon feed mechanism that always rotates the drive shaft in a fixed direction, and the ribbon drive shaft rotates in a fixed direction while the carriage is spaced left and right along the carriage shaft by the clockwise and counterclockwise rotations of the space motor. The ink ribbon In the cooling structure of a serial printer to feed printing is performed, among the ribbon feed mechanism always rotates in a predetermined direction from the gear to rotate in a fixed direction regardless of the direction of rotation of the space motor receive the driving force,
The carriage is provided with a fan for blowing air to the print head.

In the second invention, a drive force is transmitted from a gear in the ribbon feed mechanism, which rotates in a fixed direction regardless of the rotation direction of the space motor, so that the ribbon motor always rotates in a fixed direction and blows air to the print head. The carriage is provided with a fan, and the driving force transmission path from the ribbon feed mechanism to the fan transmits the driving force to the fan when the rotation number on the side driving the fan is low, and the rotation number on the side driving the fan is A clutch is provided to block the transmission of the driving force to the fan when the temperature is high.

As described above, the fan receives the driving force from the space motor for spacing the carriage on which the print head is mounted to the left and right, and always rotates in a fixed direction regardless of the rotation direction of the space motor to forcibly cool the print head. Since the carriage is provided in the carriage, an expensive microfan and a circuit for driving and controlling the microfan are not required, and it is expensive to provide an inexpensive printhead cooling structure for a serial printer.

Further, according to the second invention, in order to perform printing with a high pixel density, when the carriage is spaced at a low speed where the heat of the print head is large, the fan is rotated to perform printing with a coarse pixel density. The fan can be prevented from rotating when the carriage is spaced at high speed with less heat generated by the print head. This makes it ideal for cooling the print head when the carriage is spacing at a low speed and the print head heat is large, without considering the load on the space motor by the fan when the carriage is spacing at a high speed. The fan can be set to rotate at a high rotation speed, and a sufficient cooling effect can be expected.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a first device.

FIG. 2 is an overall perspective view of the first device.

FIG. 3 is an explanatory view showing an embodiment of the second invention.

FIG. 4 is an operation explanatory diagram of a main part of an embodiment of the second invention.

FIG. 5 is a perspective view showing a main part of a conventional printer having a cooling unit.

[Explanation of symbols]

 1 Print Head 3 Carriage 8 Space Motor 9 Pinion Gear 10 Space Rack 11 Ribbon Gear 12 Planetary Gear 16 Third Idle Gear 17 Ribbon Drive Gear 20 Fan

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-2-184486 (JP, A) JP-A-59-143667 (JP, A) JP-A-2-220874 (JP, A) JP-A-3- 261582 (JP, A) JP-A-4-197674 (JP, A) Actually open 3-55254 (JP, U)

Claims (2)

(57) [Scope of utility model registration request] 1. A carriage for mounting a print head and a ribbon cassette holder for accommodating an ink ribbon, a carriage shaft for horizontally moving the carriage, a space rack parallel to the carriage shaft, and a carriage fixed to the carriage. Space motor, a pinion gear mounted on the shaft of the space motor and meshing with the space rack, a ribbon gear mounted on the shaft of the space motor, a ribbon drive shaft for feeding an ink ribbon, and a ribbon gear to a ribbon drive shaft. First to
According to the rotation direction of the space motor, and a second driving force transmission path from the ribbon gear to the ribbon drive shaft in which the number of odd-numbered gears is larger than that of the first driving force transmission path. , Has a ribbon feed mechanism having a planetary gear that switches the transmission destination of the driving force from the ribbon gear to the first driving force transmission path or the second driving force transmission path, and rotates the space motor clockwise or counterclockwise. In the cooling structure of a serial printer, in which the ribbon drive shaft rotates in a certain direction and the ink ribbon is fed in one direction while the carriage is spaced to the left and right along the carriage shaft. Regardless of the direction of rotation, the drive force is transmitted from a gear that rotates in a fixed direction, and it always rotates in a fixed direction. Serial printers cooling structure a fan for blowing air to the head, characterized in that provided on the carriage. 2. A carriage on which a print head and a ribbon cassette holder for accommodating an ink ribbon are stored, a carriage shaft for horizontally moving the carriage, a space rack parallel to the carriage shaft, and a carriage. A space motor fixed to the space motor, a pinion gear attached to the shaft of the space motor and engaged with the space rack, a ribbon gear attached to the shaft of the space motor, a ribbon drive shaft for feeding an ink ribbon, and a ribbon gear to a ribbon. First to drive shaft
According to the rotation direction of the space motor, and a second drive force transmission path extending from the ribbon gear to the ribbon drive shaft in which the number of odd-number multiple gears is larger than that of the first drive force transmission path. , Has a ribbon feed mechanism having a planetary gear that switches the transmission destination of the driving force from the ribbon gear to the first driving force transmission path or the second driving force transmission path, and rotates the space motor clockwise or counterclockwise. In the cooling structure of a serial printer, in which the ribbon drive shaft rotates in a certain direction and the ink ribbon is fed in one direction while the carriage is spaced to the left and right along the carriage shaft. Regardless of the direction of rotation, the drive force is transmitted from a gear that rotates in a fixed direction, and it always rotates in a fixed direction. A fan that blows air to the head is provided on the carriage, and a drive force transmission path from the ribbon feed mechanism to the fan transmits the drive force to the fan when the rotation speed on the side that drives the fan is low, and drives the fan. A cooling structure for a serial printer, which is provided with a clutch that cuts off the transmission of the driving force to the fan when the rotation speed is high.