JP2927141B2 - Serial printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printer, and more particularly to an impact type serial printer using a printing wire.

[0002]

2. Description of the Related Art Conventionally, many serial printers of this kind have been developed which use a print head for printing characters and symbols using a plurality of print wires and which are small and capable of printing in Mincho style. . 2. Description of the Related Art Conventionally, as a driving means of a print wire of a print head used in a serial printer of this type, an electromagnetic print head having an operating unit utilizing magnetic attraction has been often used. In recent years, the development of a piezoelectric print head using a piezoelectric element has been energetically performed, but there are difficulties in terms of product stability, reliability, and manufacturing cost, and at present there are few examples. At present, electromagnetic printing heads occupy the majority of printing means in serial printers.

A drawback of this electromagnetic print head is that the temperature of the print head rises due to Joule heat generated from the coil. If the print head becomes extremely hot, the coating material of the coil of the print head may be burned and short-circuited. In order to prevent this, a temperature detecting element is provided inside the print head, and when the temperature of the print head exceeds the set temperature, the printer is controlled to stop printing or to insert a break time when starting a line feed. ing.

[0004] This situation will be described with reference to the drawings. FIG.
Indicates the duty of the pattern to be printed. It is assumed that a considerably high print duty continues until time t _0, and a low print duty after t ₀ .
FIG. 12 schematically shows a change in the print head temperature in this case. The print head temperature rises with the start of printing and reaches the set temperature θcr at a certain time t ₁ . Here a further slight rise in temperature is observed (referred to as overshoot this), printing from the time t ₂ is the break. Printhead from time t ₃ after the break do one-line printing, but the Joule heat generation during the printing operation, the print head temperature exceeds the set temperature θcr again. Therefore, again the print head at time t ₄ after the printing operation is entering the break. The above operation is repeated while the print duty is high. After time t ₀ ,
Since the print duty decreases, the print head temperature gradually decreases and approaches a certain temperature. FIG. 13 conceptually shows the number of prints obtained as an output when the above operation is performed. Time t ₂ when the print head first enters a break
Until then, the number of prints increases linearly. Time t during break
Since ₂ to t ₃ does not increase the number of printing line is parallel to the horizontal axis of the graph. Thereafter until the time t ₀ number of print is increased during printing, draw a line to be during a break flat, printing the number gradually increased. After time t _{0, the} number of prints again increases linearly. Here, if the printing speed is the same during printing, the increasing portions in the polygonal lines are all parallel.

[0005] When there is a break time during printing, the increase in the number of prints is small, and the so-called throughput decreases. In general, a change in temperature decreases with an increase in heat capacity. For example, measures to increase the heat capacity by increasing the weight of the print head can be considered. The state of the print head temperature and the number of prints in this case are shown by broken lines in FIGS. Since the print head temperature rise slows down, the set temperature θ
The time to reach cr becomes longer. Therefore, this measure is effective when the high duty period is short. However, if this period is long, a break of the print head is required. In this case, since the heat capacity of the print head is large, the rest time is long, and the total number of prints is not greatly improved.

[0006]

In this conventional serial printer, when the print head is heated to a high temperature and reaches a set temperature, the throughput decreases. Countermeasures such as changing the material of the coil covering material to set a higher temperature and adding fins to the print head have already been taken, but the technical limit has been reached and further improvement in throughput is difficult. It is.

[0007]

According to the present invention, there is provided a serial printer comprising: a carrier on which a print head is mounted; a shaft on which the carrier is mounted and which guides the carrier close to a platen and parallel to a center axis of the platen; Carrier driving means for reciprocating the carrier along the central axis of the platen, and the carrier which is guided by the shaft at both ends of the carrier, and whose upper side surface is detachably attached to the print head. And a pair of subcarriers.

Further, the serial printer of the present invention includes a pair of fans having a blowing direction at the left and right maximum reaching positions of the pair of subcarriers.

Further, the serial printer according to the present invention includes a plurality of heat pipes having one end close to or in contact with the print head and having excellent heat conductivity, above the pair of subcarriers.

Further, the serial printer according to the present invention is provided with notches near both right and left ends of the carrier, and one end is joined to an end of the pair of subcarriers facing the notch and the other end is arranged in the carrier direction. The other end is provided with a joint made of a bimetal having a convex portion matching the cutout shape of the carrier.

Further, the serial printer according to the present invention is characterized in that a temperature detecting element is provided on each of the upper portions of the pair of subcarriers, near the side surface which is close to or in contact with the print head.

Further, the serial printer of the present invention is provided with cutouts near both right and left ends of the carrier, respectively, and one end is joined to an end of the pair of subcarriers opposite to the cutout, and the other end is arranged in the carrier direction. A lever having a convex portion corresponding to the cutout shape of the carrier at the other end, and an operating portion mounted on the upper edges of the pair of subcarriers rotatably provided at the middle side of the lever. And a solenoid to be used.

[0013]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a front view of an embodiment of the present invention at normal temperature, and FIG. 2 is a front view of this embodiment at a high temperature. Referring to FIG. 1, a serial printer according to this embodiment includes a print head 2 facing a platen 1, a carrier 3 on which the print head 2 is mounted, a shaft 4 for guiding the carrier 3, and a carrier 3 attached to the platen 1. It has a carrier moving means 5 for reciprocating along, a left subcarrier 6 and a right subcarrier 7 at both ends of the carrier 3 and guided by the shaft 4. Upper left subcarrier 6a above left subcarrier 6
The upper surface of the right subcarrier 7 and the upper surface of the right subcarrier 7a facing the print head 2 are close to or in contact with the print head 2, and a temperature detecting element 9 and a plurality of heat pipes 8 having good heat conduction are provided. It is installed. Notches 10 are provided at the upper edges of both ends of the carrier 3, and joints 1 are provided at the upper edges of the left subcarrier 6 and the right subcarrier 7.
1 is provided, and the convex portion at the tip of the joint 11 matches the notch 10, and the left subcarrier 6, the carrier 3
The right subcarrier 7 reciprocates integrally. At this time, the temperature of the print head 2 rises due to the Joule heat of the coil, but the heat is transmitted to the upper or lower left subcarrier 6a and the right subcarrier 7a which are close to or in contact with the printhead. Therefore, the temperature rise of the print head 2 is slower than the temperature rise of the print head of the conventional printer. Further, since the heat pipe 8 is provided, the degree of diffusion of heat to the outside is large. However, when the high print duty continues for a long time, the print head reaches the set temperature. At this time, the joint 11 is deformed, and the protrusion at the tip of the joint 11 is notched 1
Move away from zero. Therefore, as shown in FIG. 2, the left subcarrier 6 and the right subcarrier 7 are separated from the reciprocating motion of the carrier 3 and stop at the left and right ends, respectively. At this time, since the left subcarrier 6 and the right subcarrier 7 are located right above the fan 12, forced cooling is performed. After a certain time, the temperatures of the left subcarrier 6 and the right subcarrier 7 decrease, and the joint 11 returns to the initial shape. Accordingly, with the movement of the carrier 3, the left subcarrier 6, the carrier 3 and the right subcarrier 7 are integrated again and return to the state of FIG. Although the print head 2 is still hot, the left subcarrier 6a and the right subcarrier 7a
Since the temperature is low, heat is quickly transmitted, the temperature of the print head 2 drops, and falls below the set temperature, so that the print head continues the printing operation without a break. In this embodiment, the above operation is repeated.

FIG. 3 is a perspective view of the left subcarrier 6 of this embodiment. The subcarrier will be described in detail with reference to FIG. The surface facing the print head 3 (not shown) is substantially similar to the shape of the print head 3, and approaches or contacts the print head 3 when the left subcarrier 6 and the carrier 3 are combined. Further, the temperature detecting element 9 is arranged in the vicinity of the surface facing the print head 2. A plurality of heat pipes 8 are arranged on the upper part 6a of the left subcarrier.

FIG. 4 is an enlarged view of the vicinity of the carrier at normal temperature according to the first embodiment of the present invention. The notch 10 and the joint 11 of this embodiment will be described in detail with reference to FIG. The joint 11 has a base joined to the upper edge of the right subcarrier 7, a tip made of a bimetal member extending in the upper edge direction of the carrier 3, and a projection 1
1a is provided. A notch 10 is provided at the upper edge near the end of the carrier 3. The notch shape of the notch 10 and the convex portion 11a match each other, and the carrier 3 and the right subcarrier 7 are integrated by the joint 11 at normal temperature. This situation is the same for the carrier 3 and the left subcarrier 6.

FIG. 5 is an enlarged view of the vicinity of the carrier at a high temperature in this embodiment. The operation of this embodiment will be described with reference to FIG. 5 in conjunction with FIG. 1, FIG. 2 and FIG. At normal temperature, the carrier moving means 5 causes the left subcarrier 6, the carrier 3 and the right subcarrier 7 to reciprocate as a unit by the joint 11 to perform a printing operation. At this time, the temperature of the print head 2 rises due to the Joule heat of the coil, but the heat is transmitted to the upper or lower left subcarrier 6a and the right subcarrier 7a which are close to or in contact with the printhead. Therefore, the temperature rise of the print head 2 is slower than the temperature rise of the print head of the conventional printer. Further, since the heat pipe 8 is provided, the degree of diffusion of heat to the outside is large. However, when the high print duty continues for a long time, the print head reaches the set temperature. At this time, as shown in FIG. 5, the joint 11 made of a bimetal is deformed, and the projection 11a is separated from the notch 10. Therefore, as shown in FIG. 2, the left subcarrier 6 and the right subcarrier 7 are separated from the reciprocating motion of the carrier 3,
Stop at the left and right ends respectively. At this time, since the left subcarrier 6 and the right subcarrier 7 are located right above the fan 12, forced cooling is performed. At this stage, the print head 2 takes an appropriate break during printing, and the throughput is reduced. The throughput at this time is the same as that of the conventional printer. After a certain period of time, the temperatures of the left subcarrier 6 and the right subcarrier 7 decrease, and the joint 11 made of bimetal returns to its initial shape as shown in FIG. Accordingly, with the movement of the carrier 3, the notch 10 and the convex portion 11a match again, and the left subcarrier 6, the carrier 3 and the right subcarrier 7 are integrated again and return to the state of FIG. Although the print head 2 is still hot, the left sub-carrier 6a and the right sub-carrier 7a are low in temperature, so that heat is quickly transferred, and the temperature of the print head 2 drops to fall below the set temperature. The printing operation will be continued without a break. Therefore, the throughput at this stage is larger than that of the conventional printer. In this embodiment, the above operation is repeated.

FIG. 6 is an enlarged view of the vicinity of the carrier at normal temperature according to the second embodiment of the present invention. The vicinity of the notch in this embodiment will be described with reference to FIG. A small solenoid 14 is provided in the vicinity of the surface of the right subcarrier 7 facing the carrier 3, and its working end has its base joined to the upper edge of the right subcarrier 7, and the tip is the upper edge of the carrier 3. It is rotatably joined to a lever 13 extending in the direction. The protruding portion 13a at the tip of the lever 13 has a shape that matches the notches 10 of the carrier 3 with each other.
At normal temperature, the carrier 3 and the right subcarrier 7 are integrated by the lever 13. This situation is the same for the carrier 3 and the left subcarrier 6.

FIG. 7 is an enlarged view of the vicinity of the carrier at a high temperature in this embodiment. The operation of this embodiment will be described with reference to FIG. 7 in combination with FIG. 1, FIG. 2 and FIG. At normal temperature, since the left subcarrier 6, the carrier 3 and the right subcarrier 7 are integrated by the lever 13, the same operation as in the first embodiment is performed. When the high print duty continues for a long time, the print head reaches the set temperature.
At this time, the solenoid 14 is driven, and the lever 13 is deformed as shown in FIG.
The left subcarrier 6 and the right subcarrier 7 depart from the reciprocating motion of the carrier 3. After a certain period of time, the temperatures of the left subcarrier 6 and the right subcarrier 7 decrease,
This temperature change is detected by the temperature detecting element 9. Here, when the temperature reaches a certain set temperature, the solenoid 14 is driven again, the lever 13 is deformed, and the notch 10 and the convex portion 13a coincide again as shown in FIG. Therefore, returning to the state of FIG. 1, the same operation as in the first embodiment is performed.

The temperature of the print head 2 and the number of prints when the above operation is performed will be described with reference to a graph. FIG. 8 shows the print duty of the pattern to be printed. FIG.
Referring to, until the time t ₀ is quite high print duty is followed by time t ₀ and later assumed to be low print duty. The temperature change of the print head 2 in this case is shown by a solid line in FIG. The temperature change of the print head of the conventional printer is shown in FIG. The temperature of the print head 2 rises with the start of printing, and at a certain time t _{1, the} set temperature θcr
Reach The time required to reach the set temperature is longer because the heat capacity and heat transfer coefficient of the print head 2, left subcarrier 6 and right subcarrier 7 of the present invention are larger than those of the conventional printer. Therefore, if the time t ₀ is short, a break occurs in the conventional printer, but does not occur in the printer of the present invention. After some of the overshoot, the print from time t ₂ is the break. At this time, the left subcarrier 6 and the right subcarrier 7 are
Has been removed from Although the print head from the time t ₃ after the break perform one-line printing, the print head 2 by the printing operation
Again exceeds the set temperature θcr. Thus the print head 2 again at time t ₄ after the printing operation into the break.
On the other hand, the temperature of the separated left subcarrier 6 and right subcarrier 7 has dropped during this time. This temperature change is shown by a broken line in FIG. For example, time t sufficiently cooled left subcarrier 6 and right sub-carrier 7 is left subcarrier 6 print head 2 is cooled if incorporated into the carrier 3 at just after _4, right subcarriers 7 and the carrier 3 reaches thermal equilibrium . Time t at which this temperature change falls below the set temperature θcr
_{After 5,} printing will be performed without a break. After time t ₀ , the print duty decreases, so that the temperature of print head 2 gradually decreases and approaches a certain temperature. FIG. 10 shows the number of prints obtained as an output when the above operation is performed. Also, the number of prints by a conventional printer is indicated by a two-dot chain line in FIG. Until time t ₂ when the print head 2 enters the break increases printing speed is linearly. T ₃ from the time t ₂ is in the rest
Until the number of prints does not increase, the straight line of the graph becomes parallel to the horizontal axis. Since after time t ₅ is not performed break, fold lines is increased in a straight line again. Therefore, while the print head 2 is at a high temperature, the number of prints is reduced because of the successive breaks as in the conventional printer.
By combining the right subcarrier 7 and the right subcarrier 7, the print head temperature can be lowered more quickly than in the case of the conventional printer, and a state without a break can be returned, and the total number of prints exceeds that of the conventional printer.

In the first embodiment, since the carrier 3 and the left subcarrier 6 and the right subcarrier 7 are attached and detached by bimetal, the structure is simple. On the other hand, in the second embodiment, since the solenoid 14 is controlled by the temperature detecting element 9, the left subcarrier 6 and the right subcarrier 7 can be intentionally attached and detached.

[0021]

As described above, according to the present invention,
By providing a pair of sub-carriers that can be detached from the carrier that is guided by the shaft at both ends of the carrier and whose upper side surface is close to or abuts the print head,
Throughput is improved.

[Brief description of the drawings]

FIG. 1 is a front view of an embodiment of the present invention at normal temperature.

FIG. 2 is a front view at the time of high temperature in FIG. 1;

FIG. 3 is a perspective view of a left subcarrier of FIG. 1;

FIG. 4 is an enlarged view of the vicinity of a carrier at normal temperature according to the first embodiment of the present invention.

FIG. 5 is an enlarged view of FIG. 4 at a high temperature.

FIG. 6 is an enlarged view of the vicinity of a carrier at normal temperature according to a second embodiment of the present invention.

FIG. 7 is an enlarged view at the time of high temperature in FIG. 6;

FIG. 8 is a graph of print duty change according to the present invention.

FIG. 9 is a graph of a print head temperature change of the present invention.

FIG. 10 is a graph of a change in the number of prints according to the present invention.

FIG. 11 is a graph of a change in print duty in a conventional example.

FIG. 12 is a graph of a print head temperature change in a conventional example.

FIG. 13 is a graph showing a change in the number of prints in a conventional example.

[Description of Signs] 1 Platen 2 Printhead 3 Carrier 4 Shaft 5 Carrier moving means 6 Left subcarrier 6a Upper left subcarrier 7 Right subcarrier 7a Upper right subcarrier 8 Heat pipe 9 Temperature detection element 10 Notch 11 Joint 11a Convex part 12 Fan 13 Lever 13a Convex part 14 Solenoid

Claims (6)

(57) [Claims] 1. A carrier on which a print head is mounted, a shaft on which the carrier is mounted and which guides the carrier close to a platen and parallel to a central axis of the platen, and a carrier along the central axis of the platen. Carrier driving means for reciprocating movement, and a pair of subcarriers which are detachably mounted on the carrier which is guided by the shaft at both ends of the carrier and whose upper side is close to or in contact with the print head. Serial printer. 2. The serial printer according to claim 1, further comprising: a pair of fans having a blowing direction at maximum left and right positions of the pair of subcarriers. 3. A heat pipe having a plurality of heat pipes, one end of which is close to or in contact with the print head, is provided above the pair of sub-carriers.
Serial printer described. 4. A notch is provided in the vicinity of both left and right ends of the carrier, one end is joined to an end of the pair of subcarriers opposite to the notch, and the other end is arranged in the carrier direction. 2. The serial printer according to claim 1, further comprising a joint made of a bimetal having a convex portion matching the notch shape of the carrier. 5. The serial printer according to claim 1, wherein a temperature detecting element is provided near an upper surface of each of the pair of subcarriers, which is close to or in contact with the print head. 6. A notch is provided in the vicinity of both left and right ends of the carrier, one end is joined to an end of the pair of subcarriers opposite to the notch, and the other end is arranged in the carrier direction. A lever having a convex portion conforming to the notch shape of the carrier, and a solenoid mounted on upper edges of the pair of subcarriers and having an operating portion rotatably provided at a middle side of the lever. The serial printer according to claim 5, wherein: