JPH0114433Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small printer such as a thermal printer, and particularly to a platen support structure that allows the platen to be easily attached.

In a small printer such as a thermal printer, a platen, a printing member facing the platen, and a paper feed roller are arranged in a dense manner on a portion of the base. Therefore, the support mechanism or drive mechanism for each member becomes complicated, making assembly work difficult.

The present invention has been made in view of the above-mentioned problems, and provides a platen support structure for a small printer in which the platen and paper feed roller can be efficiently arranged in a narrow space and the platen can be easily attached. The purpose is to

The platen support mechanism for a small printer according to the present invention is a small printer that includes a base, a platen, and a printing member that moves along the platen while facing the platen.
A shaft supporting a paper feeding roller is installed along the movement area of the printing member, a shaft holding groove is formed in the platen, the shaft holding groove is fitted into the shaft, and the shaft holding groove is fitted into the shaft. The apparatus is characterized in that an elastic member is provided that urges the platen to rotate in the direction of the printing member using the joint as a fulcrum.

In the present invention, the platen is urged toward the printing member by an elastic member using the fitting portion with the shaft as a fulcrum, and this urging force presses the printing paper against the printing member. Changes in the thickness of the printing paper are absorbed by the platen moving in a direction opposite to the elastic member using the shaft fitting portion as a fulcrum.
Moreover, since the platen is fitted onto the paper feeding shaft, the supporting mechanism for the platen is simplified.

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is an exploded perspective view showing the paper feeding mechanism of a thermal printer, which is an example of a small printer, Fig. 2 is a perspective view showing the platen and paper feeding roller, Fig. 3 is a sectional view showing the paper feeding mechanism, and Fig. 4 figure. FIG. 5 is a plan view of the thermal printer showing its operation.

First, the configuration and operation of this thermal printer will be outlined with reference to FIGS. 4 and 5.

Reference numeral 1 in the figure represents a base made of resin, and a platen 2 made of resin is installed within a notch 1a of this base 1. A rubber mat 3 is attached to the paper support surface 2a of the platen 2, and the thermal paper 4 is placed with its back to the rubber mat 3 (see FIG. 3). The lower part of the thermal paper 4 is held between a paper feed roller 5 and a pinch roller 6 (detailed structure will be described later), and rotation of the paper feed roller 5 causes the thermal paper 4 to
is sent upward to update the line to be printed. A guide shaft 7 is provided between the guide surface 1b of the base 1 and the platen 2, and a carriage 9 is movably attached to the guide shaft 7. The carriage 9 is made of resin, and the portion facing the platen 2 is equipped with a thermal head 10. As shown in FIG. 3, the holding surface of the thermal head 10 of the carriage 9 is an inclined surface having approximately the same angle as the paper supporting surface 2a of the platen 2. As shown in FIG. Guide surface 1 on the upper surface of the carriage 9
A notch 11 is formed in the part facing b, the left end of this notch 11 is a narrow part 11a, the right end is a wide part 11b, and both parts 11a and 11b are continuous via a slope 11c. ing. A driver element 12 made of resin is interposed within the cutout portion 11 . A wire 13 connected to both ends of the drive element 12 connects to idler pulleys 1 provided on both left and right sides of the base 1.
4 and 15, and is further wound around the drive pulley 16 and fixed. This drive pulley 16 is driven in both forward and reverse directions by a pulse motor (not shown).

In FIG. 4, the carriage 9 is in the standby position at the right end. Notch 11 of carriage 9 and guide surface 1
b The relief portion 1c at the right end and the slope 1d continuous thereto face each other, and the driver 12 is located in the space between the two. When the drive pulley 16 is driven to move the driver 12 to the left in the figure,
First, the driver 12 enters the narrow portion 11a and comes into contact with the left end of the notch 11. At this time, the driver 12
are the cutout portion 11, the relief portion 1c, and the slope 1d.
Since the carriage 9 moves without resistance within the space between the two, the carriage 9 will not start before the driver 12 comes into contact with the left end of the notch 11. Furthermore, when the driver 12 is moved to the left, the carriage 9 is also moved to the left. After moving a little, the driver 12 moves to the narrow part 1.
It intervenes between 1a and guide surface 1b. As a result, the carriage 9 is pushed by the driver 12, and the thermal head 10 comes into light pressure contact with the thermal paper 4 (third
Fig. 5). And from now on, the carriage 9
As the paper moves, the heating point of the thermal head 10 is selectively heated to write dot-like characters on the thermal paper 4.

After the carriage 9 moves to the left end in the figure and one line of printing is completed, the pulse motor reverses the driving pulley 16 and moves the driver 12 to the right in the figure. In this initial stroke, the driver 12 first comes out of the narrow portion 11a and then the wide portion 11b.
move inward (dotted line state in Figure 5). at this point
The pressing force applied to the carriage 9 by the driver 12 is removed, and the thermal head 10 only lightly contacts the thermal paper 4. Thereafter, the driver 12 comes into contact with the right end of the notch 11, and the carriage 9
At the same time, it moves to the right and returns to the standby position shown in FIG. Also, during this time, the paper feed roller 5 rotates,
The thermal paper 4 is fed upward, and the next line becomes ready for printing.

Next, the configuration of the characteristic parts of the present invention will be explained with reference to FIGS. 1 and 2.

The paper feed roller 5 is fixed to the central portion of the drive shaft 21. Both ends of the drive shaft 21 are rotatably supported by both side walls of the notch 1a of the base 1. A gear 22 is fixed to the right end of the drive shaft 21. Although not shown, this gear 22 is interlocked with a gear integrated with the idle pulley 14 via a one-way clutch. Based on the power intermittent function of this one-way clutch, when the carriage 9 is moving in the writing direction (to the left in FIG. 4),
The drive shaft 21 does not rotate, and while the carriage 9 is moving in the return direction (to the right in FIG. 4), the drive shaft 21 rotates in the direction of the arrow shown in FIG. 1 to feed the paper. A roller 5 feeds the thermal paper 4 upward by one line.

Further, a shaft holding groove 2b is formed in a lower portion of the platen 2 than the paper supporting surface 2a. As shown in the cross-sectional shape of this shaft holding groove 2b in FIG.
It is shaped to be slightly longer than the That is, when the shaft holding groove 2b of the platen 2 is forcibly fitted onto the drive shaft 21, the platen 2 is fitted onto the drive shaft 21.
It is designed not to fall off. Furthermore, in order to allow the drive shaft 21 to rotate within the shaft holding groove 2b in this fitted state, the inner diameter of the shaft holding groove 2b is formed to be slightly larger than the outer diameter of the drive shaft 21. Further, as shown in FIG. 2, an escape groove 2c is formed in the center of the platen 2.
A part of the paper feed roller 5 can be accommodated within this relief groove 2c. Furthermore, projections 2d are integrally formed on the upper portions of both sides of the platen 2.
One end of the spring 23 is hung on this.
Grooves 1e are formed on the upper surface of both sides of the notch 1a of the base 1.
is formed, and a pin 1f is integrally formed inside it. The other end of the spring 23 is hung on this pin 1f, and the spring 23
3 is housed in the groove 1e. Due to the elastic force of the spring 23, a biasing force is applied to the platen 2 in the direction of the arrow Sa around the drive shaft 21 in FIG. 3. Further, an inclined stopper surface 1g is formed inside the groove 1e,
The protrusion 2d of the platen 2 comes into contact with this stopper surface 1g, and movement in the direction of the biasing force Sa is restricted.
As mentioned above, the thermal paper 4 is inserted between the platen 2 and the carriage 9, and during the writing operation, the drive element 12
By intervening in the narrow width portion 11a, the thermal paper 4 is pressed between the platen 2 and the carriage 9. At this time, the variation in the thickness of the thermal paper 4 is caused by the spring 2
3 extends and is absorbed by the platen 2 retreating. Further, the elastic force of the spring 23 allows the pressure of the carriage 9 (thermal head 10) against the thermal paper 4 to be adjusted appropriately.

A guide plate 24 is provided almost directly below the platen 2. The guide plate 24 is formed of sheet metal and has an L-shaped cross section. Support pieces 24a are formed at both ends of the guide plate 24, and the lower ends of the springs 25 are hung on these parts. ing. Further, the upper end of the spring 25 is hung on a support pin 26. Although only the spring 25 and support pin 26 on the right side are shown in FIG. 1, the spring 25 and support pin 26 are also hung on the support piece 24a on the left side. base 1
A vertical groove 1h and a support groove 1i are integrally formed on both inner surfaces of the notch 1a. The support piece 24a of the guide plate 24 is inserted into the support groove 1i, the spring 25 is housed in the vertical groove 1h, and the support pins 26 are installed on both sides of the upper end of the vertical groove 1h. One end of the pin 26 is installed on the upper surface of the pin 1f). The guide plate 24 attached in this way uses the fitting part between the support piece 24a and the support groove 1i as a fulcrum, and is supported by the spring 25.
It is receiving a biasing force in the direction of arrow Sb in FIG. In addition, a notch 2 is provided at the center of the guide plate 24.
4b is formed, and bearing portions 24c are formed on both sides of the cutout portion 24b. This bearing portion 24c is simply formed by molding the guide plate 24 into a concave shape. A shaft 6 is provided at both ends of the pinch roller 6.
a is integrally formed, the shaft 6a is received by the bearing portion 24c, and the pinch roller 6 is positioned within the notch portion 24b. Since the guide plate 24 is urged in the direction of arrow Sb by the spring 25, the pinch roller 6 is pressed against the paper feed roller 5 by this force. Moreover, this pressure contact force prevents the shaft 6a from falling off from the bearing portion 24c. The pinch roller 6 rotates as a result of the paper feed roller 5.

In the illustrated embodiment, a thermal printer is shown as an example of a small printer, but other non-impact printers such as ink jets, as well as
It can also be applied to type impact printers.

As described above, according to the present invention, the following effects can be achieved.

(1) Since the platen is fitted onto and supported by the shaft of the paper feeding roller, the platen, roller and shaft are almost integrated.
It can be efficiently arranged in a narrow space, and the overall size of the printer can be reduced.

(2) Assembly work is simple, as all that is required is to first attach the roller shaft to the base, then fit the platen onto the roller shaft, and hang the spring between the platen and the base.

(3) Since there is no need to provide a mechanism to support the platen on the base body side, the structure of the base is simplified and molding of the base is facilitated.

(4) A shaft holding groove is formed in the platen, and an elastic member is provided that fits the shaft into the shaft holding groove and urges the platen to rotate in the direction of the printing member using the fitted portion as a fulcrum. Since the thermal paper is pinched by the pressing force between the platen and the printing member by this elastic member, even if there is a variation in the thickness of the thermal paper, it can be absorbed by the elongation of the elastic member. This makes it possible to perform good printing regardless of variations in paper thickness.

(5) Since an elastic member is provided that urges the platen to rotate in the direction of the printing member using the fitting part between the platen and the shaft as a fulcrum, adjustment of the pressure contact force between the platen and the printing member is performed using the elastic member. This can be easily done by adjusting the elastic force.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing the platen and roller mounting portion of a thermal printer as an embodiment of the present invention, Fig. 2 is an exploded perspective view showing the fitting portion of the platen and paper feed roller, and Fig. 3 is a paper Cross-sectional views showing the feeding section and the pressure contact section of the printing member, FIGS. 4 and 5
The figure is a plan view of each operation of the thermal printer. 1... Base, 2... Platen, 2b... Shaft holding groove, 5... Paper feed roller, 9... Carriage,
10... Printing member (thermal head), 21...
Drive shaft, 23...spring, Sa...biasing force.

Claims (1)

[Scope of utility model registration request] In a small printer that includes a base 1, a platen 2, and a printing member 10 that moves along the platen 2 while facing the platen 2, the base 1 supports a roller 5 for paper feeding. A shaft 21 is installed along the movement area of the printing member 10, and a shaft holding groove 2b is formed in the platen 2, and the shaft holding groove 2b is fitted into the shaft 21, and this fitting portion is used as a fulcrum. A platen support mechanism for a small-sized printer, characterized in that an elastic member 23 is provided to urge the platen 2 to rotate in the direction of the printing member 10.