JPH0126455Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printer such as a thermal printer, and more particularly to a platen mechanism that has a sliding function against paper and a function to prevent slippage during paper feeding.

2. Description of the Related Art Conventionally, in printers such as thermal printers in which a printing member is in pressure contact with a platen, the platen is made of a rubber sheet or the like. However, this platen made of a rubber sheet has poor slippage during paper feeding, resulting in poor paper feeding. Additionally, a platen with a thin resin sheet adhered to the surface of a rubber sheet has been considered to improve slippage, but in this case, there is a risk that the thin sheet may peel off due to the frictional force when feeding the paper. It was hot.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to provide a platen mechanism for a printer that has good slippage during paper feeding and does not cause peeling of the thin film sheet.

The platen mechanism of the printer according to the present invention includes a platen formed of an elastic member and a sheet that wraps around the front and back sides of the elastic member without adhering the surface of the elastic member facing the printing member and its inner surface. The closed end of the sheet is fixed onto a supporting pedestal, and a protrusion is provided on the pedestal that engages with the back surface of the platen and prevents the platen from shifting in the paper feeding direction. be.

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

Figures 1 and 2 are plan views of the thermal printer according to its operation, Figure 3 is an exploded perspective view of the platen mechanism, and Figure 4 is an exploded perspective view of the platen mechanism.
The figure is a - sectional view of FIG.

(Overview of overall configuration and operation) Reference numeral 1 in the figure is a resin base, and a resin pedestal 2 is installed in a cutout 1a of the base 1. A platen 20 (detailed structure will be explained later), which is a feature of the present invention, is installed on the platen installation surface 2a of the pedestal 2, and the thermal paper 4, which is recording paper, is installed with the back of this platen 20. (See Figure 4). A paper feed roller 5 and a pinch roller 6 that sandwich the thermal paper 4 are provided below the base 2 and the carriage 9. As the paper feed roller 5 rotates, the thermal paper 4 is sent upward. The lines to be printed are now updated. A guide shaft 7 is provided between the guide surface 1b of the base 1 and the pedestal 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 base 2 is equipped with a thermal head 10 as a printing member. As shown in FIG. 3, the holding surface 9a of the thermal head 10 of the carriage 9 is an inclined surface having approximately the same angle as the platen 20 installed on the front surface of the pedestal 2. As shown in FIG. A notch 11 is formed in the upper surface of the carriage 9 in a portion facing the guide surface 1b, and the left end of this notch 11 is connected to the narrow portion 11.
a, the right end is the wide part 11b, and both parts 11a, 1
1b is continuous via the slope 11c. A driver element 12 made of resin is interposed within the cutout portion 11 .
A wire 13 connected to both ends of this driver 12
is hung on idle pulleys 14 and 15 provided on both the left and right sides of the base 1, and is further hung on the drive pulley 1.
6 and is fixed. This drive pulley 16 is driven in both forward and reverse directions by a pulse motor (not shown).

In FIG. 1, the carriage 9 is in the rightmost standby position. 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 (second
Fig. 3). 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 the initial stroke, the driver 12 first comes out of the narrow portion 11a and then the wide portion 11b.
(dotted line state in Figure 2). at this point
The pressing force applied to the carriage 9 by the driver 12 is removed, and the thermal head 10 comes into contact with the thermal paper 4 only lightly. Thereafter, the driver 12 comes into contact with the right end of the notch 11, and the carriage 9
It also 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.

(Characteristics of the Present Invention) As shown in FIG. 3, the front surface of the pedestal 2 is formed into a concave shape over its entire length, and the bottom surface of this concave portion serves as a platen installation surface 2a. The platen installation surface 2a is sandwiched between a protrusion 2b on the upper edge and a protrusion 2c on the lower edge. Further, a support protrusion 2d is formed in the center of the platen installation surface 2a in parallel with each of the protrusions 2b and 2c. Further, a fixing surface 2e is formed on the upper surface of the pedestal 2. This fixed surface 2e is formed via a step 2f.

On the other hand, the platen 20 includes an elastic member 21 such as a rubber sheet, a platen stand 22 such as a stainless steel plate installed on the back side of the elastic member 21, and an elastic member 21.
1 and a sheet 23 that covers a platen stand 22. The sheet 23 is made of resin and is formed into a thin film shape. The sheets 23 are attached to each other at closed ends 23a. Further, the inner surfaces of the platen stand 22 and the sheet 23 are bonded to each other. However, the elastic member 21 and the sheet 23 and the elastic member 21 and the platen stand 22 are not bonded together. Therefore, the elastic member 2
1 is not solidified by the adhesive, and the elastic member 21 can fully exhibit its buffering function.

When installing the platen 20 on the pedestal 2, the back surface of the platen 20 is brought into contact with the support protrusion 2d.
Further, the upper end of the back of the platen 20 is engaged with the protrusion 2d, and the lower end of the back is engaged with the protrusion 2c. Also,
The closed end 23a of the sheet 23 is adhered to the fixed surface 2e on the base 2. Note that the platen 20 and the pedestal 2 are not bonded to each other at locations other than the fixed surface 2e.

Next, the operation and effects of the present invention with the above configuration will be explained.

The thermal paper 4 is placed with its back to the platen 20, and is sandwiched between a paper feed roller 5 and a pinch roller 6 at the lower part thereof. During a writing operation, the driver 12 presses the carriage 9, the thermal head 10 comes into pressure contact with the thermal paper 4, and predetermined printing is performed. During the return operation of the carriage 9, the thermal paper 4 is sent upward by the driving force of the paper feed roller 5, but at this time, the presence of the sheet 23 on the surface of the platen 20 prevents the thermal paper 4 from slipping against the platen 20. It is good and the thermal paper 4 is fed out smoothly.

Moreover, since the upper and lower parts of the back surface of the platen 20 are locked by the protrusions 2b and 2c, the platen 20 does not slide upward in FIG. 4 when paper is fed. Furthermore, since the back surface of the platen 20 is supported by the tip of the support protrusion 2d,
The platen 20 can be tilted slightly within the recess of the base 2, using the point of contact with the support protrusion 2d as a fulcrum. Therefore, while the thermal head 10 moves in pressure contact with the thermal paper 4, the platen 20 can follow the installation surface of the thermal head 10, and the thermal head 1 is moved against the thermal paper 4.
The pressure of 0 is made uniform and printing is performed reliably. In addition, the elastic member 2 in the platen 20
1 can absorb the pressing force of the carriage 9, and this also makes the pressing force of the thermal head 10 on the thermal paper 4 uniform. Although the detailed structure is not shown, the pedestal 2 and the base 1 are connected by a spring, and if the thermal paper 4 is thick, the pedestal 2 will recede due to the expansion of this spring. However, this increase in paper thickness is absorbed.

In the illustrated embodiment, projections 2b and 2c are provided on the upper and lower edges of the pedestal 2 and are engaged with the upper and lower parts of the back surface of the platen 20, but only the projections 2b are provided,
Only the displacement of the platen 20 in the paper feeding direction (upward in FIG. 4) may be prevented. Alternatively, the protrusions 2b and 2c may be eliminated, a recess may be formed in the center of the back surface of the platen 20, and the support protrusion 2d may be locked in this recess.

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

(1) Since the platen is formed by wrapping an elastic material with a sheet, the sheet and the recording paper slide smoothly during the paper feeding operation, and the paper feeding operation can be performed smoothly.

(2) Due to the presence of the elastic material, the platen exhibits a buffering function, equalizes the pressure applied to the printing member, and prints clearly. In particular, as shown in the examples, if the elastic member is not bonded to the sheet, coagulation of the elastic member by the adhesive is prevented, and the elastic function can be fully exhibited.

(3) Since a protrusion is formed on the pedestal to engage with the back of the platen, it is possible to completely prevent the platen from shifting relative to the pedestal due to the frictional force with the paper during paper feeding.

(4) Since the sliding function due to the presence of the sheet and the anti-slip function due to the presence of the protrusion are exerted as described above, the printing member can be moved by pressing directly against the platen without using paper during non-printing operations. Even if there is a problem, the printing member can be moved smoothly without any problem.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention.
Figure 2 is a plan view of the thermal printer according to its operation.
FIG. 3 is an exploded perspective view of the platen mechanism, and FIG. 4 is a cross-sectional view taken from FIG. 2. 11...Base, 2...Pedestal, 2b, 2c...
Projection, 9... Carriage, 10... Printing member (thermal head), 16... Carriage drive pulley,
20... platen, 21... elastic member, 23...
Sheet, 23a...closed end of the sheet.

Claims (1)

[Scope of utility model registration request] In a printer platen mechanism in which a platen facing a printing member is supported on a pedestal, the platen is connected to an elastic member without bonding the surface of the elastic member facing the printing member and the inner surface of the elastic member. a sheet that wraps around the front and back sides of the platen, and a protrusion that engages with the back side of the platen and prevents the platen from shifting in the paper feeding direction, and a closed end of the sheet is bonded to the pedestal. A platen mechanism for a printer, characterized in that a fixing surface is provided for the purpose of fixing the platen mechanism.