JPH0639981Y2 - Serial thermal printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a serial thermal printer for printing using a thermal head.

[Conventional technology]

Serial thermal printers perform printing by sandwiching the print medium and pressing the thermal head against the platen, so generally when a medium is loaded or a line feed is performed, a predetermined gap is formed between the thermal head and the platen, and It prevents the situation of skew and loading failure.

FIG. 10 is a plan sectional view of a main part showing a conventional example of this type of serial thermal printer, and FIG. 11 is a side sectional view of the conventional example.
FIG. 12 is an exploded perspective view of essential parts of the conventional example, and this technique is disclosed in JP-A-63-209868.

In the figure, 1 is a platen, and 2 is a thermal head facing the platen 1.

3 is fitted to the first carriage shaft 4, and the first carriage 5 moves in space. 5 is fitted to the second carriage shaft 6 shown in FIG. 12 and is engaged with the first carriage 3. The second carriage 5 is a second carriage that moves in space in association with the movement of the first carriage 3 in space, and the thermal head 2 is mounted on the second carriage 5.

Reference numeral 7 denotes a spring, which urges the second carriage 5 toward the platen 1. As a result, an appropriate pressing force is applied to the platen 1 of the thermal head 2.

Reference numeral 8 denotes a protrusion provided with a flat portion provided on the bearing 9 of the platen 1, and the protrusion 8 is provided outside the medium passing range.

Reference numeral 10 is a protrusion having a flat portion facing the protrusion 8,
The protrusion 10 is provided on the second carriage 5.

With the above configuration, an appropriate pressing force is applied to the thermal head 2 by the biasing of the spring 7 during printing, and at the time of loading or line feed of the medium, the spacing operation of the second carriage 5 causes the second carriage 5 to move. When the projection 10 of the platen rides on the projection 8 of the platen 1, a predetermined gap is formed between the thermal head 2 and the platen 1 to perform head-up.

[Problems to be solved by the device]

However, in the conventional technique with the above configuration, when the protrusion on the carriage side rides on the protrusion of the platen, the deflection of the spring that urges the carriage to the platen increases, so the carriage receives this and the spacing load is increased. Will increase.

As a result, there has been a problem that the load variation of the spacing at the time of head-up becomes large and the low torque motor cannot be used.

In view of the above problems, an object of the present invention is to obtain a configuration for reducing the load of a spring at the time of head-up, reduce the load fluctuation, and realize a serial thermal printer that can use a low torque motor. To do.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention allows the extra flexure of the spring to escape during head-up.

That is, the present invention fits a platen, a first carriage that fits on a first guide shaft parallel to the platen and moves in space, and a second guide shaft parallel to the platen. A second carriage that engages with the first carriage and moves in space in synchronism with the space movement of the first carriage; and a thermal head that is mounted on the second carriage and faces the platen.
A protrusion for urging the second carriage toward the platen side is provided, and projections having flat portions are provided on the platen side and the second carriage side, respectively, and the projection on the platen side is provided with the projection on the second carriage side. In a serial thermal printer that performs head-up by riding a section,
A through hole facing the first guide shaft is formed in the first carriage, one end of the spring is received by a follower, the follower is slidably fitted in the through hole, and a protrusion on the platen side is provided. A cam-shaped concave portion is provided at a position where the through hole faces when the protrusion on the second carriage side rides on the portion.

[Action]

According to the present invention having the above-described configuration, when the head of the second carriage-side protrusion rides on the platen-side protrusion during head-up,
Since the through hole of the second carriage and the concave portion of the first guide shaft face each other, the follower that receives one end of the spring slides in the through hole and falls into the concave portion of the first guide shaft, and the flexure of the spring is received by the follower. It works so that it can be escaped from one end.

〔Example〕

 Embodiments will be described below with reference to the drawings.

FIG. 1 is a sectional plan view of an essential part showing an embodiment of a serial thermal printer according to the present invention, FIG. 2 is a side sectional view of the same embodiment, and FIG. 3 is an exploded perspective view showing a carriage and a thermal head in FIG. 4 and 5 are exploded perspective views showing the first carriage of the same embodiment, FIG. 5 is an exploded perspective view showing the platen of the same embodiment, and FIG. 6 is an explanatory view showing an example of a thermal head element.

In the figure, 11 is the frame of the printer.
Reference numeral 11 is formed of a resin having elasticity. As shown in FIG. 5, one side thereof is provided with an insertion hole 12 and an indicator hole 13 corresponding to one side of the platen described below, and the other side thereof is provided with a platen of the platen. A support hole 14 corresponding to the other side is provided.

15 is a platen, the front is a flat elastic body such as heat resistant rubber 16
Formed on the one side of the platen 15, and a protrusion 17 protruding in a direction facing a thermal head described later,
A support shaft 20 having flanges 18 and 19 projecting in the opposite direction to the protrusion 17 is formed, and a support shaft 21 having a substantially columnar shape is formed on the other side, and the support shaft 21 is fitted into the support hole 14. By fitting the support shaft 20 through the insertion hole 12 and fitting the support shaft 13 into the support hole 13, the platen 15 can be rotated by a certain angle so that the surface of the elastic head 16 can be brought into surface contact with the thermal head described later. It is supported.

The flanges 18 and 19 prevent the platen 15 from moving in the left-right direction.

22 is a thermal head, and this thermal head 22 has a third
A flexible cable 23 is connected as shown in FIG. 6 and FIG. 6, and drive energy is transmitted from a control means (not shown).

Reference numeral 24 is a heat sink having a substantially E-shaped cross section, and fixing projections 26 are formed in the two mounting grooves 25 formed by the above-described shape, and a projection serving as a positioning reference is provided on one front side. A portion 27 is formed, and the thermal head 22 is adhesively fixed to the heat sink 24 with one side thereof aligned with the protruding portion 27.

28 is the upper guide shaft (first guide shaft), 29
Is a lower guide shaft (second guide shaft), both ends of which are supported on both sides of the frame 11 so as to be parallel to each other.

30 is the upper guide shaft 28 and the lower guide shaft 29
A drive shaft located in the middle of the
The frame 30 is supported on both sides of the frame 11 and is rotated by a space motor (not shown).

Reference numeral 31 denotes a first carriage formed of a resin having elasticity. As shown in FIG. 3, two holes are provided in the upper portion and the central portion, and the upper guide shaft 28 and the drive shaft 30 are provided with the respective holes. Penetrates through the first carriage 31
An engaging groove 32 is provided in the lower part of the.

33 is a protrusion provided on the back surface of the first carriage 31, and 34 is a cable clamp.

Reference numeral 35 denotes a second carriage formed of a resin having elasticity similar to the first carriage 31, and has a cylindrical rib 36 at the bottom.
By having the two leg portions 37 integrally coupled with each other, and by engaging the rib 36 in the engagement groove 32 of the first carriage 31 with the leg portion 37 sandwiching the lower portion of the first carriage 31, , The first carriage 31 can be moved in the vertical direction with little backlash, and the lower guide shaft 29 is passed through the ribs 36 and the leg portions 37 in series.
It is possible to reciprocate along the front surface of the platen 15 integrally with the platen 31, and the platen 15 is centered around the lower guide shaft 29.
It can rotate in the direction opposite to the front part.

Further, a cutout portion 38 corresponding to the portion between the mounting grooves 26 of the heat sink 24 and the fixing projection 27 is formed in the central portion of the second carriage 35. By fitting the fixing projections 27 into the notches 38 using elasticity, the thermal head 22 is fixed and held so as to face the elastic body 16 of the platen 15.

Here, the fitting between the fixing projection 27 and the notch portion 38 is performed by utilizing the elasticity of the second carriage 35. With such a structure, the heat sink with respect to the width of the thermal head 22 is provided. Since the width of 24 and the first and second carriages 31 and 35 can be reduced, it is possible to design them in a small size.

Further, by utilizing the wide width of the heat sink 24 as shown in FIG. 6, it is possible to mount the thermal head 22 of 16 elements and 26 elements on the heat sink 24 of the same size,
By making the dimension l between the center of the heat sink 24 and the element portion of the thermal head 22 constant, the first carriage 31, the second carriage 31 and the second carriage 31 can be used for two or more types of printers without correction of the home position and the print position. It is also possible to use the carriage 35 and the heat sink 24 as common parts.

The flexible cable 23 connected to the thermal head 22 is guided to the back side of the first carriage 31 via the lower portion thereof, is locked by the protrusion 33, and is fixed by the cable clamp 34.

39 is a spindle of the platen 15 from one side of the second carriage 35
An arm portion (projection portion on the carriage side) formed to project toward the projection portion 17 formed with 20. The front surface of the arm portion 39 is formed when the thermal head 22 comes into close contact with the elastic body 16 of the platen 15. It is set so as to be closer to the elastic body 16 side than the tip end surface of the protrusion 17, and the protrusion length of the arm 39 is such that when the second carriage 35 is located at the home position b together with the thermal head 22. The front surface has such a length that it rides on the tip surface of the protrusion 17.

Reference numeral 40 denotes a spring that biases the second carriage 35 toward the platen 15 side.
35 is constantly pressed toward the platen 15 with an appropriate force, whereby the thermal head 22 is brought into close contact with the elastic body 16 of the platen 15.

Reference numeral 41 is a through hole provided in the first carriage 31, and the through hole 41 faces the upper guide shaft 28. 42 is a follower that engages and receives one end of the spring 40,
The follower 42 is slidably fitted in the through hole 41,
The bottom of the follower 42 is in contact with the upper guide shaft 28.

Reference numeral 43 denotes a cam-shaped concave portion formed at a position on the upper guide shaft 28 where the through hole 41 faces when the arm portion 39 on the second carriage 35 side rides on the protrusion 17 on the platen 15 side.

Reference numeral 44 denotes a feed roller arranged below the platen 15, and its central shaft 45 is rotatably supported on both sides of the frame 11 and connected to a line feed motor (not shown) via a reduction gear train (not shown). There is.

A paper chute 46 is arranged along the outer circumference of the feed roller 44 and is fixed to the frame 11.

A leaf spring 47 is fixed to the paper chute 46 on the lower surface side by pre-tensioning by welding or the like, and a part of the paper chute 46 is bent as shown in FIGS. 8 and 9. A shaft 50 of a pressure roller 49 is rotatably held by the bearing portion 48 formed as described above, and the pressure roller 49 is pressed against the feed roller 44 by a leaf spring 47 via the shaft 50. The pressure roller 49 is disposed obliquely below the feed roller 44 at a position of about 45 degrees.

Next, the operation of the above configuration will be described.

7 (A) and 7 (B) are plan sectional views showing the operation of this embodiment, FIG. 8 is a sectional side view of the main part when the print medium is set, and FIG. 9 is a view taken in the direction of arrow E in FIG. is there.

First, as shown in FIG. 7 (A), when the thermal head 22 is in the normal printing position a together with the first carriage 31 and the second carriage 35, the thermal head 22 moves to the platen.
It is in close contact with the elastic body 16 of 15.

Therefore, when setting the print medium 51, first, the drive shaft 30 is rotated in a predetermined direction by a space motor (not shown), and the upper guide shaft 28 and the lower guide shaft 28 are rotated.
When the arm portion 39 provided on the second carriage 35 is provided on the support shaft 20 of the platen 15 and is located outside the medium passing range, the arm portion 39 provided on the second carriage 35 is moved to the left and right, that is, the home position b side by the guide of 29. It is gradually riding on the protrusion 17.
At this time, the follower 42 slides on the upper guide shaft 28 and moves in the direction of weakening the bias of the spring 40 along the shape of the recess 43.

Then, along with this riding operation, the arm portion 39 is projected.
The thermal head 22 is pushed by the platen 15
When the second carriage 35 rotates about the lower guide shaft 29 so as to be separated from the elastic body 16, the thermal head 22 reaches the home position b and is detected by detection means such as a micro switch (not shown), the drive shaft. The rotation of 30 is stopped, and the thermal head 22 stops at the home position b together with the first carriage 31 and the second carriage 35.

At this time, the arm 39 is projected as shown in FIG. 7 (B).
When the thermal head 22 completely rides on the rail 17, the thermal head 22 is separated from the elastic body 16 by a certain amount to obtain a gap (platen gap) G shown in FIG. 8, and the follower 42 is also a recess formed in the upper guide shaft 28. It moves to the lowest part of 43, and alleviates the increase in the urging force of the spring 40 due to the rotation of the second carriage 35. Further, the platen 15 is held non-rotatable by the pressing force of the protrusions 17 of the platen 15 between the arm portions 39.

In this state, when the print medium 51 shown in FIG. 8 is inserted between the feed roller 44 and the paper chute 46 and pushed in, the leading end of the print medium 51 is naturally aligned with the feed roller 44 along the R of the paper chute 46. The pressure roller 52 reaches the pressure contact portion.

Thereafter, by driving a line feed motor (not shown) and rotating the feed roller 44 integrally with the central shaft 45 thereof in a predetermined direction, the print medium 51 is loaded between the platen 15 and the thermal head 22, and a certain amount of the print medium 51 is loaded. The rotation of the feed roller 44 is stopped when it is loaded.

In this way, when printing is performed after setting the print medium 15, the space motor drives the drive shaft.
Rotate 30 in the opposite direction.

As a result, the thermal head 22 moves to the right in FIG. 1 integrally with the first carriage 31 and the second carriage 35, and along with this, the arm portion 39 gradually slides from the protrusion 17, The carriage 35 is rotated about the lower guide shaft 29 by the spring 40 in the opposite direction. In parallel with this, the follower 42 also moves along the shape of the recess 43 in the direction in which the bias of the spring 40 is gradually strengthened.

When the position a is reached, the urging force of the spring 40 is the same as that during normal printing.

Further, when the position a is reached, the arm portion 39 causes the protrusion 17
Completely away from the thermal head, as shown in Figure 4.
22 is brought into close contact with the elastic body 16 of the platen 15 via the print medium 51, and then the thermal head 22 is further moved rightward together with the first carriage 31 and the second carriage 35, as shown in FIG. 7 (A). After passing through the acceleration range, the thermal head 22 prints on the print medium 51 in accordance with the drive energy supplied through the flexible cable 23 in the print range. At this time, even if the first carriage 31 tilts, the second carriage The two legs 37 of 35 are integrally formed by the rib 36, so they cannot be opened.

When the printing of one line is completed, the feed roller 44 is rotated again by the line feed motor, which causes a line feed of the print medium 51. The line feed is performed by the thermal head 22 via the print medium 51 and the elastic body 16 of the platen 15 is inserted. It is performed in close contact with.

[Effect of device]

As described in detail above, according to the present invention, the platen, the first carriage that fits on the first guide shaft parallel to the platen and moves in space, and the second guide parallel to the platen. A second carriage that fits on the shaft and engages with the first carriage to move in space in conjunction with the space movement of the first carriage; and a thermal head mounted on the second carriage and facing the platen. And a spring for urging the second carriage toward the platen side, and a protrusion having flat portions on the platen side and the second carriage side, respectively, and the second carriage side on the platen side protrusion. In the serial thermal printer that heads up by riding on the protrusion of the first carriage,
A through-hole facing the guide shaft of the second carriage, one end of the spring is received by a follower, the follower is slidably fitted in the through-hole, and a protrusion on the platen side protrudes from the second carriage. Since the cam-shaped concave portion is provided at the position where the through holes face each other when the portion rides on, the extra bending of the spring can be released when the head is raised.

As a result, it is possible to reduce the load of the spring when the head is raised, and there is an effect of realizing a serial thermal printer in which the load fluctuation is small and a low torque motor can be used.

[Brief description of drawings]

FIG. 1 is a sectional plan view showing a main part of an embodiment of a serial thermal printer according to the present invention, FIG. 2 is a side sectional view of the same embodiment, and FIG. 3 is an exploded perspective view showing a carriage and a thermal head in FIG. 4 and 5 are exploded perspective views showing the first carriage of the same embodiment, FIG. 5 is an exploded perspective view showing the platen of the same embodiment, and FIG. 6 is an explanatory view showing an example of a thermal head element, and FIG. (A) and (B) are plan sectional views showing the operation of the present embodiment, FIG. 8 is a sectional view of the main part when the print medium is set, and FIG. 9 is a view taken in the direction of arrow E in FIG. FIG. 11 is a plan sectional view of a main part showing a conventional example, FIG. 11 is a side sectional view of the conventional example, and FIG. 12 is an exploded perspective view of a main part of the conventional example. 15 …… Platen 17 …… Projection 22 …… Thermal head 28 …… Upper guide shaft 29 …… Lower guide shaft 31 …… First carriage 35 …… Second carriage 39 …… Arm section 40 …… Spring 41 …… Through hole 42 …… follower 43 …… concave

Claims (1)

[Scope of utility model registration request] 1. A platen, a first carriage that fits on a first guide shaft parallel to the platen and moves in space, and a second carriage that fits on a second guide shaft parallel to the platen. A second space that engages with the first carriage and moves in space in synchronization with the space movement of the first carriage.
Carriage, a thermal head mounted on the second carriage and facing the platen, and a spring for urging the second carriage toward the platen, and flat parts are provided on the platen side and the second carriage side, respectively. A serial thermal printer in which a head portion is provided by providing a protrusion portion having the protrusion portion on the platen side, and a protrusion portion on the second carriage side is mounted on the protrusion portion on the platen side. A hole is provided, one end of the spring is received by a follower, the follower is slidably fitted in the through hole, and the through hole is formed when the protrusion on the platen side rides on the protrusion on the second carriage. A serial thermal printer characterized in that a cam-shaped concave portion is provided at a position facing each other.