JPH0235489Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Field of application of invention] The present invention relates to a thermal printer.

[Background of the idea]

Conventionally, a printing tape containing a heat-melting material is placed between a recording paper and a thermal head, and a plurality of heat-generating elements provided in the thermal head are selectively heated as the thermal head moves, thereby increasing the temperature of the printing tape. A thermal printer has been proposed in which a heat-melting material is melted and transferred onto recording paper. This thermal printer is said to have the advantage of not producing noise during printing compared to other types of printers, but it uses an electromagnetic solenoid to separate the thermal head from the platen when the carriage equipped with the thermal head returns. was. For this reason, there was a drawback that noise was generated when the carriage returned as described above.

To solve this problem, a thermal head, a carriage mounted with the thermal head and driven by a motor, a platen on which recording paper is mounted, and a carriage are movably provided, and the thermal head is a carriage guide plate that is swingable so as to move into and out of contact with the platen; a cam means for swinging the carriage guide plate; and a cam operation driven by the motor to operate the cam means. A thermal printer has already been proposed. A specific example of this conventional thermal printer will be explained based on the drawings.

FIG. 2 is a plan view showing the overall configuration of the conventional example. In FIG. 2, 1 is a platen around which a recording paper (not shown) is wound, 2 is a platen rubber attached to the front position of the platen 1, that is, the printing position, and 3 is a guide for the recording paper wound around the platen 1. It is a paper guide. 4 is a thermal head which is arranged to face the platen rubber 2 and has a plurality of heat generating elements; 5 is a carriage to which this thermal head 4 is attached; 6 is a printing tape having a heat-fusible material to be transferred to the recording paper; Reference numeral 7 denotes a tape cassette in which the printing tape 6 is stored, and this tape cassette 7 is detachably attached to the carriage 5.

Reference numeral 8 denotes a carriage guide plate on which the carriage 5 is movably attached, and as shown in FIG. Carriage 5 as shown in figure b
A groove 11 is provided for guiding a carriage guide shaft 10 fixedly attached to the carriage. In addition, these carriage guide plate 8, carriage guide shaft 10, and groove 1
1 constitutes a carriage guide mechanism that guides the carriage 5 along the front surface of the platen 1.

Reference numeral 12 denotes a pressure spring that urges the carriage 5 on the carriage guide plate 8, that is, the thermal head 4, in a direction toward the platen rubber 2.

Further, reference numeral 13 shown in FIG.
5 is a pulley arranged on the carriage guide plate 8 side and around which the wire 13 is wound; 16 is a drive pulley around which the wire 13 is wound and has gears on both sides, for example. The wire 13 and pulleys 14, 1 mentioned above
5 and the drive pulley 16 constitute a carriage moving means for moving the carriage 5 along the platen 1.

Reference numeral 17 denotes a paper feed roller against which the recording paper comes into contact, and 18 denotes a paper feed shaft on which the paper feed roller 17 is supported. This constitutes recording paper feeding means for feeding the recording paper in the direction of arrow A.

19 shown in FIG. 2 is a stepping motor;
20 is a motor gear provided on the output shaft of this motor 19, and 21 is an idle gear that engages with this motor gear 20 and also engages with a gear on one side of the drive pulley 16 described above. 22 is a first intermittent gear that engages with the gear on the other side of the drive pulley 16; 23 is a second intermittent gear that engages with this first intermittent gear 22; and 24 is this second intermittent gear 23.
25 is a movable contact piece mounting base,
26 is a ratchet that engages with the paper feed gear 24;
Reference numeral 27 denotes a ratchet that can be engaged with and disengaged from the ratchet 26. 28 is a ratchet spring that biases the ratchet 27 in the direction of engagement with the ratchet 26;
29 is a washer that restricts one end of the ratchet spring 28. 30 is a manual knob that moves the ratchet 27 in a direction away from the ratchet 26 and has a gear on the circumferential side that can be engaged with a gear formed on the ratchet 27; 31 is a lever that rotatably supports the manual knob 30; It is.

The above-mentioned motor gear 20, idle gear 21,
The drive pulley 16, the first intermittent gear 22, the second intermittent gear 23, and the paper feed gear 24 are gear parts capable of interlocking the above-described carriage moving means and recording paper feeding means, that is, reciprocate the carriage 5. Together with this, it constitutes a gear section that feeds a certain amount of recording paper in the direction of arrow B in FIG. 2 in accordance with one reciprocating movement of the carriage 5.

In addition, the ratchets 26, 27 and manual knob 30 described above are used to manually reverse the recording paper.
In other words, it constitutes a manual paper feeding mechanism capable of feeding the paper in the direction of arrow C in FIG.

Further, as shown in FIGS. 2 and 5, the motor 1
A drive gear 32 is provided on a shaft extending from the motor gear 20 of No. 9, and an idler 33 is attached to the drive gear 32.
It engages with the joining gear 34 via. This joining gear 34 is composed of a fixed gear 34a that engages with the drive gear 32, and an abutment gear 34b that is connected to the fixed gear 34a by a spring 35. mesh with.
This rack body 36 consists of two rows of toothed parts, one of which is a toothless part 36a with missing teeth at both ends that meshes with the fixed gear 34a, and the other toothed part is a toothed part 36a with missing teeth at both ends that meshes with the fixed gear 34a. This is a full tooth portion 36b that meshes with each other.
The driving gear 32, joining gear 34, rack body 36, etc. constitute a cam operating means. Further, a T-shaped protrusion 37 is provided protruding from the rack body 36, and this protrusion 37 is connected to the low part 38a and the high part 38b shown in FIG. 4, and the slope between the low part 38a and the high part 38b. A cam 38 consisting of a portion 38c.
The inner space 38d is provided so as to be reciprocatable.

The cam 38 is brought into contact with the shaft portion 40 of the receiving portion 39 extending from the support portion 9 of the carriage guide plate 8, as shown in FIGS. 3 and 4.

Therefore, when the receiving portion 39 is located at the lower portion 38a of the cam 38 as shown in FIG. 4a, the platen 1
When the platen 1 and the thermal head 4 are in contact with each other, and when the receiving part 39 is located on the high part 38b of the cam 38 as shown in FIG. The movement or return of the carriage 5 is performed by the wire 13 mentioned above.

By the way, although the drive gear 32 of the cam operating means is always driven by the motor 19,
On the other hand, since the stroke of the cam 38 or the rack body 36 is set within a certain range by the stopper 41, the rack body 36 has the missing tooth portion 36a and the full tooth portion 3.
The fixed gear 3 of the joining gear 34 has a two-row configuration of 6b.
4a is engaged with the toothless portion 36a, and when the receiving portion 39 is located at an arbitrary position on the cam 38, that is, when the connecting gear 34 is located at either end of the rack body 36, the driving force of the motor 19 is In order to prevent it from directly engaging the rack body 36 or the cam 38, the fixed gear 34a is not engaged with the rack body 36, and the abutting gear 34b is allowed to idle.

Furthermore, in order to eliminate the influence on each member due to sudden changes due to forward/reverse rotation of the motor 19, the rack body 3
The protrusion 37 of No. 6 is positioned in the space 38d within the cam 38, and the rack body 36 and the cam 38 have play. Similarly, as shown in FIG. 6, in the engagement relationship between the carriage 5 and the wire 13, there is a movement play between the enlarged diameter portion 13a provided on the wire 13 and the frame body 5a provided on the carriage 5. gap D
The carriage 5 is not moved until after the platen 1 and the thermal head 4 have been completely moved to a desired state.

By the way, in this conventional example, since a cam mechanism is used to move the carriage toward and away,
Although it has become possible to provide a thermal printer that does not generate noise when the carriage moves back and forth unlike those using electromagnetic solenoids, the operation of the carriage guide plate 8 is controlled by the cam mechanism 38 and the pressure spring 12.
There were still some problems due to the use of . This problem is caused by the fact that the load on the pressure spring 12 is the smallest when the thermal head 4 is pressed against the platen 1 side, as shown in FIG. The problem is that the load increases because the thermal head 12 stretches, and the load reaches its maximum when the thermal head 4 is placed in a non-printing state as shown in FIG. 4b. That is, in this conventional example, the load when it is desired to press the thermal head 4 against the platen 1 side is the load necessary for printing, so a certain constant value of load is required.
When separating the thermal head 4 from the platen 1 side, it must be driven with a force greater than this minimum load, and the cam mechanism consisting of the cam 38, the receiving portion 39, the shaft portion 40 of the receiving portion 39, etc. At the same time, the strength and durability of each component are required to be higher, and at the same time, the motor for moving the cam 38 also needs to have a torque commensurate with the above-mentioned driving force, leading to an increase in cost.

[Purpose of invention]

The present invention was developed in view of the above-mentioned problems, and its purpose is to prevent the pressure when the thermal head is pressed against the platen side, that is, the necessary printing pressure, to cause the carriage guide plate to swing. The purpose of the present invention is to propose a contact/separate mechanism that can handle the maximum load when printing, and to provide a thermal printer that is highly durable and can be driven by a small torque motor.

[Summary of the idea]

In order to achieve the above object, the present invention includes a thermal head, a carriage mounted with the thermal head and driven by a motor, and a platen on which recording paper to be recorded by the thermal head is mounted. , a carriage guide plate on which the carriage is movably provided and swingable to bring the thermal head and the platen into contact with and away from each other; a cam means for swinging the carriage guide plate; and a cam means. In the thermal printer, the cam operation means is provided with a cam operating means driven by the motor to operate the cam, the cam means having a cam having a cam groove and a cam pin that is slidable and engaged with the cam groove at one end. In preparation for this, it is composed of a pressure contact lever that swings in accordance with the reciprocating motion of the cam, and a carriage guide plate is provided between the other end of the pressure contact lever and the carriage guide plate as the pressure contact lever swings. A pressure contact spring for swinging and pressing the thermal head against the platen side is stretched, and the cam operating means is driven by a joining gear that engages with a motor gear of the motor, and the engaging gear. , a rack body connected to the cam, and the connecting gear consists of a fixed gear that is always interlocked with the motor, and an abutment gear that interlocks with the fixed gear by frictional force. The body is constructed of two rows of tooth parts: a toothless part with missing teeth at both ends that meshes with the fixed gear, and a full tooth part that meshes with the abutment gear.

[Example of idea]

Hereinafter, embodiments of the present invention will be described based on the drawings. Fig. 1 is a side view showing the main parts of the embodiment of the present invention, and Fig. 1a is a thermal head pressure welding (down).
Figure 1b shows the thermal head separation (up) at the time.
Each shows the state at the time. In the drawings and description, the same or similar components as in the conventional example are given the same reference numerals.

The carriage 5 on which the thermal head 4 is attached in FIGS. 1a and 1b is movably attached to a carriage guide plate 8 and is rotatable around a support 9. Part 9
A pressure contact lever 50 is provided which can rotate around the center. A cam pin 52 that engages with a cam groove 51 (described later) is provided at one end of this pressure contact lever 50, and a contact spring 53 is stretched between the other end of this pressure contact lever 50 and the carriage guide plate 8. There is.

A cam 54 having a cam groove 51 with which the cam pin 52 engages is attached to the receiving portion 39 of the carriage guide plate 8.
A protrusion 37, which is located on an extension of the pressure contact lever 50 and protrudes from the rack body 36 of the cam operating means similar to the conventional example, is provided in a space 54d within the cam 54 so as to be reciprocatable. The cam groove 51 has a lower part 51 for lowering the thermal head 4.
A high part 51b is provided which is raised from the lower part 51a, and the lower part 51a and the upper part 51b are connected in a curved shape. Further, a stopper 55 is provided on the carriage guide plate 8 in a protruding manner, and the pressure contact lever 50 is in contact with this stopper 55 when the printer is not in use, that is, when the head is up. Other parts that are not particularly explained are constructed in the same manner as in the conventional example.

Next, the pressing and releasing of the thermal head 4 against the platen 1 will be explained.

When the thermal head 4 is not in use, it is separated from the platen 1 side as shown in FIG. It is located in the section 51b. This is because the cam 54 is connected to the rack body 36 from the motor 19 via the drive gear 32, etc.
At this time, the pressure contact lever 50 is in contact with the stopper 55, and the load applied to the pressure contact spring 53 is minimized, with the protrusion 37 connected to the pressure contact spring 53 projecting in the E direction to the maximum extent.

During printing, the protrusion 37 is driven by the motor 19 and moves in the F direction, and as the cam 54 also moves in the F direction, the pressure contact lever 5
A cam pin 52 provided at one end of the cam groove 51
, from the upper part 51b of the high part to the down part 51a of the lower part, the cam pin 52 side of the pressure contact lever 50 lowers accordingly, and rotates about the support part 9 in the right direction in the figure. When the pressure contact lever 50 rotates, the pressure contact spring 53 stretched on the other end of the lever 50 is pulled, and accordingly, the carriage guide plate 8 rotates to the right, and the carriage 5 also rotates to the right. The thermal head 4 then comes into contact with the platen rubber 2 of the platen. The pressure contact load at this time is determined by the load on the pressure contact spring 53, and the maximum load is determined by the load applied to the pressure contact spring 53.
At this point, the thermal head 4 is in pressure contact during printing. Then, when non-printing, line feed, or paper feeding occurs, the cam 54 is driven in the E direction from this state, and the pressure contact of the thermal head 4 is released.

With this configuration, the load applied to the pressure contact spring 53 during printing, that is, during head pressure contact, becomes maximum, and this corresponds to the required printing pressure, so a driving force greater than the printing pressure is not required, which is extremely rational.

[Effect of idea]

As is clear from the above explanation, the pressure contact lever is swung (rotated) by moving the cam pin of the pressure contact lever along the cam groove, and the carriage is rotated by the pressure contact spring provided at one end of the pressure contact lever. According to the present invention, which is configured to print by pressing the thermal head against the platen side, the following effects can be obtained.

During printing, that is, when the thermal head is pressed into contact, the load applied to the pressure spring is maximum, and this matches the required printing pressure, so the force required to drive the thermal head into pressure contact can be made smaller than in the past.

Since the required force is small, mechanical reliability such as durability and strength of each component of the cam mechanism is relatively improved.

The motor torque required for pressing and releasing the thermal head, that is, raising and lowering the head, is small, and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory view showing the main parts of the printhead press-contact/press-release mechanism of the embodiment of the thermal printer according to the present invention, FIG. 1a is a side view showing the state during press-contact, and FIG. 2 to 6 are explanatory diagrams showing a conventional thermal pretan, FIG. 2 is a plan view showing the overall configuration, FIG. 3a is a perspective view of the main parts, FIG. 3b is a sectional view of the carriage part, FIGS. 4a and 4b are side views showing changes in the positional relationship between the platen and the carriage,
FIG. 5 is a plan view showing the relationship between the cam and the cam operating means, and FIG. 6 is a partially enlarged view showing the relationship between the wire and the carriage. 1...Platen, 4...Thermal head, 5...
... Carriage, 8... Carriage guide plate, 19...
... Motor, 20 ... Motor gear, 32 ... Drive gear, 33 ... Idler, 34 ... Joining gear, 36
... Rack body, 50 ... Pressure contact lever, 51 ... Cam groove, 52 ... Cam pin, 53 ... Pressure contact spring, 5
4...Cam.

Claims (1)

[Claims for Utility Model Registration] A thermal head, a carriage on which the thermal head is mounted and driven by a motor, a platen on which recording paper to be recorded by the thermal head is attached, and the carriage. a carriage guide plate which is movably provided and swingable to bring the thermal head and the platen into contact with and away from each other; a cam means for swinging the carriage guide plate; and a cam means for operating the cam means. Therefore, in a thermal printer provided with a cam operation means driven by the motor, the cam means includes a cam having a cam groove and a cam pin slidable in engagement with the cam groove at one end, A pressure contact lever that swings in accordance with the reciprocating movement of the cam, and a carriage guide plate that swings as the pressure contact lever swings between the other end of the pressure contact lever and a carriage guide plate. A pressure contact spring is stretched to press the thermal head against the platen side, and the cam operating means is driven by a joining gear that engages with a motor gear of the motor, and the engaging gear, and the cam operating means is driven by the engaging gear. The connecting gear is composed of a fixed gear that is always interlocked with the motor, and a contact gear that is interlocked with the fixed gear by frictional force. A toothless portion with missing teeth at both ends that meshes with the fixed gear, and a fully toothed portion that meshes with the abutment gear.
A thermal printer characterized by consisting of a row of teeth.