JP2620345B2 - Thermal printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer, and more particularly, to a head drive system for bringing a thermal head into and out of contact with a platen and a ribbon winding system using the same drive source. The present invention relates to a thermal printer to be driven.

[Conventional technology]

FIG. 9 shows the configuration of a general thermal head. In the drawings, reference numeral 1 denotes a main body frame, on which a flat platen 2 long in the left-right direction is provided. A guide shaft 3 is disposed between the left and right frames 1a and 1b, which are part of the main body frame 1, so as to be substantially parallel to each other along the platen 2. A carriage 4 is stretched between the guide shaft 3 and the frame 1c, and is slidably supported in the axial direction of the guide shaft 3. The carriage 4 is provided with a thermal head 5 having a plurality of heating elements on a surface facing the platen 2. On the inner edge of the front frame 1c, a rack 6 is formed in parallel with the guide shaft 3,
The rack 6 meshes with a gear 13 (see FIG. 10) provided in the carriage 4. Further, a paper feed roller 7 and a small roller 8 pressed against the paper feed roller 7 are rotatably supported by the main body frame 1 at the lower part of the inner side of the platen 2. One of the paper feed rollers 7 is connected to a motor 10 via a reduction gear group 9, is rotated by the rotation of the motor 10, and performs a desired paper feed while nipping the paper between the small rollers 8.

A conventional example of a driving mechanism of the carriage 4 and a driving mechanism of the thermal head 5 in such a thermal printer will be described with reference to FIG.

A carriage driving motor 11 is provided in the carriage 4 described above.
The output pinion 12 is meshed with the rack 6 via a gear 13. The carriage 4 is reciprocally driven along the guide shaft 3 by forward and reverse rotation of the motor 11.

A fixing member 15 for the thermal head 5 is pivotally mounted on the platen 2 side of the carriage 4 with a fulcrum 14. The thermal head 5 is mounted on the tip of the fixing member 15, and It can be freely moved. The fixed member 15 of the thermal head 5 is in contact with one end 16a of a bell-crank cam follower 16 as a follower. The cam follower 16 rotates around a fulcrum 17, and the other end 16b is slidably engaged with an endless cam groove 19 of a cam member 18 which is a driving joint. A gear 20 integrally formed on the outer periphery of the cam member 18.
Is connected via a gear 21 to an output pinion 22a of a thermal head up / down motor 22 mounted on the carriage 4. Then, the rotation of the motor 22 rotates the cam member 18, and the rotation of the cam member 18 rotates the cam follower 16. The rotation of the cam follower 16 causes the fixing member 15 to be pressed by the one end 16 a of the cam follower 16. Are moved forward and backward with respect to the platen 2, and the thermal head 5 presses the ink ribbon and the recording paper against the platen 2 and releases the same.

A motor 24 for driving an ink ribbon take-up bobbin 23 for winding an ink ribbon (not shown) is also provided on the carriage 4 separately from the above-described motor 22 for thermal head up / down. The pinion 24a is connected via a gear 25 to a gear 23a provided coaxially with the ink ribbon winding bobbin 23. Further, a sensor (not shown) for detecting up / down of the thermal head 5 is provided. The sensor controls the operation of the motor 24 for running the ink ribbon in response to the up / down of the thermal head 5. It is supposed to be.

[Problems to be solved by the invention]

However, in the above-described conventional thermal printer, a drive source of a head drive system for pressing and releasing the thermal head 5 to and from the platen 2 and a drive source for feeding the ribbon include separate motors 22 and 24, respectively. Therefore, the carriage 4 is increased in size and weight, and
Two types of electric circuits for the driving source are also required, which increases the size of the printer itself, and also requires a sensor for detecting the pressure contact and release positions of the thermal head 5 in order to properly operate both motors. However, there is a problem that the circuit becomes complicated and the cost is increased.

The present invention has been made in view of these points,
The head drive mechanism and the ribbon winding system can be appropriately driven by one drive source, thereby reducing the number of various components including a sensor for detecting the pressure contact and release position of the thermal head. It is an object of the present invention to provide a small, lightweight, and extremely inexpensive thermal printer.

[Means for solving the problem]

In order to achieve the above object, the thermal printer according to the first aspect of the present invention includes a rotary drive source and a cam member for moving a thermal head toward and away from a platen by forward and reverse rotations within a predetermined center angle. A forward / reverse rotation within a certain center angle of the rotary drive source can be transmitted to the cam member as a forward / reverse rotation within the predetermined center angle,
Until the position where the thermal head is separated from the platen or the position where the thermal head is pressed against the platen, the rotation of the rotation drive source is transmitted to the cam member to rotate the cam member, and the thermal head is moved from the platen. A forward / reverse rotation output system capable of maintaining a transmission-disabled state in which rotation of the rotary drive source in the same direction is not transmitted to the cam member at a separated position or a position where the thermal head is pressed against the platen; And a positive rotation output system that transmits only the positive rotation of the rotation drive source exceeding the predetermined center angle to the ink ribbon winding system of the printer.

Further, in the thermal printer according to the present invention, the forward / reverse rotation output system temporarily separates the thermal head that is in pressure contact with the platen to a separation position in the middle of a position separated from the platen. Thus, the rotation of the rotary drive source is transmitted to the cam member, and then the thermal head is moved again in the direction of pressing against the platen. It is characterized by having.

(Operation)

According to the present invention, when one rotation drive source is rotated forward and reverse within a predetermined range, the cam member is rotated forward and reverse within a predetermined center angle via a forward and reverse rotation output system, and the head is moved relative to the platen. To perform a desired contact / separation operation. During this time, since the rotation transmission of the ink ribbon to the winding system is interrupted by the forward rotation output system, the ink ribbon is not wound.

When the rotation drive source is further rotated forward until the head is pressed against the platen, the head is kept pressed, and the ink ribbon winding system is driven via the forward rotation output system. , The ink ribbon is wound up, and normal printing is performed.

Further, when the forward / reverse rotation output system is kept in a transmission-disabled state where rotation is not transmitted, the head is separated from the platen by the cam member. When the rotary drive source is rotated forward in this state, the forward rotation exceeding the predetermined center angle is transmitted to the ink-bon winding system via the forward rotation output system, and the ink ribbon is rapidly fed.

After the fast forward of the ink ribbon is completed, the normal / reverse rotation output system is returned from the transmission disabled state to the normal transmission state,
The normal contact and separation of the head with the platen and the winding of the ink ribbon are properly performed.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

1 to 8 show an embodiment of the present invention, in which the same parts as those of the prior art are denoted by the same reference numerals.

In this embodiment, the thermal head 5 and the ink ribbon take-up bobbin 23 are appropriately driven by a motor 30 serving as one rotary drive source provided on the carriage 4.

One of the thermal heads 5 transmits a forward / reverse rotation of the motor 30 to a cam member 32 via a forward / reverse rotation output system 31, and drives the head having a cam follower 34 and the like by forward / reverse rotation of the cam member 32 at a predetermined center angle. The platen 2 is moved toward and away from the platen 2 via the system 33. In the present embodiment, the thermal head 5 is set to contact the platen 2 when the motor 30 rotates forward. Further, the forward / reverse rotation output system
Numeral 31 is also formed so that when the thermal head 5 is slightly separated from the platen 2, it can be kept in a transmission-disabled state in which rotation is not transmitted to the cam member 32.

The other ink ribbon take-up bobbin 23 is a forward rotation output system 35.
The rotation of the motor 30 is transmitted via the. When the motor 30 is rotating by a constant center angle for rotating the cam member 32 forward within the predetermined center angle, the forward rotation output system 35 shuts off the rotation transmission to the ink ribbon winding bobbin 23, The forward rotation is transmitted only when the forward rotation is performed at the predetermined center angle or more, and the ink ribbon winding bobbin 23 is rotated in a direction (counterclockwise in FIG. 1) for winding the ink ribbon.

The forward rotation of the motor 30 may be either clockwise or counterclockwise in FIG. 1. When the motor 30 is rotating forward, the thermal head 5 is swung in a direction in which it contacts the platen 2, and , Ink ribbon winding bobbin
In this embodiment, the clockwise rotation in FIG. 1 is defined as the forward rotation.

More specifically, as shown in FIG. 1, FIG. 4, FIG. 5, and FIG.
It is formed so as to appropriately transmit the rotation to 32. That is, gears 36 and 37 are sequentially meshed with the output pinion 30a of the motor 30, and a central gear 38 is integrally formed on the upper part of the gear 37. Is mounted on the carriage 4 so as to be rotatable around the center. A swing plate 41 is swingably mounted on the center shaft 39 between a stopper 40 at the upper end and an upper end surface of the gear 38, and the swing plate 41 is provided in an annular groove 42 of the center gear 38. Loaded spring
43 presses the felt 44 toward the stopper 40 via the felt 44. In addition, each support shaft 4 suspended on the lower surface of the swing plate 41
Forward rotation transmission gears meshing with the center gear 38 are provided for 5, 46, respectively.
47 and a reverse rotation transmission gear 48 are supported with their positions shifted vertically. Further, the cam member 32 is provided on the lower surface of the swing plate 41.
A pin 49 is provided to be engaged with and disengaged from an arc-shaped wall portion 50, which will be described later, which is provided on the upper surface of the device. On the other hand, a short cylindrical cam member 32
Is supported rotatably about a center shaft 51, and has a substantially spiral cam groove for driving a cam follower 34 on the lower surface thereof.
A head contacting gear 53 that meshes with the forward rotation transmission gear 47 is formed at the upper part on the outer peripheral surface, and a head separation gear 54 that meshes with the reverse rotation transmission gear 48 is formed at the lower part. ing. One of the head contact gears 53 is formed with a toothless portion 55 that is disengaged from the positive rotation transmission gear 47 when the thermal head 5 is completely pressed against the platen 2. The separation gear 54 is formed with a toothless portion 56 which is disengaged from the reverse rotation transmission gear 48 when the separation of the thermal head 5 from the platen 2 is completed.

Next, a head driving system 33 for bringing the thermal head 5 into and out of contact with the platen 2 in the form of a plate by rotating the cam member 32 forward and backward.
Will be described with reference to FIGS. 1, 4 and 5. FIG.

In this embodiment, the carriage 4 is supported by the guide shaft 3 (shown in FIG. 9) so as to be able to slide in the axial direction so as to move in parallel with the platen 2 in the same manner as the conventional one described above. In a concave portion 57 of the carriage 4 facing the platen 2, a thermal head 5 having a plurality of heating elements on its surface and printing on paper is mounted so as to be able to freely contact and separate from the platen 2. That is, in the vicinity of the concave portion 57 of the carriage 4, a head pressure contact lever 58 is pivotally mounted with a fulcrum 59. At the free end of the head pressure lever 58, there is provided a pressure pin 61 which is movable toward and away from the thermal head 5 and is always urged toward the thermal head 5 by a head pressure spring 60. This press contact pin 61
Is in contact with the back of the thermal head 5.
A substantially triangular cam follower 34 connecting the cam member 32 and the head pressure lever 58 is pivotally mounted on a central axis 66 (FIG. 7) coaxial with the ink ribbon winding bobbin 23. The spiral cam groove 52 extending from the center of rotation formed on the lower end surface of the cam member 32 toward the outer periphery is provided with the cam follower 34.
A rotatable roller 62 protruding upward is slidably and rollably engaged with a portion extending from one corner of the roller. A roller 64 protruding from the head pressure lever 58 is engaged with a long hole 63 formed in another corner of the cam follower 34. A head return spring 65 is extended between the other corner of the cam follower 34 and the thermal head 5, and the thermal head 5 is always in contact with the pressure contact pin 61 by the head return spring 65. At the same time, the movement of the cam follower 34 is followed.

Next, the forward rotation output system 35 for transmitting the forward rotation only when the ink ribbon is wound on the ink ribbon winding bobbin 23 is provided with the first rotation output system 35.
This will be described with reference to FIG. 7, FIG. 7 and FIG.

In this embodiment, the gears are connected by a reduction gear group 68 between the output pinion 30a of the motor 30 and a winding gear 67 rotatably supported on a central shaft 66 coaxial with the ink ribbon winding bobbin 23. doing. A take-up bobbin shaft 69 having an ink ribbon take-up bobbin 23 at the top is rotatably supported coaxially with the center shaft 66 above the center shaft 66 of the carriage 4. An annular play plate 71 and a felt plate 72 are provided above the flange 70 at the lower end of the winding bobbin shaft 69.
Are sequentially stacked so as to be freely rotatable with respect to the winding bobbin shaft 69. Further, a pressure contact plate 73 is laminated on the winding bobbin shaft 69 on the upper portion of the felt plate 72 by spline coupling. As a result, the pressure contact plate 73 rotates integrally with the take-up bobbin shaft 69 and is movable in the axial direction, and the press-contact spring 74 interposed between the press-contact plate 73 and the ink ribbon take-up bobbin 23.
Thereby, the play plate 71 and the felt plate 72 are pressed toward the flange portion 70. An uneven portion 75 is formed on the upper surface of the play plate 71 in order to increase the abrasion force with the felt plate 72. The projections 76a and 77a and the projections 7a for engaging each other and transmitting further rotation when the upper surface of the winding gear 67 and the lower surface of the play plate 71 are relatively rotated about one turn, respectively.
6b and 77b protrude. In this embodiment, the motor
When the rotation of the cam member 32 is performed in the forward and reverse directions within the range of a fixed center angle that allows the cam member 32 to rotate in the forward and reverse directions within the predetermined center angle, the projection of each set of the winding bobbin shaft 69 and the play plate 71 is provided.
The reduction ratio of the reduction gear group 68 from the output pinion 30a to the take-up gear 67 is set such that there is a play in which the projections 76b and 77b do not engage with the projections 76a and 77b. Thus, only when the motor 30 rotates forward by more than a fixed central angle for rotating the cam member 32 forward and backward by a predetermined central angle, the forward rotation is transmitted to the ink ribbon winding bobbin 23, and the winding of the ink ribbon is performed. Can do it. In this embodiment, two sets of projections 76a, 77a and 76b, 77b are provided because
Although the rotational force can be transmitted by the set, two sets are provided at different positions in the radial direction to increase the strength.

 Next, the operation of the present embodiment will be described.

First, as shown in FIG. 2, the thermal head 5 is moved from a head-up state in which the thermal head 5 is separated from the platen 2 to a head-down state in which the thermal head 5 is in contact with the platen 2 as shown in FIG. The case where printing is performed will be described.

In this case, according to the print command, the motor 30 is normally rotated so that the output pinion 30a rotates clockwise as shown in FIG. The rotation of this output pinion 30a is
Is transmitted to the central gear 38 via the The center gear 38 rotates clockwise in FIG. 1, and when this torque acts on the two rotation transmission gears 47 and 48, the rocking plate 41 rotates clockwise around the center axis 39, and both rotation transmission gears rotate. 47 and 48 swing from the broken line position to the solid line position in FIG.
47 meshes with the head contact gear 53 of the cam member 32. At this time, the pin 49 protruding from the lower surface of the rocking plate 41 is
Through a, it enters radially inward from the inner peripheral surface of the wall 50. As a result, the forward rotation transmission gear 47 and the head contact gear 53
The cam member 32 is rotated clockwise in FIG. With the forward rotation of the cam member 32, the roller 62 of the cam follower 34 engaged with the largest radius portion of the cam groove 52 gradually moves in the direction of the smallest radius portion of the cam groove 52, The cam follower 34 pivots counterclockwise around the central axis 66, and the engagement of the elongated hole 63 and the roller 64 causes the head pressure lever 58 to pivot clockwise around the fulcrum 59, so that the pressure pin 61
The thermal head 5 is brought closer to the platen 2 from the back through the. When the forward rotation transmission gear 47 rotates, the head contact gear 53 rotates, and when the forward rotation transmission gear 47 enters the toothless portion 55 of the head contact gear 53, the cam member 32 further rotates forward. At the same time, the thermal head 5 sandwiches the ink ribbon and the paper (both not shown) via the cam follower 34, the head pressure contact lever 58, the pressure contact pin 61, etc., and presses the platen 2 with an appropriate pressing force. It is pressed and maintains its state. In this manner, the rotation of the motor 30 until the cam member 32 rotates forward by the predetermined center angle and the thermal head 5 is in the head down state is also transmitted to the forward rotation output system 35 via the reduction gear group 68. But
Each pair of projections 76a, 77a and 7 of the take-up gear 67 and the play plate 71
6b and 77b are idle, the ink ribbon take-up bobbin 23 is not rotated, and the ink ribbon is not taken up.

After shifting to this head down state, the motor 30
Are rotated in the same direction, the projections 76a, 77a and 76b, 77b of the winding gear 67 and the play plate 71 engage with each other,
The forward rotation of the winding gear 67 is transmitted to the play plate 71. The rotation of the play plate 71 is transmitted to the press contact plate 73 via the felt plate 72 which is in pressure contact with each other, and the take-up bobbin shaft 69 and the ink ribbon take-up bobbin 23 integrally connected to the press contact plate 73 are moved to the first position. By rotating the ink ribbon in the counterclockwise direction in the figure, winding of the ink ribbon is started.

Simultaneously with the start of the winding of the ink ribbon, the carriage 4 moves in the carry direction, and further, the heating elements of the thermal head 5 are energized to perform printing.

Next, a case where the thermal head 5 is moved from the head down state in FIG. 1 to the head up state in FIG. 2 will be described.

In this case, the motor 30 is reversely rotated from the state shown in FIG. 1 as shown in FIG. As a result, the center gear 38 of the forward / reverse rotation output system 31 also rotates counterclockwise in FIG.
The swinging plate 41 also rotates counterclockwise from the state shown in FIG. 1 around the central axis 39 together with 47 and 48, and one of the gears 47 is separated from the toothless portion 55 of the head contact gear 53, and the other is. Gear 48 meshes with the head separation gear 54. At this time, the pin 49 of the swing plate 41
Is projected radially outward from the outer peripheral surface of the wall 50 through the notch 50a. The cam member 32 is rotated reversely at the same time when the gear 48 meshes with the head separation gear 54, and the cam follower is rotated.
34 moves gradually from the minimum radius portion to the maximum radius portion of the cam groove 52, and gradually moves the thermal head 5 away from the platen 2 via the head pressure lever 58 and the head return spring 65. . And the reverse rotation transmission gear
When 48 enters the toothless portion 56 of the head separation gear 54, the cam member
32 is stopped in a state where it is reversed by a predetermined central angle, and the separation of the thermal head 5 from the platen 2 is completed. When the cam member 32 rotates in the reverse direction within the predetermined center angle in this way, in the forward rotation output system 35, the projections 76a, 77a, 76b, 77b of each set of the winding gear 67 and the play plate 71 are In the idle state, the ink ribbon take-up bobbin 23 is not rotated, and the slack of the ink ribbon is prevented.

Next, a description will be given of a method of fast-forwarding an ink ribbon for performing cueing of a specific color portion of an ink ribbon when a so-called color bin is repeatedly divided into a plurality of color portions in a longitudinal direction during printing.

First, the motor 30 is rotated in reverse to slightly raise the thermal head 5 from the head-down state shown in FIG. As a result, the swinging plate 41 rotates counterclockwise in FIG. 1 in the same manner as in the normal head-up operation described above, and one of the reverse rotation transmission gears 48 and the head separation gear 54 as shown in FIG. The pins 49 are engaged with each other, and the pins 49 also go out of the wall 50 through the cutouts 50a of the wall 50. Thereafter, the motor 30 is further rotated in the reverse direction to
As shown in the figure, the thermal head 5 is separated from the platen 2 by rotating until the pin 49 of the rocking plate 41 reaches the outside of the wall 50. Next, the motor 30 is rotated forward. As a result, the pin 49 of the swing plate 41 in FIG.
Rotate slightly clockwise until it touches the outer peripheral surface of
After that, the rotation is stopped by the wall portion 50, and the forward rotation transmission gear 47 and the reverse rotation transmission gear 48 cannot mesh with the head contact gear 53 and the head separation gear 54, respectively.
The motor 32 is kept in a state in which forward rotation of the motor 30 cannot be transmitted. In this state, if the motor 30 is rotated forward more than the case where the cam member 32 is rotated by the predetermined center angle, the forward rotation output system
The ink ribbon take-up bobbin 23 is rotated forward via 35, and the ink ribbon is fast-forwarded.

After the rapid feeding of the ink ribbon of the predetermined length is completed, the motor 30 is rotated again in the reverse direction to complete the head-up operation of the thermal head 5, and then the motor 30 is rotated forward again to resume printing as described above.

As described above, according to the present embodiment, the forward / reverse rotation output system 31 and the forward rotation output system
The operation of contacting and separating the thermal head 5 from the platen 2, the operation of winding the ink ribbon, and the rapid feeding of the ink ribbon can be performed via the switch 35.

Note that the present invention is not limited to the above embodiment, and can be modified as needed.

〔The invention's effect〕

As described above, since the thermal printer of the present invention is configured and operates, the thermal head is connected to the platen via the forward / reverse rotation output system and the forward rotation output system using the motor as one drive source. The release operation, the ink ribbon take-up operation, and the ink ribbon fast-forwarding can be performed while being appropriately switched, thereby reducing the number of various components including a sensor for detecting the pressure contact and release positions of the thermal head. It is advantageous in that it is compact, lightweight, and extremely inexpensive.

[Brief description of the drawings]

1 to 8 show an embodiment of the thermal printer of the present invention, FIG. 1 is a plan view of a carriage section showing a head down state, FIG. 2 is a plan view of a carriage section showing a head up state, FIG. 3 is a plan view of a carriage portion showing a fast-forward state of the ink ribbon, FIG. 4 is a perspective view of a cam member,
FIG. 5 is a partially cutaway side view of the cam member, FIG. 6 is a side view of a swinging plate portion of the forward / reverse rotation output system, FIG. 7 is a side view of a winding bobbin portion of the forward rotation output system, FIG. The figure shows VIII-VI in FIG.
9 and 10 are an overall perspective view of a conventional thermal printer and a plan view of a carriage section, respectively. 1 ... body frame, 2 ... platen, 4 ... carriage, 5 ... thermal head, 23 ... ink ribbon winding bobbin, 30 ... motor, 31 ... forward / reverse rotation output system, 32 ...
Cam member, 34: Cam follower, 35: Forward rotation output system,
41… rocking plate, 47… forward rotation transmission gear, 48… reverse rotation transmission gear, 49… pin, 50… wall, 52… cam groove, 53…
… Head contact gear, 54 …… Head separation gear, 55,56
... tooth missing portion, 67 ... winding gear, 69 ... winding bobbin shaft, 71 ... play plate, 76a, 76b, 77a, 77b ... projection.

 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-270366 (JP, A) JP-A-63-137881 (JP, A) JP-A-63-166571 (JP, A) JP-A-63-166571 227367 (JP, A) Fully open Showa 61-28533 (JP, U) Really open 2-12853 (JP, U)

Claims (2)

(57) [Claims] A rotary drive source, a cam member for moving the thermal head toward and away from a platen by forward and reverse rotations within a predetermined center angle, and a forward and reverse rotation within a certain center angle of the rotary drive source. The rotary drive source can be transmitted to the cam member as a forward / reverse rotation within the predetermined center angle, and the rotation drive source with respect to the cam member up to a position where the thermal head is separated from the platen or a position where the thermal head is pressed against the platen. When the thermal head is separated from the platen or the thermal head is pressed against the platen, the rotation of the rotary drive source is transmitted to the cam member in the same direction. A forward / reverse rotation output system capable of maintaining the transmission impossible state, and forward rotation of the rotation drive source being transmitted and Thermal printer having a positive rotation output system for transmitting forward rotation only exceeding the predetermined center angle of the drive source to the winding system of the ink ribbon of the printer. 2. The system according to claim 1, wherein the forward / reverse rotation output system controls the rotation of the rotary drive source so as to temporarily separate the thermal head, which is in pressure contact with the platen, to a halfway position of the position separated from the platen. 2. A structure in which the rotation of the rotary drive source for transmitting the thermal head to the platen again in a direction in which the thermal head is pressed again to the member can be maintained in a transmission disabled state in which the rotation is not transmitted to the cam member. The described thermal printer.