JPH0357497Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention selectively heats a heating element of a thermal head on a thermal transfer ink ribbon containing heat-melting ink to thermally transfer the ink onto recording paper, etc. The present invention relates to a thermal printer that performs sequential printing and recording, and particularly to an ink ribbon cassette that stores the thermal transfer ink ribbon.

[Prior Art] In general, serial type thermal printers have excellent features such as small size, light weight, low price, low noise, ease of maintenance, and high reliability. In particular, thermal transfer printers produce recorded images with good clarity and are also capable of forming multicolor images.

The thermal head of a serial type thermal printer has a single ceramic substrate mounted on a thermal head holder made of a metal plate such as aluminum. A group of heating elements are placed on the ceramic substrate.
They are arranged in one or more rows along a direction perpendicular to the direction of movement of the thermal head.

When performing thermal transfer recording, the heating element group of the thermal head is moved in the recording direction while being pressed against the thermal transfer ink ribbon, and a voltage is selectively applied to the heating element group to heat the ink ribbon. The hot-melt ink is thermally transferred onto the recording paper, and characters, etc. are sequentially recorded.

In such a serial type thermal transfer thermal printer, one end of an ink ribbon housed in a cassette is fixed to a take-up roller, and the other end is fixed to a delivery roller. During the forward stroke of the printing operation, the take-up roller is rotated by an ink ribbon take-up shaft provided on a carriage that carries a thermal head and a cassette and runs back and forth parallel to the platen shaft. . Further, the ink ribbon is not wound up during the backward stroke when printing is not performed.

Conventional ink ribbon winding mechanisms for thermal printers include a method in which the ink ribbon take-up roller is wound up using an electric motor, and a method in which the ink ribbon take-up roller is mechanically wound in conjunction with the movement of a carriage. . In either case, the ink ribbon stored in the cassette is pulled out from the original winding section, slides on the surface of the heating element of the thermal head, and is wound up on the winding section. In this process of winding up the ink ribbon, the ink ribbon must be wound up smoothly without any excessive tension being applied to it, and without causing any slack or disturbance during running of the ink ribbon.

[Problem that the invention attempts to solve]

In recent years, with the progress in the development of serial type thermal transfer printers that enable high-speed printing, various problems have arisen as follows.

(1) When printing at low speeds, e.g. 30 cps or less, scumming or rubbing on the recording surface that occurs when the surface of the ink ribbon coated with heat-melting ink is pressed against the recording paper by the thermal head is not much of a problem. However, at high-speed printing, for example, around 100 cps, the above phenomenon becomes noticeable and reduces the quality of the recorded image.

(2) In order to have high-resolution printing quality and perform high-speed printing, the thickness of the ink ribbon base material must be extremely thin (for example, 5μm) is required.
When an ink ribbon made of such a thin film-like base material is stored in a cassette and wound up at high speed in conjunction with the movement of the cassette, the ink ribbon may become disordered within the cassette, causing running defects such as slack or curling, and the ink may become loose. This results in poor conveyance and unstable running, such as uneven conveyance of the ribbon and detachment from the heating element surface of the head. These problems cause deterioration in print quality, inability to print, or printer failure.

[Means for solving problems]

This invention was developed to solve the above problems, and aims to achieve high-speed printing and high-resolution printing, and to improve the running performance of the ink ribbon even when using an extremely thin ink ribbon base material. To provide an ink ribbon cassette for a thermal printer that is stable and capable of obtaining good printing quality free from stains, scratches, etc. when pressed onto recording paper by a thermal head.

The ink ribbon cassette of the thermal printer of the present invention, which achieves this purpose, is constructed so as to apply stable backlash to the ink ribbon in the vicinity of the thermal head. Specifically, the ink ribbon cassette of the thermal printer of the present invention is configured to apply a stable backlash to the ink ribbon in the vicinity of the thermal head. In the ink ribbon cassette of the thermal printer, two leaf springs are provided between the original winding part of the ink ribbon of the ink ribbon cassette and the print recording part of the thermal head, which elastically clamp the ink ribbon in close proximity to this recording part. The ribbon is arranged so that the press-contact part of the tip of one leaf spring has a curved shape, and elastic force is applied to this leaf spring in a direction that constantly applies tension to the ink ribbon, and the ribbon is arranged so as to counteract the drag force of the other leaf spring. A holding member is provided, and a felt member is pasted on either side of the ribbon holding member that presses against the ink ribbon to prevent the ink ribbon from slipping and to provide back tension in the conveying direction of the ink ribbon. It is.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of an ink ribbon cassette according to the present invention. In the figure, 1 is a thermal transfer ink ribbon to which thermal transfer ink is applied, 2 is the original winding part of the ink ribbon 1, and 3 is a winding part of the used ink ribbon 2. 4 is an ink ribbon cassette (hereinafter simply referred to as a cassette) that stores the ink ribbon 1;
A rectangular notch 4A is provided at the center of the end on the platen 20 side. The ink ribbon 1 is exposed to the outside at this notch 5. Further, in the space between the notch 4A of the cassette 4 and the ink ribbon 1, when the cassette 4 is installed in the carriage 13 of a thermal printer, the carriage 13
Thermal head 12, which is pivotably mounted to be tiltable, is inserted from below.

The original winding section 2 is a roller of the ink ribbon 1 tightly wound around a winding core 5 that loosely fits on the outer diameter of the cylindrical protrusion 4B of the cassette 4. The outermost ink ribbon 1 of the original winding section 2 is pulled out and placed in the thermal head 1.
2 is installed, and is wound onto a core 6 by a winding section 3. The winding core 6 is loosely fitted into a circular protrusion (not shown) provided at the inner bottom of the cassette 4 and is rotatable. One end of the ink ribbon 1 is fixed to the outer diameter of the core 6, and is wound into a roll by rotating the core 6 in the direction of the arrow.
The inner diameter of the winding core 6 has a hollow circular shape with a plurality of notches, into which a winding shaft 14 having a plurality of protrusions on the carriage 13 side is fitted.

Fixing pins 7 and 8 are integrally formed inside the cassette 4, and guide the ink ribbon 1 to stretch it. Reference numeral 4C is a guide portion that forms part of the inner wall of the cassette 4 and has a curved tip, which slides into contact with the ink ribbon 1 and regulates the running direction. 4D and 4E are the cutout portions 4 of the cassette 4.
This is a curved guide portion that forms the frontmost surface of both side walls of A. The ink ribbon 1 is attached to the guide portions 4D, 4.
It is strung between E.

Fixed pins 4F, 4G, 4H, and 4J are integrally provided inside the cassette 4 and hold leaf springs to be described later. 4K is a slit portion provided on the side of the guide portion 4C.

The bent part at the right end of the leaf spring 9 is the slit part 4K.
, and the flat part of the leaf spring 9 comes into contact with the fixing pin 4F. The left end of the leaf spring 9 is a curved surface having a substantially cylindrical shape, and the ink ribbon 1 is in sliding contact with the outer periphery of this curved surface and is supported by the elastic force of the leaf spring 9.

The leaf spring 10 is an elastic plate bent into an L shape, and is held by a portion of both side walls of the notch 4A and fixing pins 4G, 4H, and 4J.
A felt plate 11 is attached to the upper surface of the right end of the leaf spring 10. The ink ribbon 1 is here a felt plate 11 elastically supported by a leaf spring 10.
It is elastically held between the upper surface of the leaf spring 9 and the outer periphery of the curved surface portion at the left end of the leaf spring 9. The clamping position of the ink ribbon 1 is always maintained in a pressure-clamped state even when the ink ribbon 1 is pulled up by the thermal head 12 as shown in FIG.

The ink ribbon cassette of the thermal printer according to the present invention is constructed as described above.
One end of the ink ribbon 1 wound into a roll around the core 5 is wound around the outer periphery of the fixing pin 7 and changes direction, slidingly contacts the guide portion 4C, and connects the curved surface of the leaf spring 9 and the felt plate 11. The guide parts 4D and 4E at both ends of the opening-shaped cutout part 4C are stretched between the guide parts 4D and 4E, and the outer circumference of the fixing pin 8 is wound around the core 6 of the winding part 3. It is rolled up into a shape. In this way, the ink ribbon 1 is stretched between the pressure contact position of the felt plate 11 and the leaf spring 9 and the take-up section 3, so that the ink ribbon 1 is pulled out to the outside of the cassette 4 by the thermal head 12. Even if
Alternatively, even if the ink ribbon 1 in the original winding section 2 becomes slack, the ink ribbon 1 near the recording section is always under tension and remains in a tensioned state.

The leaf springs 9 and 10 are obtained by pressing a spring material such as a phosphor bronze plate or a stainless steel plate. The plate thickness is 0.05 to 0.5 mm, the plate width is approximately equal to the width of the ink ribbon 1, and it is designed to obtain an appropriate pressing force. The felt board 11 is made of a material with good elasticity and friction resistance, such as natural fibers or synthetic fibers, and is formed into a cloth-like shape by shrinking the material.
If the felt plate 11 is attached to the ink ribbon sliding contact point on the curved surface of the plate spring 9 instead of the plate spring 10, the felt plate 11 will remove dust, paper powder, etc. attached to the surface of the ink ribbon 1 coated with hot-melt ink. can do. Further, the portions of the leaf springs 9 and 10 that come into pressure contact with the ink ribbon 1 may be rotatable rollers.

FIG. 2 is a partially cutaway plan view showing the printing state when the cassette is mounted on the carriage of a serial character type thermal printer, and FIG. 3 is a perspective view showing the main parts of the thermal printer.

The mechanical part of a thermal printer consists of a recording paper feeding part,
It is composed of a carriage unit that mounts a thermal head and drives it to travel, and a ribbon winding mechanism that winds and drives the ink ribbon housed in a cassette.

The recording paper feeding section includes a cylindrical platen 20 that winds and conveys the recording paper P, and a paper feeding roller 21 that presses against the platen 20. Platen 20
is rotatably supported by bearings on the left and right side plates of the printer body frame 22, and is driven to rotate intermittently in the direction of the arrow by a drive motor 23 such as a pulse motor or a servo motor.

In front of the platen 20, a guide shaft 24 and a guide bar 25 having rack teeth are installed on the printer body frame 22. The carriage 13 is fitted into a guide shaft 24 and guided by a guide bar 25 so as to be movable in a direction parallel to the central axis of the platen 20. The carriage 13 has an endless toothed belt 26 on its underside.
A part of it is fixed. The toothed belt 26 is stretched between a toothed pulley 27 and a toothed pulley 29 that is integrated with a drive shaft of a drive motor 28 .
The motor 28 rotates left or right based on the print signal, thereby rotating the toothed belt 26 and further moving the carriage 13 in the left-right direction.

A pinion gear 15 is rotatably provided at the end of the carriage 13 on the guide bar 25 side, and meshes with the rack teeth 25A of the guide bar 25. The gear 15 is an idle gear 1 that can be freely engaged and disengaged.
A gear 17 coaxially fixed to the winding shaft 14 via 6
It fits perfectly.

A thermal head 12 is pivotally mounted on the side of the carriage 13 close to the platen 20 so as to be tiltable. Although not shown, the thermal head 12 is always urged by a spring in the direction away from the platen 20, and during the forward stroke of the printing operation (when moving rightward in FIGS. 2 and 3), the thermal head 12 moves away from the platen 20.
It is forcibly tilted to the 0 side using a solenoid or the like.

The recording operation of a serial type thermal printer equipped with an ink ribbon cassette having such a configuration will be described below. During the forward stroke of the printing operation, the thermal head 12 is forcibly tilted toward the platen 20 by a solenoid or the like. As a result, the ink ribbon 1 is drawn out of the cassette 4 by the thermal head 12 and is pressed onto the platen 20. When the ink ribbon 1 is being pulled out, the take-up shaft 14 is stationary, so the ink ribbon 1 is pulled out from the original winding section 2, but the ink ribbon 1 is elastically held between the leaf spring 9 and the felt plate 11. Therefore, the ink ribbon 1 protruding near the recording section is in a tensioned state and does not become loose or wrinkled. Here, the heating element of the thermal head 12 presses the back surface of the ink ribbon 1 (the surface on which ink is not applied), and also presses the recording paper P against the platen 20 to bring the front surface of the ink ribbon 1 into contact with the recording paper P. let In this state, if a print signal is applied to the thermal head 12 while moving the carriage 13 linearly to the right via the toothed belt 26 by the driving force of the motor 28, a matrix of dots will be created on the recording paper P. A print is formed.

When the carriage 13 moves to the right, the rack tooth profile 2 of the guide bar 25 fixed to the printer body
The pinion gear 15 meshing with 5A is rotated,
A take-up shaft 14 coaxial with the gear 16 is rotated via the idle gear 16. Since the winding core 6 of the winding section 3 in the cassette 4 is fitted into and engaged with the upper end of the winding shaft 14, by moving the carriage 13 in the right direction, the used material with one end fixed to the winding core 6 is removed. The ink ribbon 1 is wound up in the direction of the arrow.

Thus, in the printing process, the thermal head 12
The ink ribbon 1 held between the recording paper P is wound around the winding shaft 14 in an amount equal to the traveling length of the carriage 13, and a new ink ribbon 1 is taken up from the original winding section 2.
is pulled out and sent to the printing section. During this time, the ink ribbon 1 near the printing section is always held by the leaf springs 9, 1.
It is held under pressure by an elastic force of 0 and is in a tensioned state.

During the backward stroke without printing (when moving to the left in FIGS. 2 and 3), the thermal head 12 first separates from the platen 20 and closes the notch 4 of the cassette 4.
After returning to position A, the carriage 13 moves slightly to the right and once stops. As a result, the excess ink ribbon 1 near the opening of the notch 4A of the cassette 4 is wound up by the winding section 3 and does not loosen.

When or just before the carriage 13 changes direction to leftward movement, the idle gear 16 and the gear 17
In this state, the carriage 13
Since it moves to the left, the take-up shaft 14 does not rotate and the ink ribbon 1 is not taken up.

[Effect of idea]

As explained above, according to the present invention, the ink ribbon is held between two leaf springs that are close to the recording position of the thermal head and are given elastic forces in mutually opposite directions, so that the ink ribbon runs smoothly. It is possible to control the back tension during printing and when printing is stopped, and in particular, it is effective for high-speed printing because the running performance of the ink ribbon is stable even when an extremely thin ink ribbon base material is used. Furthermore, an ink ribbon cassette is realized which is free from stains, scratches, etc. and can provide good print quality when pressed onto recording paper by a thermal head.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of an ink ribbon cassette according to the present invention, Fig. 2 is a partially cutaway plan view showing the printing state when the cassette is mounted on a serial type thermal transfer thermal printer, and Fig. 3 shows the main parts of the above-mentioned thermal printer. FIG. 1...Thermal transfer ink ribbon, 2...Main volume, 3
... Winding section, 4 ... Ink ribbon cassette, 4A
...Notch part, 4D, 4E...Guide part, 4F, 4
G, 4H, 4J... Fixed pin, 5, 6... Winding core,
7, 8... Fixed pin, 9, 10... Leaf spring, 11
...Felt board, 12...Thermal head, 13
... Carriage, 14 ... Winding shaft, 15 ... Pinion gear, 20 ... Platen, 25A ... Rack tooth profile.

Claims (1)

[Scope of utility model registration request] In an ink ribbon cassette for a thermal printer that performs thermal transfer recording on a recording paper via an ink ribbon using a thermal head, there is a space between the ink ribbon original winding part of the ink ribbon cassette and the print recording part of the thermal head, which is close to this recording part. Two leaf springs are arranged to elastically sandwich the ink ribbon, and the press-contact portion at the tip of one of the leaf springs is shaped into a curved surface, and an elastic force is applied to the leaf spring in a direction that constantly applies tension to the ink ribbon. A ribbon clamping member arranged to counteract the drag force of the other leaf spring is provided, and a felt member is pasted on either side of the ribbon clamping member that comes into pressure contact with the ink ribbon to prevent the ink ribbon from slipping and transport the ink ribbon. An ink ribbon cassette for a thermal printer, characterized in that it is given back tension in the direction.