JPH01257085A - Ink ribbon cassette for thermal transfer printer - Google Patents

Abstract

PURPOSE:To moderate startup characteristics and prevent transfer due to rubbing from occurring by a construction wherein two rollers or a fixed post for bending an ink ribbon to restrict the circumferential velocity of the ribbon is disposed in the vicinity of a position corresponding to a maximum roll diameter of the ribbon on each core. CONSTITUTION:A felt 30 makes contact with a surface of an ink ribbon 4. As the ribbon 4 is taken up, the outer roll diameter of the ribbon 4 is gradually reduced, and a spring force of a tension spring 28 is also reduced. Therefore, a tangent line position at which the felt 30 makes contact with the ribbon 4 is continually varied, so that an increase in a braking force due to adhesion of an ink to the felt 30 does not occur. The ribbon 4 paid out from a pay-out core 31 is fed while being bent between rollers 26d, 26 for preventing the reverse rotation of the core 31, whereby a braking force is applied to the ribbon 4. The ribbon 4 is then again braked by a fixed post 32 and a roller 26a while being fed in contact with a roller 26b, and is taken up by a take-up core 29.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal transfer printer, and particularly to a technique for stabilizing the tension of an ink ribbon and aligning and winding the ink ribbon, which can stabilize the quality of an ink ribbon cassette. .

[Conventional technology]

In a thermal transfer printer using an ink ribbon, (1)
Over-rotation of the core when the thermal head is pressed at the start of printing or when the ribbon winding is stopped, (2) slack of the ink ribbon due to reverse rotation of the supply side core due to ink ribbon reaction force, (3) sagging of the ink ribbon at the constant braking force application section. Increased braking force due to ink adhesion due to the use of felt has traditionally been caused by the friction transfer phenomenon (the moment the thermal head presses the ink ribbon against the transfer paper to start printing, the ink ribbon moves relative to the transfer paper). This has caused problems such as the ink ribbon being rubbed on the transfer paper, resulting in paper stains) and poor winding of the ink ribbon. In the above items (1) and (2), conventionally, a protrusion is provided so that the end of the ink ribbon comes into contact with the bottom surface of the cassette case of the ink ribbon cassette, which generates a braking force when the core rotates and prevents over-rotation. A configuration in which viscous resistance is applied to the sliding surfaces of the core and core seat using grease or the like has been devised. In the former case, there are protrusions on the winding side and the supply side, and the supply side becomes a load on the winding side. or,
Since the convex part is in contact with the end of the ink ribbon, there is a drawback that the sliding load on the ink ribbon increases due to irregular winding, resulting in poor winding. Due to variations in the amount of grease applied, etc., the viscous resistance force becomes unstable, which has the disadvantage of causing poor winding due to an increase in braking force, etc.

Therefore, the present invention solves the above-mentioned drawbacks by always keeping the ink ribbon tension constant, which is a completely different method from the above-mentioned invention.

[Problem to be solved by the invention]

In view of the above, an object of the present invention is to prevent scratch transfer caused by over-rotation of the core that occurs when the thermal head is pressed at the start of printing or from sagging of the ink ribbon due to reverse rotation of the supply side core due to reaction force of the ink ribbon. It has an ink ribbon winding configuration that can achieve high printing quality by eliminating ink ribbon winding defects caused by increased braking force due to ink adhesion on the brake force applying part, and stabilizes the braking force of the ink ribbon cassette. Furthermore, the present invention aims to provide an ink ribbon cassette which incorporates two features: no adjustment of the tension spring that applies braking force, and a reduction in assembly costs.

[Means to solve the problem]

In order to obtain an ink ribbon winding structure that achieves the above object, the present invention is constructed as follows. (1) At the moment when the thermal head presses the ink ribbon against the transfer paper at the start of printing, the ink ribbon winding operation starts before the thermal head press operation so that the ink ribbon does not move relative to the transfer paper. to run the ink ribbon. For this reason, the ink ribbon running speed (ink ribbon circumferential speed) is suddenly decelerated to the head moving speed at the moment the thermal head is pressed, so the larger the take-up side ink ribbon diameter, the more inertia the take-up side ink ribbon tension becomes. It becomes extremely large due to force. This inertial force forcibly drags the ink ribbon toward the take-up side, causes relative movement between the ink ribbon and the transfer paper, and causes rubbing transfer. The cause of this is
This is because there is a large difference between the ink ribbon traveling speed (ink ribbon circumferential speed) when the thermal head is pressed and the head moving speed. This can be achieved by delaying the rise characteristic of the ink ribbon running speed. As a means for this, a tension spring applies a braking force to the surface of the ink ribbon wound around the supply core, and at the same time, the ink ribbon is wound around the supply core within a roller disposed in the ink ribbon cassette. A roller is provided near each of the ink ribbon and the ink ribbon wound around the take-up core, and a meandering guide means is installed to make the ink ribbon meander using two rollers or a roller and a fixed post. In addition, the rollers near each core among the rollers are designed to prevent the ink ribbon from sagging due to the reverse rotation of the supply side core due to the ink ribbon reaction force caused by the ink ribbon running speed, which occurs the moment the thermal head is no longer pressed. To prevent this, at the same time as the ink ribbon surface is brought into contact with the roller, the running resistance must be arranged so that the winding side and the supply side are in inverse proportion. In other words, since the running resistance changes depending on the ink ribbon diameter, braking force is applied while keeping the overall tension ratio constant.

As a result, it is possible to completely prevent an increase in the tension of the ink ribbon due to an inertial force that occurs as the diameter of the ink ribbon in the take-up core increases.

[Effect]

The ink ribbon wound around the take-up core has a larger inertia force at the end of the winding than at the beginning of the winding.As a means of softening this inertial force, the ink ribbon is wound more slowly as the ink ribbon diameter increases. The braking force on the receiving side increases. On the supply side, on the other hand, the diameter at the beginning of the winding is large, and the core reverses at the moment the thermal head separates from the ink ribbon. The above problem can be solved by installing two rollers or fixed posts for bending the ink ribbon of the present invention near the maximum ink ribbon diameter of each core to suppress the peripheral speed of the ink ribbon, thereby softening the rise characteristics and preventing the rubbing transfer phenomenon. It can be prevented.

In addition, since the braking force is applied by a roller, unlike the use of viscous resistance, it is not affected by environmental conditions, and the printing quality is stable from the beginning to the end of the roll. As described above, the present invention is an extremely effective means for preventing rubbing transfer.

〔Example〕

Hereinafter, the configuration and effects of the embodiments of the present invention will be explained.

FIG. 6 shows an external view of the thermal transfer printer.

A shaft 12 is fixed between the side plate 1o and the side plate 11.

Further, a carriage 13 is arranged so as to be able to slide on the shaft 12, and an ink ribbon cassette 5 and a thermal head 3 according to the present invention are mounted on the carriage 13, and an ink ribbon 4 is mounted in the ink ribbon force sets 1 to 5. is stored.

The carriage 13 is configured to be movable in the left and right directions in the figure by a carriage motor 14 via a timing belt 15. A line feed motor 16 transmits driving force to a gear 17 fastened to the shaft of the platen 1 to feed the transfer paper 2. Paper can also be fed in the same way by turning the platen knob 18 by hand. 19 is a paper guide. By moving the release lever 20 in the front-rear direction, the paper pressing roller 22, which is slidably disposed on the shaft 21, is pressed onto or separated from the paper surface.

23 is a home position sensor, and 24 is a flat cable for supplying electricity to the thermal head 3 and the like. This printer is a printer of a type in which the ink ribbon 4 is wound up when the carriage 13 moves to the right, but it is not wound up when the carriage 13 moves to the left. Also, a carriage motor 14, a line feed motor 16. Home position sensor 23. It is assumed that the thermal head 3 and a ribbon sensor (not shown) for detecting the end of the ribbon are controlled by a CPU 25 which is a controller.

FIG. 1 shows the structure of an ink ribbon cassette embodying the present invention. The ink ribbon cassette 5 is manufactured by inserting the mating boss 35 of the cassette case 5b into the hole 33 of the cassette case 5a and fixing the cassette case 5a and the cassette case 5b with fixing screws (not shown) or the like. , is configured to be a hollow case, and inside thereof is an ink ribbon 4 and a tension spring 2 that applies a constant pack tension (braking force) to the ink ribbon 4.
8. A roller 26a and the like are incorporated. Supply side core 31
The ink ribbon 4 that is wound on the ink ribbon 4 has its maximum diameter at the beginning of the winding. The outer periphery of the ink ribbon 4 is held down by a tension spring 28 to apply a braking force. Tension spring 28
is fixed by a fixing boss 34a and a stopper boss 34b, and applies a braking force to the ink ribbon 4 by spring force. 3o is felt, and is in contact with the surface of the ink ribbon 4. The outer periphery of the ink ribbon 4 is brought into contact with the ink ribbon 4, and as the ink ribbon 4 is wound up, the outer diameter of the ink ribbon 4 becomes smaller.

Correspondingly, the spring force of the tension spring 28 also decreases.

Therefore, the tangent position of the felt 30 disposed on the tension spring 28 with respect to the ink ribbon 4 constantly changes. As a result, there is no increase in braking force due to ink adhesion. The ink ribbon 4 discharged from the supply core 31 is moved by the roller 2 to prevent the supply core 31 from reversing due to inertial force.
While bending between 6d and 26c, the fixed boss 32 and the roller 2 are applied with braking force and are in contact with the roller 26b.
Braking force is applied again at 6a, and the winding side core 29
The structure is such that it can be wound up.

Next, the main points of the present invention will be explained with reference to FIG.

The ink ribbon 4 wound around the supply-side core 31 has its maximum diameter at the beginning of winding. Therefore, at the beginning of winding, the supply side core 31
To prevent reverse rotation due to the reaction force of the ink ribbon 4, α1
〉It is necessary to set it to α2.

Here α1. α2 indicates an angle. The rollers 26d, 26C, and 26a are located at positions where the running resistance increases as α (ink ribbon winding angle) increases.

The key point of the present invention is to install the fixed post 32. At the end of winding, the diameter of the ink ribbon 4 of the winding-side core 29 increases, so that α2>α1 is set.

- The dotted chain line indicates the state of the ink ribbon 4 at the end of winding.

Next, with reference to FIG. 3, changes in running resistance of the roller installation portion of the present invention will be explained.

The horizontal axis is the winding ink ribbon diameter 1, and the vertical axis is the running resistance F2/
Taking F1 (Fl is the ejection force, F2 is the inlet tension), at the beginning of winding, the running resistance H of the ink ribbon nearest to the supply side core is
It is clear that AKI is large and the opposite is true at the end of winding, and the running resistances closest to the core on the supply side and winding side are in an inversely proportional relationship.

Next, referring to FIGS. 4 and 5, a phenomenon in which the ink ribbon sag due to reverse rotation due to the ink ribbon reaction force of the supply side core of the conventional ink ribbon cassette will be explained. FIG. 4 is an explanatory diagram of the configuration of a conventional general ink ribbon cassette in which the ink ribbon 4 is sandwiched between the tension spring 37 and the supply side fixed boss 36b to set a constant brake force.

38 is a spring presser boss. In this ink ribbon cassette, there is no roller structure that takes into account the influence of inertia caused by a change in the diameter of the ink ribbon 4, as in the present invention. Furthermore, since the ink ribbon 4 is always sandwiched between the tension spring 37 and the supply-side fixing post 36b, there is a risk that ink particles may adhere to and accumulate on the tension spring 37, increasing the braking force and making it impossible to wind the ribbon. I know it's Hime. FIG. 5 is an enlarged view of the constant braking force applying section of the conventional general ink ribbon cassette. Reference numeral 39 indicates a spring fixing boss, and the tension spring 37 has a spring presser boss 38 as its fulcrum. As shown in the figure, at the moment when the thermal head separates from the ink ribbon 4, the supply core 31 does not stop rotating immediately due to inertia and becomes over-rotated. It becomes sagging between 31 and 31. This slack causes a relative movement between the ink ribbon 4 and the transfer paper, causing rubbing transfer, which significantly reduces print quality. 40 is a felt attached to the tension spring 37, and the ink ribbon 4 runs between it and the felt 41.

FIGS. 7 and 8 are top plan views of an ink ribbon cassette showing an application example of the present invention to solve the above-mentioned problems.

FIG. 7 shows a TV structure in which the rollers are replaced with cylindrical fixing posts 44. The relationship between αl and α2 is the same as that of the roller structure.

FIG. 8 is a structural diagram when the roller is made of a spring material 42 or the like. The contact surface with the surface of the ink ribbon 4 is made of felt 4.
Try to hit with 3. The elastic body 43 is adhered to the tip of the spring member 42 with double-sided tape or the like.

Reference numeral 46 denotes a stopper boss of the spring member 42, and this stopper boss 46 is shown in the figure. The relationship between α1 and α2 can be kept constant. α without stopper boss 41
Since the angle of l cannot be adjusted due to the difference in the diameter of the ink ribbon 4, the provision of the stopper boss 46 is an essential condition.

〔Effect of the invention〕

According to the present invention, the ink ribbon running resistance is generated by the plurality of rollers disposed near the maximum diameter of the ink ribbon wound around the supply side core and near the maximum diameter of the ink ribbon wound around the take-up side core. This softens the rise characteristic of the ink ribbon running speed before the moment the thermal head is pressed. Furthermore, the ink ribbon traveling speed that occurs at the moment when the thermal head stops pressing can be reduced. These two have the following effects.

(1) Since the tension of the ink ribbon due to the inertia of the ink ribbon on the winding side, which occurs at the moment when the thermal head is pressed, becomes extremely small, rubbing transfer can be prevented.

(2) Over-rotation and reverse rotation of the winding-side core and over-rotation and reverse rotation of the supply-side core can be prevented, so it is possible to prevent relative aFIJ between the ink ribbon and the transfer paper due to slack in the ink ribbon, resulting in stable Ink ribbon winding operation becomes possible.

(3) Since the amount of unnecessary winding of the ink ribbon before the thermal head is pressed can be saved, the ink ribbon can be used effectively and the running cost of the printer can be reduced.

(4) The structure is very simple and there is no need to adjust the tension spring, so assembly costs can be reduced.

Due to the above effects, it is possible to provide customers with stable ink ribbon cassettes with good printing quality.

[Brief explanation of the drawing]

FIG. 1 is an open perspective view of the inside of an ink ribbon cassette embodying the present invention, FIG. Figure 3 is an explanatory diagram of the characteristics of the running resistance on the supply side and the running resistance on the winding side in the range from the start of winding to the end of winding. Figure 4 is a perspective view of a conventional general ink ribbon cassette. Figure 5 shows the state of looseness of the ink ribbon. FIG. 6 is a perspective view of a thermal transfer printer using the ink ribbon cassette of the present invention, and FIGS. 7 and 8 are views showing the inside of the ink ribbon cassette in an applied modified example of the present invention opened upward. FIG. 1... Platen, 2... Transfer paper, 3... Thermal head, 4... Ink ribbon, 5... Ink ribbon cassette. 5a... Sea urchin case, 5b... Shita case, 10.
...Side plate, 11...Side plate, 12...Shaft, 13...
Carriage, 14... Carriage motor, 15...
Timing belt, 16... line feed motor,
17... Gear, 18... Platen knob, 19...
Paper guide, 20...Release lever, 21...Shaft,
22... Paper press roller, 23... Home position sensor, 24... Flat cable, 25 ・CP
U, 26a, 26b, 26+26d...roller, 27
... Pin, 28 ... Tension spring, 29 ... Take-up side core, 3o ... Felt, 3 ... Supply side core,
32... Fixed post, 33... Hole, 34a... Fixing boss, 34b... Stopper boss, 35... Matching boss, 36a... Winding side post, 361... Supply side Post, 37... Tension spring, 38. Spring holding boss, 39... Spring fixing boss, 4o... Elt, 41... Felt, 42... Spring material, 43. Elastic material, 44 ...Cylindrical fixed post, 45...Boss for strut horn.

Claims (1)

[Claims] 1. A thermal transfer printer comprising a thermal head, a platen against which the thermal head is pressed, and a carriage that moves laterally and is equipped with an ink ribbon cassette that stores an ink ribbon whose surface is coated with solid ink. In this ink ribbon cassette, among the rollers arranged in the ink ribbon cassette, the rollers closest to the ink ribbon wound around the supply side core and the ink ribbon wound around the take-up side core are is an ink ribbon cassette for a thermal transfer printer that is always in contact with the solid ink surface of the ink ribbon. 2. In the product described in claim 1, the running resistance of the nearest roller portion is applied to the ink ribbon wound around the supply side core and the ink ribbon wound around the take-up side core. The thermal transfer printer is characterized in that the rollers are disposed at a position where the supply side is large and the take-up side is large at the end of winding, and the running resistances of the two rollers are in an inversely proportional relationship. Ink ribbon cassette. 3. The thing described in claim 1, characterized in that the tension ratio (winding force/total braking force) is kept constant by using both the braking force by the tension spring and the braking force by the plurality of rollers. Ink ribbon cassette for thermal transfer printer. 4. In the product described in claim 1, the roller winding angle of the ink ribbon with respect to the roller closest to the diameter of the ink ribbon wound around the supply side core of the ink ribbon cassette before use is determined on the winding side. An ink ribbon cassette for thermal transfer printers that is larger than the original size.