JPS62214983A - Ribbon cassette - Google Patents

Abstract

PURPOSE:To apply a required back tension according to the running direction of a ribbon to obtain a stable running of the ribbon in a ribbon cassette using the back- face of the ribbon, by a method wherein a tension applying member made of a plate spring, etc. is allowed to act on a pressed portion in a direction offset by a predetermined angle from the vertical direction to the pressed portion. CONSTITUTION:A plate spring 8 is bent inward at a top end thereof 8b to be engaged with a projecting portion 2h. A plate spring 9 is also shaped symmetrical to the plate spring 8. The plate spring 8 has an engaging portion 0 with a projecting portion 2k serving as a fulcrum to press the projecting portion 2h at a pressing portion A by a force P at right angles to OA. In this case, since the projecting portion 2h is not forced at right angles to the acting direction of the plate spring 8 but offset by an angle theta therefrom, a component force P' of the force P vertical to the surface of the projecting portion 2h acts as a force acting on the surface of the projecting portion 2h. As a result, when a ribbon 5 is fed in a direction of Arrow (m), the component force P' comes to assist in the pressing action of the plate spring 8 against the projecting portion 2h at the top end thereof 8b. The reverse running direction of the ribbon 5 makes all the frictional force act in the reverse direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to ribbon cassettes used in thermal transfer printers and thermal transfer typewriters.

Conventional technology In recent years, thermal transfer type printers and typewriters have been attracting attention due to demands for higher speed, lower noise, and multicolor printing.In particular, serial thermal heads and ribbon cassettes have been developed to realize low-cost equipment. are increasingly being used.

Furthermore, when considering the economical efficiency of ribbons, ribbons that can be used many times are emerging.

There are two ways to put this into a cassette.

One is the same as an audio cassette, and has a so-called reel-to-reel structure in which two reels are built in, the ribbon is wound from one part to the other, and when it reaches the end, the cassette is turned over and used again. Another method is a so-called endless structure in which the beginning and end of the ribbon are connected.

The former allows for a configuration that is approximately the same as that of normal one-way running, and also makes it easier to stabilize the ribbon running, but it requires a mechanism to replace the ribbon cassette at the end or run on the opposite axis. In the latter case, the ribbon becomes thicker and the ribbon running tends to become unstable.

An example of the former ribbon cassette described above will be described below with reference to drawing ft.

FIGS. 6, 6, and 7 show the appearance of the former ribbon cassette and the disassembled state.

1.2 are an upper case and a lower case that constitute the case of the cassette. 3.4 is two reels. Reference numeral 6 denotes a heat transfer ribbon whose starting and ending ends are locked to the reels 3 and 4, and a portion thereof is exposed through the opening of the ribbon cassette.

Upper case 1. A leaf spring 6.7 is provided inside the lower case 2. The ribbon 5 extends from the reel 4 to protrusions 21L, 2b, 20°2d, 2 provided on the lower case 2.
e, 2f, 2g, and 2h while being wound on the reel 3.

On the other hand, the bent portion 6a of the leaf spring 6 is held by the protruding portion 21.2j on the lower case 2, and the upper case 1 is engaged with the lower case 2. The provided protrusion 1a engages with the leaf spring 6 and also engages with the protrusion 2k, so that the felt provided at the tip 6b presses against the protrusion 2h via the ribbon 6. As a result, ribbon 6
However, when this part slides, it receives a certain amount of frictional force and operates as a tensicon. Leaf spring 6 sticks out! Since a force perpendicular to the surface of 1s2h acts, the same frictional force, ie, the same tensicon, acts regardless of the direction in which the ribbon moves. Note that a leaf spring 7 is provided at a symmetrical position and has a similar effect.

Because of this configuration, when the ribbon cassette is installed in a thermal transfer printer, the same tensicon operates even when the ribbon cassette is installed upside down.

In the case of printing, if the ribbon is fed out from the reel 4 and wound onto the reel 3, the tension from the leaf spring 7 acts on the ribbon 6 as a back tension controller.
In the case of mounting in the opposite direction, the reel 3 and the ribbon 6 are unwound and wound onto the reel 4, so that the leaf spring 3 acts as a back tension controller.

Problems to be Solved by the Invention However, in the above configuration, if the ribbon 6 is wound onto the reel 3 from the reel 4, the pack tension is effectively applied by the leaf spring 7 to stabilize the ribbon running. However, the frictional force caused by the plate springs 6 does not contribute in any way to stabilizing the running of the ribbon 60, and rather the torque for winding up the reel 3 must be increased more than necessary, which makes it difficult to use battery-operated printers, etc. However, this method has the disadvantage of requiring a large amount of current consumption, and also causes problems such as ink particles from the ribbon adhering to the felt, which tends to cause fluctuations in frictional force. In the case of a ribbon cassette that is used only for traveling in one direction, it is of course unnecessary to provide the leaf spring 6, but rather it is used by attaching it in the opposite direction.

Ideally, the pressing force of the leaf springs 6, 7 against each protruding portion should ideally change automatically depending on the running direction of the ribbon.

In view of the above problems, the present invention provides a system in which a back tension controller is automatically added depending on the mounting state of the ribbon cassette.
Another object of the present invention is to provide a ribbon cassette that reduces the frictional force of the ribbon on the winding side.

Means for Solving the Problems In order to solve the above problems, the ribbon cassette of the present invention includes an upper case and a lower case for forming a casing;
Two reels located within both cases, a ribbon whose starting and ending ends are fixedly wound around these reels, and which runs so that a portion thereof is exposed through an opening formed in the case, and a case. It is composed of two tension applying members made of a plate spring or the like, one end of which is configured to press against a protrusion provided inside through a ribbon. It is characterized by being configured to differ by a predetermined angle in the vertical direction.

According to the present invention, when one tension applying member runs in the direction in which the ribbon is unwound from the neighboring reel,
When the ribbon is biting in and a large frictional force acts on it, resulting in an effective pack tension, on the other hand, when the ribbon runs in the direction that the reel winds up, it has a tendency to escape and only a small frictional force acts on the winding side. A winding torque with little unnecessary loss is sufficient to rotate the reel.

EXAMPLE Hereinafter, a ribbon cassette according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a leaf spring according to an embodiment of the present invention. In FIG. 2, the tip 8b of the leaf spring 8 that engages with the protrusion 2h is bent inward. The leaf spring 9 also has a symmetrical shape.

Moreover, FIG. 1 shows the state in which the plate springs 8 and 9 are installed, and the protruding portions 2& are shown in comparison with FIG. 7.

2h is changing direction.

Next, the operation will be explained.

In FIG. 3, the plate spring 8 is assumed to press the protrusion 2hl with a force P in a direction perpendicular to Om at the pressure contact part M, using the engagement part O with the protrusion 2 as a fulcrum. In this case, the protrusion 11s2h does not receive the force at right angles to the acting direction of the leaf spring 8, but is deviated by θ from the right angle, so the force acting on the surface of the protrusion 2h is in the direction perpendicular to the surface of the protrusion 2h of P. component force P
' becomes P' = □ bunch θ. These are the rest states of the ribbon.

Next, let us consider a case where the ribbon 6 moves in the direction of the arrow m. As the ribbon 6 travels in the direction of arrow m, a force μP' acts on the ribbon 6, where the coefficient of friction between the plate spring 8 and the ribbon is μ, and the reaction force acts on the plate spring 6 as μP'. It acts in the direction of C. Since the direction of this force is shifted by θ with respect to 0 m, μP'sinθ is the component force on the leaf spring 8.
The tip 8b helps in suppressing the protrusion 2h. Moreover, if the running direction of the ribbon 6 is the opposite direction, all the frictional forces will be in the opposite direction.

When the ribbon 6 travels in the m direction, the reel 3 in the vicinity is in the supply direction, and when the ribbon 6 travels in the opposite direction, it is in the winding direction.

Therefore, the pressing force Q exerted by the leaf spring 8 on the protrusion 2h via the ribbon 6 is summarized in the following cases.

(1) Ribbon stopped state Q1 = P' (2) When the ribbon is fed out (traveling in the m direction) Q
2 = P'+μP' θ (3) When the ribbon is rolled up (when traveling in the opposite direction to +!1) Qs = P'-μP' θ As is clear from these equations, when θ is O, Same as before, the force is constant (Q = p' = P) regardless of the running direction, but as the value of θ is increased, the difference in pressing force depending on the ribbon running direction (Q2 - Qs) = 2μ It is clear that θ.

As described above, according to this embodiment, by applying a force in a direction that deviates the tension applying member, which is made of a leaf spring or the like, by a predetermined angle from the perpendicular direction with respect to the suppressing portion, it is possible to apply a force according to the running direction of the ribbon. It is possible to add a pack tensile strength to the ribbon, and when two are installed symmetrically, the amount of tensile strength added to the ribbon can be reduced on the winding side, which is unnecessary, and the ribbon can be run in either direction. This has the effect that not only stable ribbon running can be obtained, but also the torque applied to the take-up υ reel does not need to be increased more than necessary.

In addition, as an example, the tensilan applying member was explained using a leaf spring, but the effect is the same even if it is a rotary lever.
Furthermore, it is clear that the same effect can be obtained even if the protrusion that is subjected to the suppression of the plate spring is a rotary roller.

Effects of the Invention As described above, the present invention allows the frictional force on the ribbon to change automatically in the ribbon running direction by only slightly changing the shape of the tension applying member such as a leaf spring. When acting as a ribbon cassette, a desired large force is applied and a small force is applied on the take-up side, allowing stable ribbon running in a ribbon cassette that is used many times by turning the ribbon over.

[Brief explanation of drawings]

Fig. 1 is an exploded plan view showing one embodiment of the ribbon cassette of the present invention, Fig. 2 is a perspective view of a leaf spring used in the cassette, and Figs. 3 and 4 are schematic diagrams showing the force relationship of the cassette. figure,
FIG. 6 is an external view of a conventional ribbon cassette, FIG. 6 is an exploded perspective view of the conventional ribbon cassette, and FIG. 7 is an exploded plan view of the conventional ribbon cassette. 1...Top case, 2...Bottom case, 3
．． 4...Reel, 6...Ribbon, 8,
9... Leaf spring. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 02 Figure 3 Figure 4 Figure 2 Figure 5 Figure 7 δ

Claims (1)

[Claims] An upper case and a lower case for forming a casing, two reels disposed within the two cases, and an opening that is wound with a starting end and a terminal end fixed to the reels, and a part of which is formed by the case. The tension applying member includes a ribbon that runs so as to be more exposed, and a leaf spring or the like configured such that one end presses a protrusion provided in the case through the ribbon, In a ribbon cassette in which a tension applying member is provided in a symmetrical shape near each of the reels, each of the tension applying members is deviated from the perpendicular direction by a predetermined angle with respect to the protrusion, so that the tension applying member The frictional force against the ribbon is that when the ribbon runs in the direction in which it is unwound from the neighboring reel, it bites in and a large frictional force is exerted, while when it runs in the direction in which it is wound up on the neighboring reel, a large frictional force is exerted on the ribbon. A ribbon cassette characterized by being configured so that only a small frictional force acts on it by turning it on its own.