JPH0453956Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a carrier drive device for a serial printer.

Conventional technology Conventionally, a strip material such as a belt or wire, which is partially held by a carrier, is wound around multiple pulleys arranged on the left and right, one pulley is connected to a motor, and the other pulley is used as a support member to freely rotate. There is one in which the carrier is supported by a carrier and driven by a motor to move the carrier by the tensile force of the strip.

If the strip material stretches due to long-term use, the feed rate of the carrier will become inconsistent. In order to prevent this, there is a conventional example in which a support member supporting the driven pulley is held movably and the support member is fixed at an arbitrary position with a screw.

Another conventional example is one in which the support member that supports the driven pulley is biased by a spring to prevent the strip from loosening.

Problems to be Solved by the Invention Among the conventional examples described above, in the former, the screw must be tightened while measuring the tension of the strip, making adjustment work troublesome.

In the latter case, when the direction of movement of the carrier changes, the amount of deflection of the spring changes, and the position of the carrier differs between the forward and return trips, causing deviations in printing and erasing positions.

Means for solving the problem An endless strip is provided that is stretched between a fixed pulley connected to a motor and a movable pulley attached to a support member that is stretched in position, and the strip is reciprocated along the platen. A part of the strip is fixed to a movably held carrier, and the support member is biased by a composite spring in which a plurality of coil parts with different initial tensions are successively formed, and the support member is attached to a fixing device. Fix it by.

Action When the strip stretches, loosening the fixing device causes the support member to be displaced by the combined spring force, applying tension to the strip. Therefore, when the support member is fixed with the fixture, the strip does not expand or contract even if the direction of movement of the carrier changes, thereby preventing the carrier from being misaligned.

Furthermore, by using a composite spring made up of several consecutive coil parts with different initial tensions, the coil part with a higher initial tension increases the tension of the entire composite spring, and the coil part with a lower initial tension is deflected beyond a certain level. To reduce the change in load due to change in deflection of the entire composite spring after soldering. Therefore, it is possible to apply the load of the composite spring to the support member in a high load area where the load changes with respect to changes in the deflection of the entire composite spring is small and the amount of elongation of the strip is small. Even if the amount of tension is large, composite springs can expand the range of tension applied to the strips and extend the service life of the strips.Moreover, the tension applied to the strips can be increased by reducing the change in load relative to the overall elongation of the composite springs. can be set within a certain narrow range.

Embodiment A first embodiment of this invention will be described based on FIGS. 1 to 3. 1 is a carrier, and the carrier 1 holds a printing head 2 and a ribbon cassette 3. The carrier 1 is slidably held by a carrier shaft 5 parallel to the platen 4 and a guide 6. A belt 7, which is a strip member partially held by the carrier 1, is wound around a pulley 9 directly connected to a motor 8 and a pulley 11 supported by a support member 10. The support member 10 is rotatably held by a frame 13 by a shaft 12, and is biased by a composite spring 14. Further, an arc-shaped elongated hole 15 whose radius is centered around the shaft 12 is formed in the support member 10 . Then, the frame 13 is inserted into the elongated hole 15 as a fixture.
A tightening screw 17 is provided which is screwed into the protruding piece 16 of.

The above-mentioned composite spring 14 is formed by continuously forming two coil parts 14a and 14b having different initial tensions. One coil portion 14a is a normal tightly wound portion and has a high initial tension, and the other coil portion 14b is a tightly wound portion and has an initial tension lower than that of the coil portion 14a.

In such a configuration, when the tightening screw 17 is loosened, the support member 10 rotates by the force of the composite spring 14 and is balanced with the composite spring 14 to apply just the right amount of tension to the belt 7. Tightening screw 1
7 is tightened and the support member 10 is fixed,
Even if the motor 8 is rotated in both forward and reverse directions to reciprocate the carrier 1, the support member 10 rotates and the belt 7
does not expand or contract. Therefore, as long as the number of steps for driving the motor 8 is determined and the carrier 1 is moved, the position of the carrier 1 will not change depending on the difference between the outward and return trips. The operation for applying tension to the belt 7 is extremely easy, as it is only necessary to loosen and retighten the tightening screw 17.

In this case, if the characteristics of the composite spring 14 are shown in FIG. 3, when the composite spring 14 is deflected in the extension direction, the coil portion 14b is first deflected, and when the deflection amount reaches l ₁ , the load is P There is ₁ . P ₁ at this time is the same as the initial tension of the coil portion 14a. Therefore,
When the composite spring 14 is bent further by l ₂ , l ₃ , etc., both the coil parts 14a and 14b are stretched, and the load is
P ₂ , P ₃ ... and so on. In this way, the coil portion 14a with a high initial tension increases the strength of the entire composite spring 14, and has the effect of reducing the change in load with respect to the change in deflection in the region where the deflection of the coil portion 14b with a low initial tension is increased. show. Therefore, the load P ₂ to l ₃ changes from l 2 to l ₃ .
By applying P ₃ to the support member 10, even if the amount of elongation of the belt 7 is large, the range in which tension is applied to the belt 7 by the composite spring 14 is expanded and the belt 1 is
It is possible to extend the period of use of the belt 7, and moreover, it is possible to reduce the change in load with respect to the elongation of the entire composite spring 14, and to set the tension applied to the belt 7 within a certain narrow range.

A second embodiment of this invention will now be described with reference to FIGS. 4 and 5. In this embodiment, the composite spring that biases the support member 10 is changed. That is, the composite spring 18 is formed by continuously forming two coil portions 18a and 18b having different initial tensions. One coil part 18a is a part in which the wire is closely wound while applying high tension, and the initial tension is extremely high.The other coil part 18b is a part in which the wire is tightly wound, and its initial tension is lower than that of the coil part 18a. .

Therefore, if the characteristics of the composite spring 18 are shown in FIG. 5, when the composite spring 18 is deflected in the direction of extension, the coil portion 18b is first deflected, and the deflection amount is l ₁
The load when it reaches is P ₁ . This P ₁ is the initial tension of the coil portion 18a. Therefore, when the composite spring 18 is bent further by l ₂ , l _{3 , .} . . , the coil portions 18a, 18b are both stretched, and the load is increased by P ₂ , P ₃ , .
...changes. In this way, the coil portion 18a with a high initial tension increases the strength of the entire composite spring 18, and has the effect of reducing the change in load with respect to the change in deflection in the region where the deflection of the coil portion 18b with a low initial tension is increased. show. The composite spring 18 in this second embodiment is the composite spring 1 in the first embodiment.
It is possible to achieve the same objective as the first embodiment only by having a power stronger than 4.

Effects of the invention Since this invention is constructed as described above, when the strip stretches, tension can be applied to the strip by the composite spring simply by loosening the fixing device, and the supporting member is fixed using the fixing device. Therefore, even if the moving direction of the carrier changes, the strip does not expand or contract, and it is possible to prevent the carrier from misaligning.Moreover, it is possible to continuously connect multiple coil parts with different initial tensions. By using a composite spring made of a composite spring, the tension of the entire composite spring is increased by the coil part with a higher initial tension, and the change in the deflection amount of the entire composite spring after the coil part with a lower initial tension is deflected beyond a certain level. Therefore, the load of the composite spring can be applied to the support member in a region where the load changes with respect to a change in the deflection of the entire composite spring is small and a high load is applied. Therefore, even if the amount of elongation of the strip is large, the range in which tension can be applied to the strip can be expanded by the composite spring, making it possible to extend the service life of the strip.Furthermore, the change in load with respect to the overall elongation of the composite spring can be extended. This has the effect of making it possible to set the tension applied to the strip within a certain narrow range by reducing the tension.

[Brief explanation of the drawing]

Figures 1 to 3 show the first embodiment of this invention, with Figure 1 being a perspective view, Figure 2 being an enlarged side view of a compound spring, and Figure 3 being an enlarged side view of a compound spring. Graphs showing the characteristics, Figures 4 and 5, show the second embodiment of this invention. Figure 4 is an enlarged side view of the composite spring, and Figure 5 shows the characteristics of the composite spring. It is a graph. 1...Carrier, 7...Belt (strip material), 8...
...Motor, 9...Pulley, 10...Support member, 1
1...Pulley, 13...Frame, 14...Compound spring, 14a, 14b...Coil portion, 17...Tightening screw (fixing tool), 18...Compound spring, 18a,
18b...Coil part.

Claims (1)

[Scope of utility model registration request] An endless strip is provided between a fixed pulley connected to a motor and a movable pulley attached to a support member that is stretched in position. A serial article characterized in that a part of the strip is fixed, the support member is biased by a composite spring formed in series with a plurality of coil parts having different initial tensions, and the support member is fixed by a fixture. Printer carrier drive.