JPS5913357B2 - Printer ribbon ribbon - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to web tension control devices, and more particularly to tension control devices for ink ribbons used in continuous printer devices.

In an apparatus in which any web member is guided or fed from a rotating reel, drum, spool, spindle, or similar element to another similar compatible element, the web member It is usually necessary to provide means for maintaining some tension in the web member while it is being fed.

This tension is for economic reasons and to ensure that a large amount of web material can be accommodated in each receiving element during feeding, and also to ensure that the web material is tightly wound onto the receiving element so that it does not fall out during handling. This is desirable for web members because it is acceptable to users. Additionally, it would be desirable to have a means for braking the feed element in the event that the web member breaks and the feed element ceases to continue feeding the web member for 30 minutes. In certain cases, such as ink ribbons used in continuous printers, a certain amount of tension is required to achieve proper ribbon feeding and to obtain acceptable print quality of the printed member. It is said that Although the invention is applicable to a variety of webs, tapes, strips, and ribbons, it has been found to be particularly useful with ink ribbons such as those used in continuous printers.

Therefore, without being limited to the meaning of the term "ribbon", the invention will be described in this case. When any web member is guided between a pair of reels, drums, spools, spindles, etc., the tension applied thereto tends to vary due to geometric and inertial variations.

In continuous printer ribbon systems, certain changes in tension on the ribbon do not adversely affect ribbon feeding or print quality. In order to wind the ink ribbon onto the take-up spool, it is necessary to apply force to the take-up spool. The amount of force required for this will vary and is determined by the amount of ink ribbon on the take-up spool. The force normally applied is the value required to rotate the take-up spool when the ink ribbon is wound up to its maximum diameter. Thus, since this device does not have any compensation means, the force applied to the take-up spool is only needed when a small amount of ink ribbon is wound on the take-up spool.
If the value of D is much larger, a greater tension will be applied to the ink ribbon than when the take-up spool has almost completely wound up the ink ribbon. Fiber ribbons are less sensitive to tension changes than matrix-type plastic ribbons. This is because the six-fiber ribbon does not strain or break as easily, and also more easily follows the physical shape of the characters during the printing operation.
Excessive tension acting on the ribbon can cause the ribbon to become taut, 6 wrinkled, and/or folded around the center of deformation, 6 or break, all of which has a significant effect on print quality.

Also, excessively low ribbon tension can allow the ribbon to shift from its printing position to the extent that characters are partially or completely missing. In this field, it is necessary to continuously change the braking force of the unwinding reel in relation to the tension of the wound web member, and to immediately stop the unwinding reel in the event of a break in the web member. It is well known that U.S. Patent No. 32431
This is the letter D disclosed in No. 37.

It is also known to use pawl and ratchet brakes, such as those disclosed in U.S. Pat. .

In US Pat. No. 3,621,968. A roller and spring arrangement is disclosed for tensioning the endless ribbon within the ribbon cartridge. U.S. Patent No. 3797773
Regarding the number. A reed switch (Taper Shun) is used to control the motor that drives the take-up spool.
An apparatus is disclosed for maintaining tension in a ribbon wound on an intermittently driven take-up spool using a winding spool (having a t). U.S. Patent No. 531402;
Nos. 1,340,710 and 1,364,259 disclose various types of brake drag devices that are mounted on the sides of the spool to provide braking and/or tensioning of the web member. Such prior art solutions have used mechanical or combined mechanical/electrical means to provide essential control of the tension in the web member.

In view of these problems with the prior art, it is an object of the present invention to maintain tension in a take-up spool ribbon-like member substantially uniformly while the take-up spool helipon-like member is being fed from a supply spool. be.

Another object of the invention is to improve the feeding and braking of web members fed between two spools or reels. Yet another object of the present invention is to improve the performance of ink ribbons contained in cartridges of the type commonly used in continuous printers.

Yet another object of the invention is to provide an efficient configuration of an anti-car pad friction device that acts on the side of a reel or spool of material.

Yet another object of the invention is to construct an economical method and apparatus for braking an ink ribbon for a continuous printer.

Other objects and advantages will become apparent from the written description and claims and the accompanying drawings which illustrate the invention.

These and other objects of the present invention are achieved by a frictional drag device in frictional contact with the edge of the ring member located on the supply spool.

As the amount of ribbon member remaining on the supply sprue decreases, the value of the frictional force due to the frictional drag device formed also decreases. The tension of the ribbon is determined by the frictional force of each minute area of the frictional drag device formed in contact with the edge of the ribbon, and the radius from the center of the reel is integrated for each minute area. The sum of these values divided by the outer radius of the reel (at any instant) is a measure of ribbon tension. The formed friction surface of the friction drag device supported on the edge of the ribbon member can be any material having a substantially constant coefficient of friction. The preferred material is felt-covered D.
fiber composition. 6 Experiments have shown that this configuration tends to exhibit minimal differences between static and dynamic friction. Vesicular tissue (Ce
lular or spongy materials have similar properties. This frictional drag device applies a substantial force to the ribbon member as it moves from a fully wound supply spool to an empty supply spool during torque fluctuations as the ribbon member moves from a fully wound supply spool to an empty supply spool. It is formed to give a constant tension to the Other objects and features of the invention will become more apparent from reading the following description in conjunction with the accompanying drawings.

Referring now to the drawings, and in particular to FIG. 1A, there is shown one embodiment of the web tension control apparatus of the present invention.

A web or ribbon member 12 is wound onto a supply spool 16 which is rotatably mounted on a shaft 14. Frictional drag devices 17 and 18 are in frictional contact with the upper and lower edges of member 12 by means of pressing forces 20 and 21.
When a force is applied to the end 24 of the web member to cause the web member to unwind from the supply spool, tension is exerted on that portion of the web member that extends from the spool of the web member 12. Because, f
) This is because the resistance of the frictional drag devices 17 and 18 acts on the unwinding of the web member. The tension applied to this web member depends on the frictional force of each minute area of the friction drag devices 17 and 18 that come into contact with the edge of the web member 12, which is the sum of the radius from the center of the spool 16 for each minute area. The sum of these numbers divided by the outside diameter of spool 16 (at any particular time) is a measure of ribbon tension. As shown in FIG. 1B, a rectangular friction drag device cannot provide an overall constant tension, even though the friction drag device provides a web member tension value that is acceptable for many applications. do not have. As shown in FIG. 2A, the shape of the friction drag device has been changed such that a smaller area of the friction drag device contacts the edge of the web material located further from the center of the spool.

Going outward from the center of the ribbon spool, the angle covered by the generally curved section defining the tapered section of the friction drag device varies inversely as the square of the radius. This will be explained in more detail below. This results in a substantially constant tension value in the web member, as shown in FIG. 2B. Depending on the member used, the tension desired, and the particular circumstances to be considered, the shape of the friction drag device may be varied to provide the desired tension on the web member.

If the web member is wound very loosely on a flangeless supply spool, two friction drag devices may be provided against both edges of the web member to cause the drag forces of the drag devices to act symmetrically. desirable. If the supply spool has a flange on one side, drag can and should only be applied to one edge of the web member. This is because the flange retains the web member on the supply spool. Matrix style ribbons are usually wound onto a supply spool (without flanges) under sufficient tension. Frictional drag can only act on one edge. The main problem with the frictional drag used in the prior art is that the frictional drag is applied to some portion of the supply spool or to the mounting shaft.
D. This constituted a constant torque device.

Constant torque devices are undesirable when substantially constant tension in the web member is desired. Referring to FIG. 3, it is shown that the prior art technique using frictional drag forces is unable to provide a substantially constant tension in the web member. Third
In the figure. FD is a frictional force applied to a certain portion of the supply spool at a constant distance from R. FT is the force applied to the free end of the web member to unwind it from the supply spool, distance R2
It is given at the position of In the equation, the torque expression is (1) FT-R2 = FO-R, since FO-R is constant and 6R2 decreases in value as the web member unwinds from the supply spool. F
T must increase as R2 decreases to satisfy the equation.

As FT increases, the tension in the web member increases until it remains substantially constant as desired. Fifth
In prior art ribbon cartridges used in continuous printers such as those shown in the figures, the drag device used in conjunction with the ribbon supply spool is mounted on the ribbon supply spool shaft 14 within the ribbon cartridge. The rubber O-ring was worn out.

Due to the configuration of the ribbon cartridge 32, pressure was applied to the O-ring 6 on one side by the boss of the ribbon supply spool and on the other side by the flat bottom of the ribbon cartridge. This pressure applied to the O-ring created a frictional drag force against the boss of the ribbon supply spool.
During feeding of the ribbon from a fully wound supply spool to an empty supply spool. ．． In order to maintain ribbon tension within reasonable limits, the ribbon supply spool must be varied enough to reduce drag when emptying the ribbon.
This had to depend on the wear characteristics of the ring. This ribbon 33 is wound onto the boss of a take-up spool mounted on a shaft 37 driven by a belt 36 and a shaft 35. A ribbon feed motor (not shown) drives the shaft 35 intermittently. Tension in the ribbon 33 must be maintained properly during movement between the ribbon guide 34 and the front of the print wheel 31 for acceptable printing to occur. If the O-ring does not maintain sufficient drag, the ribbon will fall out of the printing position in front of the print wheel 31. If the O-ring provides too much drag, the ribbon will stretch, curl, and/or break, resulting in unacceptable print quality or complete loss of printed characters. While this O-ring method for maintaining tension in the ribbon is satisfactory, the present invention provides a better solution. Fifth
In arriving at the ultimate form of the present invention incorporated into the continuous printer ribbon cartridge shown in the figures, the following equations were developed.

Starting with the basic formula, 6 (2) W (torque) = R (radius) x T (tension) A minute change in torque can be expressed as follows.

That is, (3) Dw=R-DT+T-DR If the torque is constant. DT is O. Substituting this into (3): (4) Dw=T-DR To determine the torque imparted by the present invention when placed against the edge of the ribbon, the fourth Reference is made to the figure 2 (5
) DW-K'-DA-R where K5 is a unique coefficient (6) DW=Kl・(R・θ・DR)・R(7) D
W-K'-R2・θ・DR Substituting this into (4), we get (8) TdR=K'R2θDR Simplification is (9) T=K'R2θ It is shown that the angle occupied by the frictional drag device changes in inverse proportion to the square of the radius as one moves towards the other.

If R=1 unit, θ1=K. If R.theta.-2 units, then .theta.2-''.

If θ1 is an R-3 unit, then θ3-1(' exists.

When R is small (close to the center of the ribbon), the maximum angle that the frictional drag device can occupy is clearly 3600. Therefore, the actual tests conducted were to determine the shape of the present invention near the center of the ribbon spool. It was conducted. Frictional drag device 45 such as used in the ribbon cartridge shown in FIG.
The exact shape of the ribbon supply spool is shown in FIG. The tapered portion 42 extends almost to the outer circumference of the upper ribbon member.

In the specific shape of the embodiment shown in FIG. 6, the outer diameter e of the generally curved portion 41 is approximately 10.16 mm (0.16 mm).
41n. ), and the inner radius d is approximately 7.11 mm (
0.281n(1) and approximately 3.05711m(0
．． 12in. ) has a width c. At the center h of this roughly curved portion 41, there is a tapered portion 42 that tapers outward (extends in a straight line approximating the theoretical value).
is provided. The width g of the base of the roughly curved portion 41 of this tapered portion 42 is approximately 6.1 dragons (0
．． 241n(1), and the width f at its outer end is approximately 3.05 mm (0.121 n.). The total length b of the frictional drag device 45 is 29.2111 m (1.151 n (1)
Approximately 63.34 - 65.0cm as a fully wound spool.
Used with spools of ribbon material varying from 8811 Lm (2.1 to 2.21 n.). The thickness of this frictional drag device 45Q is 4.77511m (0.1881n.)
It is. Other materials have been tested for use as friction drag devices for ribbon cartridges.

Foamed plastic (mouth shear RFF-263) and 11
0.72y/Cd (4tb/Cu.ft.) 25.411E in non-reticulated polyester foam of ester type
1 L/V) 60 holes (Scotto 4tb custom form) were both found to be suitable materials for the ribbon cartridge situation shown in FIG. As shown in FIG.
The center of the generally curved portion 41 is positioned and oriented within and is coaxial with the ribbon supply spool shaft 41.

Tapered portion 42 is positioned at the 5 o'clock position relative to ribbon supply spool shaft 14. This ribbon member is unwound from the spool onto the ribbon supply spool shaft 14 near the 12 o'clock position. Although the orientation of tapered portion 42 is not critical, ribbon cartridge 32
It was decided to conveniently place and tighten the frictional drag device 45 against the inside of the bottom of the device and to be able to operate continuously in that position. This frictional drag device 45
was tightened with adhesive to the inside of the ribbon cartridge 32, and the ribbon supply spool was then inserted into the ribbon cartridge over the supply spool shaft 14.
The ribbon member is approximately 17.47571171L (0.688
1n. ) with a diameter of
(0.0641 n.)) is always able to rest on the generally curved portion 41 of the friction drag device 45, regardless of the amount of ribbon material remaining on the supply spool, so that the ribbon material on the supply spool This provides a minimum constant tension on the ribbon member even as the amount approaches zero. When the top of the ribbon cartridge is attached to the ribbon cartridge 6, the top applies pressure against the ribbon supply spool to provide the necessary force between the frictional drag device 45 and the lower edge of the ribbon member. Referring to FIG. 5, ribbon cartridge 321 print wheel 31. Ribbon guide 34. Ribbon feed motor (not shown). A print hammer (not shown) and a ribbon lift (not shown) are all mounted on a movable carriage (not shown) to allow movement along the print line.

Prior to a printing operation, the portion of ribbon cartridge 32 proximate platen 30 is pivoted upward to position the ribbon at the print station between the character slug of print wheel 31 and platen 30. After printing, the ribbon cartridge 32 pivots downwardly to its non-printing position, allowing the operator to view the printed characters. It is therefore apparent that there has been provided by the present invention a friction drag device for a web member which fully satisfies the objects, intentions and advantages set forth above.

While the basics of the invention have been made clear by the illustrated embodiment, it is obvious that alterations, modifications and changes will become apparent to those skilled in the art. Accordingly, it is intended to cover all changes, modifications, and variations falling within the spirit and scope of the claims.

[Brief explanation of the drawing]

FIG. 1A is a perspective view of one specific example of the present invention, and FIG. 1B is a perspective view of a specific example of the present invention.
FIG. 2A is a perspective view of another embodiment of the present invention, and FIG. 2B is a graph of tension versus diameter of the web member shown in FIG. 2A. FIG. 3 is a plan view showing an exemplary ribbon supply spool and a torquer acting on it; FIG. 4 is a schematic diagram used to calculate the optimal shape of the friction drag device; and FIG. 5 is a continuous printer and ribbon that can use the present invention. FIG. 6 is a perspective view of the cartridge, FIG. 6 is a plan view of the present invention as used in the ribbon cartridge, and FIG. 7 is a partial plan view of the ribbon cartridge showing the frictional drag device therein. 12... Ribbon member or web member, 14... Shaft. 16... Supply spool, 17, 18, 22,
23...Frictional drag device. 20, 21...Press force 62
4... Pull-out end of ribbon member, 31... Print wheel, 32... Ribbon cartridge, 33... Ribbon, 34... Ribbon guide. 35...shaft,
36... Belt, 41... Roughly curved part, 4
2...Tapered portion, 45...Frictional drag device.

Claims (1)

[Claims] 1 a carrier movable laterally to move between a platen and a print line; a printhead assembly supported on the carrier for collision with the platen for printing characters; and feeding an ink ribbon through the printhead. a ribbon feeding device supported on the carrier to provide a ribbon feeding device; and a ribbon cartridge supported on the carrier for rotatably supporting a ribbon supply spool;
A ribbon tension control system for a continuous printer, the device comprising: a device for rotatably supporting a ribbon take-up spool; and a device for moving the ribbon between the supply spool and the take-up spool; a friction drag device disposed in frictional engagement with an edge on at least one side of a ribbon positioned on a supply spool, the friction drag device applying substantially uniform tension during transport of the ribbon; a generally curved portion coaxial with the supply spool;
a tapered portion extending outward from a central portion of the generally curved portion to approximately the outer periphery of the ribbon member on the supply spool. .