JPH085243B2 - Printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus that prints by pressing a thermal head against a sheet of paper via an ink ribbon.

<Prior Art> In some cases, it is necessary to write down the date of copying, the person who copied the image, other notes, etc. on a sheet of paper on which an image has been copied by an image forming apparatus, such as a copying machine.

In such a case, since the work of creating the memo writing by handwriting or stamping is troublesome, a printer is provided inside the image forming apparatus so as to automatically perform the work.

In this printing device, a cassette in which a belt-shaped ink ribbon is wound by a feed reel and a take-up reel is attached to a casing, and a thermal head is pressed against a sheet passing through a platen roller via the ink ribbon. To print.

In addition, in this printing apparatus, the ink ribbon is always brought close to the passage through which the high-temperature paper passes, even though printing is performed only when necessary. There was a problem of deterioration.

In order to solve such a problem, with the ink ribbon between the delivery reel and the take-up reel slackened,
A printing device is known in which the above printing is performed, and after the printing is completed, the thermal head is retracted to release the slack of the ink ribbon and separate the ink ribbon from the high temperature passage (Japanese Patent Laid-Open No. 63-297085). reference).

With this printing device, when winding of the take-up reel is stopped, the pull-out force of the tension coil spring causes the take-up reel to rotate in the direction opposite to the take-up reel and rotates the ink ribbon at a fixed angle to take out the ink ribbon. The slack is released by winding on a reel.

<Problems to be Solved by the Invention> However, in the above-described printing apparatus, even when the delivery reel is rotated by a certain angle by the tension coil spring, when the amount of the ink ribbon wound by the delivery reel is small, the delivery reel is fed out. Since the winding radius of the reel becomes small, the length of the ink ribbon that can be wound around the delivery reel becomes short, and there is a problem that the slack of the ink ribbon cannot be released.

Therefore, even if the amount of the ink ribbon wound by the delivery reel is small as described above, the rotation angle of the delivery reel by the tension coil spring is increased in order to reliably release the slack of the ink ribbon. It is also possible.

However, in this case, when the amount of the ink ribbon wound by the delivery reel is large, tension is always applied to the ink ribbon after the slack is released, which lowers the durability of the ink ribbon. was there.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the invention to provide a printing apparatus that can surely cancel the bending of the ink ribbon and that does not reduce the durability of the ink ribbon.

<Means for Solving the Problem> In order to achieve the above object, the present invention provides an ink ribbon between a feed reel and a take-up reel of a cassette in which the ink ribbon is wound by a feed reel and a take-up reel. In the state where the ink ribbon is slackened, the thermal head is pressed against the paper through the ink ribbon to print characters and the like, and after the printing is completed, the thermal head is retracted to release the slack of the ink ribbon. A torque limiter that restricts the transmission of drive torque over the set torque TL to the take-up roller, and the ink ribbon is taken up on the take-up roller with the thermal head retracted, and after loosening the ink ribbon, A friction braking torque TB larger than the set torque TL of the torque limiter is applied to the winding means to be stopped and the feed roller. Friction resistance load means for

<Operation> According to the above configuration, the winding means causes the ink ribbon to be wound around the winding reel after printing is completed,
The slack of the ink ribbon is released, and the ink ribbon between the take-up reel and the delivery reel is in a stretched state. At this time, the friction braking torque TB by the friction resistance load means is
The take-up reel is loaded through the delivery reel and the ink ribbon in the stretched state, but the take-up reel is limited by the torque limiter from transmitting the drive torque equal to or higher than the set torque TL. Moreover, since the friction braking torque TB is larger than the set torque TL of the torque limiter, the unused ink ribbon is not pulled out from the delivery reel and supplied to the take-up reel side. After that, the winding means is stopped, and the ink ribbon between the delivery reel and the winding reel becomes unloaded.

On the other hand, when slackening the ink ribbon between the delivery reel and the take-up reel to perform printing, the friction braking torque TB applied to the delivery reel is the torque set by the torque limiter, as in the case of releasing the slack. Since it is larger than TL, the ink ribbon wound by the take-up reel at the time of releasing the slack is unwound from the take-up reel.

<Example> Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 7 is a schematic side view showing a copying machine equipped with a printing apparatus according to an embodiment of the present invention. In FIG. 7, the copying machine has an original image in a housing 1 as a main body of the copying machine. According to the above, an optical system 11 for forming an electrostatic latent image on a photoconductor 12a, an image processing unit 12 for developing the electrostatic latent image into a toner image and transferring it onto a copy sheet, a manual paper feeding unit 14, a paper feeding unit. An image processing unit 12, a fixing device 17 that heats and fixes an image on a copy paper, a printing device 2, and a punching device 18 that punches punching holes for binding the paper sent from the cassette 15a or the paper feed cassette 15b. It has a paper transport unit 13 for sequentially discharging the paper and discharging it onto a discharge tray 19.

With reference to FIGS. 1 to 3, the printing device 2 includes:
The ink ribbon 3 is sent out from the reel 41 and the take-up reel 42.
The cassette 4 wound by the above, the friction resistance load means 5 which is disposed in the cassette 4 and exerts the friction braking torque TB on the delivery reel 41, and a plurality of minute resistors are energized to generate heat. It has a thermal head 6 for forming a print pattern on a sheet, and a motor 8 as a winding means for driving the take-up reel 42 via a torque limiter 7.

As shown in FIG. 3, the thermal head 6 is movable between a printing position A and a releasing position B, and when the thermal head 6 is moved to the printing device A, the ink between the feeding reel 41 and the take-up reel 42 is moved. The ribbon 3 is pulled out from the cassette 4 and loosened, and the ink ribbon 3 is pressed against the sheet passing through the platen roller 90. In this state, by rotating the platen roller 90, the ink ribbon 3 is pulled out from the delivery reel 41 to the thermal head 6 side, printing is performed, and the ink ribbon 3 passing through the thermal head 6 is wound by the winding means 8. It is taken up by the take-up reel 42. And
After the printing is completed, the thermal head 6 is moved to the releasing position B so that the slack of the ink ribbon 3 can be released (see FIG. 4).

The frictional resistance loading means 5 is the inner surface of the body 43 of the cassette 4.
A compression coil spring 51 having one end 51a attached to 43a.
Attached to the other end 51b of the compression coil spring 51, and the end surface of the delivery reel 41 is attached by the compression coil spring 51.
And a friction plate 52 which is pressed by 41a. The frictional resistance load means 5 generates a friction braking torque TB that regulates the rotation of the delivery reel 41 by the frictional force between the end surface 41a of the delivery reel 41 and the friction plate 52.

The motor 8 drives the take-up reel 42 so as to take up the ink ribbon 3 during printing, but also after the printing is completed, the take-up reel 42 is driven so that the take-up reel 42 causes
The loose ink ribbon 3 is wound up. Then, when the winding of the ink ribbon 3 is completed after a lapse of a predetermined time from the completion of printing, the drive of the winding reel 42 is stopped.

The torque limiter 7 applies a compression coil spring 73 to the friction material 71 driven by the motor 8 via the gear 9.
By pressing the friction member 72, the driving force of the motor 8 is transmitted to the shaft 74 connected to the take-up reel 42. Then, the torque limiter 7 causes friction with the friction material 71 when a tension equal to or higher than a predetermined tension is applied to the wound ink ribbon 3, that is, when a driving torque equal to or higher than the set torque TL is applied to the torque limiter 7. A slip is caused between the member 72 and the member 72. As a result, the torque limiter 7 is set to the set torque.
The transmission of the driving torque of TL or more is avoided, and the ink ribbon 3 to be wound is not applied with a tension of more than a predetermined value. Further, the magnitude of the set torque TL is set to be smaller than the friction braking torque TB by the friction resistance load means 5.

According to this embodiment, after the printing is completed, the motor 8 drives the take-up reel 42 to wind the ink ribbon 3 in the slack state on the take-up reel 42, thereby releasing the slack of the ink ribbon 3. Then, the ink ribbon 3 between the delivery reel 41 and the take-up reel 42 is in a stretched state (fifth position).
See figure).

At this time, the friction braking torque by the friction resistance load means 5
TB is loaded on the take-up reel 42 via the delivery reel 41 and the ink ribbon 3 in the stretched state. The take-up reel 42 does not transmit a drive torque equal to or higher than the set torque TL. Since the friction braking torque TB is limited by the torque limiter 7 and is larger than the set torque TL of the torque limiter 7, the unused ink ribbon 3 is pulled out from the delivery reel 41 and supplied to the take-up reel 42 side. It is possible to reliably release the slack of the ink ribbon 3 between the delivery reel 41 and the take-up reel 42 without causing the slack.

After that, the motor 8 is stopped, and the ink ribbon 3 between the feed reel 41 and the take-up reel 42 is in a no-load state, and there is no fear that the durability of the ink ribbon 3 is adversely affected by the tension.

On the other hand, when the ink ribbon 3 between the delivery reel 41 and the take-up reel 42 is loosened to perform printing, the friction braking torque TB applied to the delivery reel 41 is the same as when releasing the looseness. Limiter 7 set torque TL
Therefore, the ink ribbon 3 wound by the take-up reel 42 when the slack is released is unwound from the take-up reel 42 (see FIG. 6). Therefore,
The ink ribbon 3 returns to the state at the end of printing, and the unused portion of the ink ribbon 3 is not wastefully sent to the take-up reel 42 side, which is advantageous in terms of cost.

Further, in the conventional example in which the ink ribbon is wound on the delivery reel side by the tension spring, a torque limiter is arranged on the take-up reel side, and the tension spring is set to a torque greater than the set torque of the torque limiter. If the tensile force is large, the ink ribbon that has already been used for printing and that has been wound on the take-up reel will be wound on the delivery reel side, and the used ink ribbon that has been wound on this delivery reel will be However, there is a risk that printing defects may be sent out during printing and used again for printing, but in the present embodiment that does not use a tension spring, there is no such fear.

Then, during printing, the feed force exerted by the platen roller 90 on the ink ribbon 3 via the paper is larger than the friction braking torque TB applied to the feed reel 41, so that the ink ribbon 3 is fed from the feed reel 41. . The ink ribbon 3 that has passed through the thermal head 6 and has been used for printing is taken up by the take-up reel 42.

The present invention is not limited to the above-mentioned embodiment, and various design changes are made within a range not changing the gist of the present invention, for example, by providing the frictional resistance load means 5 outside the cassette 4. be able to.

<Effects of the Invention> As described above, according to the present invention, the winding means causes the ink ribbon to be wound onto the take-up reel after printing is completed. Is limited by the torque limiter, and the friction braking torque TB applied to the delivery reel is larger than the torque limiter set torque TL, so that the slack of the ink ribbon can be reliably released. it can. After the slack is released, the winding means stops and the ink ribbon between the feed reel and the take-up reel becomes unloaded, so that the durability of the ink ribbon does not deteriorate due to the influence of tension. There is a unique effect that can be done.

[Brief description of drawings]

1 is a partially cutaway plan view showing a printer as an embodiment of the present invention, FIG. 2 is a perspective view of a cassette, FIG. 3 is a schematic side view showing the printer in a printing state, and FIG. Is a schematic side view showing the printer immediately after printing, FIG. 5 is a schematic side view showing a state in which the loose ink repon is wound up after printing, and FIG. 6 is a schematic showing the printer ready for printing. A side view and FIG. 7 are schematic configuration diagrams of a copying machine including a printer. 2 ... printing device, 3 ... ink ribbon, 4 ... cassette, 5 ... friction resistance loading means, 6 ... thermal head, 7 ... torque limiter, 8 ... winding means, 41 ... feed reel, 42: Take-up reel, TL: Set torque, TB: Friction braking torque.

Claims (1)

[Claims] 1. A thermal head in which a cassette in which an ink ribbon is wound by a delivery reel and a take-up reel is slackened between the delivery reel and the take-up reel, and the ink ribbon is slackened. In the printing device that presses against the paper to print characters, etc., and after printing is completed, retracts the thermal head to release the slack in the ink ribbon, and a drive torque greater than the set torque TL is transmitted to the winding roller. The torque limiter that controls the temperature of the ink ribbon, the winding means that winds the ink ribbon on the take-up roller with the thermal head retracted, and releases the slack of the ink ribbon, and then stops the take-up roller. And a frictional resistance load means for applying a friction braking torque TB larger than the set torque TL of the limiter. Printing apparatus.