JPH0377787B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cassette for printing ribbon for use with a typewriter. The cassette includes a case housing a supply spool with ribbon wound thereon and a take-up spool intended for receiving the used ribbon in cooperation with the drive means. Braking means are provided on the supply spool to tension the ribbon between the two spools. The cassette has a blocking mechanism for the take-up spool intended to prevent unwinding of the take-up spool when the cassette is removed from the typewriter. The blocking mechanism includes a blocking lever having a tip that resiliently engages between the gear teeth.

This type of cassette is the subject of European patent application no.
Known from number 0042955. This cassette is 2
It includes two blocking levers which engage teeth on a gear wheel integral with the take-up spool and carried by the case of the cassette.

This arrangement has the disadvantage that it is not possible to disengage the blocking levers from the teeth since these levers are rotated when the cassette is used on a typewriter. Moreover, said arrangement greatly complicates the manufacture and assembly of the case and take-up spool.

The aim of the invention is to overcome these inconveniences. According to the invention, the gearwheel is integral with the take-up spool and the blocking lever is integral with the case. The blocking lever includes a freely exposed portion for cooperating with fingers on the typewriter to disengage the tip from the teeth during installation of the cassette on the typewriter.

The accompanying drawing schematically shows, by way of example, a preferred embodiment of a cassette for printing ribbons according to the invention.

The ribbon cassette includes a case having a cover 3 that fits over the bottom 2, a supply spool onto which the printing ribbon 6 is wound, and a take-up spool 5 around which the used ribbon is wound.

The supply spool 4 is coaxially superimposed with a take-up spool 5 which is rotatably driven by a drive means 7 outside the cassette.

The supply spool 4 includes braking means for creating some tension on the printing ribbon 6. Said braking means comprises a steel wire comprising a portion wrapped around the brake 31 on the hub means 12 of the supply spool 4, an end 9 moored within the case, and an end 10 comprising a tip 11. Spring 8 is included. The printing ribbon 6 is guided by a tip 11 at the curved end 10 of a steel wire spring 8 before it is wound onto a guide 13 and traverses an optical character reader 14.
pass around.

When the ribbon 6 is pulled by the drive means 7 on the take-up spool 5, the tension in the ribbon on the curved end 10 tends to open the wrapped portion or loop of the brake 31, preventing the ribbon 6 from being unwound. Make it. To stop the drive means 7, the loop of the brake 31 cooperates with the hub means 12 to brake the supply spool 5.

The optical character reader 14 is intended to detect the end of the ribbon 6 and includes a light source 15, a photoelectric detector 16 and a light guide 17. light source 1
5 and the detector 16 are fixed on the typewriter, while the light guide 17 is integral with the bottom 2 of the case 1 of the cassette.

Light guide 17 includes two prismatic light guides 18 and 19. The upper ends of the two guides 18, 19 present two surfaces oriented at substantially 45 degrees to the axis of said guides in a manner that reflects light from one of the guides to the other. The printing ribbon 6 is connected to the guide 1
It passes between the two upper surfaces of 8 and 19. It is usually opaque but has transparent edges. When this transparent end reaches the optical character reader, the light beam coming from the light source 15 is transmitted by the ribbon to the other guide 19 and reaches the photodetector 16.

The photoelectric detector then, after suitable amplification, acts on a part of the interpreter (not shown) on the one hand and thus makes it possible to stop printing, and on the other hand acts on a part of the interpreter (not shown) and on the other hand acts on a part of the interpreter (not shown). ) It emits a sensitive signal of acting on the body.

The case 1 includes two extensions 20 and 21, the ends of which are open and have guide members 22 and 2.
It has 3. The part of the ribbon 6 located outside the case 1 between the guide members 22 and 23 is intended to be engaged in the fork of a typewriter guide ribbon (not shown) provided for receiving the cassette. has been done. The ribbon then passes onto the guide member 24 and is wound onto the take-up spool 5. The cassette includes a blocking mechanism 25 forming part of the take-up spool 5 and intended to prevent unwinding of the spool when the cassette is withdrawn from the typewriter. This blocking mechanism consists of teeth 28 of a gear 29 which is angularly integral with the take-up spool 5.
includes a lever 26 including a tip 27 intended to engage between the levers 26 and 26; The lever 26 is made of an elastic material, such as synthetic resin, and is integral with the bottom 2 of the case 1. The lever 26 is arranged in such a way that it supports the tip 27 in a flexible manner relative to the teeth 28. When the cassette is mounted on a typewriter, a finger 30 integral with the cassette tightening mechanism on the typewriter (not shown) engages the lever 2.
6 allows the tip 27 to be removed from the tooth 28 against the tension exerted by the tooth 28. For this purpose, the case 1 includes openings 32 for the passage of the fingers 30. The lever 26 is connected to this opening 3.
2 and extends through the center of the opening 32.

It will be understood that the embodiments described above are not limiting in nature and that numerous embodiments may be made without changing the essence of the invention.

[Brief explanation of drawings]

FIG. 1 is a plan view with the cassette opened to show the various elements containing the cassette. FIG. 2 is an exploded side view taken in the direction of arrow B in FIG. FIG. 3 is a sectional view taken along line CC in FIG. 1. FIG. 4 is a sectional view taken along line DD in FIG. 1. DESCRIPTION OF SYMBOLS 1... Case, 4... Supply spool, 5... Winding spool, 7... Drive means, 25... Blocking mechanism, 26... Blocking lever, 27... Tip, 28...
...teeth, 29...gear, 30...finger, 31...
Brake, 32...opening.

Claims (1)

[Claims] 1 having a case, a supply spool, and a take-up spool in the case, wherein the supply spool is wound with a ribbon, the take-up spool receives the used ribbon, and the ribbon is engaged with the take-up spool. and a supply spool brake means for creating ribbon tension between the two spools to prevent unraveling of the take-up spool when the cassette is withdrawn from the typewriter. Printing for use in typewriters, comprising a closing mechanism for a take-up spool, said closing mechanism comprising a closing lever with a tip resiliently engaging between the teeth of a toothed wheel. In a ribbon cassette, the toothed wheel is integral with the take-up spool, the closure lever is integral with the case, and the fingers are adapted to remove the tip from the teeth when the cassette is installed in a typewriter. provided in a typewriter, said lever having a freely exposed part for cooperating with said fingers, said case having an opening for the passage of said fingers, and said closing lever said A cassette for printing ribbon for use in a typewriter, characterized in that it is integral with the edge of the opening and extends over the opening.