CARRIAGE MECHANISM OF PRINTER

Abstract: A carriage mechanism of a printer comprising a carriage frame (1); a print circuit board (4) mounted on said carriage frame (1) and having an exposed portion of wiring (5) and a plurality portion of guide holes (6); a cable (11) having an exposed portion of wiring (12) at one end thereof, said exposed portion of wiring (12) being elecrically connectable with said exposed portion of wiring (5) of said print circuit board (4); an inked ribbon feed mechanism (7) mounted on said carriage frame (1), said inked ribbon feed mechanism (7) having guide projections (9) to be inserted in said holes (6) and a plurality of elastic hooks (10) for fastening said carriage frame (1) said guide projections (9) and a plurality of elastic hooks (10) respectively are provided on reverse side of said inked ribbon feed mechanism (7); a cable fixing mechanism having a flexible film (16) connected to a movable body to be superimposed over the end of the flexible cable (11) and fixed thereto, one end of the flexible film (16) is shaped as the end of the flexible cable (11) and the other end is progres­ sively narrower to its end and projects toward folded portion of the flexible cable (11) as a free end.

Description: The present invention relates to a printer for printing characters and symbols, etc., on a printing medium while moving a carriage having a printing head thereon in the printing line direction. Various types of printers are employed in information processing and business machines. One type of these printers has come to be frequently employed in recent years wherein a printing head having many printing wires thereon almost perpendicularly to the direction of a printing line is mounted on a carriage and travels in the printing line direction so that character data are printed on a printing medium one by one line. This type of printer can be miniaturized and made light-weight as well as be available at a low price. The printer selectively strikes a printing medium with a printing wire via an inked ribbon for printing. A carriage of the printer having thereon an inked ribbon case including the inked ribbon therein as well as a printing head including printing wires thereon is moved in the printing line direction, while the printing medium is properly fed substantially perpendicularly to the printing line direction. Although the carriage is moved in the printing line direction by use of a toothed belt and a screw shaft, another type of carriage, called a self-propelled carriage mechanism, with use of a rack and a pinion has begun to be profitably employed, which has a driving source for moving the carriage itself. Such a self-propelled carriage mechanism, as disclosed in,for example,USP No.4,526,486, comprises in general an inked ribbon feed mechanism mounted on a carriage frame, and a flexible cable connected with this mechanism, including a motor for self-propelling located on the lower surface of the carriage frame, pinions attached to both ends of a shaft of the motor, a lower one of the pinions being engaged with a rack mounted on a printer frame for self-propelling while an upper one thereof engaged with a gear of the inked ribbon feed mechanism for feeding an inked ribbon. Namely, the self-propelled carriage mechanism is such arranged that a movable body is connected with a flexible cable. Such arrangement is assured by putting the inked ribbon feed mechanism on the carriage frame, fixing them with screws, and inserting a plug of the flexible cable into a socket provided on the carriage frame for electrical connection. Moreover, although a ribbon cable is also employed, it shall be termed flexible cable. However, with this type of carriage mechanism, an inked ribbon mechanism placed on a carriage frame must be screwed up in assembling a printer to integrally fix them. For this, alignment of tapped holes with screws is required together with screwing of screws into the tapped holes. Namely, in a line process of automatic assembly, such operations as longitudinal and transversal positioning of tapped holes and screws, insertion of the screws into the tapped holes, and turning the screws are needed. These operations are complicated along with the line getting intricate because of many working processes required therefor. Furthermore, also upon inserting the socket into the plug, they must be aligned with each other for the insertion operation thereafter. Thus, it is likewise complicated. In addition, the prior carriage mechanism has another trouble wherein repetitive bending operations of a flexible cable due to reciprocating movement of the carriage causes bending stress to be concentrated in the vicinity of a connecting portion between the flexible cable and the plug. As a result, a conductor pattern is sharply deteriorated and disconnected near the connecting portion. A further carriage mechanism of a printer which is to be assembled by means of screws is disclosed in EP-A-0 117 090. DE-A1-29 13 683 discloses a carriage for a typewriting machine where the parts of the carriage are aligned by means of guide pins and fixed to each other by means of locking levers. It is an object of the present invention to provide a carriage mechanism of a printer capable of assembling parts by having access thereto in the prescribed direction. Another object of the present invention is to provide a carriage mechanism of a printer capable of simplifying an assembly line with extremely simple assembly operation for reducing the assembly operation and the time required therefor. Still another object of the present invention is to provide a carriage mechanism of a printer capable of effecting wiring and assembly of an inked ribbon feed mechanism onto a carriage frame only with a vertical operation from the upper to the lower portion. A still further object of the present invention is to provide a carriage mechanism of a printer capable of securely connecting wiring. A still further object of the present invention is to provide a carriage mechanism of a printer capable of reducing the costs for assembly thereof because the number of parts and the times of assembly operations can be decreased. Still another object of the present invention is to provide a carriage mechanism of a printer capable of reducing bending stress concentrated in the vicinity of a connecting portion between the flexible cable and the movable body and thereby preventing a conductor pattern in the vicinity of the connecting portion from being disconnected. To achieve the above objects, a carriage mechanism according to the present invention has an inked ribbon feed mechanism molded with synthetic resin including guide projections provided on the lower surface thereof and a plurality of hooks projected on the circumference thereof, a carriage frame including guide holes made at positions corresponding to the guide projections and a printed circuit board provided thereon with wiring exposed to the outside at an end of the printed circuit board, and a flexible cable with wiring exposed in its end. Accordingly, the guide projections of the inked ribbon feed mechanism are vertically lowered so as to be aligned with the guide holes of the carriage frame, and the hooks are engaged with the peripheral edge of the carriage frame by making use of elasticity of the hooks, while the exposed portion of the wiring of the flexible cable are put on the exposed portion of the wiring of the printed circuit board on the carriage frame for electrical connection. Further, a carriage mechanism according to the present invention employs a flexible film, an end of film is formed in substantially the same way as the shape of the end of the flexible cable, and the other end of the films is progressively narrower at its end, an end of the film is superimposed over an end of the flexible cable connected with movable body and fixed thereto, the other end of the film is projected to the direction of folded portion of the flexible cable as a free end. Accordingly, with the reciprocating movement of the movable portion, the flexible cable is gently bent because the upward movement of the cable is suppressed by the film, for thereby reducing bending stress concentrated in the vicinity of a connecting portion between the flexible cable and the movable body and thereby preventing a conductor pattern in the vicinity of the connecting portion from being disconnected. The present invention will be described with reference to the accompanying drawings, in which common elements are affixed to the same numerals. Fig. 1 is a perspective view of the portion of the self-propelled carriage mechanism mounted on the printer according to an embodiment of the present invention. Fig. 2 is an exploded perspective view of the self-propelled carriage mechanism of the embodiment of the present invention. Fig. 3 is a further exploded perspective view of the self-propelled carriage mechanism of the embodiment of the present invention. Fig. 4 is an exploded perspective view of another embodiment of the present invention. Fig. 5 is a view showing a status of the connection portion between the flexible cable and the movable body according to another embodiment of the present invention. Fig. 1 shows a main portion of the printer, Fig. 2 is an exploded view of an self-propelled carriage mechanism, Fig. 3 is a further exploded perspective view of the carriage mechanism. In these figures, a carriage frame 1 has a motor (as shown in Fig. 5) in the reverse surface thereof, an end of the shaft of the motor projects over the surface of the frame carriage, and has a pinion 2 at its end, the other end of the shaft of the motor has a pinion (not shown) for travelling which is opposed to a roller mounted on the reverse surface of the carriage frame 1. The carriage frame 1 travels by the roller and the pinion while a rack 3 is interposed. A printed circuit board 4 is mounted on the upper surface of the carriage frame 1 on the end of which exposed portion of wiring are formed. Designated at 6 are a plurality of guide holes penetrating the carriage frame 1 and the printed circuit board 4 and opposite to the exposed portion of wiring at one end of the printed circuit board. A ribbon case 8 having an inked ribbon and a gear taking up the ribbon is detachably mounted on an inked ribbon feed mechanism 7 integrally molded with synthetic resin, the gear is connected with a manual knob 81 for taking up the ribbon and engaged with a shaft 71 of the inked ribbon feed mechanism 7 so that the inked ribbon is taken up by engagement of the pinion 2 and the gear via a gear accomodated in the inked ribbon feed mechanism 7. A reverse side of the inked ribbon feed mechanism 7 has a guide projection 9 at the position opposite to the guide hole 6 of the carriage frame 1. Designated at 10 is a plurality of hooks provided at the lower end of the inked ribbon feed mechanism and v-formed at the peripheral side surface thereof and slightly expandable outwardly by its resiliency. The flexible cable 11 has an exposed portion of wiring 12 and the holes 13 for inserting the guide projection 9 are provided at both ends of the exposed portion of wiring 12. A mat 14 made of silicon, rubber or the like for uniformly pressing the exposed portion of wiring 12 of the flexible cable 11 is engaged with the guide projection 9. A printing head 21 is mounted on the carriage frame 1 by a means (not shown) and is disposed to be inserted into the hollow portion of the ribbon case 8. The carriage frame 1 is fixed to the cylindrical fixed portion 22 which is slidably mounted on a guide shaft 23. As the guide shaft 23 is provided in parallel with a platen (not shown), the carriage frame 1 travels with the platen, namely, to the direction of the printing line. A printing medium 24 is urged by a pressure roller 26 to the platen (not shown), fed appropriately in the perpendicular direction to the direction of the printing line with the rotation of the platen. When the printing medium 24 is wound over or set to the platen, the roller 26 is remoted from the platen by operating a cam 27. When printing at the prescribed position of the printing medium 24, the printing medium 24 is set with use of the gauge of the column indicator 25. Assemblage and operation of the carriage mechanism are described as follows: The projection 9 of the inked ribbon feed mechanism 7 is previously inserted into the hook hole 15 of the mat 14. The hole 13 of the flexible cable 11 is fitted over the guide hole of the carriage frame 1 and the inked ribbon feed mechanism 7 is superimposed over the carriage frame 1, the guide projection 9 is guided and inserted into each of the guide holes 6. At the same time, the hook 10 is held by the peripheral side corner of the carriage frame 1 with use of its elastic force so that the tip end of hook 10 is expanded in the form of an L whereby the inked ribbon feed mechanism 7 is integrally engaged with the carriage frame 1, at the same time, the flexible cable 11 is fixed. Accordingly, the wire exposed portions 5, 12 of the printed circuit board and the flexible cable 11 are layered and electrically connected with each other. As a result, it makes it possible to assemble the wire connection and the carriage frame with the inked ribbon feed mechanism only by the process of vertical operation from the upper portion to the lower portion omitting the operation of positioning of screws forward, backward, left and right, further by the rotation of the screws in all directions. The assembly line is simple and the operation and the time for assemblage is reduced. Further the parts to be assembled is reduced to thereby provide the mechanism with low cost. Fig. 4 is an exploded view showing another embodiment of the self-propelled carriage mechanism of the present invention. A film 16 is provided in this embodiment in addition to the mat 14 in the first embodiment, an end 17 of the film 16 is formed in the same shape as the end portion, an exposed portion of wiring 12 of the flexible cable 11. The elongated hole 19 is provided at the end 17 and the other end 18 is progressively narrower to its end. The end 17 of the film 16 is superimposed over the end of the flexible cable 11 and jammed between the mat 14 and the exposed portion of wiring 12 and fixed thereto, and the other end 18 projects to the direction of folded portion of the flexible cable 11. The elongated hole 19 provided on one end 17 of the film 16 acts to force the mat 14 to be pressed by the inked ribbon feed mechanism 7 so that the mat 14 has directly contact with the flexible cable 11, whereby each terminal of the flexible cable 11 is uniformly pressed and connected with the terminal of the printed circuit board. Operation of the second embodiment is described with reference to Fig. 5. In these figures, each element is briefly illustrated for easy explanation. When a motor 20 is normaly rotated, the printed circuit board 4 is moved with the carriage frame 1 in the direction of the arrow a as shown in Fig. 5(a) during operation of pinion 2 and rack (rack 3 as shown in Fig. 4). In the connecting part of the flexible cable 11 and the printed circuit board 4, namely, portion A is bent downwardly as the conventional one. On the other hand, when the motor 20 is reversely rotated, the printed circuit board 4 and the carriage 1 is rotated in the direction of the arrow b as shown in Fig. 5(b), the portion A of the flexible cable 11 tends to bent upward. The flexible cable 11 is not bent upward because the movement of bending upward is suppressed by the film 16 located above the portion A. Further, as the film is progressively narrower to its end, the flexible cable 11 is gently bent at the other end 18 for thereby permitting the bending stress applied to the portion A of the flexible cable 11 to be reduced. According to the second embodiment, one end 17 of the film 16 is inserted and fixed between one end of the flexible cable 11 and the mat 14. When the terminal of the flexible cable 11 and the printed circuit board 4 is connected by welding, the end 17 of the film 16 is superimposed over the end of the flexible cable and fixed thereto for thereby omitting the elongated hole 19 as shown in Fig. 4 because of disuse of the mat 14. Although the carriage mechanism is a self-propelled type driven by the motor accomodated therein as a movable body fixing the flexible cable 11, the effect is achieved by the mechanism having the movable body being electrically connectable. Further, a shape of the film 16 is not limited to substantially pentagon at the portion,except the end 17. The shape is well enough to be triangle, semicircular or semi-elliptical if the end 18 is progressively narrower in the end.

Claims: A carriage mechanism of a printer comprising a carriage frame (1), an inked ribbon feed mechanism (7) mounted on said carriage frame (1), and a cable (11), characterized in that (a) a printed circuit board (4) is mounted on said carriage frame (1) and has an exposed portion of wiring (5) and a plurality of guide holes (6); (b) said cable (11) has an exposed portion of wiring (12) at one end thereof, said exposed portion of wiring (12) being electrically connectable with said exposed portion of wiring (5) of said printed circuit board (4); (c) said inked ribbon feed mechanism (7) has guide projections (9) to be inserted in said holes (6) and a plurality of elastic hooks (10) for fastening said inked ribbon feed mechanism (7) to said carriage frame (1); said guide projections (9) and said plurality of elastic hooks (10) being respectively provided on the reverse side of said inked ribbon feed mechanism (7); wherein said inked ribbon feed mechanism (7), said cable (11), said printed circuit board (4) and said carriage frame (1) are in turn layered. A carriage mechanism of a printer according to claim 1, wherein an elastic mat (14) is disposed between said inked ribbon feed mechanism (7) and said cable (11). A carriage mechanism of a printer according to claim 1, wherein said cable (11) is flexible. A carriage mechanism of a printer according to claim 1, further including a flexible film (16) provided between said end of the cable (11) and a mat (14), one end of said film (16) being of the same shape as the end of the cable (11) and being superimposed over the outer surface side of the folded portion of said cable (11), and the other end of said film (16) being progressively narrower to its end and being projected to the direction of the folded portion of said cable (11) as a free end. A carriage mechanism of a printer according to claim 4, wherein said cable (11) is flexible.

Inventors: HAYASHI, KUNIHARU C/O OKI ELECTRIC IND. CO., LTD., KIKUCHI, HIROSHI C/O OKI ELECTRIC IND. CO., LTD., MAEKAWA, MASANORI C/O OKI ELECTRIC IND. CO., LTD., OBARA, KAZUKI C/O OKI ELECTRIC IND. CO., LTD., OTA, YUKIO C/O OKI ELECTRIC IND. CO., LTD., WATANABE, SHYOICHI C/O OKI ELECTRIC IND. CO., LTD.
Applicants: OKI ELECTRIC INDUSTRY COMPANY, LIMITED
Application year: 1986
Main classification: B41J19
IPC codes: B41J19