Technical Field

The present invention relates to a printing apparatus and more particularly, but not exclusively, to a printing apparatus employing a dot matrix print head supported on a movable carriage which also supports circuit means for providing electrical power to the print head.

Background Art

It is known in the field of dot matrix printers to provide a print head carriage which is mounted for reciprocal movement along a horizontal direction. It is also known to provide a flat, flexible cable containing a plurality of leads or conductors for distributing power from an electrical source to a number of solenoid-type, print wire drive elements or actuators. The flexible cable is designed to have the source end stationary and to provide sufficient length of cable so that when the print head moves across the printer, a portion of the cable moves with the print head.

U.S. Patent No. 4,518,269 discloses a printer employing a print head having a flexible cable pressed between the core frame and the nose member of the print head.

One of the drawbacks of the above printer design is that considerable installation time may be required when replacing the print head. This arises because of the need to disconnect the flexible cable from the old print head and subsequently reconnect the flexible cable to the new print head. Furthermore care is required in the disconnection and reconnection process to avoid damage to connections on the print head.

A further drawback is that a sufficiently long length of flexible cable must be provided in order to couple the print head to the power source. In addition to the expense of the flexible cable care is required in guiding and securing the flexible cable to the carriage of the printer to provide a safe and suitable path for connection to the print head.

Disclosure of the Invention

It is an object of this invention to provide a design of printing apparatus which alleviates the above drawbacks and facilitates the installation or replacing of the print head.

Accordingly, the present invention provides a printing apparatus including a print head mounted on a carriage movable in a transverse direction, a first printed circuit member affixed to and extending from said print head, said first printed circuit member being coupled to flexible cable means for providing electrical power to said print head, characterized by a second printed circuit member supported by said carriage, said second printed circuit member having receiving means secured thereto for receiving one end of said first printed circuit member thereby forming an operable coupling between said first and second printed circuit members, and further characterized in that said flexible cable means is affixed at one end thereof to said second printed circuit member.

It will be appreciated that since, in a printing apparatus in accordance with the invention, the flexible cable is connected directly to a separate printed circuit member supported on the carriage rather than to a printed circuit member forming part of the print head, it is possible to employ a shorter length of flexible cable and to employ simple means for guiding the cable, thereby reducing cost. Also, since the printed circuit member forming part of the

print head is not connected directly to the cable, it is possible to use a relatively thin and inexpensive printed circuit card as this member.

Brief Description of the Drawings

An embodiment of the present invention will now be described by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a side elevational view of the print head and carriage assembly in accordance with one embodiment of the present invention;

Fig. 2 is an enlarged top plan view of the print head carriage with the print head thereon;

Fig. 3 is an elevational view taken on the line 3-3 of Fig. 1;

Fig. 4 is a sectional view taken on the line 4-4 of Fig. 2?

Fig. 5 is a view illustrating the printed circuit board with the conductor runs embedded therein; and

Fig. 6 is a perspective view of a printer.

Best Mode for Carrying Out the Invention

Prior to describing the structure in detail it should be noted that a printer in accordance with one embodiment of the present invention may be of a multi-function type that can accommodate a receipt, a journal and a slip or form which form consists of one or more parts. The printer can be set in one of five different modes of operation which includes printing a journal only, printing a receipt only, printing a receipt and a journal, printing a slip or form only, or printing a slip or form and a journal.

Referring now to the drawing. Fig. 1 shows a side elevational view of a print head carriage 20 supporting a print head 22. The print head 22 is shown in phantom lines to indicate that part of the

print head assembly which is removable or easily replaced. The carriage 20 includes bearing means in the form of a pair of front bearings 24 and 26 (Fig. 2) that are supported by and move along a guide rail or supporting shaft 28. A rear bearing 30 provides a journal and support for a guide rail or supporting shaft 32 that is parallel to the shaft 28. The guide rail or supporting shaft 28 is supported in suitable manner from side frames of a printer 29 (Fig. 6). The shaft 32 is likewise supported from side frames of the printer.

The print head carriage 20 is a molded part which may be made of Lexan material and is of unitary construction and of a complex shape to accommodate the many functions that the carriage is required to perform. The carriage includes a nose or front portion 34 of generally plate-like shape to support the nose portion 36 of the print head 22. The nose portion 34 of the carriage includes a pair of spaced hubs 38 and 40 for receiving and securing the print head 22. A projection 42 at the front of the nose portion 34 of the carriage 20 serves to guide the print head 22 when installing the print head and to maintain the nose portion 36 in position on the carriage. An upright plate portion 44 of the carriage 20 supports the nose portion 34 and connects a pair of bridging portions 46 and 48 that are integral with the front bearings 24 and 26. The bridging portions 46 and 48 are integral with and connect with a generally horizontal plate portion 50, the plate portion providing an opening 52 therein between the bridging portions 46 and 48 for receiving a lower portion of the print head 22.

The carriage 20 also includes a pair of downwardly extending arms 54 and 56 (Fig. 3) which support a printer circuit board 58 (Fig. 5) that provides electrical power to the print head 22. The

carriage 20 has a recess 60 formed therein at a location just rearward of the bearing portion 26 for receiving an end portion 62 (Fig. 5) of the printed circuit board 58. The other end 64 has recesses or cutouts 66 and 68 for engagement by tip portions or snaps 70 and 71 which support the end 64 of the board 58.

The printed circuit board 58 includes a receptacle or like device 72 secured to the top of the board for receiving a printed circuit card 76 of the print head 22. The receptacle 72 is permanently affixed to the end 62 of the board 58. The printed circuit card 76 is sandwiched between the nose portion 36 and the coil portion 78 of the print head 22.

The carriage 20 has a plurality of lugs or guides 80 integral with the plate portion 50 and spaced thereacross for the purpose of routing a flat, flexible cable 82 (Figs. 1, 2 and 4). The cable 82 is also permanently affixed to the printed circuit board 58, as seen in Fig. 4, and is trained through a passageway formed by a clamp or like element 84 and a guide or like element 86, both integrally formed or molded as a part of the carriage 20. The cable 82 is trained in a suitable path from the top of the plate portion 50 to a source 85 or like connection.

Fig. 5 shows the printed circuit board 58 with the layout and routing of the conductors or runs 88 which are embedded in the substate of the board. The conductors 88 are sufficient in number and arranged to accommodate a nine wire dot matrix print head and include a pair of common conductors. The illustrated runs 88 terminating at the right side of the portion 62 of the board 58 are provided for accommodating a nine wire print head.

In the practice of the embodiment, and assuming that the print head 22 is being assembled to the carriage 20, or that a print head 22 is being

replaced, the printed circuit board 58 is placed into the recess 60 of the carriage while the end 64 is held in a lowered position (Fig. 1). The board 58 is then raised up and the edges of the board, at cutouts 66 and 68 thereof (Fig. 5), engage the angled surfaces of the tip portions or snaps 70 and 72. The cantilever- type arms 54 and 56 are sprung outwardly to receive the printed circuit board 58 and then are sprung back with a snap action to contain the board in a secure manner.

The receptacle 72 is thereby positioned to receive the printed circuit card 76 when the print head 22 is lowered into place between the hubs 38 and 40 and onto the plate portion 34 of the carriage 20 for securing the print head.

It is thus seen that herein shown and described is a carriage on which is installed a dot matrix print head that has a self-contained printed circuit card for simple and convenient assembly. The printed circuit card is received in a receptacle that is affixed to a printed circuit board. A flat, flexible cable is affixed to the printed circuit board.