Carriage Supporting Device for a Printer

The present invention relates to a device for supporting a carriage for a printer, such as a dot matrix printer as an output device of a computer system, in which the carriage is reciprocated so that a print head mounted thereon moves along a platen for performing the printing operation.

FIG. 1 shows a conventional device for supporting a carriage in a printer. The carriage device comprises a base plate 6 of a frame 6b, a carriage guide bar 2 supported on the frame 6b and disposed in parallel with a platen 1 rotatably supported on the frame. A carriage 3 having a print head 5 mounted thereon is slidably mounted on the guide bar 2 at the front end portion thereof. The base plate 6 has an upright portion 6a to which a guide plate 7 is secured by screws 8, an end of the guide plate 7 being projected from the upright portion 6a towards the carriage 3. A pair of rollers 9 and 10 are provided on a bending portion 3a formed on the rear end of the carriage 3, engaging with the projected end of the guide plate 7 at both sides thereof, so that the carriage is supported so as to move along the guide bar 2 and guide plate 7.

However, in such a carriage supporting mechanism, the structure is complicated and the carriage has a complicated shape, which results in increase of parts and of the step of assembling process. Further, the flexual rigidity of the base plate 6 is insufficient.

The object of the present invention is to provide a carriage supporting device for a printer which is simple in structure and may improve the flexual rigidity of a base plate in the device.

According to the present invention, there is provided a carriage supporting device for a printer comprising: a base plate, a guide bar supportedon a frame, a guide portion formed at a rear portion of the base plate, the guide portion having an L-shaped section comprising an upright portion and a guide rail projecting outwardly, a carriage slidably mounted on the guide bar, a guide chip engaged with a connecting portion formed at a rear portion of the carriage, the guide chip having an engaging groove slidably engaged with the guide rail.

In an aspect of the present invention, the base plate is made of metal plate and the guide portion is formed by bending a rear portion of the base plate, and the guide chip is made of plastics. The guide chip has a J-shaped section to form the engaging groove and has a hole engaged with the connecting portion of the carriage.

These and other objects and features of the present invention will become more apparent from the following description with reference to the accompanying drawings.

FIG. 1 is a side view showing a conventional carriage supporting device, a part of which is shown in section;

FIG. 2 is a side view of a carriage supporting device for a printer according to the present invention, a part of which is shown in section; and

FIG. 3 is an exploded perspective view of the carriage supporting device of the present invention.

Referring to FIGS. 2 and 3, a carriage supporting device of the present invention is provided with the carriage guide bar 2 supported on the frame 6b and disposed in parallel with the platen 1 as hereinbefore described about the prior art as shown in FIG. 1. A base plate 16 of the present invention is made of metal plate and bent at a rear portion to form a guide portion 16c. The guide portion 16c comprises an upright portion 16a at the rear end portion and a guide rail 16b formed by bending an upper portion of the upright portion 16a to be outwardly and horizontally projected. Thus, base plate 16 has the guide portion 16c having an L-shaped section. A carriage 13 has a cylindrical portion 13b oriented in the axial direction of the guide bar 2 to be engaged with it, a body portion 13c extending from a central portion of the cylindrical portion 13b for mounting the print head 5, and a connecting portion 13d horizontally extended from the rear portion of the body portion 13c. A driving cable 11 is connected to both sides of the body portion 13c at both ends thereof, which is wound on a driving drum (not shown) for moving the carriage 13 along the platen 1. Engaged with the connecting portion 13d and with the guide rail 16b is a guide chip 12 made of plastics. The guide chip 12 has a J-shaped section comprising an upper horizontal portion 12a and a lower horizonal portion 12b and a connecting portion 15 in the form of a hole, formed in the upper horizontal portion 12a, having a rectangular cross section. Between the upper and lower portions 12a and 12b, an engaging groove 12c is formed the surface of which is made slippery.

As shown by an arrow in FIG. 3, the connecting portion 13d is inserted into the connecting portion 15 and engaged with the guide chip 12, and the guide portion 16b is inserted into the groove 12c. The guide rail 16b is slidably engaged with the surface of the groove 12c. Accordingly, the upper portion 12a of the guide chip 12 is integrally engaged with the connecting portion 13d of the carriage 13, while the upper and lower horizontal portions 12a, 12b are slidably engaged with the guide portion 16b of the base plate 16.

Thus, the carriage 13 is supported on the guide rail 16b by the engagement of the guide chip 12 with the connecting portion 13d and with the guide rail 16b of the base plate 16 at opposite side to the guide bar 2. In such a state, the carriage 13 is moved on the guide bar 2 and reciprocated along the platen 1 for performing the printing operation by the print head 5.

In accordance with the present invention, since a carriage supporting mechanism comprises guide rail 16b formed by bending base plate 16 and guide chip 12 engaged with the guide rail 16b, the structure is simplified and the number of parts are reduced. Further, the guide chip 12 can be easily assembled by engaging with the connecting portion 13d and the guide rail 16b. Moreover, the flexual rigidity of the base plate 16 is improved by the construction of an L-shaped section at the guide portion. Since the guide rail 16b is bent so as to outwardly project, the press work for forming the portion can be easily done by a simple press machine.

While the invention has been described in conjunction with preferred specific embodiments thereof, it will be understood that this description is intended to illustrate and not limit the scope of the invention, which is defined by the following claims.