Printing Device

1. Field of the Invention

The present invention relates to a printing device capable of detecting information such as an end point of and several species of.

2. Description of the Prior Art

The ink ribbons employed in the printing devices have different feeds according to the species of ribbon. A so-called one-time typing ribbon can be used only once and is fed each time by an amount approximately equal to one character. On the other hand so-called multiple typing ribbon is usable several times and is advanced each time by an amount corresponding to 1/2 to 1/3 of one character. For this reason a printing device designed for using these different species of ink ribbons needs to have an adjustable feed for the ink ribbon, and there also is required a means for detecting the species of the ink ribbon.

Also when using an ink ribbon it has been necessary to detect a suitable changing time for the ink ribbon, for example the arrival time of an end point of ink ribbon at the printing position, in order to maintain a satisfactory print quality. In this manner the conventional printing devices utilizing ink ribbons have required the detection of a plurality of information concerning the ink ribbon. Thus, these devices have required plural detecting means, which leads to a larger sized device and a higher cost for making the device. Besides such detecting means, which usually are composed of contact-type elements such as microswitches, are unstable and usually result in a complicated structure.

The object of the present invention is to provide a compact and inexpensive printing device.

Another object of the present invention is to provide a printing device in which one detecting means is capable of detecting a plurality of information of the ink ribbon.

Still another object of the present invention is to provide means capable of detecting the information on the ink ribbon.

Still another object of the present invention is to provide means for shifting a cassette case so as to detect different information of the ink ribbon at the printing position and at a position for confirming that printing has been completed.

FIG. 1 is a schematic cross-sectional view of a printing device embodying the present invention; and

FIG. 2 is a perspective view of ink ribbon detecting means.

FIG. 1 is a schematic view of a printing device embodying the present invention wherein there are shown a platen 1, a daisy-wheel type printing wheel 2, a hammer 3, a cassette 4 housing an ink ribbon 5. In the non-printing state shown in FIG. 1, the cassette 4 is in the full-lined position below the printing position in order to allow easy confirmation of the obtained print by the operator. A plate member 6 detachably supporting the cassette is rotatably supported by a shaft 7 fixed on an carriage (unshown) of the printing device. A magnetic solenoid 8 drives a plunger 8a to determine the position of said ink ribbon. There is also provided a detector 9 composed of a reflective photointerrupter for detecting the end point of the ink ribbon and for identifying the species thereof.

At the printing operation the solenoid 8 is energized to rotate the plate member 5 and cassette 4 about the shaft 7, whereby said cassette is lifted to a double-dotted chain line 4'. After the printing action with the hammer 3, the ink ribbon is advanced while the cassette is still lifted. The ink ribbon advancement is achieved by an unrepresented stepping motor. After the ink ribbon advancement the solenoid 8 is deactivated to return the cassette rapidly to the full-lined position 4 to enable the confirmation of the obtained print, but the cassette may also be retained in the lifted position to enter the succeeding print operation if the succeeding print signal is supplied in continuation.

FIG. 2 shows a detector positioned inside a ribbon guide arm of the ribbon cassette, wherein said guide arm is provided with an indicating aperture 4b through which the ink ribbon 5 is directly visible. The ink ribbon 5, of normally black color, is provided with a reflective metal foil at the end points thereof whereby the detector 9 is capable of detecting the change in the reflective light. Above the indicating aperture 4b formed is a species indicating area 4c which indicates the species of the ink ribbon, for example by a black tape for a one-time ribbon or by a reflective tape for a multiple ribbon.

When the cassette is retained at the full-lined position 4 in FIG. 1 below the printing position, the detector 9 is positioned to face the indicating area 4c to identify the species of the ink ribbon used, so that an unrepresented control circuit regulates the number of pulses supplied to the stepping motor according to an output signal from said detector 9. When the ribbon cassette is lifted to the position 4' in the printing operation, the detector 9 faces the aperture 4b to detect the state of the ink ribbon. When the reflective metal foil which indicates the end point of the ink ribbon, appears in said aperture 4b, the detector 9 transmits the corresponding information to the control circuit, which immediately interrupts the printing operation and gives a warning to the operator to change the ink ribbon.

In this manner the printing device of the present invention indentifies the species of the ink ribbon merely by attaching a black tape or a reflective tape to the ribbon cassette, and assures reliability since the detector is maintained contact-free even during the exchanging operation of the ink ribbon.

As explained in the foregoing, the present invention, which identifies the information concerning ink ribbon such as the end point thereof and the species of ink ribbon by means of a single detecting means, is featured by a simple structure which permits compactization and a cost reduction of the device.

It will be apparent from the foregoing explanation that a same effect can be obtained by shifting, instead, the detecting means so as to face different indicating areas.