DD251253A3 - DEVICE FOR TURNING AND TILTING A THERMAL PRINT HEAD FROM THE PRESSURE PEN - Google Patents

Abstract

The invention relates to a thermal printer with a pivotable about an axis print head carrier. With the aim of being able to clean the printhead without disassembly, the object is to ensure a wide pivoting of the printhead. Geloest the task is characterized by - that a lever 7 is pivotally mounted on the axis 6 of the Druckkopfftraegers 3, which rests with a nose 21 during the pivoting movement on the print head 3, -that on the base plate 11 of the frame a pawl 9 is pivotally mounted, which rests by the action of a spring 19 in the rest position against a stop 13, that the pivoting area b of an arm 12 of the lever 7 projects into the pivoting area a of the pawl 9 and that the pawl 9 during the printing position of the print head 3 on a cylinder pin 15th the print head 3 rests and thus keeps him in print position. Fig. 1

Description

For this 2 pages drawings

Field of application of the invention

The invention relates to a device for pivoting on and off a thermal print head with a pivotable about an axis print head carrier.

Characteristic of the known technical solutions

Some of the known thermal printers are provided with devices which serve to pivot the printhead off the platen to ensure better registration of the paper or print transfer medium to be printed. In the printer shown in US-PS 4,170,422, for example, by printing on a bar (47) a slight lifting of the print head, limited by an axis (29), take place. In the example shown in EP-PA 0094469, the - likewise slight - lifting of the print head is effected by a lever (25), wherein a cam (22) located on a shaft is the leg of a torsion spring, which is in communication with the print head, raising. In the printer shown in DE-OS 3226194 lifting takes place by pressing a lever (15), whereby two located on the print head frame locking pins (24) from a first detent position (print position) in a second detent position (Abschwenkstellung) reach and the print head in a small distance from the pressure roller is held.

The known devices thus have the disadvantage that they do not allow further pivoting of the pressure roller in order to perform a quick cleaning of the print head without disassembly can. In the example of DE-OS 32 26194 also by the heat transfer belt (13) the view and the access to the print head is blocked.

Object of the invention

It is an object of the invention to allow easy cleaning with field of view of the printhead without disassembly.

Explanation of the essence of the invention

Technical task

The invention has for its object to provide a device for wide pivoting of printheads of the platen to allow good visibility and access to the print head for cleaning purposes or the like.

Features of the invention

The task is solved by

- That a lever is pivotally mounted on the axis of the print head carrier, which rests with a nose during the pivoting movement on the print head carrier,

- That on the frame a pawl is pivotally mounted, which bears by the action of a spring in the rest position against a stop,

- That the pivoting range of an arm of the lever protrudes into the pivoting range of the pawl and

- That the pawl rests against a nose of the print head carrier during the printing position of the print head carrier and thereby keeps it in print position.

Advantageous embodiments will become apparent from the dependent claims.

embodiment

The invention will be explained below using an exemplary embodiment. In the accompanying drawing show:

Fig. 1: a perspective view of the device according to the invention Fig.2a-d: the movement during pivoting of the print head.

The embodiment shows a thermal printer, the print head 1 (Fig. 1) rests during the pressing on the pressure roller 2 with the necessary pressure force. The print head 1 is resiliently attached to a print head carrier 3. The details of the printhead attachment will not be discussed here. The print head carrier has two wings 4; 5, through whose bores a frame-fixed axis 6 extends. About this axis 6 of the print head carrier 3 with the print head 1 is pivotable. On the same axis 6 is a lever 7. By the bent tongue 8 of the print head carrier 3, which projects into the U-shaped bent lever 7, the lever 7 - apart from a minor game - no longer relative to the print head carrier 3 on the Axis 6 are moved.

On the frame, a pawl 9 is arranged, which is mounted with its cutting edge 10 in the base plate 11 of the frame. In the rest position (FIG. 2 c), the pawl 9 bears against a stop 13 of the base plate 11 under the action of the tension spring 19. As a result of the knife-edge bearing, the pawl 9 can be pivoted about the axis indicated by the line 22 (FIG. 1). Her swivel range a (Fig.2c) protrudes into the pivoting range b of an arm 12 of the lever 7.

Figures 1 and 2a show the print head 1 in printing position. In this case, the pawl 9 is engaged, i. it lies with its edge 14 under a cylindrical pin 15, which protrudes from the print head carrier 3, and thus holds the print head carrier 3 against the action of the resilient attachment of the print head 1 on the print head carrier 3 and a leg spring 16 in the printing position. In this case, the arm 12 of the lever 7 rests against a lug 17 of the pawl 9.

The sequence of movements when pivoting the printhead show the figures 2a to 2c. The operator pivots the lever 7 in the clockwise direction. A corresponding handle is provided in the form of the web 18 of the lever 7. In this case, the lever arm 12 pivoted in his sliding over the inclined plane of the projection 17, the pawl 9 against the action of the tension spring 19. The pawl 9 moves away from the print head carrier 3 (Fig. 2 b) until it releases the cylindrical pin 15. Now, the print head carrier 3 can be swung with the print head 1. The leg spring 16 supports the Abschwenkbewegung and keeps the print head in the pivoted position (Figure 2c), with their legs are supported on the one hand on the print head carrier 3 and on the other hand on the frame 20. The pivoting is of course possible without leg spring 16, but the print head is then not held in the end position of the pivoted-down position.

When pivoting the print head lan the pressure roller 2, the lever 7 is pivoted by pressing on the web 18 in the counterclockwise direction. In this case, the nose 21 of the lever 7 applies to an edge of the print head carrier 3. As a result, the pivoting movement of the lever 7 is transmitted to the print head carrier 3. The pivoting movement is completed and the printing position is reached when the pawl 9 with its edge 14 again placed under the cylinder pin 15 of the print head carrier 3

The wide pivoting of the print head 1 allows a very good visual inspection and cleaning of the front of the printhead without disassembly of the head.

Claims (2)

1. Device for pivoting on and off a thermal print head from the printing drum with a swivelable about an axis print head carrier, characterized thereby, - That a lever (7) is pivotally mounted on the axis (6) of the print head carrier (3) which bears with a nose (21) during the pivoting movement on the print head carrier (3), - That on the frame a pawl (9) is pivotally mounted, which rests by the action of a spring (19) in the rest position on a stop (13), - That the pivoting range (b) of an arm (12) of the lever (7) in the pivoting region (a) of the pawl (9) protrudes - And that the pawl (9) during the printing position of the print head carrier (3) against a nose (15) of the print head carrier (3) and thereby keeps it in Druckstetlung. 2. Apparatus according to claim 1, characterized in that for holding the print head carrier (3) in the pivoted position, a about the axis (6) wound leg spring (16) is provided, whose legs on the one hand to the print head carrier (3) and on the other hand (20) are present.