GB2159770A

GB2159770A - Thermal printer

Info

Publication number: GB2159770A
Application number: GB08504798A
Authority: GB
Inventors: Donald Hardy
Original assignee: Control Systems Ltd
Current assignee: Control Systems Ltd
Priority date: 1984-03-10
Filing date: 1985-02-25
Publication date: 1985-12-11
Also published as: GB2159770B; GB8504798D0

Abstract

This invention is concerned with a thermal element print unit comprising a print head embodying a plurality of heat elements arranged in linear formation and adapted to be selectively energised, means for feeding a web of thermo-reactive paper past the print head, an electrical connection for the print head and a series of control circuits for controlling the selective energisation of the print heads wherein the print heads are mounted in a pivoted cover so that the thermal elements may be readily moved away from the web of paper for cleaning and other purposes.

Description

SPECI FICATION Improvements in or relating to print units This invention has reference to print units and has particular reference to print units having a line of thermal elements which are selectively energised. The invention has particular reference to such print units embodied in a ticket printing and issuing machine. These thermal elements are positioned on one side of a web of thermo reactive paper to be printed on and a drive roller is provided on the other side of the web, that is to say, the roller is on the opposite side of the web to that on which the elements are located. Marks are thermally induced on the face of the paper corresponding to the elements which are energised.It is arranged that the paper web is fed between the elements and the roller and the elements are selectively energised in a repetitive pattern so that an impression of a character is built up by thermal inducement of the elements on the paper as the paper is fed past the elements. (A typical printer is described by way of example in British Patent Specification No. 1547984). Printers of this kind are inclined to have the disadvantage that the elements are difficult to keep clean. Moreover such elements tend to be inaccessible because of the difficulty of having the elements arranged in close proximity to the web of paper and associated drive roller.

It is an object of the present invention to provide an improved thermal element print unit.

It is a further object of the present invention to provide an improved thermal element print unit in which the heat elements are arranged to be accessible for cleaning and other purposes.

According to the present invention a thermal element print unit comprises a print head embodying a plurality of heat elements arranged in linear formation and adapted to be selectively energised, means for feeding a web of thermo relative paper past the print head, an electrical connection for the print head, a series of control circuits for controlling the selective energisation of the print heads wherein the print heads are mounted in a pivoted cover so that the thermal elements may be readily moved away from the web of paper for cleaning and other purposes.

A thermal element print unit in accordance with the present invention will now be described by way of example with reference to the accompanying drawings wherein; Figure I is a plan view of a print unit; Figure 2 is a side view of the print unit shown in Fig. 1; Figure 3 is a side view of the cover; Figure 4 is a perspective view of a print head with a connection; Figure 5 is a view of a print head; Figures 6 and 7 are circuit diagrams, and Figures 8 and 9 are typical input and output driver circuits respectively.

Referring to Figs. 1 and 2 of the drawings there is shown a thermal element print unit more particularly comprising part of a ticket printer for use typically on a ''one man bus'' ticket printing machine application and may comprise part of a ticket printing mechanism as described in pending European Patent Application No. 823002829 (0057080) or pending British Patent Application No.

8311049. As shown the thermal element print unit comprises a chassis 1 with a cover 2 pivoted to the chassis 1 by a hinge 3 (Fig.

2). This hinge is located at the rear of the cover 2. The cover 2 carries a print head 4 including a line of thermal elements 5. The thermal elements are arranged to be selectively energised so that the selected elements create a dot on the thermo reactive paper and the selected dots continue to make up a number of letters or symbols as required. A web of thermo-reactive paper is fed from a roll 6 along a web-guide 7 and over a platen roller 8, rotation of which feeds the paper web. The web is shown diagrammatically in chain dotted lines in Fig. 2. The paper web is fed over a bracket 9 (shown in Fig. 2.) away from the line of feed of the paper because the cover is shown partly open.A print head 10 is associated with the bracket 9 and is connected up in a control circuit so that a warning is given (or the machine is stopped) if no paper is positioned adjacent to the bracket as when the roll is exhausted or the web becomes torn.

The elements of the print head impinge upon the paper web fed over the platen roller 8. As shown in Figs. 4 and 5 the line of elements 5 are mounted in a metal carrier block 5a with the leading ends of the elements projecting through a window 11 in the block. The elements are associated with means for selectively energising them and a Ribbon cable 12 connects the means for selectively energising the elements with a connector strip 13. This connector strip is secured on the body of the print unit carried by the chassis 1. The carrier block 5a is spring loaded in the cover 1. A serrated tear off strip 14 enables a ticket to be detached. The chassis 1 also carries the ticket machine keys and associated control mechanism as described, for example in Specification No.

1547984.

The elements are selectively energised by control circuits shown diagrammatically in Figs. 6 and 7.

Fig. 6 shows a 100 element print head circuit and Fig. 7 is a schematic circuit diagram of the control circuits to determine which character is to be printed (and hence which element is to be selectively energised) as the paper web is fed. Fig. 8 is an input circuit and Fig. 9 is an output driver circuit.

When a print unit as described is to be used in a ticket printer for example for a ''one man bus'' application the roll 6 of paper web is self-positioned in a recess 14 in the chassis part of the ticket machine and the leading end of the paper web is passed over the web guide 7 and over the driver roller, so that on closing the cover 2, the paper web is held between the print head and the drive roller. Information about the matter to be printed on the ticket web is entered on the keys of the ticket printer and relevant information is printed on the ticket.

The paper is fed by the driver roller 5 and as the paper is fed the elements are selectively energised and make a respective mark on the paper. The marks are made on the paper in matrix fashion to make up a series of numbers, letters or symbols etc. to provide the required data on the paper. When all the information is entered a ticket is detached by tearing off on the serrated edge.

Because the line of elements are mounted in the cover 2 which is capable of being pivoted away from the chassis 1 as shown by the arrow 2 in Fig. 2, the line of elements 5 are then readily accessible for cleaning and other purposes, obviating the need to withdraw machines from use for servicing.

Claims

1. A thermal element print unit comprising a print head embodying a plurality of heat elements arranged in linear formation and adapted to be selectively energised, means for feeding a web of thermo-reactive paper past the print head, an electrical connection for the print head, a series of control circuits for controlling the selective energisation of the print heads wherein the print heads are mounted in a pivoted cover so that the thermal elements may be readily moved away from the web of paper for cleaning and other purposes.

2. A thermal element print unit according to claim 1 wherein the pivoted cover is hinged at the rear of the cover to the printer chassis.

3. A thermal print unit according to claim 1 or 2 having a bracket over which the paper ticket web is fed for spacing the web.

4. A thermal print unit according to any one of the preceding claims wherein a recess is provided in the chassis part of the ticket machine for receiving a ticket web roll from which the leading end of the paper web is passed towards the heat elements.

5. A thermal element print unit constructed arranged and adapted to operate substantially as herein described with reference to the accompanying drawings.