GB2050661A

GB2050661A - Electrically-controlled Printing Apparatus

Info

Publication number: GB2050661A
Application number: GB7920883A
Authority: GB
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1979-06-15
Filing date: 1979-06-15
Publication date: 1981-01-07
Also published as: GB2050661B

Abstract

A computer output printer avoids pre-operational manual positioning of paper beneath the printhead by means of a line advance mechanism 10 and a fractional line advance mechanism 11 both reversibly operator controllable from printer operation control buttons 14 which change to a paper positioning control function whenever a switch 9 detects that the printer cover or yoke is open. <IMAGE>

Description

SPECIFICATION Improvements in or Relating to Electrically controlled Printing Apparatus This invention relates to electrically-controlled printing apparatus and, in particular, to apparatus designed to print on fanfolded continuous stationery. The invention will be described hereinafter with reference to form printers of the kind used as a computer output device.

A form may be defined as any piece of paper presented to a computer computer peripheral printer for the printing of characters thereon.

In the simplest case, the form is a piece of paper, fanfolded to a long chain of other pieces of identical paper, whose only characteristic is to have a page top and a page bottom defined by the position of the folds. In the most complicated case, the form may be what the man in the street would call a form, a piece of paper having a plurality of well defined areas into which specific information is to be written.

It is essential, even in the simplest case, for the printer to know where it is on the form. It is a simple matter for the printer to have knowledge of the printing position across the form, since the printer knows how many characters there are in a line and where it is on any line at a given time. On the other hand, the printer only knows how far down a form it is by counting the line shifts it has performed from the start of its operation. The printer has no way of knowing whether or not it was started with the form set up correctly, so that what the printer took to be the top line of the form was indeed the top line of the form.

It bedomes essential that the operator of the printer have some means provided whereby he may accomplish the correct vertical registration of the form in the printer prior to allowing the printer to commence operation.

The problem of correct vertical registration of the form, and the exact manner in which it may be accomplished, may be termed 'the form indexing problem.' In the prior art, when a form was presented to a printer, the paper was manually adjusted by the operator, in the vertical direction, after the operator had disengaged a clutch on the paper feed mechanism. The printer would stop, ready for the next form. The printer knew that the next line to be printed was the top of a page. In order that the printer should not confuse its line count, the paper advance mechanism was disengaged from drive, the rotations of which the printer counted in order to establish its vertical position on a page. The paper could then be advanced or retarded by hand so that the correct line of the form appeared under that row next due for printing.The mechanical intervention of the operator did not allow for great precision in the registration of the form, and created an added risk of paperfoulup because of possible misalignment of the paper.

From one aspect the invention consists in electrically-controlled printing apparatus including paper feed means, first manually controlled means for causing said paper feed means to advance the paper by a distance equal to the distance between successive lines of type, second manually controlled means for causing said paper feed means to advance the paper by a distance equal to a predetermined multiple of the distance between successive lines of type, and change-over switch means for changing the function of said second manually controlled means so that it causes said paper feed means to move the paper by a distance equal to a predetermined fraction of the distance between successive lines of type.

Thus the present invention provides apparatus in which a form may be brought into vertical registration with great precision, and without the intervention of the operator into the mechanics of the printer.

In one embodiment of the invention, the changeover switch is a microswitch controlled by the top cover of the printer so that the function of the second manually controlled means is changed over whenever the top cover of the printer is opened.

In another embodiment of the invention, the microswitch is controlled by the yoke assembly of the printer. This assembly contains the printer character belt and motor, and is opened to allow loading of the forms. The yoke is located to the front of the machine under the top cover.

Many known printers are provided with a plurality of control buttons, for example, four.

These four control buttons may be: 1 ) a Line Feed button; 2) a Form Feed button; 3) a Stop button; and 4) a Print button.

The Line Feed button corresponds to the first manually controlled means and serves to initiate advance of the form by one line. The Form Feed button corresponds to the second manually controlled means and, in normal operation, serves to advance the paper by a plurality of lines equal to the number of lines on a form. As already mentioned, this distance may correspond to the distance between adjacent folds of the fanfolded paper.

The Stop button, in normal operation, serves to stop printing, whereas the Print button serves to initiate printing.

In an advantageous embodiment of the invention, the Stop button and the Print button are used as third and fourth manually controlled means, the functions of which are changed over by the microswitch controlled by the yoke assembly of the printer, In this embodiment, when the top cover of the printer is open, the Stop button is used to select forward motion of the paper, while the Print button is used to select reverse motion of the paper.

Whenever the yoke assembly is opened, the operator may press these buttons until the form is positioned to his satisfaction. On opening the yoke assembly, the machine assumes that a forward direction is required. The operator may press the Line Feed button to cause the form to advance one line at a time, or may press the Form Feed button to cause the form to advance by the predetermined fraction of a line. If it is desired to change direction, the Print button is pressed to select reverse motion of the paper. Reverse movement will then remain selected until the Stop button is pressed to restore forward movement.

As soon as the top cover is closed again, the buttons revert to their normal function, and the printer's vertical counter is initialised to the correct value.

From another aspect the invention consists in any features of novelty, taken singly or in combination, of the embodiment of the invention illustrated in the accompanying diagrammatic drawings.

Figure 1 of the drawings illustrates a known form of fanfolded printer which may be used as the output device on a computer. This printer serves to print characters on a series of forms joined together end-to-end on continuous stationery 1. As already stated, a form is regarded as the piece of paper between two adjacent fold lines 2.

The printer includes a hingable top cover 3 and is provided with a group of four control buttons 4.

Details of the control buttons are given in Figure 2.

From this drawing, it will be seen that the first button 5 serves as the Line Feed button under normal circumstances, and is converted to a Coarse Feed button when the yoke assembly is open.

The second button 6 is normally the Form Feed button, and is converted to a Fine Feed button when the yoke is open. The third button 7 is normally the Stop button, and becomes the Forward button when the printer is open. Finally, the button 8 is normally the Print button, and becomes the Reverse button when the printer is open.

Figure 3 illustrates the overall system of apparatus in accordance with the invention. It will be seen that this system includes a yoke switch 9.

In a more general sense, this may be regarded as a first component for indicating that it is desired to adjust the vertical registration of the form. This component could be realised in a number of different ways, and it is to be understood that the microswitch operated by the yoke assembly of the printer is only one example.

The system also includes coarse feed apparatus. This may be the normal paper feed of the printer. Fine feed apparatus 11 may be regarded as a third component of the present invention. This causes the form to move a small fraction of a line height, and is additional to the normal paper feed of the printer. A fourth component of the system is direction apparatus 12. This acts on both the coarse and fine feed apparatus, dictating the direction of movement of the paper.

The fifth component of the system is a controller 13. This controller extracts signals indicative of the desired movement and relays them to the appropriate feed. In addition, on closure of the yoke assembly of the printer, the controller may be arranged to reset the line counter of the printer to the appropriate location on the page. In most cases, however, the line counter is only reset when the machine electronics have been initialised via the Initialise push button or by the machine being switched off and on. Normally, forms would be loaded after the machine had been switched on and, if fresh forms are required in the middle of a print run, the new forms can be positioned in exactly the same place as the old ones stopped.

The sixth component of the system is the manually controlled means 14. This signals the operator's intention and, as already described, may consist of the four buttons marked Line Feed, Form Feed, Stop and Print.

Claims

1. An electrically controlled printing apparatus including paper feed means, change-over switch means and first manual means, for controlling a first function of said apparatus when said changeover switch means is in a first state and for causing said paper feed means to move the paper a predetermined fraction of the minimum distance said apparatus is operable to advance the paper during printing, when said change-over switch means is in a second state.

2. An apparatus according to claim 1 including second manual means for controlling a second function of said apparatus when said change-over switch means is in said first state and for causing said paper feed means to move the paper in a forward direction in response to said first manual means when said change-over switch means is in said second state, and third manual means, for controlling a third function of said apparatus when said change-over switch means is in said first state and for causing said paper feed means to move said paper in a backward direction in response to said first manual means when said change-over switch means is in said second state.

3. An apparatus according to claim 2 including fourth manual means for controlling a fourth function of said apparatus when said change-over switch means is in said first state and for causing said paper feed means to move said paper a distance substantially equal to the minimum distance that said apparatus is operable to move said paper during printing when said change-over switch means is in said second state.

4. An apparatus according to claim 3 wherein said second manual means is responsive to said change-over switch means being in said second state to cause said paper feed means to move the paper in a forward direction in response to said fourth manual means and said third manual means is responsive to said change-over switch means being in said second state to cause said paper feed means to move said paper in a backward direction in response to said fourth manual means.

5. An apparatus according to any one of the preceding claims wherein said change-over switch means is placeable into said second state responsively to said apparatus being placed in a condition necessary for physical operator intervention with said paper feed means.

6. An apparatus according to claim 5 wherein said condition is the opening of a protective cover for said paper feed means.

7. An apparatus according to claim 6 wherein said change-over switch means is a microswitch for detecting when said cover is at least partially open.

8. An apparatus according to any of the preceding claims wherein said first function is any one from a list of functions comprising: causing said paper feed means to advance the paper a distance equal to the minimum distance said apparatus is operable to advance the paper during printing, causing said paper feed means to advance the paper a distance equal to a predetermined integral multiple of the minimum distance said apparatus is operable to advance the paper during printing, causing said apparatus to initiate printing operations, and causing said apparatus to terminate printing operations.

9. An apparatus according to claim 8 when dependent upon claim 2, wherein said second function is one and said third function is another from said list exclusively of said first function.

10. An apparatus according to claim 9 when dependent upon claim 3, wherein said fourth function is a function from said list exclusively of said first function, said second function and said third function.

11. An apparatus according to any one of claims 1 to 7 wherein said first function is the causing of said paper feed means to advance the paper a predetermined integral multiple of the minimum distance said apparatus is operable to advance the paper during printing.

12. An apparatus according to any one of claims 2 to 7, or claim 11 when dependent upon claim 2, wherein said second function is the causing of said apparatus to terminate printing operations and said third function is the causing of said apparatus to initiate printing operations.

13. An apparatus according to any one of claims 3 to 7 or claim 11 or 12, when dependent upon claim 3, wherein said fourth function is the causing of said paper feed means to advance the paper a distance equal to the minimum distance said apparatus is operable to advance the paper during printing.

1 4. An apparatus according to any of the preceding claims wherein the or each of said manual means is a push button.

1 5. An apparatus according to claim 14 when dependent upon claim 6, wherein the or each of said push buttons is mounted on said cover.

1 6. An apparatus substantially as herein described with reference to the accompanying drawings.