EP0103591B1

EP0103591B1 - Paper advancing device in printers, typewriters or the like office machines provided with a paper magazine

Info

Publication number: EP0103591B1
Application number: EP83900816A
Authority: EP
Inventors: Göte Christer PERSSON
Original assignee: Facit AB
Current assignee: Facit AB
Priority date: 1982-03-08
Filing date: 1983-03-04
Publication date: 1986-11-12
Also published as: IT8319946A0; SE8201399L; IT1212710B; SE444536B; EP0103591A1; WO1983003075A1; JPS59500307A; DE3367559D1

Abstract

The invention relates to a paper advancing device in a printer, typewriter or like office machine (11) provided with a paper magazine (10), said machine including friction feed means (19, 20) for advancing a sheet (29) of paper past a printing apparatus arranged in the machine, the paper magazine similarly being provided with friction feed means (15) adapted for coaction with those of the machine, for transferring a sheet from the paper magazine to a printing start position in the machine. A sensing means (27) is adapted to indicate passage of the forward edge of a sheet (29) which is transferred to the machine (11), said indication controlling the magazine friction feed means (15) for advancing the sheet a predetermined distance from the moment of indication into contact with the friction feed means (19, 20) of the machine, both friction feed means (15; 19, 20) being adapted for coaction during the continued conveyance of the sheet (29) to the print start position, the magazine friction feed means (15) being activated at least as long as any part of the sheet (29) is in contact therewith.

Description

Technical field

The present invention relates to a printer, typewriter or like office machine provided with a paper magazine and particularly relates to a paper advancing device for such a machine as defined in the preamble of the Claim (US-A--4268021).

Background art

In a known printer with a separate paper magazine coupled to the printer, transfer of a sheet from the magazine to the printer takes place so that friction drive means arranged in the printer takes hold of and pulls the sheet out of the magazine. In this movement the sheet in turn drives friction drive means with which it is in frictional engagement in the magazine, and the movement of this drive means can be detected e.g. by a code disc coupled to the drive means, the code disk activating a transducer during its rotation. When such movement is indicated, the magazine friction drive means is activated and gives advancing assistance for a predetermined distance, subsequent to which such help ceases until the paper is stretched, to once again drive the magazine friction drive means, for movement thereof to be detected by the transducer. In the known embodiment, there is a great risk of slip occurring in the friction drive means of the machine, and this can result in a sheet being advanced askew.
One method of avoiding the above-mentioned slip is to let the machine give an order for advancing assistance from the paper magazine simultaneously as it starts its own friction feed. Advancing assistance can then be given under the major portion of the transfer distance. However, advancing assistance must be broken off during the latter part of conveying the sheet, due to variation in the length of the sheet. For example, if the magazine is allowed to give advancing assistance for a distance which is too long, there is the risk that subsequent sheets are also advanced a minor amount. The advancing errors. thus occurring will accumulate, so that after a plurality of sheet advances it may happen that simultaneously with a sheet being correctly advanced into the printer, subsequent sheets will at least partially be fed into it with a breakdown of the paper feed as a result.
In paper magazines of the kind mentioned, it is usual to arrange some form of separation means, for ensuring that only one sheet at a time is advanced from the magazine. A separation means often used comprises two oblique edges extending over and partially covering the forward corners, seen in the advancing direction, of a paper holder arranged in the magazine. Thereby the uppermost sheet in the holder will be lifted in its central portion on being advanced, while the forward corners are retained by the oblique edges and the sheet is separated from remaining sheets in the holder before the sheet is entirely released from these oblique edges.
In accordance with what has been mentioned above, it is desirable that the uppermost sheet in the magazine be advanced without subsequent sheets being affected. If advancing assistance is to be obtained from the magazine along the entire length of the sheet, a subsequent sheet may also be somewhat affected, so that it assumes its curved separating position. If the sheet remains thus for any length of time, it may receive a durable deformation which makes subsequent conveyance through the magazine and the paper channels arranged in the printer more difficult. To obviate this problem it is desirable that the magazine advancing assistance be extended so that a subsequent sheet is also advanced so far that the separation position has been passed, although without the occurrence of any accumulated advancing error, as mentioned above.

Disclosure of the invention

An object of the invention is to remove the drawbacks mentioned above, and to provide a paper advancing device of the kind in question, allowing a sheet of paper to be transferred without being pulled out of line and with controlled advance of subsequent sheets from the paper magazine to a printing start position in the typewriter. The object is achieved with a paper advancing device having the characterizing features disclosed in the claim.

Brief description of drawings

An embodiment of the invention will now be described with reference to the appended drawings.
Figures 1-3 schematically illustrate a section through a paper magazine connected to a printer, with a sheet of paper depicted in different positions during transfer from the magazine to the printer.
Figures 4 and 5 are sections as in Figures 1-3 but depict the path of a sheet while being advanced from the printer to the paper magazine.
A paper magazine 10 is schematically illustrated in Figure 1, and arranged above the printer, which is only indicated in the Figure and denoted by the numeral 11. Two paper holders 12, 13 are arranged in the magazine, each having at their lower edges an aperture 14 through which the sheets are advanced. There is also an opening in each holder accommodating a friction feed means 15 in the form of a drive roll engaging against the uppermost sheet 29 of a stack 30 of sheets in the holder. Engagement pressure between the drive roll 15 and the sheet is created by a movable side wall 31, against which the stack in the holder rests, the side wall being urged against the drive roll by springs 32. A chute 16 from the holder 12 and a chute 17 from the holder 13 guide a sheet from the respective holder into a feed channel 18 from the paper magazine. The channel 18 opens out into a friction feed means arranged in the printer in the shape of a friction belt 19 and associated backup rolls, of which an upper one is illustrated in the Figure and has the denotation 20.

Best mode for carrying out the invention

For advancing a ready-printed document 34 to the paper magazine, the latter has a channel 21 for leading the document via a drive roll 22 and associated backup roll 23 to a collection compartment 24. A motor 25 is adapted for driving the drive roll 22 and the drive roll 15 associated with the folder 12, via unillustrated toothed belts. In a corresponding manner, a motor 26 is adapted for driving the drive roll associated with the holder 13. Between the friction feed means 15 and 19, 20 a sensing means 27 is arranged in order to indicate the position of a sheet which is to be advanced into or out from the printer. The sensing means 27 consists of a reflecting opto-unit, e.g. comprising a light emitting diode and a phototransistor. The diode emits light towards a reflecting surface 28, from which the light is reflected towards the phototransistor. When a paper intervenes between the sensing means 27 and the reflecting surface 28, substantially less light will be reflected back again to the opto-unit phototransistor, which can thereby indicate that the forward edge of the paper, seen in the advancing direction, has passed.
It is assumed for the following description of the function of the paper advancing device that the advancing sequence is controlled by a unit arranged in the printer, and not described in greater detail, said unit preferably being a microcomputer. An advancing sequence is accordingly initiated by the control unit giving an order for the transfer of a sheet from the paper magazine. The motor 25 then starts and the drive roll 15 advances the uppermost sheet 29 in the paper holder 12 to the position shown in Figure 1, in which the paper is just about to pass the beam of light rays from the opto-unit. When the beam of light rays has been passed, the sensing means 27 sends a signal to the control unit ordering the motor 25 to drive the roll 15 to advance the paper a predetermined distance to bring it into contact with the friction feed means 19, 20, the sheet 29 being inserted in the space between the friction drive belt 19 and the backup roll 20 in the printer as illustrated in Fig. 2. In this position the rear part of the sheet has still not left the paper magazine 10. The control unit, orders advance of the sheet with a certain excess whereby the forward edge of the sheet is urged into said space. The control unit now orders a motor (unillustrated), arranged in the printer, to start the friction belt 19 for continued advance of the sheet to a printing start position in the printer. The control unit simultaneously requests advancing assistance from the paper magazine, whereby the drive roll 15 is also activated. Advancing help remains as long as any part of the sheet is in contact with the drive roll 15.
Oblique edges covering the forward corner edges of the paper are arranged in the paper holder 12 in conjunction with advancing aperture 14. The object of this is to ensure that only one sheet at a time is advanced. To enable advancing assistance along the whole length of the paper, the drive roll 15 is activated for a length of time such that a subsequent sheet 33 is also advanced a minor distance. The advantage of this is that the subsequent sheet is advanced such that is passes the separating edges and thus assumes a flat unaffected condition. No accumulated advancing errors occur if the advance of the subsequent sheet is stopped before the forward edge thereof has passed the sensing means 27. When the first sheet has left the drive roll 15 and the latter has caused the short advance of the subsequent sheet, the motor 25 is stopped and the friction drive belt 19 by itself advances the sheet to the print start position.
A ready-printed document is advanced via the paper channel 21 by the drive roll 22 and backup toll 23 to the collection compartment 24. The sensing means 27 can here be utilized for indicating that a sheet is fed up from the printer and also that the sheet has passed the common paper channel 18, so that a new sheet can be fed down from the paper magazine. Figure 4 illustrates a sheet during advance through the paper channel 21, while Figure 5 shows the paper in the collection compartment 24.

Claims

A paper advancing device in printers, typewriters or like office machines (11) provided with a paper magazine (10), said machine also including a first friction feed means (19, 20) for advancing a sheet (29) of paper past a printing unit arranged in the machine, the paper magazine including a sheet separating means and being further provided with a second friction feed means (15) adapted to coact with the first friction feed means (19, 20) of the machine for transferring a sheet from the paper magazine to a printing start position in the machine, the first and second friction feed means (15; 19, 20) being adapted for coaction during conveyance of the sheet (29) to the printing start position, sensing means (27) being positioned between the first and second feed means (15; 19, 20) adapted for indicating the passage of the forward edge of a sheet (29) which is transferred to the machine (11), the sensing means signal controlling the second friction feed means (15) of the magazine to advance the sheet a predetermined distance to bring it into contact with the first friction feed means (19, 20) with a rear portion of the sheet (29) still being in the paper magazine (10), characterized in that the second friction feed means (15) is adapted, from the moment when the uppermost sheet (29) has completely passed the second friction feed means (15), to advance a subsequent sheet (33) so far that its forward edge has passed the separating means, and in that the sensing means (27) is placed so much apart from the separating means in the direction towards the printer (11) that the advancing of the subsequent sheet (33) to the point where the forward edge has passed the separating means is stopped before said sheet reaches the sensing means.