WO1992003294A1

WO1992003294A1 - Device for verification of a character combination

Info

Publication number: WO1992003294A1
Application number: PCT/SE1991/000551
Authority: WO
Inventors: Anders Berndtsson
Original assignee: Rns Grafotronic Ab
Priority date: 1990-08-21
Filing date: 1991-08-21
Publication date: 1992-03-05
Also published as: SE9002714D0; AU8399791A; SE466052B; SE9002714L

Abstract

Device for verification of the angular position of a character wheel in a mechanical counter intended for numbering of printed documents whereby said counter includes a number of character wheels bearing on a common axis whereby for each character wheel (1) is placed a detector apparatus (101) inside the shaft of the character wheel (2) which preferably is made in non magnetic material and that the portion of the character wheel which is situated closest to the shaft is provided with one or more sectors (3A, 3B) of material which can be permanent magnetized, said material generates a magnetic flow (B) which is transversal to the shaft direction, whereby said detector apparatus consists of two orthogonally placed sensors (10, 11) by means of which the direction of the flow generated by said sector can be unambiguously determined.

Description

DEVICE FOR VERIFICATION OF A CHARACTER COMBINATION

The present invention refers to devices by printing units and more precisely to a device for verification of the position of a character wheel in a mechanical counter inten¬ ded for numbering of printed documents.

Background.

Numbering of printed document in running sequence is done to 90% by a mechanical counters, which has its origin from the end of 1800-th century and which still today are produced according to the same principles.

By generation of valuable documents such as bank-notes, checks, stocks, bonds and so forth it is a demand that one has a unbroken number series which is numbered by mechanical counter-and printing units and subsequently is scrutinized manually so that 100% safety will be achieved.

Until now devices known for verification of the position of an individual character wheel in a printing unit is con¬ structed so that each character wheel by its outer periphery is scanned by a detector device which reads a code - prefe¬ rably magnetic code which is coupled to each individual sign - for example 0 - 9 on the character printing wheel. In this manner is obtained information about which digit each character printing wheel prints. The information signals from each sensor obtained are processed by a computer, which verifies the number and stops the output if some error arises.

The above technical solution entails 10-12 permanent magnets as well as 4 st sensors (hall sensors) per character prin¬ ting wheel. A digit printing unit has 8 to 12 character wheels and for a big printing-press for bank-note production is used about 50 digit printing units. This solution gives consequently a system with about 500 permanent magnets and 200 hall sen¬ sors.

The location of the sensors and of the permanent magnets make them bulky and much exposed to mechanical influence. This makes the system sensitive and difficult to use with many false standstill as a result.

The purpose of the invention and most important characteris- tics

It is a purpose with existing invention to achieve a position detecting system for a character wheel which is not exposed to external mechanical influence and from which system is obtained the absolute the value of the an- gular pposition of the character wheel.

The above purpose is achieved by a detector device which is placed inside the axis of the character wheel which is preferably made in non-magnetic material and that the por¬ tion of the character wheel which is situated nearest the axis is provided with one or more sectors of material which can be permanent magnetized, which material generates a magnetic flow B which is transversal against the axis direc¬ tion, whereby said detector device consists of an aggregate of two ortogonally positioned sensors by means of which the direction of the flow generated by said sector unambiguously can be determined.

That ensure the absolute value of the angular position of the character wheel in a counter unit in which a number of sensors is included, a reference detector is provided inside the axis for temperature compensation, which detects a magnetic reference flow B₀ directed along the character wheel axis which is generated by a ring-shaped magnet which surrounds the axis.

With reference to the enclosed drawing in the following a preferred embodiment of the invention will be described. In the drawing Fig 1 is a frontal view of a character printing wheel accor¬ ding to the invention;

Fig 2 is a lateral view of a character printing unit in¬ cluding the verifiering device according to the invention partly dismounted;

Fig 3 is a block diagram of the signal processing unit with the verifiering device according to the invention. With reference to fig. 1 is shown a frontal view of a character printing wheel 1 including along a periphery part 12 provided equidistant protruding digits 4 or other code designations the position of which in relationship to a point of reference shall be determined. The bearing of the character wheel is constituted by of a hollow axis 2, which extends through the whole the group of character wheels which form the printir-j unit.

A central portion 13 of magnetic non conducting material (aluminum or polymer composite) partly forms a bearing surface for the character printing wheel against the hollow the axis 2 and partly bearer of permanent magnets 3A;3B, which generate a magnetic flow B which is detected by the magnetic sensors 10 and 11. The flow from the rod shaped permanent magnets 3A and 3B closes itself through the pe¬ riphery part 12 which then is made as a whole or to a part of magnetic conducting material. It is important that it magnetic flow in a wheel does not influence the sensors of the adjacent wheel. The poles for respective magnets are designated by e.g. 3AS and 3AN;3BS and 3BN. Between the poles 3AN and 3BS exists essentially air gap magnetization with a relatively great air gap. Suitable magnetic material for the permanent magnets 3 is anisotropic ceramic material with strontium and barium which has low price and high coercive force which means high stability of the magnetic flow ( flux density ca 0,15 Tesla) by large air gaps apart from the temperature dependence of said flow.

That magnetic the flow in a character wheel according to the invention can also be generated by only one magnet, which means that for example the magnet 3B is replaced by corre¬ sponding volume soft magnetic material. This action leads to somewhat lower air gap flux and corresponding lowering of the detektor output signal.

They magnetic the sensors 10 and 11 are constituted by hall generators which are ortogonally positioned and give an output signal whose amplitude and polarity is proportional to the resultant the projection of the flux density B again¬ st the normal of the detector surface respectively nlO and nil.

With reference to Fig. 2 is shown a lateral view of a character printing unit including a number character wheel 1, whose individual positions are detected by a detector apparatus 101 including the ortogonal sensors 10 and 11. The individual detector apparatuses are fixed by a bearer 20, which simply is displaced into in the axis 2 by assembly of the verifiering device according to the invention. In the corresponding manner at an eventual service occasion the whole set of detector apparatus simple is controlled or exchanged.

In order to reduce temperature influence in the system at one end of the character wheels is provided an axial refe¬ rence magnet 3C with the flow B₀ and a reference detector 102 with the perpendicular to the detector surface in axial direction whereby the sensor gives a output signal corre- sponding to variations in temperature of the system.

With reference to Fig. 3 is shown a block diagram of a detector device of a character printing wheel according to the invention.

A hall element H contained in a sensor 11 is fed via a voltage regulator REG from a supply source V_cc. The output signal from the hall element is supplied to an amplifier A, whose output signal is analogue - digital converted in the block 21. The output signals from the ortogonal hall element HIO and the reference element H102 is converted in a similar way in respective blocks 22 and 23 . The parallel data signals 21P,22P and 23P are supplied to a microprocessor uP, which evaluates the position signals with regard to the value of the reference flow BO to an absolute value for the angle of respective character wheel 1 in a printing unit. The signals from respective sensors 10 and 11 are multi¬ plexed to respective. A/D -converter 22 and 21 in a multi¬ plexer not shown.

Claims

PATENT CLAIMS

1. Device for verification of an angular position of a character wheel in a mechanical counter intended for numbering of printed documents whereby said counter includes a digit character wheel with bearings on a common shaft c h a r a c t e r i z e d t h e r e i n, that for each character wheel (1) is positioned a detector apparatus (101) inside the shaft (2) of the charac¬ ter wheel which preferably is made in non-magnetic material and that the portion of the character wheel which lies nearest the axis is provided with one or more sectors (3A,3- B) of material which can be permanent magnetized, said material generates a magnetic flow (B) as is transversal against the axis direction, whereby said detector apparatus consists of two ortogonally placed sensors (10,11) by means of which the direction for the flow generated by said sector unambiguously can be determined.

2. Device according to claim 1, c h a r a c t e r i z e d t h e r e i n , that in a counter which includes a number of sensors, inside the axis (2) is provided a reference detector for temperature compensation, which detects a magnetic reference flow (B₀) directed along the character wheel shaft (2), which is generated by a ring-shaped magnet (3C), which surrounds the shaft (2).