EP1065631A1 - Method and device for reading record carrier shaped like a sheet - Google Patents

Abstract

A transmitter (3) is placed below a recording medium (1) like a bank note. A reading station (2) tests transmission from the bank note. The transmitter consists of an illuminating device (5) and an illuminating slit diaphragm lens (6). A receiver (4) consists of a measuring sensor (7) and a sensor lens (8) connected in series. The bank note is passed between the transmitter and the receiver. An illuminated column of a specific width shows on the bank note.

Description

The present invention relates to a method and an apparatus for Reading of sheet-like record carriers during a relative movement compared to a reading station that has at least one transmitter for sequential Emitting at least two signals of different signal types, a common receiver for the different signal types Detect these signals and modulated by the record carrier has an evaluation unit for the detected signals. This reading station detects a "measuring surface" on the recording medium at any time with a certain length in the direction of relative movement. Due to the Relative movement occurs when the record carrier is scanned in cycles per clock a "raster element" of the record carrier is detected is larger than the measuring area of the reading station. The size of the grid element decreases with the relative speed and the duration of a signal emission ("Signal clock") too.

Such methods and devices are used, for example, to: to determine the currency and value of banknotes and them to check for their authenticity or validity. In addition, it goes without saying also an insert for reading and checking any other Record carriers such as certificates, ID cards etc. possible.

A corresponding device for reading and checking the authenticity Banknotes are described in EP 0 537 513 A1. Here, the Banknotes passed a reading station, which consists of several transmitters for emitting light of different colors or infrared signals and a common recipient. During the relative movement the banknote opposite the reading station will be the different Signals sequentially emitted onto the banknote. The recipient catches that reflected from the banknote or transmitted through the banknote and consequently signal modulated by the banknote. This signal will then evaluated.

Using the different transmitters and the common detector several physical properties of the banknote are checked. To the signals from the individual transmitters are sequential in a sequence delivered and at the same time the banknote moves in its relative movement away. This creates with respect to those arising for each signal type different images inevitably gaps. These gaps are disadvantageous if there are structures of the order of magnitude on the record carrier the gaps lie. With repeated measurements it can then there are quite large variations in the measured values.

In GB-A-2 107 911 a bank note checking device is described, which the Passing banknote only in three, side by side transverse to the direction of movement lying, short sections with different signal types scans. This involves multiple oversampling for each section carried out. This results in a very large amount of measurement data and a slow conveying speed in relation to the scanning frequency. Moreover only certain, strip-like areas of the banknote surface scanned.

The invention has for its object a method and an apparatus specify at the highest possible conveying speed a full-surface scan of the record carrier with respect to at least two physical properties is possible.

This object is achieved by a method and by an apparatus the secondary claims solved.

According to the invention, in this method or the device a suitable design of the transmitter and / or receiver geometry Reading station and by an appropriate choice of the relative speed and the cycle times ensured that the length of the detected by the reading station Measuring surface for each of the signal types corresponds exactly to the path length, which the recording medium is in one from the beginning of the radiation Signal type up to the beginning of the next radiation in the same Signal type ("period") moved. The cycle times are determined by both Length of each signal clock of the different signal types as well influenced by the distances between the signal clocks. With others Words become the geometric parameters of the reading station and the time parameters the sampling selected so that with successive signal clocks different signal type the length of the detected by the reading station Measuring area exactly the spatial distance from the start or end of two Signal clocks corresponds to the same signal type. The spatial distance between two Signal clocks is thus determined by the time interval between the clocks, i.e. the duration given a period multiplied by the relative speed. On in this way gaps are avoided.

Since the banknote continues to move during a signal cycle, it shifts the measuring area captured by the reading station during the signal cycle relatively above the record carrier. It will therefore also apply to this Moving a raster element on the record carrier during the cycle that is longer in the direction of movement than that of the Reading area captured measuring surface. This leads to an overlap of the scanned raster elements, i.e. to a partial double scan.

The double-scanned areas are special because of the selected geometry and time parameters only around the border areas of the raster elements that come from the reading station during a bar "Measured" measuring surface "run out" or "run" into the measuring surface and which is therefore not captured by the reading station over the entire cycle duration as is the case with the other areas of the raster element. This "underrepresentation" of the edge areas within a signal cycle becomes by double sampling in two successive signal cycles exactly balanced. Since the areas on the record carrier are consequently with a high level of reading reliability, they can be completely read without having to read multiple times high throughput is possible on the one hand and on the other hand the processing and storage effort for the measurement data is relatively low.

The transmitter can be, for example, a transmitter with different ones Lighting systems act in the wavelength distinguish, that is, which light of different colors or infrared signals send out. At least one of the signals is preferred an infrared signal and at least one further signal a light signal certain wavelength in the visible range.

In an alternative preferred embodiment, the sampling is done at least with a brightfield signal and a darkfield signal. It However, there are also other distinguishing features, such as the Polarization of light possible.

It is also advantageous if the transmitter or the receiver are formed so that the grid element is in a line shape transverse to the relative movement extends over the entire record carrier. For example by a strip-shaped transmitter in the form of a lighting device with a slit diaphragm, and a correspondingly arranged strip-shaped CCD receiver or another sensor with a corresponding upstream optics, for example a rod lens will be realized. With such a system can be simple and quickly captures the entire surface of the record carrier and to be read.

Fig. 1

eine schematische Darstellung der Vorrichtung (mit nur einem Sender),

Fig.2a

die Lage des Beleuchtungsspalts (Beleuchtungsintensität 1 = 100%) auf dem Aufzeichnungsträger zu Beginn eines Signaltaktes,

Fig.2b

die Lage des Beleuchtungsspalts gemäß Fig. 2a auf dem Aufzeichnungsträger zum Ende des Signaltaktes,

Fig. 3

die Lage zweier aufeinanderfolgender in einer Signalart abgetasteten Rasterelemente mit der innerhalb des Signaltaktes bezüglich der jeweiligen Orte im Rasterelement vorliegenden Dosisverteilung auf dem Aufzeichnungsträger,

Fig. 4

eine Darstellung einer zeitlichen Abfolge und Dauer von Signaltakten dreier verschiedener Signalarten (oberer Teil) mit der zugehörigen Lage und der örtlichen Dosisverteilung der einzelnen Rasterelemente jeder Signalart auf dem Aufzeichnungsträger (unterer Teil), und

Fig. 5

eine schematische Darstellung der Lage und Erstreckung von Meßflächen (Pixeln) unterschiedlicher Signalart auf einem Aufzeichnungsträger (zur Verdeutlichung sind nur zwei Meßflächen der einen Signalart dargestellt).

The method and the device according to the invention are explained in more detail below using an exemplary embodiment with reference to the accompanying drawings. Show it:

Fig. 1

a schematic representation of the device (with only one transmitter),

Fig.2a

the position of the lighting gap (lighting intensity 1 = 100%) on the recording medium at the beginning of a signal cycle,

Fig.2b

the position of the illumination gap according to FIG. 2a on the recording medium at the end of the signal cycle,

Fig. 3

the position of two successive raster elements scanned in a signal type with the dose distribution present on the recording medium within the signal cycle with respect to the respective locations in the raster element,

Fig. 4

a representation of a chronological sequence and duration of signal clocks of three different signal types (upper part) with the associated position and the local dose distribution of the individual raster elements of each signal type on the recording medium (lower part), and

Fig. 5

a schematic representation of the position and extent of measuring surfaces (pixels) of different types of signals on a record carrier (for clarification only two measuring surfaces of one type of signal are shown).

Figure 1 shows a schematic representation of a reading station 2, wherein for the sake of simplicity, only one transmitter 3 is shown, which is located below of the record carrier 1, here a banknote 1. At this reading station 2, the transmission of banknote 1 is checked.

The transmitter 3 consists of an illumination device 5 and an illumination optics 6 in the form of a slit diaphragm. The receiver 4 consists of a Sensor 7 and an upstream sensor optics 8, here a rod lens.

The banknote 1 is passed between the transmitter 3 and the receiver 4 in the transport direction R. The corresponding selection and arrangement of the lighting device 5, the lighting optics 6, the sensor optics 8 and the measuring sensor 7 result in a specific lighting characteristic on the bank note 1 with a lighting gap of a specific width. This gap width corresponds exactly to the length s _B of the measuring surface in the direction of movement R detected by the reading station 2 during a specific point in time.

As shown in FIGS. 2a and 2b, lies within the lighting gap, i.e. within the measuring area, approximately an illumination intensity 1 out of 100%, whereas outside the lighting gap Illumination intensity 1 is almost 0. Of course, in reality generally the boundaries are not as sharp as shown in the figures.

Furthermore, FIGS. 2a and 2b show the changing position of the measuring surface on the banknote 1 while moving along the transport direction R. FIG. 2a shows the position at the beginning of an exposure time with a specific signal, ie at the beginning of a signal cycle, and FIG. 2b at the end of this exposure time, ie at the end of the cycle. During this signal cycle, the bank note 1 has been shifted at a constant relative speed exactly by the distance l ₁ in the transport direction R. As can be seen from the figures, the points A and D on the banknote 1 lie outside the measurement area during the entire exposure time. In contrast, points B and C lie within the measurement area during the entire exposure time. The points in the range between B and C therefore contribute maximally to the measured value. The points between A and B and between C and D, on the other hand, only make a partial contribution to the measured value, since they slide into the measuring surface or move out of the measuring surface during the exposure time.

Overall, a measured value of a specific signal clock contains information from all points on bank note 1 between points A and D. The distance between A and D is therefore the extent of the scanned raster element in the direction of movement. The contribution of the respective points A to D to the measured value corresponds to dose P, which is determined by the intensity 1 of the signal multiplied by the time that the point in question lies within the measurement area during the signal cycle. With a uniform movement and a rectangular illumination profile as shown in FIGS. 2a and 2b, the contribution of the points between A and B on the banknote 1 increases linearly, between C and D it decreases linearly. The dose distribution shown in FIG. 3 therefore results between points A and D. The illumination gap length is designated with s _B and the grid element length with s _R. The maximum dose P again corresponds to 100%.

The length of the ramps AB or DC of the dose distribution depends on the duration of the signal cycles for a given measuring surface geometry and a given relative speed. It corresponds exactly to the path length l ₁ which the bank note 1 covers during the cycle duration T ₁ . It is therefore essential that during a signal cycle the bank note 1 only covers a distance l ₁ which is smaller than the length s _{R of} the measuring surface. In order to achieve a seamless scanning of the banknote, it is sufficient if the following signal cycle of the same signal type starts again, if the point located at the beginning of the first cycle in the transport direction R on the front edge of the measuring surface (point B in FIG. 2a) that Has reached the end of the measuring surface. Exactly then, the grid elements are gaps relative to each other in such a way that only the areas between points A and B and C and D of two successive grid elements of length s _R overlap. Due to the uniform speed and the resulting linear increase or decrease in the dose P in these areas, the dose of these points detected in the adjacent raster elements again adds up to exactly 100% (FIG. 3). This means that every point on the record carrier is viewed with the same sensitivity. His information is therefore always 100% scanned. However, it can be distributed over two adjacent measured values. This is independent of the cycle length.

The time between two signal clocks of a signal type Q ₁ , that is to say the duration T of the period minus the clock duration T ₁ , can now be used to scan the bank note 1 with signals of another signal type Q ₂ , Q ₃ (FIG. 4). A corresponding width of the illumination gap for these further signals, that is to say a corresponding length s _{B of} the measuring surfaces with respect to this type of signal, can also be used to achieve a complete scanning in the same way. In the example shown in FIG. 4, the illumination gap width or length s _{B of} the measuring surfaces is identical in each case.

4 shows, using the example of three different signal types Q ₁ , Q ₂ , Q ₃ , how a period of successive signals can be divided in any manner into time periods T ₁ , T ₂ , T ₃ and T ₀ in which the individual signal systems are active are. Here only the requirement must be fulfilled that for all signal types Q ₁ , Q ₂ , Q ₃ the length s _{B of} the measuring surface is equal to the product of the relative speed and the duration T of the period, so that there is always a complete scanning of the signal channels Banknote 1 in the desired manner results. The distances l ₁ , l ₂ , l ₃ , l _{0 covered} during the individual time periods T ₁ , T ₂ , T ₃ , T ₀ add up again exactly to the length s _{B of} the measuring surface, ie to the width of the illumination gap.

4 also shows that the individual signal durations T ₁ , T ₂ , T _{3 of} different signal types Q ₁ , Q ₂ , Q ₃ do not necessarily have to add up to 100% within the period T. In principle, the individual signal durations T ₁ , T ₂ , T _{3 can} also be different, so that, for example, one signal type Q _{1 has} a shorter signal duration T ₁ within one period and the other signal types Q ₂ , Q _{3 have} a longer signal duration T ₂ , M ₃ . A time T ₀ remaining within the period of signals can be used, for example, to read out the sensors or to carry out calibration measurements or the like.

5 shows the position of the measuring surfaces 10, 20 for two different signal types, here measuring surfaces 10 of a red color signal and measuring surfaces 20 of an infrared signal. As can be seen, in the method according to the invention the measuring surfaces 10, 20 of the two signal types are shifted from one another on the bank note 1. Measuring surfaces 10, 20, which do not extend over the entire width of the bank note 1, are shown here for better visibility. In addition, only two measuring surfaces 10 of the red light signal are shown. The dashed line shows, by way of example, the overlap area or the length s _{R of} the raster element 20 on a series of measuring surfaces 20 of the infrared signal.

In a preferred embodiment, not shown, extend the measuring surfaces across the transport direction R over the entire width the banknote.

The method according to the invention offers a complete, full-surface scanning the banknote with high banknote throughput. Here is your measurement data only a small amount of processing and storage is required. As before As mentioned above, the invention is of course not based on reading and checking banknotes, but can also be used for any other Record carriers are used.

Claims (8)

Method for reading sheet-shaped record carriers (1) during a relative movement relative to a reading station (2), which has at least one transmitter (3) for sequentially emitting at least two signals of different signal types (Q ₁ , Q ₂ , Q ₃ ), one for the different signal types (Q ₁ , Q ₂ , Q ₃ ) common receiver (4) for detecting these signals modulated by the recording medium (1) and an evaluation unit for the detected signals, the reading station (2) in each of the signal types (Q ₁ , Q ₂ , Q ₃ ) cyclically raster elements (10, 20) with a certain extent (s _R ) along the relative movement direction (R) are scanned and a measuring surface with a certain length (s _B ) in the relative movement direction (R) is opened at any time of a cycle the recording medium (1) can be detected, characterized in that the length (s _B ) of the measuring surface detected by the reading station (2) for each signal type (Q ₁ , Q ₂ , Q ₃ ) is selected equal to the path length (1) that the recording medium (1) takes for a given relative speed during the duration (T) of a period of two successive signals of one signal type (Q ₁ ; Q ₂ ; Q ₃ ) moved relative to the reading station (2). Method according to claim 1, characterized in that a scanning takes place with at least one infrared signal and at least one light signal of a certain wavelength in the visible range. Method according to Claim 1 or 2, characterized in that scanning is carried out with at least one bright field signal and at least one dark field signal. Method according to one of claims 1 to 3, characterized in that the measuring surface extends across the entire recording medium in a line shape transverse to the relative movement. Device for reading sheet-shaped record carriers (1) during a relative movement relative to a reading station (2), which has at least one transmitter (3) for sequentially emitting at least two signals of different signal types (Q ₁ , Q ₂ , Q ₃ ), one for the different signal types (Q ₁ , Q ₂ , Q ₃ ) common receiver (4) for detecting these signals modulated by the recording medium (1) and an evaluation unit for the detected signals, the reading station (2) in each of the signal types (Q ₁ , Q ₂ , Q ₃ ) intermittently scans raster elements (10, 20) with a certain extent (s _R ) along the relative movement direction (R) and at the same time a measuring surface with a certain length (s _B ) in the relative movement direction (R) on the Record carrier (1) detected, characterized in that the transmitter and / or receiver geometry of the reading station (2) is designed in this way and the relative speed t and the cycle times are selected such that the length (s _B ) of the measuring surface detected by the reading station (2) for each signal type (Q ₁ ; Q ₂ ; Q ₃ ) is equal to the path length (1) which the record carrier (1) takes at the given relative speed for the duration (T) of a period of two successive signals of one signal type (Q ₁ ; Q ₂ ; Q ₃ ) relative to the reading station (2 ) moved. Apparatus according to claim 5, characterized by at least one infrared transmitter and at least one transmitter for generating a light signal of a certain wavelength in the visible range. Apparatus according to claim 5 or 6, characterized by at least one transmitter for generating a bright field signal and at least one transmitter for generating a dark field signal. Device according to one of Claims 5 to 7, characterized in that the transmitter or transmitters and / or the receiver are designed and / or arranged in such a way that the measuring surface extends across the entire recording medium in a line shape transverse to the relative movement.

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