GB2284695A

GB2284695A - Bar-code reader

Info

Publication number: GB2284695A
Application number: GB9325306A
Authority: GB
Inventors: Christopher Stafford Cox
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 1993-12-10
Filing date: 1993-12-10
Publication date: 1995-06-14
Also published as: GB9325306D0

Abstract

An optical reader for reading a multi-colour code has a white light source 3 and detectors 7a - 7c which produce an on-off type signal for each colour in the code, the signals then being use to indicate the presence of a particular code, and thus a particular item, in front of the reader. <IMAGE>

Description

BAR-CODE READER.

The present invention relates to a reader for multi-colour coded data displays, in particular those displays of a bar-code type.

Readers of the type which operate by detecting changes in the intensity of projected light which is reflected from a bar-code display are well known. These readers are used to produce electrical signal when the intensity of reflected light incident on the detector exceeds a pre-determined threshold level which is conventionally referred to as the 'on' signal. Below this threshold level no electrical signal is produced and this is conventionally referred to as the 'off' state.

This type of on/off barcode system has the disadvantage that in order to increase the amount of encoded data the physical size, eg.

length, of the coded data display must be increased to accomodate more bars. This is often unachievable because of the constraints imposed by the size of the article on which the display is recorded.

According to the present invention there is provided a reader device, suitable for reading multi-colour coded data displays, comprising a light source capable of projecting a number of wavelengths of light at a target coded data display and detector means capable of producing a signal when the intensity of projected light which is reflected from the target display means exceeds a pre-determined threshold level, characterised in that the detector means is arranged to differentiate between the individual changes in intensity of at least two selected coloured light wavelengths from within the wavelengths of the reflected light.

Particularly provided is a reader as described above having detector means that is capable of producing a signal or series of signals characteristic of a particular arrangement of colours on a multi-colour coded data display. Thus, for example, the detector should be able to produce an on-off type signal for each colour in a display, the signal then being use to indicate the presence of a particular code, and thus a particular item, in front of the reader.

The order of these colours and relation to a particular one of the bars is determined in the known way by scanning the source light across the code display such that a temporal spacing between each bar width and colour is perceived by the detectors.

A typical multi-colour code might be expressed in a number of ways, eg. as variously coloured dots or as concentric circles of varying colour. Most typically a bar-code will be provided wherein use of different colours for individual bars in the code may be detected by the reader and the signal produced thereby compared with a stored signal for identification of the item bearing the code. Thus where a conventional bar code reader would report a signal bearing details of for example 30 bars, the reader of the present invention can read a multi-coloured code and report on it using a signal indicative of say 20, each with a number of further fields based upon the occurence of particular colours in particular bars. Using a three colour reader three conditions for each of the 20 bars would be reportable.For example the first bar would be reported with a signal indicative of colour, eg. -red, while the second might be eg. -blue, and a third eg. -green. Thus for a 20 bar code the possible combinations would be increased approximately three fold should only the first bar be coloured. With all 20 bars in one of the three colours the number of combinations would be increased approximately 320, (ie. less those codes where a zero bar was present).

In this manner the individual colours of the multi-colour coded data display can be used as an element of the cipher which is employed to encode further data. The reader of the invention has the advantage over the known type of reader that more data can be encoded without increasing the physical size of the display or substantially reducing the data reading accuracy of the reader, while at the same time allows presentation on a consumer product to be rendered more attractive. In still mopre preferred embodiments individual patterns might be provided for individual products whereby the code would be effectivel camouflaged and rendered more tamper proof.

In a preferred embodiment of the present invention the detector means comprises a number of photodetectors, each of which is arranged to respond to a different colour from within the spectrum of the projected light by having an optical filter which permits only light of a selected colour to pass through without substantial attenuation disposed in the path of the reflected light between the active surface of the photodetector and the target display. By monitoring the electrical signal which is output from each photodetector the colour of the reflected light causing the signal and hence the colour of that section of the target display from which the light was reflected can be determined, together with its duration in relation to the scanning time of the light emitted from the light source.

Most usefully the signal produced by the reflected light which is incident upon the detector means can be output to a signal handling system capable of analysing the signal by its duration or the colour of reflected light producing it. The reader itself may be provided as a hand held unit or as a fixed unit provided adjacent a work station, eg. a supermarket till with a conveyor. There is no theoretical limit on the number of colour detectors that might be used; only the relative size of the detectors and the reader itself need limit this, Thus for a 3 bar colour code 27 times normal options are provided.

Further provided by the present invention is a system including the reader device of the present invention comprising data links to a computer having stored in its memory reference values of on-off code values for specific items characterised in that these are related by colour as well as bar presence. Thus the computer will relate a series of colour-on-off data such as 1-red+2-blue+3-green to a particular item selected from 33 colour options; that offering 27 times the resolution of items for three colours with only three bars.

The computer, having matched the code with an item then proceeds to transmit further details of the items to a display unit, ie. a small VDU, adjacent an operators work station, eg. a till.

The reader of the present invention will now be further described by way of illustration only by reference to the folowing Example and Figure. Further embodiments of the invention will occur to those skilled in the art.

FIGURE 1; shows a schematic diagram of the essential elements a reader device system of the present invention.

FIGURE 2; shows a schematic diagram of the essential elements of a the interior of a reader device of the present invention.

EXAMPLE 1.

A system according to the present invention, as shown in Figure 1, is provided with a reader device (1) orientated to project a spectrum of light (2) in a scanning format, eg. white light, from a source (3), such that an item to be identified (4) may be placed in the path of this light and reflected wavelengths reenter the device from a multi-colored bar-code thereupon (5). Projected and reflected light may leave and enter the reader through a shared transparent window (6) as shown, or may use separate windows.

Inside the reader are provided a number of light detectors (7a-c), as shown in Figure 2, each sensitive to a particular range of wavelengths of reflected light by virtue of optical filters (8a-c) placed between them and the only light path from the window (6). The filter (8a) only allows passage of blue light, (8b) only red and (8c) only yellow.

Each detector outputs an electrical signal indicative of its on/off state as the scanning light traverses a bar-code on the item in its path, and this signal is fed to a computer (9) for comparison with colour and on/off data relating to catalogued items stored in its memory (10). Once a colour-on/off match is determined further data associated with the particular code is relayed to a diplay unit (11) where it can be accessed by an operator for further processing of the item (4).

It will be realised that in this embodiment that the background colour is not one to which the reader is sensitive; in other embodiments itmay be that such background colour is detected, in which case a further detector will be required to distinguish background.

Claims

CLAIME

1. A reader suitable for reading multi-colour coded data displays comprising (a) a light source capable of projecting light comprising a number of wavelengths at a target coded data display and (b) a detector means capable of producing an electric signal when the intensity of projected light which is reflected from the target display exceeds a pre-determined threshold level; characterised in that the detector means is arranged to differentiate between the individual intensities of at least two selected colours from wavelengths of the projected light refelected from the target coded data display.

2. A reader as claimed in Claim 1 characterised in that the number of selected colours is greater than two.

3. A reader as claimed in Claim 1 or Claim 2 characterised in that the detector means comprises a number of photodetectors, each of which is arranged to respond to a different colour from within the wavelengths of the projected light by having an optical filter which permits only light of a selected colour to pass therethrough without substantial attenuation disposed in the path of the reflected light between the active surface of the photodetector and the target display.

4. A reader as claimed in any one of the preceding claims characterised in that the detector means is arranged to output the electrical signal produced by the light reflected from the target display to a signal handling system capable of analysing the signal by its duration or the colour of reflected light producing it.

5. A reader as claimed in any one of the preceding claims characterised in that the light source provides a beam of light that scans across an item placed in its path, whereby the width of colour elements in the code display thereon may be determined by the duration of the signal produced by the detector that is sensitive to that particular wavelength of reflected light.