GB2305283A - Laser unit for a bar code reader - Google Patents

Abstract

This invention relates to a laser unit for a bar code reader and fitable as a retro-fit into a hand-held computer. A laser unit (10) for a bar code reader (40) has electrical connections, a source of laser light and means to analyse reflected light, the unit being adapted for fitment into the casing (38) of a selected hand-held computer (42) with its electrical connections coupled to those of the computer processor.

Description

LASER UNIT FOR A BAR CODE READER, BAR CODE READER FITTED THEREWITH, AND METHOD OF PRODUCING A PORTABLE LASER BAR CODE READER FIELD OF THE INVENTION This invention relates to a laser unit for a bar code reader, to a bar code reader fitted therewith, and to a method of producing a portable laser bar code reader. In particular, the invention relates to a laser unit fittable as a retro-fit into a hand-held computer.

BACKGROUND TO THE INVENTION The use of bar codes to identify products is becoming increasingly common, and many shops and supermarkets for example use fixed bar code readers at the check-outs to determine the products being purchased and the price to be charged. However, portable bar code readers are also becoming increasingly widespread, and have utility for example in stock control, wherein an operator can carry the reader to identify which products are stored at a particular location.

DESCRIPTION OF THE PRIOR ART Bar code readers fall broadly into three general classes, (i) contact reader or wand devices, fii) charge coupled devices (C.C.D.s), and (iii) laser devices.

The first of these classes requires an operator relatively to move the wand across and in contact with the bar code to be read. The wand includes a light source which when illuminated is selectively reflected by the black and white areas of the bar code, a photoelectric sensor which responds by way of an analogue signal to the quantity of light reflected from the bar code so as to distinguish between the black and white areas and their respective thicknesses, and most commonly electronic means connected to the photoelectric sensor to convert the analogue signal into a digital signal representative of the bar code. This digital signal can then be processed by a decoder which converts the signal usually into ASCII form, so that the bar code can be read by a computer and thus the associated goods can be identified.

The electronics are able to resolve certain variations in the speed at which the wand is moved across the bar code, but are unable to resolve large variations, and so the performance of such a device is operator-dependent. In addition, the bar code to be read must be substantially flat. Accordingly, this class of bar code reader suffers a relatively large proportion of reject readings, requiring a repeat movement over the same bar code, though if the operator is not alert and believes that the bar code has been read use of this reader may result in an incorrect total i.e. of the number of goods in store or amount owing by a customer.

The second class of bar code reader does not need to be moved across the bar code but uses a charge coupled device to obtain a simultaneous image of the whole of the bar code, which image is assessed by electronic means to determine the bar code. The majority of devices in this class suffer from the disadvantage that the depth of field is small, so that the acceptable distance of the bar code reader from the bar code must be tightly controlled, i.e. a bar code which is outside the depth of field will not be read, with the resulting incorrect totalling as discussed above for the wand-type bar code reader. These devices are thus referred to as contact, or near-contact, readers.

The third class of bar code reader employs a source of laser light which is energised to provide a beam which results in a light spot which in use is moved at high relative speed across the bar code, the device also including a photoelectric sensor adapted to determine the quantity of laser light reflected from the bar code. The electronics developed for such bar code readers enable the reading of bar codes even from non-planar surfaces, and the depth of usable field is much larger than for most other readers, so that laser bar code readers are able to read bar codes over a significant depth range (including from a considerable distance from the bar code); for both these reasons this third class is less dependent on operator accuracy and so is widely preferred.This class of reader in general also has a lower response time i.e. it can often read bar codes faster than either of the first and second classes described above and is preferred for this reason also.

Computers are also well-known which provide calculating, memory and perhaps the control of printing and other external functions. Smaller computers have been developed and are in widespread use, as "desk-top", "lap-top" and "hand-held" models of successively smaller size and lower weight. Handheld computers are sometimes also referred to as "portable data terminals" since they provide a portable means for the input, utilisation, display (and perhaps output) of data.

It is known to mount a laser bar code reader externally upon a hand-held computer, the reader decoding the bar code being read and communicating this to the computer, the computer storing this information and manipulating it if necessary.

However, since the bar code reader is substantially a separate unit connected to an existing hand-held computer, such devices are cumbersome, and we believe this is a major factor limiting their more widespread use.

STATEMENT OF THE INVENTION We have developed a laser unit which will fit within the casing of a hand-held computer, usefully replacing a movable battery and memory carrier, whereby to provide a bar code reader. Locating the unit within the casing of the computer protects the unit from impact damage, permits the electrical connections between the unit and the computer processor to be located completely within the casing, permits the lengths of those connections to be minimised, does not materially increase the dimensions of the computer, and does not adversely affect the ergonomics of the computer. This new unit thus greatly facilitates the provision of acceptable portable bar code readers.

Thus as one feature of the invention we provide a bar code reader which includes a hand-held computer, the computer casing having a recess characterised by a laser unit fitted into said recess. Preferably, the recess is the one provided for receiving a movable battery and memory carrier for the hand-held computer.

We also provide a laser unit for a bar code reader, the laser unit including electrical connections and a source of laser light, the unit being adapted for fitment into the casing of a hand-held computer with its electrical connections coupled to those of the computer processor and with the source providing a laser light beam directed away from the computer, and with means to receive reflected light from the bar code and to analyse that reflected light.

The laser unit preferably comprises a laser "engine", at least one battery providing electrical power for the engine, output electronics to convert the electrical signals of the laser engine into a form readable by the computer processor so that the laser unit can become integrated therewith, and a computer interface. Preferably, the said battery provides power for the computer processor also.

The laser engine preferably includes means to produce and move the spot of laser light, a photoelectric sensor to measure the quantity of reflected laser light, and electronic means to determine the bar code being read. Usefully, the laser engine is a SymbolTM SE1022 laser engine.

A suitable hand-held computer is a Psion WorkaboutTM, whose range of uses is therefore increased, and the preferred laser unit is selected to be sized and shaped to fit within the recess obtained by the removal of the solid state drive drawer of such computer.

In such a computer, the reader is readily portable, offers one-handed operation, and is far less cumbersome than similar previously available readers. The provision of a laser unit within a widely-available and relatively low cost hand-held computer will we believe permit the use of the superior laser-type bar code readers in circumstances and situations which were previously impossible, undesirable, or impractical.

We also provide a method of producing a portable laser bar code reader including the steps of: fi) selecting a suitable hand-held computer, (ii) removing the solid state drive drawer therefrom, iii) creating a laser unit comprising a laser engine, at least one battery, output electronics, and a computer interface; and (iv) inserting the laser unit into the recess created by removal of the solid state drive drawer.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig.l is a plan view, partly in section, of a laser unit according to the invention; Fig.2 is a view of the end cap of the unit of Fig.l, viewed from the "inside" of the end cap; Fig.3 is a side view of the unit of Fig.l; and Fig.4 is a schematic rear view of a bar code reader according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The laser unit 10 of Figs.l-3 comprises a first printed circuit board 12 to which is mounted a laser engine 14, a second printed circuit board 16 (carrying the decoding electronics of the laser engine), a pair of heavy-duty rechargeable batteries 18, a serial interface connector 20, and a multi-channel computer interface connector 22. Also secured to the first printed circuit board 12 is an end cap 24, which cap carries the reader window 26.

In the embodiment shown the laser engine 14 is a Symbol TM SE1022 laser engine, and the unit is adapted to fit within the recess created by the removal of the solid state drive drawer of a Psion WorkaboutTM hand-held computer.

Thus, the Psion WorkaboutTM hand-held computer comprises an outer casing into which is located a main internal, or CPU, frame, which main internal frame slidably receives a solid state drive drawer. The solid state drive drawer, in the assembled computer, is able to slide partially out of the casing, to expose a pair of removable memory cartridges, a pair of main (non-rechargeable or rechargeable) batteries, and a back-up battery. The slidable solid state drive drawer enables the replacement of the batteries when required, and also enables the computer to be used for the collection of data for subsequent use by another computer, the data being transferred to the said another computer by way of the memory cartridges. The laser unit 10 is adapted to replace the solid state drive drawer.

The second printed circuit board 16 carries the electronics provided with the laser engine, which electronics control the creation, movement, and detection of a beam of laser light, and the subsequent decoding of the bar code being read. The second printed circuit board 16 is normally mounted to the rear face 30 (Fig.3) of the engine 14, but in this embodiment is detached therefrom and secured directly to the first printed circuit board 12. The laser engine 14 is secured to the printed circuit board 12 by way of a mounting bracket 28 (the bracket connecting to the engine by way of the screw holes provided therein for the second printed circuit board).

Electronic componentry on the board 16 convert the signals from the laser unit into a form usable by the computer processor, and vice versa. The serial interface connector 20 links the second printed circuit board 16 to the first printed circuit board 12.

The electrical connections between the engine 14 and the second printed circuit board 16 is by way of an existing flexible printed circuit (FPC). The connections between the second printed circuit board 16 and the serial interface connector 20, and between the computer interface connector 22 and the computer processor are each by way of a new FPC. The electrical connections between the serial interface connector 20 and the computer interface connector 22, and between the batteries 18 and the various components, are by way of electrical leads or tracks on the first printed circuit board 12 in known fashion. None of the electrical connections are shown in the drawings, but will be understood by those skilled in this art.

The batteries 18 are also connected to the computer processor and related electronics, to power both the laser unit 10 and the host computer. The batteries 18 thus replace the batteries which were carried by the solid state drive drawer, so that the computer when fitted with the laser unit according to the invention may be operated in normal fashion with the exception of the removable memory cartridges; however, the computer has sufficient built-in memory to carry out the tasks normally required of it.

A recharging socket for the batteries 18 is provided in the computer casing.

The first printed circuit board 12 also carries a back-up battery and a piezo-sounder (neither of which is shown in the drawings); the sounder is activated when a bar code has been successfully read, in known fashion.

The end cap 24 is mechanically connected to the first printed circuit board 12 by way of screws or other fixing devices passed through the board 12 into lugs 32. The end cap, and thus the laser unit, is secured to the main internal frame (or CPU frame) of the computer by screws or other fixing devices passed through apertures in the main internal frame and into lugs 34. The main internal frame is secured to the computer casing in known fashion. Lugs 32 and 34 may carry tapped inserts, usefully of brass, if desired.

Thus in the assembled condition of Fig.4, the laser unit 10 (shown in dotted outline) fits within the recess 36 in the casing 38 of the hand-held computer 42, to provide a portable laser bar code reader 40.

By reversing some or all of the above assembly procedure, the main internal frame, and thus the laser unit, may be removed from the computer casing for inspection and repair of the laser unit.

It will be understood that the particular arrangement of the components on the first printed circuit board 12 as described herein is suitable for a laser engine fittable into a Psion WorkaboutTM computer; however the components could be arranged differently for this or other host computers, either as desired or as necessary to fit the available recess.

The end cap 24 is sized and shaped to fit to the end of the hand-held computer in place of the end cap carried by the solid state drive drawer. Thus, when the computer has been fitted with a laser unit according to the invention it is substantially identical in size and shape to the computer "as manufactured", so that the ergonomics of the computer are not adversely affected despite the addition of this new use and the consequent substantial increase in its utility.

We have thus realised that it is possible to provide the advantages of a laser bar code reader in a portable and convenient form. When assembled into a host computer, our laser unit is largely protected from impact damage by the computer casing; also, it has shorter and more reliable connections to the computer, and is far less cumbersome, than the prior known portable laser bar code readers.

In the embodiment shown, we have utilised a Psion WorkaboutTM computer since this is a widely used and well-respected computer having a recess which is suitable for receiving our laser unit. It is believed that our laser unit will find its greatest utility with such a computer. However, alternative hand-held computers could be used provided that they have a suitable recess into which our laser engine could be adapted to fit.

Claims (13)

1. A laser unit for a bar code reader, the laser unit including electrical connections, a source of laser light, means to receive reflected laser light and means to analyse that reflected light, the unit being adapted for fitment into the casing of a selected hand-held computer with its electrical connections coupled to those of the computer processor.

2. A laser unit according to claim 1 which includes at least one battery providing electrical power for the engine.

3. A laser unit according to claim 2 in which the said battery also provides power for the computer processor.

4. A laser unit according to claim 2 or claim 3 in which the unit includes output electronics to convert the electrical signals of the laser engine into a form readable by the computer processor.

5. A laser unit according to any of claims 1-4 in which the unit includes a computer interface.

6. A laser unit according to any of claims 1-5 in which the laser unit includes means to move the beam of laser light produced by the said source, a photoelectric sensor to measure the quantity of reflected laser light, and electronic means to determine a bar code being read.

7. A laser unit according to any of claims 1-6 in which the laser unit includes a SymbolTM SE1022 laser engine.

8. A bar code reader which includes a hand-held computer, the computer body having a recess into which is fitted a laser unit according to any of claims 1-7.

9. A bar code reader according to claim 8 in which the recess is adapted to receive a movable battery and memory carrier.

10. A laser unit according to any of claims 1-7, or a bar code reader according to either of claims 8 or 9, in which the hand-held computer is a Psion WorkaboutTM, the laser unit being sized and shaped to fit within the recess obtained by the removal of the solid state drive drawer of such computer.

11. A method of producing a portable laser bar code reader including the steps of: (i) selecting a suitable hand held computer, (ii) removing a component therefrom to provide a recess in the body of the computer, (iii) creating a laser unit comprising a laser engine, at least one battery, output electronics, and a computer interface; and fivj inserting the laser unit into the said recess.

12. A method according to claim 11 in which the said component is the solid state drive drawer.

13. A laser unit constructed and arranged substantially as described in relation to Figs. 1-3 of the accompanying drawings.