GB2409081A - Scanner hood - Google Patents

Abstract

A hood 100 for use with an optical scanner 10 (e.g. bar code scanner) is an opaque tube having, at one end, flaps 114 for connection to the scanner and, at its other end, a window 120 for resting on the surface to be scanned. The window is inclined with respect to a long axis 150 of the hood, which axis is arranged, in use, to be substantially parallel to the light emitted by the scanner. The hood is of a length such that the window is at the focal length of a camera 16 of the scanner, thus optimizing positioning of the scanner with respect to the scanned surface. The internal surfaces of the hood are matt black to reduce internal reflections. The sides 122, 124, 126, 128, 130, 132 of the window 120 are not all planar, so that in use, the surface to be scanned is not entirely shrouded by the hood and at least part of the surface is visible.

Description

240908 1 Scanner Hood

This invention is in the field of scanning

technology. Bar code scanners are ubiquitous, appearing in many different arenas. They comprise a light source illuminating a bar code on an object to be identified.

The scanner has a camera to image the bar code matrix from the reflections detected, and a processor to process the images recorded and report a code when one is isolated and identified from the images received.

Bar codes used in retail applications are generally large. They are generally highly contrasting. And they generally contain redundant information, not just in the code itself (for example, the laser reads a line perhaps 1 mm thick, whereas bar codes can often be more than 10 mm thick) but also in that the code is usually also reproduced as a manually readable number. The number id... . there in the event that the scanner fails to read they. ..

code for any reason, so that an operative can input manually into the apparatus the number that it requires. 2..

However, machine readable codes are also increasingly .

used n industry for the purpose of identifying and....

tracing parts or components. In these circumstances, it, is often the case that the code is permanent, caused, for example, by mechanical deformation of the surface of the object, so that deterioration over time of the code is minimized, and the opportunity for tampering is reduced.

Indeed, frequently, the code may be given as a small matrix square having a coded pattern of dots that gives the coded information. In this case, the code is not read by reading a one dimensional line, as in bar codes,

but by recording a two-dimensional image field and

processing the image to identify the various dots of the code. This reduces the redundancy of the space occupied by the code, which is minimised since the code is permanent, and not intended to be removed with packaging, for example, as is the case with many consumer goods.

Sometimes, if the component in question is small, the resolution required of the scanner to distinguish between dots is high. Also, given that there is reduced redundancy in the matrix, the scanner either detects the dots, or not. Moreover, there is neither room (frequently) to provide an alternative, manually readable number, nor any inclination to do so. The requirement for a manually readable code defeats the object of a machine readable one, which is both to reduce operator input errors and the time taken to input such information.

Consequently there is a need for accurate and precise scanners. Such scanners do indeed exist today, but nevertheless there are occasions when scanners fail to read codes, either at all, or simply in a reasonable space of time.

A further problem with permanent markings of the typed mentioned above, formed by dot peen marking of metal Objects, is that the contrast between the code markings and the background is not great. In many smooth metal applications, off-axis scanning is best. Here, the light from the scanner is primarily reflected away from the scanner camera, off unmarked surfaces of the object and therefore appears dark to the camera. On the other hand, the light is reflected back to the camera from the internal surfaces of indentations, particularly dots, in the marked surface, and therefore appears as bright dots

to the camera. But in this scenario, background

illumination is a problem that reduces contrast.

The cameras of scanners generally have a fixed focal length. Again, bar codes have such built-in redundancy that the camera imprecisely focussing on the code is not often a problem. However, with matrix codes this is not necessarily the case and holding the scanner at precisely the right distance from the object can have greatest reliability of reading. Indeed, often, two cameras are provided in the scanner, each focussing at a different distance. Then, provided that the scanner is held at some approximation of either focal length, usually within ranges that overlap (although that does depend also on the quality of the object), the code can be read.

Finally, scanners, at their proper focal range produce an image covering a specific area. Obviously, this area is chosen to be larger than the largest code is likely to occupy. However, this has the disadvantage that the processor of the scanner frequently processes parts of its image which are merely of the background surrounding the code. This is particularly the case where components are small and small dot matrix codes are employed. ' .. : It is therefore an object of the present invention to:.

provide a means which increases the opportunity of ape. . scanner to correctly identify a code on an object, and to do so quickly and efficiently. In accordance with the present invention, there is . provided a hood intended for use with a scanner, which hood comprises an opaque tube having, at one end, means for connection to a scanner and, at its other end, a window, wherein the window is inclined with respect to a long axis of the hood, which axis is arranged, in use, to be substantially parallel light emitted by a scanner connected to said connection means, the hood being of a length such that the window is at the focal length of a camera of the scanner for which the hood is intended.

In another respect, the invention provides a scanner with a hood, which scanner has a light emitter to emit light along a light axis and a camera focussed at a distance along said axis, said hood comprising an opaque tube having, at one end, means for connection to the scanner and, at its other end, a window, wherein the window is inclined with respect to a long axis of the hood, which hood axis is arranged, in use, to be substantially parallel said light axis, the hood being of a length such that the window is at the focal length of said camera.

Preferably, the internal surfaces of the hood are matt black to reduce internal reflections.

Preferably, the sides of the window are not all planar, so that, when the window rests on a surface to be scanned, the surface is not entirely shrouded by the hood and at least part of the surface to be scanned is visible, whereby the position of the hood and scanner can be adjusted with respect to an object code on the surface within the confines of the window.

Preferably, the window has an acute side and two inclined sides, the sides being planar and at said inclination with respect to the long axis of the hood, which inclination is less than a right angle, preferably between 30 and 50 , ideally about 45 . Preferably said inclined sides merge into open sides in the same plane as said inclined sides, said open sides merging into a connecting side parallel said acute side. Thus, when said acute and inclined sides are placed against a planar 3C surface to be scanned, a viewing window is created for the operator defined by the open and connecting sides.

Preferably, said open and inclined sides are substantially at right angles to one another, whereby the hood is reversible. This is reversible in the sense that the hood can be placed against a surface to be scanned with the open and connecting sides lying against the surface, and the long axis will form the same angle to the surface to be scanned as when it is the acute and inclined sides that are against the surface. Preferably, the inclined sides are longer than the open sides.

Indeed, a ratio of 3:2 of their respective lengths is preferred. Then, when the short sides lie against the surface to be scanned, the viewing window is maximized, facilitating use. On the other hand, if the incidence of environmental light is to be reduced because it interferes with the scanners ability to recognise the code, the long sides can be lain against the surface, thereby minimizing the viewing window.

Preferably, the size of the window is less than the field of view of the scanner camera at the distance of the window from the camera. This has the advantage that when the internal surfaces of the wall are mart black, a .

black frame surrounds the field of view minimising the. ..

processing required of the image viewed. . . Indeed, it is a feature of some scanners that a.. , .

targeting light beam is produced which it is necessary to coincide with a part of the matrix code. This is because the scanner begins processing of the image it receives from a point coincident with the centre of the target.

Consequently, if this point is within the matrix code the code is most likely to be identified.

An embodiment of the invention is further described hereinafter, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a scanner and hood combination in accordance with the present invention; Figure 2 is an end view, in the direction of Arrow II in Figure 4, of the hood shown in Figure 1 and also in accordance with the present invention; Figure 3 is a side view of the combination of Figure 1, wherein the hood is fitted on the scanner; Figure 4 is a side view of the hood of Figure 3 alone; and Figure 5 is a plan view of the hood.

In the drawings a scanner 10 is provided with a hood 100. The scanner is any type of scanner, but in this embodiment may conveniently be a CR2 code reader supplied by MASS Group, Inc. Chatsworth, California, USA. Such a reader is versatile having a dual path optical system, a 1.3 million pixel CMOS sensor and a 400MHz processor. It has two fields of view, a near field and a far f eld, having focal lengths of 100 mm and 230 mm respectivei--i.

It has an optimal decode zone centred on about 85 mm for 5.8 mm Datamatrix, 50 character code. It has both .

cordless and cabled operating capacities. It has a..

1024x640 resolution and a gray scale of 256 divisions. . . However, for the smallest codes (such as the just.. . ë

mentioned 5.8 mm Datamatrix), its operating field is very narrow, of the order of 7 mm. Consequently, it is not easy to find the correct distance to read such small codes. Moreover, when contrast is not good, it is easy to fail to read, even at the right distance: several attempts may be required, holding the scanner at different angles to maximise contrast.

Accordingly, the hood 100 is connected to the front end 12 of the scanner 10. Front end 12 has various scanner components including illumination LEDs 14, twin camera lenses 16, target laser 18, and scanning lasers 20. Buttons 22 are user operated to effect a scan. No further description of the scanner 10 is required as it is in the public domain. However, in the case of the present scanner, this is provided with an elastomeric shield 24 surrounding the front end 12 and protecting the components exposed there. The shield provides a convenient and effective grip location for the hood 100, which has side flaps 110 that grip the shield 24. The hood 100 is a single moulding of any opaque plastics material, and has a matt black finish on its interior surface 112. Top edge 114 of the hood passes over shield 24 which abuts a bottom edge 116 of the hood, forming a light-inhibiting seal around the shield 24. An internal lip 118 may be provided in the hood 100 to maintain squareness of the hood with respect to the shield 24.

The lip 118, and bottom edge 116 are a specific distance from a mouth 120 of the hood 100.

The mouth 120 is defined by an acute bottom edge 122, two inclined sides 124,126, two open sides 128,130, and a top edge 132. The inclined edge 122 and side edges 124' lie in a plane which is inclined at an angle alto respect to a long axis 150 of the hood. Axis 150 is also coincident, or at least parallel, the light axis of the scanner 10 when the latter has its shield 24 squarely .

abutting edge 116 and lip 118. Angle 1.S preferably 45 , but this depends on the application. Where the code.

to be read is formed by dots impinged in a metallic surface, by indenting with a square-nosed punch, then an angle of 45 is appropriate. This angle will put a part of the dot perpendicular to the light from the scanner, which will therefore be reflected straight back at the camera with maximum intensity. However, if the matrix is printed or etched in the substrate surface, or indented with a differently angled punch, a different angle may give the best contrast.

Side edges 124,128 and 126,130 are preferably also coplanar respectively, and subtend a right angle between them Open edges 128,130, and connecting edge 132 are also coplanar, and also subtend an angle of 45 to the long axis 150. Finally, the length of sides 128,130 is about 1 5 times the length of the sides 124,126.

The hood has a constant rectangular section along about half its length (C in Figure 5, about 60 mm) and a tapering rectangular section along its remaining length D, about 55 mm Indeed, the sides 142 taper at an angle J. while the top and bottom sides 144,146 taper at angles E and H respectively (J. E and H being about 10 in each case The effect of this tapering of the hood 100 can be seen in Figure 2, where the hood has a main width A (about 45 mm) and depth B (about 30 mm) corresponding to the dimensions of the shield 24. However, the mouth 120 is much smaller Moreover, the field of view 140 of the cameras 16 at the mouth 120 is much larger than the mouth.

so that the captured image will always have a black,..

border defined by the mouth 120 and the edge of the field of view 140. The blackness here is provided by the.... . internal matt-black finish of the hood 100.. . ë A typical data matrix code 200 on a substrate 210 ë fits within the confines of the mouth 120. At least, it is entirely visible inside the mouth 120 when the latter is offered to the substrate with its acute and inclined side edges 122,124,126 abutting the substrate 210. The target beam 212 is essentially coaxial with axis 150 and is visible on the matrix code 200 to the user through the aperture 130 created between the open and connecting edges 128,130,132 and the substrate 210.

In this position, the scanner 10 is placed at the ideal angle and position to read a low contrast, high resolution data matrix code If still too much transient light enters through the viewing window 130, the scanner and hood can be rotated 180 about the axis 150 and the viewing window is closed by 50%.

The flaps 110 constitute a means of connection of the hood to the scanner. However, different scanners require a different means of connection, depending on their construction. Such means will be straightforward to arrange for a person skilled in the art.

ate .e

Claims (13)

1.A hood for use with a scanner, which hood comprises an opaque tube having, at one end, means for connection to a scanner and, at its other end, a window, wherein the window is inclined with respect to a long axis of the hood, which axis is arranged, in use, to be substantially parallel light emitted by a scanner connected to said connection means, the hood being of a length such that the window is at the focal length of a camera of the scanner for which the hood is intended.

2.A scanner with a hood, which scanner has a light emitter to emit light along a light axis and a camera focussed at a distance along said axis, said hood comprising an opaque tube having, at one end, means for connection to the scanner and, at its other end, a window, wherein the window is inclined with respect to a long axis of the hood, which hood axis is arranged, in use, to be substantially parallel said light axis,,..

the hood being of a length such that the window is at.

the focal length of said camera.

: .:.

3.Apparatus as claimed in claim 1 or 2, in which the.. . internal surfaces of the hood are matt black to reduce internal reflections. .

4.Apparatus as claimed in claim 1, 2 or 3, in which the A sides of the window are not all planar, so that, when the window rests on a surface to be scanned, the surface is not entirely shrouded by the hood and at 0 least part of the surface to be scanned is visible, whereby the position of the hood and scanner can be adjusted with respect to an object code on the surface within the confines of the window.

5.Apparatus as claimed in claim 4, in which the window has an acute side and two inclined sides, the sides being planar and at said inclination with respect to the long axis of the hood, which inclination is less than a right angle.

6.Apparatus as claimed in claim 5, in which said inclination is about 45 .

7.Apparatus as claimed in claim 5 or 6, in which said inclined sides merge into open sides in the same plane as said inclined sides, said open sides merging into a connecting side parallel said acute side, wherein, when said acute and inclined sides are placed against a planar surface to be scanned, a viewing window is created for an operator which is defined by the open and connecting sides.

8.Apparatus as claimed in claim 7, in which said open and inclined sides are substantially at right angles to one another, whereby the hood is reversible.

9.Apparatus as claimed in claim 7 or 8, in which the inclined sides are longer than the open sides. :.

10. Apparatus as claimed in claim 9, in which the ratio.

of the lengths of said inclined sides to said open sides is 3:2. . :.

11. Scanner as claimed in claim 2, or apparatus as claimed in any of claims 3 to 10 when dependent on. . claim 2, in which the size of the window is less than the field of view of the scanner camera at the distanc cf the window from the camera.

12. Apparatus as claimed in claim 11, in which the scanner produces a targeting light beam, which it is necessary to coincide with a part of the matrix code.

13. A scanner and hood substantially as hereinbefore described with reference to the accompanying drawings.