Electric heating – Metal heating – By arc
Reexamination Certificate
1999-12-03
2002-03-26
Evans, Geoffrey S. (Department: 1725)
Electric heating
Metal heating
By arc
Reexamination Certificate
active
06362451
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates in general to a device and method for laser marking. More particularly, the present invention relates to a portable laser marking device having a small marking head which is suitable for deep and permanent marking of hard-to-reach components of assembled products, items having variable sizes, items dispersed over a wide area and/or stationary items, which marking is both very difficult to alter, and if altered, the alteration is readily detected by a casual observer.
The need to mark objects ranges from the simple requirement such as (i) for putting a name tag on an object for recognition by its owner (e.g., a school bag for a child, or a garment sent for dry cleaning), (ii) for conveying certain information to a user of the object (e.g., expiration date on a manufactured food item), and (iii) for marking an object for future identification (e.g., in case of theft) or authentication (e.g., in case of art items).
Many methods for marking objects presently exist, the most common being printing the information either directly on the object, or on a separate sticker which is thereafter attached to the object. In many cases this level of marking is satisfactory, either because the duration of time the marking is expected to survive is limited, such as in the case of short lived shelf items, or in cases where there is no significant risk involved if the marking is altered.
However, other situations exist, where permanent marking is necessary, such that it is both very difficult to alter the marking, and if such an alteration is attempted, it may be readily detected by a casual observer.
It is clear that a detachable sticker cannot serve the purpose of a permanent marking means, as it can be removed, or replaced by another sticker. Even if the removal and replacement of the sticker can eventually be traced and detected in a laboratory, the purpose of immediate detection by an observer is not fulfilled.
Theft of motor vehicles is a well known problem all over the world. The standard way to combat theft is by making it difficult to start and move a parked vehicle by a variety of active and passive protection schemes, and indeed many such schemes are presently marketed globe wise. The usefulness of these schemes, however, is limited, and even though the vast majority of vehicles are protected, the epidemic of vehicle theft is ongoing and increasing. The stolen vehicles are used for joyrides and/or resale, but mostly for the stripping of parts for resale of the stripped parts. The stolen vehicles are therefore disassembled, and the parts are resold as spare parts.
Law enforcing agencies find it difficult to stop this trade in stolen property, as it is virtually impossible to prove that a certain spare part (e.g., a vehicle door) was stolen from a specific vehicle, and therefore it is very difficult to convict the thief, the merchant or the user of the stolen goods.
Engine blocks, chassis, and possibly other components may be marked by the original producer, but these markings are located in difficult places, and may not be directly related to the declared identity of the vehicle (referred hereinafter as the vehicle identification code, typically the vehicle identification number (VIN) and/or its license plate number), and are therefore not very useful for immediate identification of stolen property in the field.
Few years back a sand-blasting based marking method was developed and employed for marking a vehicle identification code on various parts thereof. Nevertheless, this method failed as an anti-theft approach, since as far as metal surfaces are of concern, sand blasting is limited to highly superficial marking which can be easily disguised by simple procedures (e.g., repainting the surface, etc.).
Laser systems are known for quite a while and are used in many fields such as but not limited the field of medicine, weapon systems, detection systems, etc. Laser systems are also used for marking various information on objects. Presently used laser marking systems are based on a relatively large stationary chassis, where the marking head is fixed in space and the objects to be laser marked are fed (manually or automatically) into the laser system. The marking is usually done on a single plane and the entire object to be marked enters the system, thus limiting laser marking to small size objects.
Such a prior art laser system
10
is depicted in FIG.
1
and typically includes (i) a control cabinet
12
, which houses the laser power supply and a computer, and is connected to an external water system; (ii) a laser head
14
, which is connected to control cabinet
12
by electrical and internal water cooling lines, indicated by
16
; and (iii) a marking head
18
, typically formed as an integral part and in continuation to laser head
12
, from which marking head
18
a laser beam
20
emits.
The operation of system
10
is as follows. Laser head
12
and marking head
18
are stationary placed above a marked field in which an object
22
to be marked is placed.
Two alternative methods are used for marking, both methods employ a two dimensional displacement system to generate a relative displacement between laser beam
20
and object
22
, to enable obtainment of two dimensional laser marks.
According to the first method, object
22
is placed on a conveyor
24
which displaces object
22
along a first Cartesian displacement mode, say X, as indicated by arrows
26
and
28
, whereas marking head
18
is capable of changing the direction of beam
20
such that beam
20
may follow a second Cartesian displacement mode, say Y, as indicated by arrows
30
and
32
. Thus, as conveyor
24
displaces object
22
along displacement mode X, beam
20
is displaced at displacement mode Y and a two dimensional mark is formed on object
22
. The first method is suitable for marking products on manufacturing lines such as last marketing date on food items and expiration date on medicines.
According to the second method, object
22
is stationary placed relative to marking head
18
. In this case marking head
18
is capable of changing the direction of beam
20
along both the first (X) and the second (Y) Cartesian displacement modes to form a two dimensional mark on object
22
. The second method is suitable for marking items which are not manufactured in lines.
According to both methods, the relative displacement along the first and second Cartesian displacement modes between beam
20
and object
22
is under the control of the computer housed in control cabinet
12
.
Nevertheless the prior art marking systems suffer limitations rendering them not suitable for some marking purposes. First, such systems require an external water cooling system, employ large laser heads which require stationary support and are therefore robust and non-portable. Typical dimensions of such systems (in mm) are indicated in FIG.
1
. Second, as a result of the robustness and non-portability of the systems, such systems are not suitable for marking hard-to-reach components of assembled products such as vehicle parts, items which have varying sizes, items dispersed over a wide area and/or stationary items.
There is thus a widely recognized need for, and it would be highly advantageous to have, a portable laser marking system having a small marking head which is suitable for deep and permanent marking of hard-to-reach components of assembled products, items having variable sizes, items dispersed over a wide area and/or stationary items, which marking is both very difficult to alter, and if altered, the alteration is readily detected by a casual observer.
SUMMARY OF THE INVENTION
According to the present invention there is provided a portable device and method for deep and permanent laser marking of hard-to-reach components of assembled products, items having variable sizes, items dispersed over a wide area and/or stationary items, which marking is both very difficult to alter, and if altered the alteration is readily detected by a casual observer.
According t
Karni Ziv
Kinrot Opher
Eitan Pearl Latzer & Cohen-Zedek
Evans Geoffrey S.
Lumenis Ltd.
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