Registers – Coded record sensors – Particular sensor structure
Reexamination Certificate
2000-08-18
2001-08-21
Pitts, Harold I. (Department: 2876)
Registers
Coded record sensors
Particular sensor structure
C235S462240
Reexamination Certificate
active
06276606
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a full range bar code scanner, more particularly, to a bar code scanner having a wider reading range without the distance restriction in scanning the bar code signals.
2. Description of the Prior Art
A conventional bar code scanner, as shown in
FIGS. 1 and 2
, contains a scanner housing
1
inside of which a light source
2
, a lens set
3
and a CCD-sensing device
4
are disposed. The light source
2
shines on a bar code
5
in front thereof, and the reflection light
6
is focused by the lens set
3
and the image of the bar code
5
is formed on the CCD-sensing device
4
. After read by the CCD-sensing device
4
and decoded by an electrical circuit, the image is converted into digital data for use.
As described above, the scanning distance at which a clear image is formable is not the same because of the difference of the curvature of the lens set
3
and the focus design between the lens set
3
and the CCD-sensing device
4
. The principle thereof is similar to that of the diopter of the spectacles and the magnifying glass. Being too far will cause a difficult recognition due to the insufficient brightness and the small image. Being too near will cause a difficult forming of image or the image-forming range beyond the capacity of the CCD-sensing device
4
. Therefore, the effective distance (depth of focus, symbolized by “X”) of the reflection light of the bar code upon the CCD-sensing device
4
is fixed. Accordingly, the reading distance of the conventional bar code scanner is restricted by the lens set
3
in such a way that the image of the bar code beyond the standard reading range can't be formed on the CCD-sensing device
4
. As a result, the conventional scanner designated for reading a remote bar code is not suitable for reading a bar code within a short distance. In the contrary, the scanner for reading a bar code within a short distance isn't suited for reading a remote bar code. In addition, the depth of focus “X” of the common scanners for recognizing the bar code is not enough, causing the inconvenience in using that the user has to repeatedly adjust the distance between the scanner and the bar code.
SUMMARY OF THE INVENTION
It is therefore a primary object of the present invention to provide a full range bar code scanner which overcomes the restriction of the depth of focus of the conventional scanner and extends the range of the scanner in recognizing the bar code with a most simple and effective structure to facilitate a rapid reading of the bar code.
In order to reach the above-mentioned object, the full range bar code scanner in accordance with the present invention primarily comprising a scanner housing inside of which a light source, a lens set and a CCD-sensing device are mounted. The light source emits light to reflect upon a bar code in front thereof. Thereafter, the created reflection rays are focused after passing through the lens set so that the image of the bar code is formed on the CCD-sensing device and converted into digital data for use after being read by the CCD-sensing device and decoded by an electrical circuit. This improvement is characterized in that a spectroscope (through which some of rays pass and on which some of them reflect) is mounted at the path of the reflection rays in front of the lens set. One side of the spectroscope opposite to the lens set is constructed as reflection face with reflection effect, and at least one secondary reflector is installed near the spectroscope. By means of the spectroscope and the secondary reflector, the image of the object or the bar code within a short distance (beyond the depth of the lens focus) reflects upon two lens in order to prolong a false light travel for reaching a focusing of a long distance and the range of the depth of focus. Thus, the image of the bar code is formed on the CCD-sensing device
4
after passing through the lens set. Accordingly, a bar code scanner with a full scanning range of a short and long distance is attainable.
The spectroscope is filmed in such a way that only about 90% of rays can pass through the spectroscope. Moreover, at least 90% of rays are able to be reflected by the reflection face.
Accordingly, the focus (light-focusing travel) is fixed so that the scanner in accordance with the present invention is able to read the bar code at a great distance within the depth of focus by means that the original reflection rays of the bar code directly pass through the spectroscope. The reflection rays of the bar code (at a short distance) beyond the range of the original depth of focus reflect upon the secondary reflector and the spectroscope first to prolong the projection distance. Consequently, the scanner is mated to the position of the less depth of focus to form a clear image on the CCD-sensing device so that the effect and the aims of bar code scanner with a full scanning range for the bar code at a short and long distance is attainable.
REFERENCES:
patent: 5744790 (1998-04-01), Li
Liou Kenneth
Tien Kai-Yuan
Bacon & Thomas PLLC
Pitts Harold I.
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