CN2821700Y - Bar code reader - Google Patents

Abstract

The utility model relates to a bar code reader which comprises a bar code identifying and reading device (1) and an optical system (2), wherein the bar code identifying and reading device (1) comprises a charge coupling device (3) and a bar code decoding unit (4), and the optical system (2) is a convex lens or a lens assembly which forms a real image. The distance between the charge coupling device (3) and the center of the convex lens or the equivalent center of the lens assembly which forms the real image is more than 2 times the focal length of the convex lens or the equivalent focal length of the lens assembly which forms the real image. The bar code reader which is provided by the utility model solves the problem that the existing bar code reader can not read a miniature bar code so that the application of the miniature bar code in each field is turned to be possible.

Description

Bar-code reader

Technical field

The utility model relates to a kind of bar-code reader.

Background technology

Bar code symbol normally is made up of rectangular strip with many kinds possibility width or element.The specific layout of element is determined to characterize character according to set of rule and definition, and these rules and definition are determined by the bar code symbol representation.Bar and empty relative size are to be determined by the coding kind that is adopted, and bar and empty physical size also are like this.The number of characters that the bar code symbol per inch is characterized is called as the density of symbol.Can to characterize or data quantity stored in order being increased on the given surface area, except bar code, also to have developed two-dimensional bar code, two-dimensional bar code is not only stored data in the horizontal direction, also can store data on the vertical direction.

The existing bar-code reader of charge-coupled image sensor recognition bar code that adopts comprises bar code reader and optical system, described bar code reader comprises charge-coupled image sensor and bar code decoding unit, described optical system is convex lens, bar-code reader can also comprise the scanning window, and this scanning window is the high level crossing of transmittance.Existing bar-code reader can be read the bar code of conventional size easily, but the function that optical system is not amplified bar code.

Yet miniature bar code has and is difficult for being found and duplicating, and prevents the advantage of being palmed off by the lawless person effectively.The bar of bar code and the empty size bar code littler than the resolution of the charge-coupled image sensor of bar-code reader are referred to as miniature bar code.For example the charge-coupled device (CCD) of bar-code reader adopts high-resolution charge-coupled image sensor usually, by the size and the ultimate resolution of charge-coupled image sensor, can calculate the distinguishable distance of minimum space between each pixel.For example the target surface of 1/2 inch charge-coupled image sensor is of a size of 6.4mm * 4.8mm, if resolution is 640 * 480, then the minimum distinguishable distance between per two pixels is 0.01mm, if bar code represents that the bar of information and the distance between the sky are less than 0.01mm, then the charge-coupled image sensor that is adopted just can not be distinguished out bar code information, and this moment, this bar code can be considered miniature bar code.The making of miniature bar code relies on prior art to realize at an easy rate, but existing bar-code reader but can not be distinguished miniature bar code, and the application of this miniature bar code is restricted.

The utility model content

The purpose of this utility model is to overcome existing reader can not read miniature bar code, thereby the problem that such bar code is promoted the use of provides a kind of bar-code reader that can read miniature bar code.

The bar-code reader that the utility model provides comprises bar code reader 1 and optical system 2, described bar code reader 1 comprises charge-coupled image sensor 3 and bar code decoding unit 4, wherein, described optical system 2 is convex lens or the combination of lenses that becomes real image, charge-coupled image sensor 3 and convex lens center or to become the distance at equivalent center of the combination of lenses of real image be more than 2 times of combination of lenses equivalent focal length of described focal length of convex lens or one-tenth real image.The existing bar-code reader of the device solves that the utility model provides can not be read the problem of miniature bar code, makes miniature bar code apply to the false proof possibility that becomes.

Description of drawings

Fig. 1 is the structural drawing of an embodiment of the present utility model;

Fig. 2 is the structural drawing of another embodiment of the present utility model;

Fig. 3 is the index path of optical system imaging of the present utility model.

Embodiment

The utility model is described in further detail below in conjunction with the drawings and specific embodiments:

The bar-code reader that provides according to the utility model, as shown in Figure 1, this bar-code reader comprises bar code reader 1 and optical system 2, described bar code reader 1 comprises charge-coupled image sensor 3 and bar code decoding unit 4, wherein, described optical system 2 is convex lens or the combination of lenses that becomes real image, charge-coupled image sensor 3 and convex lens center or to become the distance at equivalent center of the combination of lenses of real image be described focal length of convex lens or more than 2 times of combination of lenses equivalent focal length that become real image are preferably 2-10 doubly.

According to the bar-code reader that the utility model provides, as shown in Figure 2, this bar-code reader can also and preferably include the shell 5 that surrounds bar code reader 1 and optical system 2, and bar code reader 1 and optical system 2 are fixed on the shell 5.

The bar-code reader that provides according to the utility model, as shown in Figure 2, this bar-code reader can also and preferably include scanning window 6, and this scanning window 6 is the high level crossings of transmittance, lay respectively at the both sides of optical system with charge-coupled image sensor (3), itself and optical system apart from coincidence formula (1):

$\frac{1}{l^{\′}}+\frac{1}{l}=\frac{1}{f^{\′}}---\left(1\right)$

Wherein, l is for scanning window 6 and convex lens center or become the distance at equivalent center of the combination of lenses of real image, l ' is charge-coupled image sensor 3 with the convex lens center or becomes distance, the focal length of f ' convex lens or the equivalent focal length of combination of lenses at equivalent center of the combination of lenses of real image.

With reference to figure 3, number in the figure 7 indication dotted lines are the bar code plane, and label 8 indication dotted lines are the CCD focal plane, and label 9 and 10 indication band arrow straight lines are respectively two light.Scanning window 6 and convex lens center or become the distance at equivalent center of the combination of lenses of real image, be bar code plane 7 with the convex lens center or to become the distance at equivalent center of the combination of lenses of real image be image distance, charge-coupled image sensor 3 and convex lens center or become the distance at equivalent center of the combination of lenses of real image, the distance that is the equivalent center of focal plane 8 and the convex lens center of charge-coupled device (CCD) 3 or the combination of lenses that becomes real image is an object distance, satisfied object distance like this, imaging relations between image distance and the focal length, guaranteed that scanning back enlarged image becomes real image on the focal plane of charge-coupled image sensor 3, make to adopt to have the miniature bar code that bar code reader can not be discerned now, can be offered an explanation by charge-coupled image sensor 3.

According to the bar-code reader that the utility model provides, wherein, charge-coupled image sensor 3 is used to obtain bar code image, the graphics processing unit of bar-code identification unit 4 for having decoding function.The structure of charge-coupled image sensor 3 and bar-code identification unit 4, kind are conventionally known to one of skill in the art.

An embodiment of the present utility model is as optical system 2 with convex lens, concrete enlargement factor is calculated according to the minimum distinguishable distance of distance between the minimal information bar code of miniature bar code and charge-coupled image sensor 3, for example, adopting 1/2 inch, resolution is 640 * 480 charge-coupled image sensor, if the distance between the minimal information bar code of miniature bar code is 0.005mm, then need to amplify 2 times at least.

The position of convex lens can be determined by formula (1) according to the relation of the equivalent focal length of object distance, image distance and focal length of convex lens or combination of lenses.With reference to figure 3, amplify twice if desired, then needing image distance l ' and the ratio of object distance l is 2.For example the distance from the bar code to the charge-coupled image sensor is 6cm, l '=4cm then, l=2cm.This moment focal distance f '=1.33cm.Calculate thus as can be known, amplify in the bar-code reader of twice at needs, focal length be the convex lens of 1.33cm be placed on the miniature bar code 2cm of distance, apart from the place of charge-coupled image sensor 4cm, both can realize this bar-code reader function.Be applicable to bar code and two-dimensional bar code based on this principle the utility model.

According to one of the utility model preferred embodiment, use combination of lenses into real image as optical system 2.The combination of lenses of described one-tenth real image is equivalent to convex lens, and its equivalent center and equivalent focal length are defined as conventionally known to one of skill in the art.The combination of lenses of described one-tenth real image can be the combination of a plurality of convex lens, or the combination of one or more convex lens and one or more concavees lens.Use existing optical design software, as optical design software such as ZMAX or CODEV, those skilled in the art can simulate the combination of lenses system according to enlargement factor and object distance, the image distance distance of system, can obtain the combination of lenses that aberration is better than the aberration of single lens.

The bar-code reader that the utility model provides can also comprise the lighting device that independently exists or be fixed on housing exterior or inside, to strengthen the brightness and contrast of image.

According to one of the utility model preferred embodiment, as lighting device, can reduce the aberration that brings by multispectral light source with the light source of single wavelength like this.

Adopt system described in the utility model, solved the problem that bar-code reader of the prior art can not be discerned miniature bar code, thereby make miniature bar code become possibility in the application of every field.

Claims (8)

1. bar-code reader, comprise bar code reader (1) and optical system (2), described bar code reader (1) comprises charge-coupled image sensor (3) and bar code decoding unit (4), it is characterized in that, described optical system (2) is convex lens or the combination of lenses that becomes real image, charge-coupled image sensor (3) and convex lens center or to become the distance at equivalent center of the combination of lenses of real image be more than 2 times of combination of lenses equivalent focal length of described focal length of convex lens or one-tenth real image.

2. bar-code reader according to claim 1, wherein, described charge-coupled image sensor (3) and convex lens center or become the distance at equivalent center of the combination of lenses of real image be focal length of convex lens or the combination of lenses equivalent focal length that becomes real image 2-10 doubly.

3. bar-code reader according to claim 1 and 2, wherein, this bar-code reader also comprises the shell (5) that surrounds bar code reader (1) and optical system (2), bar code reader (1) and optical system (2) are fixed on the shell (5).

4. bar-code reader according to claim 3, wherein, this bar-code reader also comprises scanning window (6), this scanning window (6) is the plane transmission mirror, lay respectively at the both sides of optical system with charge-coupled image sensor (3), and be fixed on the shell (5), scanning window (6) meets following formula with the distance of optical system (2):

$\frac{1}{l^{\′}}+\frac{1}{l}=\frac{1}{f^{\′}}$

Wherein, l is for scanning window and convex lens center or become the distance at equivalent center of the combination of lenses of real image, l ' is charge-coupled image sensor with the convex lens center or becomes the distance at equivalent center of the combination of lenses of real image that f ' is the focal length of convex lens or the equivalent focal length of combination of lenses.

5. bar-code reader according to claim 1 and 2, wherein, described bar-code reader also comprises lighting device.

6. bar-code reader according to claim 3, wherein, described bar-code reader also comprises the lighting device that is fixed on housing exterior or inside.

7. bar-code reader according to claim 5, wherein, the lighting device of described bar-code reader is the light source of single wavelength.

8. bar-code reader according to claim 6, wherein, the lighting device of described bar-code reader is the light source of single wavelength.

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