JPH08255215A - Bar code reader - Google Patents

Abstract

PURPOSE: To make possible stable reading even when a bar code symbol for circulating commodity having a long code length and an ordinary bar code having a comparatively short code length are mixed by changing the diaphragm diameter of an diaphragm part corresponding to the reading position of the bar code reader and the wavelength of illumination light. CONSTITUTION: When reading is performed by a flood part light source having the comparatively small quantity of light without requiring any reading depth, a second iris part 52 inside an adiapragm member 5 passes the wavelength near the light source of a flood part so that the diameter 51a of the second diaphragm part 52 is made valid as a diaphragm effect. Therefore, the diaphragm diameter is comparatively enlarged and even a code having narrow bar width or a code having faint printing can be read. When reading is performed by external light such as indoor illumination having the comparatively larger quantity of light while requiring the reading depth, the second diaphragm part 52 of the diaphragm member 5 does not pass the wavelength except the wave-length of the light source of the flood part so that a first diaphragm part 51 having the small diaphragm diameter is made valid as a diaphragm effect. Therefore, reading is possible even at any position away from the bar code reader.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reader which optically scans a bar code using an image sensor to read the bar code.

[0002]

2. Description of the Related Art As is well known, in 1987, JIS-X-502 was standardized as a bar code symbol for physical distribution products. This standardized bar code has a maximum code length exceeding 200 mm in consideration of printing on a cardboard or the like. When reading such a bar code with a bar code reader using an image sensor, FIG.
As shown in Fig. 5, the reading port of the barcode reader 1 is enlarged according to the barcode label 2, or
As shown in (a), it is necessary to separate the barcode reader 1 from the barcode label 2 and perform the reading with the field of view of the reader widened as shown in a in the figure. 5A shows the field of view of the barcode reader 1 and b the distance to the barcode label 2.

[0003]

However, when the reading port of the bar code reader 1 is enlarged as shown in FIG. 4, the shape of the bar code reader 1 becomes large and the weight of the bar code reader 1 increases. There is a drawback that the operability becomes poor.

As shown in FIG. 5A, when the barcode reader 1 is read in a floating state, the focus position of the optical system of the barcode reader 1 is the position shown in FIG.
However, if a general bar code label 2, for example, a JAN code, is read at this in-focus position as shown in FIG. 5B, an image cannot be formed on the image sensor due to the deviation from the in-focus position, resulting in image blur. Therefore, it has a drawback that it cannot be read.

In order to solve the above drawbacks, FIG.
(B) It is necessary to reduce the aperture shape of the reader optical system and deepen the depth of focus of the optical system so that image blur does not occur at either position. However, when the diaphragm shape is made smaller, the amount of light received by the image sensor decreases, and the image sensor output signal amplitude decreases, especially when reading with only the illumination light of the light projecting portion of the bar code reader 1 as in the case of FIG. 5B. In addition, there is a drawback that a thin print label or a narrow bar width label cannot be read.

A technique for improving these is disclosed in JP-A-60
As disclosed in Japanese Patent Laid-Open No. 235277, a technique using a liquid crystal capable of varying a diaphragm area for a diaphragm member has been disclosed, but the liquid crystal itself is expensive, and an additional circuit for controlling the area of the liquid crystal. Has the drawback that it is necessary.

The present invention solves such a problem, and an object of the present invention is to provide a bar code reader capable of stably reading a bar code in both cases of FIGS. 5 (a) and 5 (b).

[0008]

In order to achieve the above object, the present invention has the following constitution. That is, the bar code reader of the present invention forms a bar code image by receiving light reflected from the bar code label and a light projecting unit that irradiates light onto the bar code label, and converts the bar code image into an electric signal. An image sensor for converting and a circuit unit for processing the image sensor output signal and reading the barcode, and having a diaphragm member for narrowing down the barcode image between the image sensor and the barcode label. The aperture member includes a first aperture portion that passes a wide range of wavelengths including the wavelength of the light source, and a portion of the light source including the periphery of the first aperture portion and excluding the first aperture portion. It is a bar code reader provided with a second diaphragm portion having a filter effect that passes near the wavelength.

[0009]

With this configuration, when the reading depth is not required as shown in FIG. 5B and the light is emitted from the light source of the light projecting portion which has a relatively small amount of light, the second diaphragm having a large diaphragm diameter is effective. As shown in FIG. 5A, when the reading depth is required as shown in FIG. 5A and the reading is performed by the external light such as indoor lighting having a relatively large amount of light, the first diaphragm having a small diaphragm diameter is effective.
(B) Stable reading can be realized in two states.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an example of the configuration of the bar code reader of the present invention. In FIG. 1, reference numeral 3 denotes a light projecting unit for illuminating the bar code label 2, which is composed of a plurality of LEDs. In this embodiment, a red LED with a wavelength of 660 nm is used.
Was used. The light receiving optical system refracts the reflected light from the barcode label 2, and the diaphragm member 5 that forms the image of the label on the diaphragm image sensor 7 with the refracted reflected light.
And a light receiving lens 6. The image sensor 7 converts a barcode image into an electric signal, and the circuit unit 8 processes the output signal of the image sensor 7 to read barcode information.

FIG. 2 shows the structure of the diaphragm member 5 described above. The first diaphragm portion 51 which passes a wide range of wavelengths including the wavelength of the light source of the light projecting portion 3 and the hatched portion shown in the drawing are used for the first diaphragm portion 51. First
The second diaphragm 52 includes the periphery of the diaphragm 51 and has a filter effect that passes near the wavelength of the light source of the light projecting unit 3. In this embodiment, the pass wavelength of the filter is set to 6
It was set to 60 ± 10 nm. In the drawing, 51a and 52b indicate the diameters of the respective diaphragms.

An example of reading the two bar code labels shown in FIGS. 3 (a) and 3 (b) with the configuration example of FIGS. 1 and 2 will be described.
The bar code label 2 in FIG. 3A is a product code printed on food miscellaneous goods and has a minimum bar width of 0.26 m.
m, the cord length is about 25 mm. The bar code label 2 in FIG. 3 (b) is a code for physical distribution products, and the minimum bar width is 1.
The length is 0 mm and the cord length is about 150 mm. The operation of reading the bar code label 2 in FIG. 3A is performed by the bar code reader 1 with the reading port applied to the bar code label 2.
In this case, the light source for irradiating the barcode label 2 is as shown in FIG.
The light source of the light projecting unit 3 shown in FIG. At this time, the diaphragm member 5
Since the second diaphragm 52 in FIG. 4 allows the wavelength in the vicinity of the light source of the light projecting unit 3 to pass, the diameter of the second diaphragm, that is, 52a in FIG. 2 is effective as the diaphragm effect. Therefore, in the case of FIG. 3A, since the aperture diameter is relatively large and the amount of light received by the image sensor 7 is large, it is possible to read even a narrow bar width code or a thin print code.

In the case of reading as shown in FIG. 3B, the light of the light projecting portion 3 does not reach the bar code label 2 and the bar code label 2 is illuminated with indoor light or outdoor sunlight. Generally, the amount of illumination light in a room is 500 to 1000 L
X, the amount of light exceeds 10,000 LX outdoors in the daytime, which is larger than the light amount of the light projecting unit 3 of the barcode reader 1. The second diaphragm section 52 of the diaphragm member 5 does not pass any wavelength other than the wavelength of the light source of the light projecting section 3, and thus blocks most of the light under room light or sunlight as in the case of FIG. As an effect, the first diaphragm portion 51 having a small diaphragm diameter is effective, and the reading depth of the barcode reader 1 is improved. Therefore, FIG.
Even when the barcode label 2 is located away from the barcode reader 1 as shown in (b), the barcode label 2 can be read.
In this embodiment, the diameter 51a of the first throttle portion 51 of the throttle member 5 is
Was 0.9 mm, and the diameter 52a of the second throttle portion 52 was 2 mm.

[0014]

As is apparent from the above description of the embodiments, in the bar code reader of the present invention, since the diaphragm diameter of the diaphragm portion is changed depending on the reading position of the bar code reader and the wavelength of the illumination light, the code length is changed. Stable reading is possible even when a long bar code symbol for logistics products and a normal bar code with a relatively short code length are mixed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a bar code reader according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a diaphragm member in the barcode reader.

FIG. 3A is a perspective view when a barcode label having a long code length is read by the barcode reader, and FIG. 3B is a perspective view when a barcode label having a short code length is read by the barcode reader.

FIG. 4 is a perspective view of a conventional barcode reader.

5A and 5B are explanatory views of a conventional barcode reader reading state.

[Explanation of symbols]

 1 Bar Code Reader 2 Bar Code Label 3 Light Emitting Section 4 Reflecting Mirror 5 Aperture Member 51 First Aperture Section 52 Second Aperture Section 6 Light-Receiving Lens 7 Image Sensor 8 Circuit Section

Claims (1)

[Claims] 1. A light projecting unit for irradiating light onto a barcode label, and an image for receiving a reflected light from the barcode label to form a barcode image and converting the barcode image into an electric signal. A sensor and a circuit unit that processes the image sensor output signal and reads the barcode, and has a diaphragm member that narrows down the barcode image between the image sensor and the barcode label. The member includes a first diaphragm portion that passes a wide range of wavelengths including the wavelength of the light emitting portion light source, and a region near the wavelength of the light emitting portion light source in a region including the periphery of the first diaphragm portion and excluding the first diaphragm portion. A barcode reader provided with a second diaphragm having a filter effect of passing therethrough.