JP2779362B2 - Barcode scanning scanner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanner for reading a bar code, and more particularly to a laser scanner.

[0002]

2. Description of the Related Art A conventionally used bar code reading laser scanner reads a bar code printed in two dimensions (vertical and horizontal) in one dimension.

[0003] This type of apparatus is disclosed in, for example, JP-A-60-100273, JP-A-61-26185, and JP-A-3-25585.

[0004]

However, in the above-mentioned prior art, since the barcode is scanned one-dimensionally, if the barcode has printing unevenness or dirt called voids or spots on the upper side. A reading error occurred and the reading had to be performed again. For this reason, problems remain in the reduction of the reading speed and the reliability of the reading result.

SUMMARY OF THE INVENTION An object of the present invention is to provide a bar code reading scanner capable of reliably reading even if the bar code label has uneven printing or dirt.

[0006]

In order to achieve the above object, the present invention irradiates a bar code label with a light beam from a light source, photoelectrically converts the reflected light by a light receiving element, and decodes a signal for decoding. in the scanner reading the bar code to obtain, in the direction perpendicular to the main scanning direction of the light source barcode
Sub-scanning that performs sub-scanning in the form of a sine wave for the data label
Means and a plurality of points in one cycle on the sub-scanning waveform
At the sampled point.
A holding circuit for holding sampling data;
Control means for controlling light emission of the light source so as to synchronize with each other.
From the plurality of data of the holding circuit by majority decision.
Determines the emission level.

[0007]

According to the above-described means, the light beam from the light source is sub-scanned in a direction orthogonal to the scanning direction, and the bar code label is scanned in a sine wave shape. As a result, even if the barcode label has printing unevenness or dirt, reading is reliably performed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments, the basic operation of the present invention will be described.

FIG. 2 shows a trajectory (a thin line drawn obliquely) when a barcode is scanned using a conventional laser scanner.
It is. As described above, the spot diameter of the laser is made small in order to increase the resolution, and therefore, it becomes a linear locus.

FIG. 3 shows a trajectory by the scanner of the present invention. The trajectory is a band (or a plane) in contrast to a conventional linear shape. FIG. 4 shows the locus of FIG. 3 in an enlarged manner. In practice, the sub-scan is performed with a simple vibration and modulation so as to be orthogonal to the scanning direction of the laser, not the plane. , A sinusoidal locus is left.

FIG. 5 shows a state in which a bar code having voids and spots is scanned by a conventional scanner, and an output signal waveform obtained by converting the bar code into an electric signal. As illustrated, spots 2 and voids 3 are scattered on a scanning trajectory 4 formed in a direction orthogonal to the bar codes 1a and 1b. Normally, the output signal waveform of the scanner is "0" because the barcodes 1a and 1b are black, and the signal level is "1" because the space between the codes is white. However, if there is a spot 2 or void 3, the spot 2 portion becomes "1", the void 3 portion becomes "0", and there are two codes within the width of the bar code 1a. It is erroneously read that one code is inserted between the codes 1b.

However, according to the present invention, as shown in FIG. 4, the scanning trajectory describes a sine curve.
If the sampling of the point is performed, it is possible to determine whether the scanned area is white or black by using majority logic. As a result, the adverse effects of the spot 2 and the void 3 can be eliminated.

However, as shown in FIG. 6, in the scanning along the sequence of bar codes, the reading is performed without any problem as described above. However, as shown in FIG. Therefore, the sample points come and go in the changing range of the code, and normal operation cannot be expected by simple majority logic. However, as shown in FIG. 8, run
査although substantially shifted in a short time is Ru Oh, can be regarded as being performed at the same time the same number of scanning and the number of samples in a modulated one period (here 5 points). This means that the output of the black / white discrimination at the sampling points “1 to 5” shown in FIG. 8 has the same shape of the output waveform itself only with a time lag. So, for example,
Detected change of first sample point from white to black
In this case, the second and subsequent sample points are also
Until the sample point where black is detected, it is regarded as white, and black is detected.
At which point black is detected for the first time,
By taking the form of synchronous detection, scanning oblique shown in FIG. 7 is set to be equivalent to the FIG. 6

Hereinafter, embodiments of the present invention will be described.

FIG. 1 is a block diagram showing an embodiment of a bar code reading scanner according to the present invention.

Laser diode (LD) as light source
5 generates a laser beam toward the bar code label, the light reflected from the surface of the bar code label is received by a photodiode (PD) 6, and an electric signal corresponding to the reflected luminance is output from the photodiode 6. You. An amplifier (AMP) 7 is connected to the photodiode 6, and sample-and-hold circuits (hereinafter, referred to as S / H circuits) 8a to 8c are connected in parallel to the amplifier 7 (in the above description, sampling is performed). Although the operation is performed at five points, the case of three points is illustrated here, and therefore, the number of S / H circuits is three.) S / H circuit 8a,
A / D (analog / digital) conversion circuits 9a, 9b, 9c are connected to each of 8s, 8c, a synchronization circuit 10 is connected to these, and a majority decision circuit 11 is connected to the synchronization circuit 10. The output of the majority circuit 11 is sent to a decoder (not shown). Further, a control circuit 12 is provided for controlling the laser diode 5 and the S / H circuits 8a, 8s, 8c. This control circuit 12
Is further connected to a sub-scanning drive unit 13 for driving the laser diode 5 for sub-scanning.

FIG. 9 is a block diagram showing an example of the scanning optical system, and FIG. 10 is a block diagram showing another example of the scanning optical system.
Here, FIG. 9 uses a polygon mirror for the scanning mechanism, and FIG. 10 uses a galvanometer mirror.

In the configuration shown in FIG. 9, the optical lens 14 and the polygon mirror 1 are placed on the exit optical path of the laser diode 5.
5 (here, drawn in a circle for simplicity of illustration, but actually forms a polygon in the circumferential direction), and the reflected light of the polygon mirror 15 is a bar code label 16 And are scanned from one side to the other as shown in FIG. The reflected light from the barcode label 16 is
The light received by the photodiode 6 is input to a decoder 17 constituted by a circuit excluding the laser diode 5 and the photodiode 6 in FIG.

On the other hand, in the configuration of FIG. 10, a gas laser 18 is used in place of the laser diode 5, and a galvanomirror 19 is provided on the emission optical path. The other configuration is the same as that of FIG. 9, and the duplicated description is omitted here.

9 and 10, laser light from a light source (laser diode 5 or gas laser 18) is applied to a polygon mirror 15 or a galvanometer mirror 19.
Scans the bar code label 16. The scanning trajectory at this time is linear, and it is necessary to perform the sub-scanning in a sine wave shape as shown in FIG. 6, but specifically, in a direction perpendicular to the rotation direction of the polygon mirror (galvano In the case of a mirror, the laser beam is oscillated in a direction perpendicular to the direction of the oscillation. As this means, it is possible to directly move the polygon mirror 15 or the galvanometer mirror 19, but in addition, a method of oscillating the light source, a method of inserting a mirror in the optical path and oscillating this mirror, etc. are also conceivable. . In this embodiment, FIG.
As shown in FIG. 1, sub-scanning is performed by directly vibrating the light source.

In FIG. 11, the laser diode 5
A bar 22 having a permanent magnet 21 attached to the other end is set to a shaft 22 near the laser diode 5, and a permanent magnet 2
The laser diode 5 is vibrated in the vertical direction as shown in the figure by disposing an electromagnet 23 so as to face 1 and applying an AC power supply 24 to the electromagnet 23.

Next, the operation of the embodiment having the above configuration will be described.

The control circuit 12 applies a driving sine wave signal (about 10 KHz in the case of 100 scans / second) to the electromagnet 23 of the sub-scanning drive unit 13. As a result, FIG.
The scanning trajectory as shown in FIG. In this case, a signal that takes into account the delay time from the current supplied to the electromagnet 23 of the sub-scanning drive unit 13 to the operation of the drive unit mechanism is controlled so that sunring is performed at each of the first to third points. Circuit 12
To the S / H circuits 8a, 8s, 8c. Also, S
In order to ensure the operation of the / H circuits 8a, 8s and 8c, a signal as shown in FIG.

On the other hand, the synchronization circuit 10 is synchronized as shown in FIG. This figure shows a state in which the laser scanning light is approaching the bar code portion, and 1 to 3 show A / D conversion outputs at each sample point. Despite it is already on the barcode with sample point "1",
Points “2” and “3” scanned with a delay in time have not yet been applied to the bar code portion. Therefore, the number of sub-scans
From the buffer that stores the period, it is apparently first turned black.
In other words, since the sample point “1” is inverted,
When the other two sample points turn black in descending
Until it is white, and when it is detected that it is inverted to black,
For example, the sample point is set to be inverted to black for the first time.
By taking a kind of synchronization, sample point "1" ~
"3" is equivalent to information of a point orthogonal to the scanning direction on the barcode . After synchronizing in this manner, in the present embodiment, after inversion, disturbances such as voids and spots can be removed by using majority logic in one sampling cycle.

FIG. 15 is a block diagram showing an example of the majority logic circuit.

The synchronization circuit 10 includes a binary conversion circuit 111
The output terminal of the binary conversion circuit 111 is connected to one input terminal of a two-input comparator 112, and the other input terminal of the comparator 112 is an output terminal of a reference value generation circuit 113 for outputting a reference value. Is connected. As the comparator 112, for example, TTL “74LS85” can be used. This "74L
S85 "has two sets of inputs A and B each consisting of 4 bits.

For example, in the configuration of FIG.
Therefore, the input A of the comparator 112 is A /
After the outputs of the D conversion circuits 9a, 9b, and 9c pass through the synchronization circuit 10, they are converted by binary conversion (converted to binary codes) and connected. Assuming that white is “1” and black is “0”, “0” is for all black, “1” for white “1”, black “2”, and “1” for white “2” black “1”. 2 ", if all white," 3 "
If the reference value "1" is given from the reference value generation circuit 113 to the B input of the comparator 112, it is determined that the A> B output has many whites. By using this output, many of the A inputs are known, and as a result, noise can be removed. Further, as shown in this embodiment, the S / H circuit 8
By using a, 8s, and 8c, an A / D conversion circuit, which is one of the bottlenecks in speeding up, can be easily designed.

[0028]

As described above, the present invention relates to a bar code reading scanner which irradiates a bar code label with a light beam from a light source and photoelectrically converts the reflected light by a light receiving element to obtain a decoding signal. The size of the bar code label in a direction orthogonal to the main scanning direction of the light source.
Sub-scanning means for performing sub-scanning in emission wave shape, the wave of the sub scanning
Sampling is performed at multiple points in one cycle of the shape,
Holds sampling data at sampled points
And a light source so as to synchronize with the sub-scanning.
Control means for controlling the light emission of the holding circuit.
Since the reflected light level is determined by majority decision from the numerical data, the reading is surely performed even if the bar code label has uneven printing or dirt.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a barcode reading scanner according to the present invention.

FIG. 2 is an explanatory diagram showing a locus when scanning is performed using a conventional laser scanner.

FIG. 3 is an explanatory diagram showing a trajectory by a scanner according to the present invention.

FIG. 4 is an explanatory diagram showing an enlarged trajectory of FIG. 3;

FIG. 5 is an explanatory diagram showing a scanning state of a bar code having voids and spots by a conventional scanner, and an output signal waveform at that time.

FIG. 6 is an explanatory diagram for explaining a problem when sub-scanning is performed on scanning light according to the present invention.

FIG. 7 is an explanatory diagram showing oblique scanning of scanning light according to the present invention.

FIG. 8 is an explanatory diagram showing a scanning light synchronization method according to the present invention.

FIG. 9 is a configuration diagram showing an example of a scanning optical system according to the present invention.

FIG. 10 is a configuration diagram showing another example of the scanning optical system.

FIG. 11 is a configuration diagram illustrating an example of a mechanism for performing sub-scanning.

FIG. 12 is an explanatory diagram showing a scanning trajectory according to the present invention.

FIG. 13 is a waveform chart showing signal waveforms output from the control circuit to the laser diode and the sub-scanning drive unit.

FIG. 14 is a waveform chart showing an example of synchronization by the synchronization circuit of FIG. 1;

FIG. 15 is a block diagram showing an example of a majority logic circuit.

[Explanation of symbols]

 Reference Signs List 5 laser diode 6 photodiode 7 amplifier 8a, 8s, 8c S / H circuit 9a, 9b, 9c A / D conversion circuit 10 synchronization circuit 11 majority circuit 12 control circuit 13 sub-scanning drive unit 15 polygon mirror 16 barcode label 18 Gas laser 19 Galvano mirror 111 Binary conversion circuit 112 Comparator 113 Reference value generation circuit

Claims (1)

(57) [Claims] 1. A bar code reading scanner for irradiating a bar code label with a light beam from a light source and photoelectrically converting the reflected light by a light receiving element to obtain a decoding signal, wherein the scanner is orthogonal to the main scanning direction of the light source. Bar code label
Sub-scanning means for performing sub-scanning in a sine wave shape with respect to a signal , and sampling at a plurality of points in one cycle on the sub-scanning waveform.
Sampling at the point where the ring was sampled
A holding circuit for holding data, and controlling light emission of the light source so as to synchronize with the sub-scanning
Control means for controlling the reflected light from the plurality of data of the holding circuit by majority decision.
A bar code reading scanner for determining a bell .