JPH04213782A - Stationary type bar-code reader - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stationary barcode reader used for product and production management in the fields of logistics, FA, etc.

0002

[Prior Art] As is well known, a barcode reader scans a barcode label affixed to an article or a barcode printed on the surface of the article using optical means, and uses a light receiver to capture the reflected light. This device performs photoelectric conversion, waveforms the data, converts it into a digital signal, and then decodes it with a decoder to read the information in the barcode. In addition, with a stationary barcode reader, for example, the barcode reader is installed at a predetermined position on an article conveyance line, and when the article moving on the conveyance line passes the barcode reader installation point, the barcode reader is read as described above. The barcode is automatically read by scanning the code optically.

In conventional fixed type barcode readers, a light beam emitted from a light source such as a semiconductor laser is incident on a rotating multifaceted mirror called a polygon mirror, and the multifaceted mirror is rotated at high speed. It is configured to read barcodes by repeatedly scanning the barcode in one direction with a light beam reflected by a polygonal mirror.

0004

[Problems to be Solved by the Invention] By the way, in order for a barcode reader to correctly read barcode information, the light beam that scans the barcode must scan all of the bars arranged between the start code and stop code of the barcode. It is a necessary condition to be sure to cross. For example, the orientation of a barcode label affixed to an article moving on a conveyance line is not necessarily constant, and in particular, the orientation of the barcode bar may be tilted with respect to the scanning direction of the light beam.
If they are parallel, the light beam will not cross the barcode correctly, resulting in problems such as reading errors and inability to read. Similar reading errors also occur when there are void spots such as local dirt or scratches on the barcode label.

[0005]Furthermore, in recent years, an extended version of a multi-stage barcode in which barcodes are arranged in multiple lines has become popular as a barcode code system. Therefore, in order to read such a multi-stage barcode with a conventional barcode reader, the moving direction of the article is set perpendicular to the scanning direction of the light beam, and the scanning position of the light beam is adjusted while moving the article. Therefore, it is necessary to read the barcodes of each row separately, which increases the barcode reading processing time.

The present invention has been made in consideration of the above points, and it is possible to correctly read barcodes including the multi-stage barcodes described above without any restrictions such as the direction of movement of articles or the inclination of barcode arrangement. The purpose of the present invention is to provide a stationary barcode reader that can perform the following functions.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the stationary barcode reader of the present invention includes a polygonal concave mirror in which a plurality of plane mirrors are arranged in the circumferential direction and are arranged facing the barcode. , a rotating mirror having an inclined mirror surface disposed oppositely on the central axis of the polygonal concave mirror and deflecting a light beam arriving from the light source side in the circumferential direction toward the concave mirror, and between the light source and the rotating mirror; a scanning mirror system consisting of a galvano mirror located at a position where the light beam emitted from the light source is directed onto a rotating mirror and deflected in the radial direction; and a scanning mirror system that synchronizes the deflection angle of the galvano mirror with the scanning of the light beam. and a deflection angle control means for periodically changing the deflection angle so that the light beam emitted from the light source scans the barcode in a raster pattern in a plurality of directions.

Further, in the above configuration, in order to obtain a synchronization signal necessary for controlling the deflection angle of the galvanometer mirror, a reflective marker is provided at one location on the circumferential surface of the polygonal concave mirror, and the reflected light of the reflective marker is detected. The deflection angle of the galvanometer mirror can be periodically controlled by the deflection angle control means using the signal obtained as a synchronization signal.

Furthermore, in order to read a multi-tiered barcode in which barcodes are arranged in multiple lines with the barcode reader, measurement data of the distance to the object to be read and the number of lines of the multi-tiered barcode displayed on the item are required. , row pitch data are input, and based on these data, the deflection angle of the galvanometer mirror is controlled to change the number of rasters of the scanning light beam and the raster scanning pitch.

0010

[Operation] With the above configuration, the light beam emitted from the light source illuminates the barcode via the galvanometer mirror, rotating mirror, and polygonal concave mirror. When the rotating mirror is rotated, the light beam reflected from the tilted mirror surface of the rotating mirror is deflected so as to rotate backward toward the polygonal concave mirror, so that the light beam forms a plane lined up on the circumference of the concave mirror. It scans the barcode by reflecting it while moving between mirrors one after another. In this case, in the polygonal concave mirror, since the angles of the plane mirrors arranged in the circumferential direction are different, the light beam scans the barcode from different directions. here,
If the polygonal concave mirror is composed of, for example, eight plane mirrors, the scanning direction of the light beam will change eight times during one rotation of the rotating mirror, and among these, the plane mirrors facing each other in symmetrical positions with respect to the central axis will change direction. Since the circumferential direction is the same, the scanning pattern of the light beam scans the barcode back and forth from four directions: vertically, horizontally, and diagonally. Furthermore, by controlling the deflection angle of the galvanometer mirror so that the deflection angle increases over time during this scanning process, the angle of incidence of the light beam on the rotating mirror changes over time. The positions of the scanning trajectories passed by the light beams in the forward and backward directions change, and the scanning pattern becomes a raster pattern. here,
By controlling the deflection angle of the galvano mirror to be periodically changed in synchronization with the scanning of the light beam by the rotation of the rotary mirror, the above-described raster pattern scanning is repeatedly performed on the barcode.

[0011] Therefore, if the barcode displayed on the article passes through the scanning range of the light beam, one of the light beams scanning from each direction will cross the barcode correctly regardless of the orientation of the barcode. Barcodes can be reliably read without errors. In addition, even if there are void spots such as local dirt or scratches on the barcode, by scanning the light beam in a raster pattern, even if the scanning trajectory of the light beam on the outward path coincidentally overlaps with the void spot, On the return trip, the light beam scans the position avoiding void spots, so barcodes can be read correctly without read errors.

[0012] Furthermore, if the barcode displayed on the article to be read is a multi-stage barcode arranged in multiple lines,
The raster pitch of the scanning pattern is adjusted by controlling the deflection angle of the galvano mirror based on the number of lines of the multi-stage barcode entered in advance, the line pitch data, and the distance data obtained by measuring the distance to the item. By doing so, the scanning pattern of the light beam can be made to match the arrangement of the multi-stage barcode, and the multi-stage barcode can be read correctly.

[0013]

[Example] Example 1: In FIG. 1, 1 is a scanner section of a barcode reader, 2 is a decoder, 3 is a barcode to be read that moves in the direction of arrow A, and the optical system of the scanner section 1 is a light source. 4, a scanning mirror system that combines a light projection lens 5, a polygonal concave mirror 6, a rotating mirror 7, and a galvano mirror 8, and a perforated plane mirror 9 for extracting reflected light.
It is composed of a light receiver 10. Here, in the polygonal concave mirror 6, a plurality of plane mirrors 6a (eight in the illustrated example), each inclined at a predetermined angle with respect to the central axis, are placed on the inner periphery of the base, facing the barcode 3. It was lined up,
A transmission hole 6b through which the light beam passes is opened in the center thereof. Further, at one location on the inner circumferential surface of the concave mirror 6, there is a reflective marker 6 with a high surface reflectance that scatters and reflects the irradiated light beam in order to obtain a scanning synchronization signal of the light beam as described later.
c (white paint marker). The rotary mirror 7 is located on the central axis of the concave mirror 6, facing the concave mirror 6, and is configured to rotate a tilted mirror 7a tilted at a predetermined angle at high speed by a drive motor 7b.
The light beam arriving from above through the transmission hole 6b is deflected toward the polygonal concave mirror 6 in the circumferential direction. Further, the galvanometer mirror 8 has a structure similar to a galvanometer as a galvanometer, and is configured to swing the deflection mirror 8a in response to the voltage value applied to the drive unit 8a with a built-in electromagnetic coil, and is a light source. The light beam emitted from the rotating mirror 7 is deflected to change the angle of incidence on the mirror body 7a of the rotating mirror 7. Further, 11 and 12 are waveform shapers connected to the light receiver 10, 13 and 14 are voltage setting devices that provide reference potentials E1 and E2 as thresholds to the waveform shapers 11 and 12, and 15 is connected to the waveform shaper 12. frequency divider, 16 is AN
A D circuit 17 is a voltage generator that applies a driving voltage to the driving section 8b of the galvanometer mirror 8. Note that the output voltage of the voltage generator 17 increases over time with a constant time constant, and
It operates so that the output voltage is reset to the initial value in synchronization with the signal from the circuit 16.

Next, the operation of reading a barcode by the barcode reader having the above configuration will be explained. The light beam 18 emitted from the light source 4 passes through the projection lens 5 and passes through the galvanometer mirror 8.
It is reflected by the deflection mirror 8a, passes through the perforated plane mirror 9, the transmission hole 6b of the concave mirror 6, and enters the rotating mirror 7. Furthermore, the light beam 18 incident on the rotating mirror 7 is reflected by the inclined mirror 7a and directed toward the polygonal concave mirror 6, and further reflected by the plane mirror 6a of the concave mirror 6 to reach the barcode 3. When the rotating mirror 7 is rotated, the light beam reflected by the polygonal concave mirror 6 during one rotation of the rotating mirror 7 scans the barcode 3 in four directions (vertical, horizontal, and diagonal) as represented by the scanning pattern 19 shown in the figure. It will scan twice each time. Furthermore, when the voltage applied to the galvanometer mirror 8 is changed over time to change the deflection angle of the deflection mirror 8a, the incident angle of the light beam incident on the rotating mirror 7 changes, and the above-mentioned scanning pattern 19 is changed in each scanning direction. The trajectory of the light beam changes in a raster pattern.

Further, the scattered reflected light from the bar code 3 accompanying the above-mentioned scanning of the light beam reverses the irradiation optical path of the light beam, and after successively reflecting off the polygonal concave mirror 6 and the rotary mirror 7, the light is perforated. The light is reflected by the plane mirror 9 and enters the light receiver 10 located on the side thereof. The light incident on the light receiver 10 is photoelectrically converted, and the electrical analog signal is binarized by a waveform shaper 11 and then input to a decoder 2, where the information on the barcode 3 is decoded and encoded data is generated. Output to the outside as .

On the other hand, as described above, there is a reflective marker 6c on the circumferential surface of the polygonal concave mirror 6, and while the rotating mirror 7 rotates once, the light beam 18 from the light source 4 hits the reflective marker 6c.
The scattered reflected light is reflected by the rotating mirror 6,
The light enters the light receiver 10 through the perforated plane mirror 9. After the signal corresponding to the reflected light from the reflective marker 6c is detected by the waveform shaper 12, it is inputted to the frequency divider 15 and the AND circuit 16 as a scanning synchronization signal of the light beam, and this synchronization signal is input to the frequency divider 15 and the AND circuit 16. When a predetermined count number preset in step 15 is reached, a reset signal is applied from the AND circuit 16 to the voltage generator 17. As a result, the driving voltage applied to the galvanometer mirror 8 becomes a sawtooth wave that changes periodically in synchronization with the scanning synchronization signal of the light beam corresponding to the rotation of the rotating mirror 7, and the galvanometer mirror The deflection angle of 8 will also change periodically. FIG. 3 shows the above operation in a waveform diagram, and (a) in the figure shows the bar code reading signal obtained by scanning the bar code 3 (indicating a low voltage amplitude) and the signal obtained by the reflective marker 6c. synchronization signal (
(b) is a digital signal obtained by comparing the signal (a) with the reference transposition E1 set by the waveform shaper 11 and converting it into a binary signal. The output signal, (c) is the scanning synchronization signal detected by the waveform shaper 12 by comparison with the reference potential E2, (d) is the AN
The output signal of the D circuit 16 (when the count number of the frequency divider 15 is set to 2), (e) is a sawtooth output signal from the voltage generator 17 applied to the galvanometer mirror 8.

As is clear from the above explanation, the light beam emitted from the light source 4 repeatedly scans the barcode 3 from four directions: vertically, horizontally, and diagonally, and the scanning trajectory in each scanning direction is periodic. changes in a raster pattern. Therefore, the barcode 3 can be read correctly regardless of the moving direction of the article displaying the barcode 3 or the orientation of the barcode 3. Moreover, even if the barcode 3 has local dirt or void spots due to scratches, the barcode 3 can be read correctly. Since the light beam scans the barcode 3 in a raster pattern, the barcode can be read without read errors. In the illustrated example, the polygonal concave mirror 6 is composed of a plane mirror 6a divided into eight pieces, but the scanning direction of the light beam can be further multiplexed by further increasing the number of plane mirrors. It is possible.

Embodiment 2: FIG. 2 shows an embodiment of a barcode reader capable of reading multi-stage barcodes. That is, barcodes 3A and 3B are displayed in two rows on the surface of the article 20 to be read. On the other hand, on the barcode reader side, there is a data input device 21 for inputting data on the interline pitch of the multi-stage barcode (interval pitch between barcodes 3A and 3B) and the number of lines, and the barcode reader. The scanner unit 1 is equipped with a distance meter 22 that measures the distance L to the barcode display surface of the article 20 to be read, and furthermore, the scanner unit 1 has data on the interline pitch, number of lines, and distance regarding the multi-stage barcodes 3A and 3B. It includes a temporary memory 23 for storing data, and a gain setter 24 for adjusting the output voltage of the voltage generator 18 (corresponding to the deflection angle of the galvanometer mirror 8) based on the data.

When reading a multi-stage bar code with a bar code reader having such a configuration, data on the inter-line pitch and the number of lines (in the illustrated example, the number of rows is 2) of the multi-stage bar code are input in advance using the data input device 21, The multi-stage barcodes 3A and 3B are scanned in a raster pattern from a plurality of directions using a light beam using the same procedure as described in 1. Further, when the article 20 moves directly below the barcode reader, the distance meter 22 measures the distance L to the barcode, and the decoder 2 uses this distance data to calculate and correct the line pitch data input in advance. The results are output to the temporary storage section 23. On the other hand, the temporary storage unit 23 provides the data to the gain setter 14 in synchronization with the scanning synchronization signal detected by the waveform shaper 12, and based on this data, the gain setter 24 outputs the output voltage of the voltage generator 17 (galvanometer). The deflection angle of the galvanometer mirror 8 is controlled by adjusting the amplitude of the voltage applied to the mirror 8. As a result, the scanning locus of the light beam that scans the multi-stage barcode in a raster pattern is such that the raster pitch P is 3A as shown in the figure.
This will match the line spacing between and 3B, so
The barcodes 3A and 3B arranged in two rows can be sequentially scanned and read. In addition, in the waveform diagram of FIG. 4, (a)
is the same scanning synchronization signal as shown in FIG. 3(d), and (b)
, (c) represent sawtooth voltage waveforms output from the voltage generator 17 when the distance L to the bar code described above is large and small, respectively. That is, when the height of the article 20 to be scanned is low and the distance between the barcode reader and the barcode is long, the amplitude of the voltage waveform is kept low and the deflection angle of the galvano mirror 8 is made small, and the reverse If the height of the article 20 is high and the distance to the barcode is short, the amplitude of the voltage waveform is increased and the deflection angle of the galvano mirror 8 is adjusted to be large. Note that even if the number of lines in a multi-stage barcode is three or more, the number of rasters in the raster-like scanning pattern corresponds to the number of lines in the barcode.
In other words, this can be handled by changing the period of the sawtooth voltage applied to the galvanometer mirror 8 in synchronization with the scanning synchronization signal.

As described above, even if the barcode displayed on the article 20 is a multi-stage barcode, the height dimension of the article,
Regardless of the direction of movement and the orientation of the multi-stage barcodes 3A, 3B, the light beam sequentially scans each barcode lined up in multiple rows and the barcode information can be read correctly.

[0021]

Effects of the Invention As described above, according to the stationary barcode reader of the present invention, a light beam can be directed in multiple directions to barcodes displayed on articles that have moved to the installation point of the barcode reader. Since I scanned it in a raster pattern,
It is possible to accurately read barcode information, including multi-stage barcodes, without being affected by the direction of movement of the article or the orientation of the barcode, as well as being unaffected by local dirt or scratches on the barcode. , it is possible to obtain a barcode reader with significantly superior reading function compared to conventional barcode readers.

[Brief explanation of the drawing]

FIG. 1: Configuration diagram of Embodiment 1 of the present invention

[Fig. 2] Configuration diagram of Embodiment 2 of the present invention

FIG. 3 is a waveform diagram illustrating the barcode reading operation according to the embodiment of FIG. 1;

FIG. 4 is a waveform diagram illustrating the barcode reading operation according to the embodiment of FIG. 2;

[Explanation of symbols]

1 Scanner section 2 Decoder 3 Barcode 4 Light source 6 Multifaceted concave mirror 6a Plane mirror 6c Reflective marker 7 Rotating mirror 8 Galvano mirror 10 Light receiver 11 Waveform shaper (for barcode reading) 12
Waveform shaper (for synchronization signal detection) 17 Voltage generator 18 Light beam 19 Scanning pattern 21 Data input device 22 Distance meter

Claims (3)

[Claims] Claim 1: A stationary barcode reader that optically scans and reads a barcode displayed on the surface of an article, comprising:
A polygonal concave mirror in which a plurality of plane mirrors are arranged in the circumferential direction and placed facing the barcode, and the polygonal concave mirrors are arranged facing each other on the central axis to direct the light beam coming from the light source toward the concave mirror. A scanning mirror system comprising a combination of a rotating mirror having an inclined mirror surface that deflects in the circumferential direction, and a galvano mirror located between a light source and the rotating mirror to deflect the emitted light beam from the light source to the rotating mirror. and a deflection angle control means for periodically changing the deflection angle of the galvanometer mirror in synchronization with the scanning of the light beam, and scanning the barcode with the light beam emitted from the light source in a raster pattern in a plurality of directions. A stationary barcode reader featuring: 2. The stationary barcode reader according to claim 1, wherein a reflective marker is provided at one location on the circumferential surface of the polygonal concave mirror, and signals obtained by detecting reflected light from the reflective marker are synchronized. A stationary barcode reader characterized in that the deflection angle of a galvano mirror is periodically controlled by a deflection angle control means as a signal. 3. In the stationary barcode reader according to claim 1, based on measurement data of the distance to the object to be read, and data on the number of lines and line pitch of the multi-stage barcode displayed on the object, the galvanometer A stationary barcode reader characterized by controlling the deflection angle of a mirror.