JP2800261B2 - Reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A reading device capable of reading a barcode written on an article by projecting a scanning beam in a series by a plurality of projecting units having different focal lengths and projecting the scanning beam. An optical unit that scans a barcode with a scanning beam and receives reflected light, and an optical unit that receives reflected light, with the aim of providing a reading device that can read even at different distances to the code and has a high reading speed. A recognition unit that converts light into an electric signal and recognizes the light, wherein the optical unit includes a plurality of lenses having different focal lengths and a plurality of light sources that are paired with the plurality of lenses, respectively. A light-emitting unit that emits a scanning beam by energizing a light source, and a scanning beam that is sequentially cut off at a predetermined timing by a plurality of light-emitting units when reading a barcode. And a light-emission switching control means for causing the light-emission switching control means to read the barcode by one of the plurality of light-emitting parts.

[Industrial applications]

The present invention relates to a reading device that reads a bar code printed on a product packaging, a label, or the like, and particularly writes on a product by projecting a scanning beam in a series by a plurality of projecting units having different focal lengths. The present invention relates to a reading device capable of reading a read barcode.

Recently, a reading device for factory automation (hereinafter referred to as FA) or for handling goods at distribution centers etc., for example, when performing bar codes such as reading bar codes from articles of different sizes conveyed on a conveyor Is used.

Such a reading device has a limit in the readable depth, and when the size of the article is different, the reading may not be possible if the distance to the barcode is more than the limit. Although the method of adjusting the reading depth is adopted so that it can be performed, the reading speed is slow,
There is a demand for a reading device having a long reading depth and a high reading speed.

[Conventional technology]

FIG. 7 shows an example of the use of a reading device for FA. As shown in the drawing, the reading device 1 has a label 3 attached to articles 3a, 3b,. It is arranged above the gombar 2 so as to read a barcode.

As shown in FIG. 8, the reading device 1 includes an optical unit 4a and a recognition unit 5 inside, and the optical unit 4a includes a light source 6a constituted by, for example, a laser diode and a light projecting unit including a beam shaping lens 7a. The light emitted from 8a is reflected by the plane mirror 9 and emits a laser beam downward by the rotating polygon mirror 10 to scan the bar code of the article outside the apparatus, and scans the bar code of the article. It has a light receiving sensor function of reading reflected light with a light receiving sensor not shown. Here, since the polygon mirror 10 has six surfaces, scanning is performed six times in one rotation.

The recognition unit 5 converts a signal read by the light receiving sensor into an electric signal and recognizes the signal as data. The rotation mechanism, the light source 6a, and the light receiving sensor, not shown, of the polygon mirror 10 are connected to the control unit 11a.

A reading window 12 covered with a glass plate is provided on the lower surface of the apparatus,
The emitted light is emitted from the reading window 12 below the apparatus, in a direction indicated by a two-dot chain line in the figure.

With such a configuration, the articles 3 on the conveyor 2
When a, 3b,... pass below the reading device 1, the controller 11a
The bar code is scanned by the laser beam emitted from the reading window 12 by the control of the respective components, and the bar code is read by the reflection thereof and recognized as data.

In this case, there is a limited range for the reading depth of the scanning beam, and if the distance from the reading device 1 to the barcode position of the articles 3a, 3b,... That is, the readable area of the reading device is determined by the thickness of the beam diameter. As shown in FIG. 9, the beam diameter is equal to or less than the maximum beam diameter D readable by the bar code.
To Lb. Therefore, a bar code whose distance from the lens 7a is within the range of the region La to Lb can be read, but a bar code at a position beyond the range of the region La to Lb cannot be read.

As a method for coping with this, Japanese Patent Application Laid-Open No. 62-237586 discloses a bar code reading technique using a variable focus method and a multi-focus method. In addition, "Monthly magazine" barcode "1988 December
The monthly issue, pages 54 to 57, "Autofocus Laser Scanner, NEC Corporation Hiroyuki Miyazaki", describes the variable focus method and the multifocus method.

The variable focus method is a method of mechanically moving the position of the lens so that the focal position follows the position of the barcode.The multifocal method divides the required reading depth and uses a plurality of lenses with different focal lengths. In this method, a laser beam is deflected in accordance with the position of a barcode to switch a lens to be used, and a dedicated beam is assigned to each reading range.

[Problems to be solved by the invention]

According to the above-mentioned conventional method, in the variable focus method, the response time of the focus position control becomes slow, and the reading speed becomes slow.

In the multifocal method, it takes time to allocate the divided reading range, and the reading speed is reduced. Further, the optical system becomes complicated to deflect a beam projected from a single light source.

There is a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reading device that can read even if the distance to a barcode is different and has a high reading speed.

[Means for solving the problem]

 FIG. 1 is a diagram illustrating the principle of the present invention.

In the figure, reference numeral 4 denotes an optical unit, 6 denotes a light source, 7 denotes a lens, 8 denotes a plurality of lenses 7 having different focal lengths, and a plurality of light sources 6 paired with the plurality of lenses 7, respectively. A plurality of light projecting units for projecting a scanning beam, and a light projecting switching control unit 11 for sequentially switching the respective scanning beams by the plurality of light projecting units 8 at a predetermined timing and projecting the light when reading a bar code. .

Therefore, the bar code is read by any one of the plurality of light emitting units 8 by switching the light emission switching control means 11.

[Action]

When reading a bar code, a plurality of light projecting units 8 each having a lens 7 and a light source 6 having different focal lengths of the optical unit 4 are sequentially switched to be energized by the light projecting switching control means 11 to project a scanning beam. The reading is started by the scanning beam of any one of the plurality of light emitting units 8, that is, the light emitting unit 8 having the lens 7 having the focal length corresponding to the position of the bar code.

In this manner, by sequentially switching the light projection of the plurality of light projecting units 8 each having the lens 7 and the light source 6 having different focal lengths, the optical unit 4 having a substantially long focal depth is provided.
And bar codes at different distances can be read.

Embodiment An embodiment of the present invention will be described with reference to FIGS.
The same reference numerals indicate the same objects throughout the drawings.

In FIG. 2, components having the same names as those in FIG. 1 correspond to each other, and the control unit 11b in FIG. 2 corresponds to the light emission switching control means 11 in FIG.

FIG. 2 shows an optical unit 4b of a reader 1a in which the present invention is applied to the reader 1 described in the conventional example, as shown in FIG.
On both sides of a polygon mirror 10 rotated by a rotation mechanism (not shown), light sources 6a and 6b composed of laser diodes and lens 7a for beam shaping having different focal lengths,
The light-emitting portions 8a and 8b composed of 7b are arranged so that their optical axes are plane mirrors 9a and
It is arranged in the direction of 9b.

The rotation mechanism of the polygon mirror 10, the light sources 6a and 6b, and the light receiving sensor S are connected to the control unit 11b.

As shown in FIG. 3 (a), the reading depth range of the optical unit 4b is such that the scanning beams emitted from the respective light sources 6a and 6b of the light emitting units 8a and 8b are different from the focal depths of the lenses 7a and 7b according to the curve I.
And II, from the maximum readable beam diameter D, the readable range is La to Lb and Lc to Ld, and the readable range of both is La to Ld.

Therefore, as shown in FIG. 3 (b), the readable depth of the reading device 1a becomes longer.

The bar code has a start code at one end and an end code at the other end. When scanning, the start code confirms the start of reading and recognizes the end of reading by the end code.

The control unit 11b controls the rotation mechanism and the light receiving sensor of the polygon mirror 10 in the same manner as the control unit 11a described in the conventional example, and at the time of reading a barcode, emits a scanning beam from the light sources 6a and 6b to the next. Control.

The light sources 6a and 6b are switched and energized at a predetermined timing so that the projection of the scanning beam from each of the light emitting units 8a and 8b is sequentially switched, that is, each time the polygon mirror 10 is rotated once by the rotation mechanism, for example. Switch. If the polygon mirror 10 rotates 5,000 times per minute, for example, 12 ms
Switch every time. (See FIG. 5).

When the start of bar code reading is recognized by the scanning beam emitted by either of the light emitting units 8a and 8b, the next switching is suspended until the reading is completed, and the power to the corresponding light emitting unit is turned on. Continue to emit light. That is, when the scanning beams of the light emitting units 8a and 8b are scanned obliquely with respect to the bar code, and only one of the start code and the end code is scanned, the scanning beam is read by the next scanning beam. Since reading is not always started at a timing sufficient for reading as in the case immediately before the switching, scanning with the same depth of focus is continued until reading is completed.

Having such a configuration and mechanism, the operation of reading the barcode of the articles 3a, 3b,... Conveyed on the conveyor 2 will be described next with reference to the flowchart of FIG. 4 and the time chart of FIG.

First, the reading device 1a is activated.

Then, as shown in FIG. 5, the control unit 11b sequentially switches the timing from the light-emitting units 8a and 8b of the optical unit 4b and shifts the current so as to energize them.
The light is projected from the reading window 12 to the outside of the apparatus via the polygon mirror 10 and a and 9b.

The barcode of the article 3a, for example, conveyed by the conveyor 2 is placed on one of the light emitting units 8a and 8b, for example, the light emitting unit 8
Start reading with the scanning beam from a.

The control unit 11b suspends the switching until the reading of the barcode is completed, and here, the power supply to the light source 6a of the light emitting unit 8a is continued.

When the barcode is read, the following items
The following flow is repeated for reading the bar code 3b.

FIG. 6 shows a different embodiment. By using an optical unit having more light projecting parts than in the above embodiment, a longer reading depth can be realized. That is, in the figure, the optical unit 4c includes three sets of light emitting units 8a to 8c each including a light source 6a to 6c including three laser diodes and three lenses 7a to 7c having different focal lengths.
Each optical axis is arranged toward a galvanomirror 90 that swings by a swing mechanism (not shown), and the projection of the scanning beam by the light sources 6a to 6c causes the swing of the galvanomirror 90 as in the above embodiment. By performing the switching control every time, it is possible to obtain a longer reading depth and a wider reading range.

In this manner, by switching and projecting the scanning beam from the plurality of light projecting parts at a predetermined timing, it is possible to read at different focal positions, so that it is not necessary to measure the distance between the reader and the barcode, Therefore, since it is not necessary to adjust the reading depth according to the distance, a reading device having a wide reading depth range and a high reading speed can be obtained.

Further, since a plurality of laser diodes are used as the light source, the size and cost of the device can be reduced.

In the above-described embodiment, as the functions of the control unit, the function of switching the emission of the scanning beams of the plurality of emission units and the reading of the scanning beams of the emission units when barcode reading is started are started. Although the case where the function to continue until the end is provided has been described, instead of the function described above, when the bar code is incompletely read, that is, when only one of the start code and the end code can be recognized, the data is transmitted. The method may be invalidated and read again.

〔The invention's effect〕

As described above, according to the present invention, when reading a barcode written on an article, scanning beams from a plurality of light emitting units having different depths of focus are read while being switched at a predetermined timing, so that the barcode up to the barcode is read. Since there is no need to measure the distance and adjust the reading depth, it is possible to obtain a reading device having a wide reading depth range and a high reading speed.

[Brief description of the drawings]

 1 is a block diagram showing the principle of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is an explanatory diagram of the embodiment, FIG. 4 is a flowchart of the embodiment, and FIG. FIG. 6 is a configuration diagram showing a different embodiment, FIG. 7 is an explanatory diagram showing an example of use of a reading device, FIG. 8 is a configuration diagram showing a conventional reading device, and FIG. 9 is a conventional example. FIG. In the figure, 4, 4a to 4c are optical units, 6, 6a to 6c are light sources, 7, 7a to 7c are lenses, 8, 8a to 8c are light emitting units, 11 is light emission switching control means, 11a, 11b 3 shows a control unit.

Claims (4)

(57) [Claims] 1. A reading device comprising: an optical unit that scans a bar code written on an object with a scanning beam and receives reflected light; and a recognition unit that converts the received reflected light into an electric signal for recognition. An apparatus, wherein the optical unit has a light source combined with a lens having a different focal length, and a plurality of light projecting units for projecting a scanning beam by energizing the light source. Light-emission switching control means for sequentially switching the energization of the light-emission sections at a predetermined timing to emit the respective scanning beams, and the plurality of light-emission sections being switched by the light emission switch control means. A reading device for reading the barcode by a scanning beam emitted from any of the light projecting units. 2. A reading apparatus comprising: an optical unit that scans a bar code written on an object with a scanning beam and receives reflected light; and a recognition unit that converts the received reflected light into an electric signal for recognition. An apparatus, wherein the optical unit has a light source combined with a lens having a different focal length, and a plurality of light projecting units for projecting a scanning beam by energizing the light source. Are sequentially switched at predetermined timing to emit the respective scanning beams, and the start of reading the bar code is recognized by the scanning beams emitted from any of the plurality of the emitting units. And a light-emission switching control means for suspending the light-emission switching of the light-emitting part until the reading of the barcode is completed. 3. A reading device comprising: an optical unit that scans a bar code written on an object with a scanning beam and receives reflected light; and a recognition unit that converts the received reflected light into an electric signal for recognition. An apparatus, wherein the optical unit has a light source combined with a lens having a different focal length, and a plurality of light projecting units for projecting a scanning beam by energizing the light source. Are sequentially switched at predetermined timing to emit the respective scanning beams, and a part of the bar code is emitted by the scanning beams emitted from any of the plurality of the emitting units. A light emission switching control unit that suspends switching of light emission of the light emitting unit when reading is recognized. 4. The reading device according to claim 1, wherein a first reading range by a scanning beam emitted from the first light source and a second reading range by a scanning beam emitted from the second light source are part of the first reading range. 4. The reading device according to claim 1, wherein the reading device is set so as to overlap.