JP2012208658A - Bar code scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a scanning width without using a mechanical feature and a driving source thereof.SOLUTION: A bar code scanner includes: a scanning unit for scanning a scanning range according to a waveform of a supplied electric signal with light; a light receiving unit for receiving reflection light from a bar code when the scanning unit scans the bar code; a decoder unit for receiving output from the light receiving unit and decoding the bar code; and a scanning control unit for generating an electric signal of a waveform corresponding to a required scanning range based on a result of decoding by the decoder unit and supplying the electric signal to the scanning unit.

Description

  The present invention relates to a barcode scanner capable of changing a scan width in accordance with a barcode size.

  As a background art of a barcode scanner such as the present invention, a barcode reader that scans a barcode with a laser beam, collects reflected light from the barcode and reads barcode information, and scans the laser beam. There is known a bar code reader provided with a scan width varying means for changing the image to be bilaterally symmetrical (see, for example, Patent Document 1).

  Further, in a barcode reader using laser light, there is known a barcode reader provided with means for scanning laser light and a laser light shielding plate for adjusting the scanning width of the laser light symmetrically (for example, , See Patent Document 2).

Japanese Patent Laid-Open No. 5-143761 JP-A-7-334602

However, in such a bar code reader or bar code reader that controls the scan width (scan range) symmetrically, the scan width is widened, for example, the scan width reaches the left end of the bar code and still reaches the right end. If not, expand the scan width further to the right end. As a result, the scan width at the left end is further increased, and there is a risk of reaching an adjacent barcode.
The present invention has been made in view of such circumstances, and provides a bar code scanner that does not spread further if it reaches the left and right ends even if the scan width is widened.

  The present invention includes a scanning unit that scans a scanning range according to a waveform of an applied electric signal using light, a light receiving unit that receives reflected light from a barcode when the scanning unit scans a barcode, and a light receiving unit. A bar code comprising: a decoder unit that receives the output from the decoder unit and decodes the bar code; and a scanning control unit that generates an electric signal having a waveform corresponding to a required scanning range based on the decoding result of the decoder unit and applies the electric signal to the scanning unit A scanner is provided.

According to this invention, the scanning control unit gives an electric signal having a waveform corresponding to the necessary scanning range based on the decoding result of the decoder unit to the scanning unit, and the scanning unit scans the scanning range according to the waveform. The scanning range is automatically controlled electrically according to the size of the barcode.
Therefore, if the scanning range, that is, the scanning width is widened to reach the left and right ends, it will not be further widened, and the adjacent barcode will not be read erroneously.

It is a top view which shows the barcode scanner structure by one Embodiment of this invention. It is a principal part side view of FIG. It is operation | movement explanatory drawing of the principal part of the barcode scanner shown in FIG. It is operation | movement explanatory drawing of the principal part of the barcode scanner shown in FIG. It is operation | movement explanatory drawing of the principal part of the barcode scanner shown in FIG. It is a block diagram which shows the control circuit of the barcode scanner shown in FIG. It is explanatory drawing which shows the waveform of the electric signal given to the scanning part of the barcode scanner shown in FIG. It is a flowchart which shows operation | movement of the barcode scanner of this invention. It is explanatory drawing which shows the barcode reading procedure by the barcode scanner of this invention.

  A barcode scanner according to the present invention includes a scanning unit that scans a scanning range according to a waveform of an applied electric signal (voltage or current) using light, and reflected light from the barcode when the scanning unit scans the barcode. A light receiving unit that receives light from the light receiving unit, a decoder unit that receives the output from the light receiving unit, decodes the barcode, and generates an electrical signal having a waveform corresponding to a required scanning range based on the decoding result of the decoder unit. And a scanning control unit for giving.

  The scanning control unit gradually expands the scanning range of the scanning unit from the minimum value, and when it is determined from the decoding result of the decoder unit that the scanning range has reached one end of the bar code, scanning is then performed only toward the other end. The electrical signal can be generated to expand the range.

  The scanning unit includes a reflection mirror that reflects light emitted from the light source, a support unit that rotatably supports the reflection mirror, and a drive unit that rotates the reflection mirror according to a waveform of an electric signal to be applied. May be. The drive unit may include an electromagnet excited by the electric signal and a magnet that rotates the reflection mirror by a magnetic field formed by the electromagnet. The electrical signal may have a triangular waveform.

The scanning unit may be of a galvanometer type.
In order to improve the responsiveness and followability of the scanning unit to the electric signal, it is necessary to make the moment of inertia of the movable part as small as possible. Since the moment of inertia is expressed by the product of the square of the radius of rotation of the movable part and the mass, the movable part is preferably compact and lightweight.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
FIG. 1 is a top view showing a configuration of a barcode scanner according to an embodiment of the present invention. FIG. 2 is a side view of the main part of FIG. As shown in these drawings, the main body 1 includes a light emitting unit 10, a scanning unit 20, a concave condensing mirror 30, and a light receiving unit 40.

  The light emitting unit 10 includes a laser diode 11, a collimator lens 12, and an opening member 13. The opening member 13 is formed with an opening 13a for narrowing the laser beam emitted from the laser diode 11 to a beam L1. The condensing mirror 30 is formed with a through hole 31 for allowing the beam L1 to pass through in the center.

  The scanning unit 20 includes a resin oscillating mirror 21, a holding member 22 made of aluminum alloy that holds the oscillating mirror 21 on the front side, a magnet (permanent magnet) 23 mounted on the back side of the holding member 22, and a holding unit A support shaft 24 that rotatably supports the member 22 and a coil unit 25 that is opposed to the magnet 23 and arranged in parallel with a space therebetween.

  The coil unit 25 includes a coil 26 and a yoke 27 that penetrates the coil 26 in a direction perpendicular to the winding direction. The holding member 22 and the vibrating mirror 21 held by the magnet 23 and the coil unit 35 vibrate in a seesaw manner as indicated by arrows A and B. The light receiving unit 40 is composed of a light receiving element such as a photodiode.

  As shown in FIG. 2, the support shaft 24 is erected on the boss 8 a of the support base 8, and two washers 28, 29 fitted to the support shaft 24 sandwich the holding member 22 from the upper and lower sides. Yes. The magnet 23 is fixed to the holding member 22 so that the N pole is close to the coil 26 and the S pole is away from the coil 26.

Next, the functions of the magnet 23 and the yoke 27 in the scanning unit 20 are shown in FIGS.
FIG. 3 shows a state where the magnet 23 is stationary in parallel with the yoke 27. In this case, the coil 26 is not energized, and the yoke 27 does not generate a magnetic field.

In FIG. 4, the coil 26 is energized, the yoke 27 generates a magnetic field, the end 27 a side becomes the N pole, and the end 27 b side becomes the S pole, whereby the magnet 23 (that is, the vibrating mirror 21) moves to the right ( FIG. 1 shows the state of rotation by the maximum rotation angle θ _M = 15 ° (in the direction of arrow A in FIG. 1).

In FIG. 5, the coil 26 is energized in the opposite direction, the yoke 27 generates a magnetic field, and the end 27a side becomes the S pole and the end 27b side becomes the N pole, thereby the magnet 23 (that is, the vibrating mirror 21). Shows a state of being rotated to the left (in the direction of arrow B in FIG. 1) by the maximum rotation angle θ _M = 15 °.

The function of the barcode scanner having such a configuration will be described.
As shown in FIG. 1, in the main body 1, the light emitting unit 10 outputs laser light by light emission of the laser diode 11. The laser light is converted into a parallel light beam by the collimator lens 12 and is emitted as a laser beam L 1 through the opening 13 a of the opening member 13.

  The laser beam L1 reaches the oscillating mirror 21 through the through-hole 31 of the condensing mirror 30, is reflected within a predetermined angle range by the oscillation of the oscillating mirror 21, and irradiates the barcode BC, that is, by the laser spot of the laser beam L1. Scan. The bar code is composed of a plurality of black (black bar) and white (space) vertical stripes having a predetermined width determined by the standard.

  The light beam L2 reflected from the barcode BC is incident on the vibrating mirror 21 and reflected. The reflected light is collected by the collecting mirror 30. At this time, the vibrating mirror 21 is rotated as described above by the magnetic force generated between the coil unit 25 and the magnet 23.

  Therefore, the reflected light from the barcode BC over the scanning range is sent to the condenser mirror 30. The light condensed by the condenser mirror 40 enters the light receiving unit 40. The light receiving unit 40 outputs an analog electric signal corresponding to the intensity of light received.

FIG. 6 is a block diagram showing a control circuit of the barcode scanner shown in FIG.
In the figure, the activation unit 51 includes an activation switch for activating the barcode scanner and outputs an activation signal to the scanning control unit 52 and the light emission control unit 53.

  The scanning control unit 52 generates and outputs a scanning signal to the scanning unit 20, that is, an electric signal for vibrating the vibrating mirror 21 to the coil 26. The light emission control unit 53 supplies driving power to the laser diode 11 of the light emitting unit 10 until receiving the barcode decoding completion signal from the decoder unit 55 after receiving the activation signal from the activation unit 51, and causes the scanning unit 20 to emit the laser beam L1. To exit.

  When the barcode BC is scanned by the beam L1 from the scanning unit 20, the light receiving unit 40 receives the emitted light L2 from the barcode, converts it into an analog electric signal, and outputs it to the binarizing unit 54.

  The electric signal (digital signal) binarized by the binarizing unit 54 is output to the decoder unit 55 and decoded. The decoding result in the decoder unit 55 is output to the scanning control unit 52 and the light emission control unit 53. The scanning control unit 52 and the light emission control unit 53 are activated in response to an activation signal from the activation unit 51, and start output to the scanning unit 20 and the light emission unit 10, respectively.

  FIG. 7 shows a waveform of an electric signal applied to the coil 26 for rotating the oscillating mirror 21 to the left and right, here, a triangular voltage waveform. When a positive voltage is applied, the oscillating mirror 21 rotates to the right (arrow A direction in FIG. 1), and when a negative voltage is applied, the oscillating mirror 21 moves to the left (arrow B direction in FIG. 1). It is designed to rotate.

As shown in FIG. 7A, when an alternating voltage with a small amplitude is applied to the coil 26, the vibrating mirror 21 vibrates with a small amplitude. As shown in FIG. 7B, when an alternating voltage having a large amplitude is applied to the coil 26, the vibrating mirror 21 also vibrates greatly in accordance with the amplitude.
When a positive / negative asymmetrical alternating voltage is applied as shown in FIG. 7C, the oscillating mirror 21 also vibrates asymmetrically.

The operation of reading a barcode using such a barcode scanner having each function will be described with reference to the flowchart shown in FIG.
In step S1 of FIG. 8, the right rotation angle θ _R and the left rotation angle θ _L of the oscillating mirror 21 are initially set to 0 °.

  In step S2, it is determined whether or not the decoder unit 55 has completed the decoding of the entire barcode BC based on the electrical signal obtained from the light receiving unit 40 shown in FIG. 6 via the binarizing unit 54. Is done.

In steps S3 and S6, whether or not the vibration mirror 21 has reached the maximum amplitude, that is, whether or not the right rotation angle θ _R and the left rotation angle θ _L have reached the maximum rotation angle θ _M , respectively. Determined. Further, in steps S4 and S7, it is determined whether or not the decoder unit 55 has detected the right end portion and the left end portion of the barcode BC by the right turn and the left turn of the vibrating mirror 21, respectively.

  The decoder unit 55 determines that the right end or the left end of the barcode BC is detected when the electrical signal obtained from the light receiving unit 40 via the binarizing unit 54 is 0 or 1 continuously for a predetermined time or more. Then, it is output to the scanning control unit 52.

Therefore, when the barcode scanner is activated, the routine moves from step S1 to steps S5 and S8. In steps S5 and S8, the right and left rotation angles θ _R and θ _L are first increased by 1 °, respectively. The alternating voltage is applied to the coil 26.

Then, the operations in steps S2 to S8 are repeated, and the scanning range gradually increases. When one end of the barcode BC, for example, the left end is detected by the decoder unit 55 in step S7, the counterclockwise rotation is performed thereafter. The moving angle θ _L is kept constant.

Thereafter, in order to increase only the right rotation angle θ _R by 1 °, an asymmetrical alternating voltage whose amplitude gradually changes is applied to the coil 26 (step S5). When the right end is detected, decoding, that is, decoding of the barcode BC is completed (step S2).

FIG. 9 is an explanatory diagram showing the barcode reading operation shown in FIG. 8 more specifically.
As shown in FIG. 9A, when a beam spot is irradiated at an arbitrary position on the barcode, the scanning range of the beam spot gradually expands to the left and right as shown in FIG.

Eventually, when the scanning range of the beam spot reaches the left end of the barcode as shown in FIG. 5C, the expansion of the scanning range to the left side is stopped. Then, as shown in FIG. 5D, the scanning range is expanded only to the right side, and when the scanning range reaches the right end, decoding of the barcode is completed, and the expansion of the scanning range to the right side is stopped.
In this way, the barcode scanner can properly read the barcode within a scanning range that exactly corresponds to the barcode size.

DESCRIPTION OF SYMBOLS 1 Barcode scanner main body 8 Support stand 8a Boss 10 Light emission part 11 Laser diode 12 Collimator lens 13 Opening member 13a Opening 20 Scanning part 21 Vibration mirror 22 Holding member 23 Magnet 24 Support shaft 25 Coil unit 26 Coil 27 Washer 29 Washer 30 Condensing mirror 31 Through-hole 40 Light-receiving part 51 Start-up part 52 Scan control part 53 Light-emission control part 54 Binarization part 55 Decoder part BC Bar code

Claims (5)

  A scanning unit that scans the scanning range according to the waveform of the given electrical signal using light, a light receiving unit that receives reflected light from the barcode when the scanning unit scans the barcode, and an output from the light receiving unit A bar code scanner comprising: a decoder unit that decodes a bar code; and a scanning control unit that generates an electric signal having a waveform corresponding to a required scanning range based on a decoding result of the decoder unit and applies the electric signal to the scanning unit.   The scanning control unit gradually expands the scanning range of the scanning unit from the minimum value, and when it is determined from the decoding result of the decoder unit that the scanning range has reached one end of the bar code, scanning is then performed only toward the other end. The barcode scanner according to claim 1, wherein the electrical signal is generated so that a range is expanded.   The scanning unit includes a reflection mirror that reflects light emitted from a light source, a support unit that rotatably supports the reflection mirror, and a drive unit that rotates the reflection mirror according to a waveform of an electric signal to be applied. The barcode scanner according to claim 1 or 2.   4. The barcode scanner according to claim 3, wherein the driving unit includes an electromagnet excited by the electric signal and a magnet that rotates a reflection mirror by a magnetic field formed by the electromagnet.   The barcode scanner according to claim 1, wherein the electrical signal has a triangular waveform.

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