JPH1062120A - Position measuring device and carrier using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To read out data of bar codes and accurately conduct position measurement thereof by a method wherein laser beams are alternately output from each laser beams window of a bar code scanner. SOLUTION: Laser beams windows 21a, 21b are arranged apart by W in a scanning direction, and polygon mirrors 22a, 22b are arranged inside these angular windows 21a, 21b. By synchronous rotation of both mirrors 22a, 22b, laser beams are alternately emitted from the beams windows 21a, 21b of first and second laser output devices A1 , A2 , and the output laser beams are emitted to bar codes arranged outside, and are diffusedly reflected by the reflection portion. A light receiver 27 receives the laser beams which are diffusedly reflected, and outputs a voltage value corresponding to the light receiving amount to a controller 28. An A/D transducer 30 in the controller 28 converts the voltage value to binary signals and outputs to a decode circuit 31. The circuit 31 receives these binary signals and interprets ASCII codes contained in the signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position measuring apparatus using a bar code scanner for reading bar code information by scanning a bar code and measuring the position of the bar code. The present invention relates to an automatic guided vehicle that automatically steers while recognizing a traveling place using the automatic guided vehicle.

[0002]

2. Description of the Related Art A general bar code scanner used for conventional POS and FA is sufficient if it has a function of only scanning bar codes and reading bar code information. FIG. 1 shows an example of the internal configuration of this conventional bar code scanner, in which a bar code 3 is scanned by forming a scanning arc by combining one laser light source 1 and one polygon mirror 2. .

On the other hand, a barcode scanner used for automatic control and monitoring by measuring a relative position with respect to a product, a pallet, a rack, ancillary equipment, etc. to which a barcode label is attached is disclosed in Japanese Patent Application Laid-Open No. 6-124359. Positioning device "
There is a linear scanner disclosed in US Pat. In this conventional device, two points whose scanning angles are known are required on the barcode in order to perform position measurement, and the interval between the two points must be known. In this case, when the size of the barcode changes, for example, when the barcode is enlarged or reduced as specified in JIS, or when the barcode label surface is not orthogonal to the center axis of the linear scanner, the measurement is performed. There is a problem that an error occurs.

On the other hand, as shown in FIG. 2, at least two barcode scanners 4a, 4b are installed at a predetermined interval W in the scanning direction, and the scanning amount of each barcode scanner 4a, 4b is reduced. There is a position measuring device that measures based on a scanning angle and determines a scanning amount based on a scanning angle until a predetermined code is detected.

A method of measuring the distance Z between the barcode 3 and the barcode scanners 4a and 4b and the position X in the scanning direction by the barcode scanners 4a and 4b using the position measuring device shown in FIG. 2 will be described below. I do.

The origin of coordinates is set to 0. This is a bar code scanner 4 installed at an interval W in the X-axis direction.
a, 4b. The Z axis is orthogonal to the X axis. Further, each barcode scanner 4a,
The scanning center points of 4b are O ₁ and O ₂ . Further, the barcode label 3a on which the barcode 3 is printed is placed at an angle to the X axis. Wherein each bar code scanner 4a, the angle of each phi ₁ viewed point P on the bar code label 3a from 4b, and phi _2.

Here, for the sake of simplicity, each angle is represented by an angle from the Z axis. For this reason, the scan angle does not match, but the angle formed by the scan start angle and the Z axis is a value unique to the barcode scanner. That is, as shown in FIG. 2, if, for example, in one barcode scanner 4a, the scanning start angle is θs, and the angle (scanning angle) at which the point P is viewed from the scanning start is θp, θs (known) + θp (measured value ) + Φ ₁ = bar code scanner specific value,
Φ ₁ can be easily obtained.

[0008] A point P on the bar code label 3a is located at a distance of Z from the X axis. Through the point P, and X-axis parallel to the straight line and the bar code scanner 4a, 4b central axis of intersection between the (parallel to the Z-axis) and each B _1, B _2.

First, focusing on the triangle O ₁ · P · B ₁ , Z = length of the line segment P−B ₁ / tan φ ₁ , and focusing on the triangle O ₂ · P · B ₂ , Z = line minute P-B ₂ becomes long / tan [phi _2. On the other hand, W = length of the segment P-B ₂ - since the length of the line segment _{P-B 1, W = Z} × (tanφ 2 -tanφ 1) , and the _{thus, Z = W / (tanφ 2} - tanφ ₁ ). Also with respect to the X, can be calculated as X = W / 2 line _{P-B 1 = W / 2} + Z × tanφ 1 = W / 2 + (W × tanφ 1) / (tanφ 2 -tanφ 1). In this method, it is important that the barcode label 3a does not need to be parallel to the X axis.

[0010] How to determine the point P must also be explained. Generally, a bar code scanner decodes a reflected signal from a distribution bar code to determine a start code, a center code, a stop code, a manufacturer-specific code, a product-specific code, and the like. Specifically, a thick / thin judgment threshold is set based on the width of the bar or space of the start code portion scanned after the quiet zone (white zone scanned before the bar code), and the code of the start code itself is set. The type of barcode symbol depending on the pattern, for example, JAN, NW-7, I
Identify and specify TV and so on. Here, the point P is obtained by decoding the center code as a JAN code.
The method for obtaining is described. In the JAN code,
The start code is also called a lift guard bar, the center code is also called a center bar, and the stop code is also called a light guard bar.

The operation will be described with reference to the flowchart shown in FIG. First, a quiet zone (white area having a certain width or more: reflection) is detected, and a start code appearing thereafter is received. The reflection time of the first bar of the start code is regarded as one bar, and the time is set as a threshold for determining the continuous number of bars or spaces.

Thereafter, when the star code is "101" (a combination of one bar + one space + one bar), it is determined that the JAN code is targeted. In the case of other codes, it is determined that the code symbol is not JAN, and the flow shifts to another decoding flow. Furthermore, a code for 6 characters following the start code, that is, 1
Since the character is composed of 7 modules (1 module is equivalent to one bar or space), decoding of 7 modules × 6 characters = 42 modules is performed, and the codes of the manufacturer and the product are known. Since this decoding method is already known by general bar code scanners, it will not be described here.

This is followed by a center code. The scan amount is latched at the same time when the center code "101" is recognized. Specifically, as shown in FIG. 4, a comparison 3-bit register 5 is prepared in advance in a barcode reader,
"101" is set in advance. A laser light source 1 and a signal incident from a polygon mirror 2 driven by an encoder-equipped motor and reflected from a bar code 3 are also amplified from a laser receiving unit 6 through an amplifier 7 and separately set in a comparator 8 in advance. Is compared with a certain reflection intensity threshold.

As a result, 0 is set for a space (white: reflection), 1 is set for a bar (black: no reflection), and input 3
The data is input to the bit shift register 10. If the contents of the comparison 3-bit register 5 and the input 3-bit shift register 10 match, a center code detection timing is generated and input to the scanning angle counter 11. The center code detection timing is generated when the next point P, scanning angle at that time, get to phi ₁ detected with e.g. a rotation angle of the polygon mirror 2 in the rotation angle detecting means such as an encoder or potentiometer. here,
The mirror is not limited to a rotary type, and may be a vibration type swing mirror instead of a polygon mirror. If the rotation speed can be considered to be constant, the rotation angle detection means may count the rotation time using a clock.

[0015] Similar operations obtain phi ₂ is also performed by other bar code scanner. Then, according to the above formula,
Calculate the position of Z and X.

As described above, since the scanning amount is obtained at the decoding end point of the predetermined code, the probability of erroneous determination due to dirt can be extremely low as compared with a method of finding a scanning amount by simply finding a code line. In addition, the position measurement does not depend on the order in which the code lines are present.

[0017]

In the position measuring apparatus and method shown in FIGS. 2 to 4, when two bar code scanners 4a and 4b are used at the same time, the bar code 3 scatters. Since the laser light is received in a wide range, there is a problem that it is not possible to determine which bar code scanner outputs the measured reflected light from the laser light.

In order to solve this problem, a method of preventing the reflected light of the laser beam output from another bar code scanner from being received by increasing the distance between the bar code scanners 4a and 4b. However, since the same barcode 3 needs to be measured by each barcode scanner, this cannot be adopted.

As another method, Japanese Patent Application Laid-Open No. 7-200
As in the "optical symbol reader" disclosed in Japanese Patent Publication No. 714, a laser light source (laser oscillator) in each bar code scanner is sequentially turned on and off so that the laser light is not irradiated at the same time. However, a rise time of the laser light source is required, which causes a waste time. ON and OF for laser light source
It is conceivable that the load is increased and the durability time is shortened by repeating F.

[0020]

Means for Solving the Problems and Effects of the Invention
Considering the above, in a bar code scanner having a plurality of polygon mirrors and a function of simultaneously outputting a plurality of laser beams to an external bar code, one of the plurality of laser beams is provided. One of the objects of the present invention is to solve the above-mentioned conventional problem by selectively outputting two laser beams to the outside. This configuration scans a barcode with a barcode scanner that simultaneously scans at least two laser beams. Thus, in a position measuring device for measuring a relative position between a barcode and a barcode scanner, laser light is alternately output from each laser light window of the barcode scanner.

With this configuration, at least two laser beams alternately scan the bar code, whereby the laser beams output from the plurality of laser beam output devices and scanned by the bar code are output to any laser beam output device side. Thus, it is possible to easily determine whether or not the data is output from the device, and to accurately read the barcode information and measure the position thereof.

In the position measuring device having the above configuration,
As means for alternately outputting laser light from each laser light window, a polygon mirror that scans and outputs laser light from the laser light source from the laser light window is provided between the laser light source and each laser light window. The size of the scanning output angle of the laser light window is narrowed so as to block a part of the entire scanning angle of each polygon mirror, and the rotation phase of each polygon mirror is shifted so as not to be simultaneously output from each laser light window. The configuration is such that a controller is provided so as to control the scanning output from the laser light window.

A polygon mirror for scanning and outputting laser light from the laser light source from the laser light window is provided between the laser light source and each laser light window. Surfaces are alternately arranged, and a controller is provided that controls the rotation phase of each polygon mirror so that laser light from each reflection surface is output alternately from each laser light window.

Further, a shutter having two states, a state in which laser light is transmitted and a state in which laser light is blocked, is provided in the optical path between the laser light source and the laser light window, and the state in which each shutter is blocked is alternately in the optical path. Having a controller for controlling the above.

A liquid crystal shutter or a disk having a slit is used as the shutter.

Further, one laser light source is used as the laser light source in each of the above-described configurations, and the laser output from the one laser light source is irradiated on each of the polysilicon mirrors through a spectroscope that divides the laser light into a plurality of light beams. Even with laser scanning, one laser light source can be used and the cost can be reduced.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. (Embodiment 1) In FIG. 5, A ₁ and A ₂ denote first and second laser light output devices, and 21a and 21b denote respective laser light windows arranged side by side in the scanning direction at a distance of W. There is a polygon mirror 2 inside these square windows 21a and 21b.
2a and 22b are arranged. Each of the polygon mirrors 22a and 22b is connected to one motor controller 23.
The motors 24a and 24b, which are controlled synchronously, rotate and drive. Reference numeral 25 denotes one laser light source. The laser light from the laser light source 25 is
a, 22b. Reference numeral 27 denotes a light receiver for receiving the reflected light reflected on the bar code 3 emitted from each of the laser light windows 21a and 21b, and reference numeral 28 denotes a controller.

Hereinafter, two laser light windows 2 will be
The operation of alternately outputting laser beams from 1a and 21b will be described. When an operation start command is input from the controller 27, laser light is output from the laser light source 25 to the spectral mirror 26, is divided into two by the spectral mirror 26, and is input to the polygon mirrors 22a and 22b, respectively.

The operation start command from the controller 28 is also input to the motor controller 23 at the same time, and the motors 24a and 24b start rotating. At this time, the motor controller 23 has two polygon mirrors 22a and 22a.
The motors 24a and 24b are controlled so that b rotates in the same direction with a predetermined angular velocity and phase difference. In order to realize this operation, for example, each motor 24a, 2
4b rotation axis or polygon mirrors 22a and 22b
A circuit that alternately outputs a HIGH (for example, 5 V voltage) signal and a LOW (for example, 0 V voltage) signal according to the angle of the rotation axis with respect to the rotation axis is attached, and the cycle of the rectangular wave output from each circuit is set to There is a method of controlling the angular velocities of the motors 24a and 24b so that the deviation becomes a predetermined value. The spectroscopic mirror 26 divides one laser beam into two laser beams.
It can be realized by combining two mirrors at an angle and applying a laser beam to the vertex, or combining a half mirror that transmits a part of the irradiated laser beam and reflects the rest and a mirror that totally reflects the laser beam.

The laser light split into two by the spectroscopic mirror 26 is applied to the polygon mirrors 22a and 22b, respectively. Since the polygon mirrors 22a and 22b rotate at a constant angular velocity, the polygon mirrors 22a and 22b are rotated. The reflection direction of the laser light hitting each of the mirrors changes depending on the direction of the mirror at that time, and the laser light is scanned by the polygon mirrors 22a and 22b in an arc at a constant angular velocity. .

Here, both polygon mirrors 22a, 22b
The polygon mirrors 22a and 22b are set so that the scanning directions of the laser light by
21b. In other words, each polygon mirror 22a, the total scan angle theta ₀₁ of 22b, theta ₀₂ are the same, scanning starting L _a1 of the first polygon mirror 22a is coincident with the upstream open end of the scanning direction of the laser beam window 21a, The scanning center L _b1 of の of the total scanning angle L ₀₁ is the laser light window 21a.
, And the scanning end _Lc1 from the scanning center _Lb1 is shielded by the shielding frame 29a.

On the other hand, the scanning center L _b2 from scanning starting L _a2 of the total scan angle theta ₀₂ of the second polygon mirror 22b is shielded by the shielding frame 29 b, 1/2 of the scanning center L of the total scan angle L _{02 b2} coincides with the upstream opening end of the laser light window 21b, and the scanning end _Lc2 coincides with the downstream opening end of the laser light window 21b.

The two polygon mirrors 22a, 22a
When b rotates synchronously, both polygon mirrors 22a and 22b
Reflects the laser light in the same direction at the same total scanning angles θ ₀₁ and θ ₀₂ , respectively, but the reflected light from the first polygon mirror 22a is output from the laser light window 21a from the scanning start end _La1 to the scanning center _Lb1. Is done. On the other hand, at this time, the reflected light of the second polygon mirror 22b is moved from the scanning start end _La2 to the scanning center L
It is shielded by the shielding frame 29b over _b2 .

The light reflected by the first polygon mirror 22a is shielded by the shielding frame 29a while scanning from the scanning center _Lb1 to the scanning end _Lc1 . On the other hand, at this time, the reflected light of the second polygon mirror 22b is _shifted from the scanning center _Lb2 to the scanning end L
_c2 is scanned, and the laser beam is
1b.

As described above, the two polygon mirrors 22a, 22
b, the first and second laser output devices A ₁ ,
Laser light window 21a of the A _2, 21b laser light is alternately output from the bar code 3 is scanned alternately by the first, second laser beam output device A _1, A _2.

The output laser beam is applied to a bar code 3 provided outside, and if the irradiated location is a reflective portion (generally a white bar) of the bar code 3, the laser beam is irregularly reflected there. The light receiver 27 receives the irregularly reflected laser light and outputs a voltage value corresponding to the received light amount to the controller 28. A / D converter 3 in controller 28
At 0, the voltage value is converted into a binary signal of HIGH and LOW and output to the decoding circuit 31. Decode circuit 31
Receives this binary signal and decodes the ASCII code contained in the signal. Further, a signal for recognizing the direction in which the laser is output, such as a rectangular wave used for controlling the motors 24a and 24b, is also input to the controller 28.
By this operation, the first and second polygon mirrors 22a, 22a
It is possible to determine which code can be read by which laser beam 2b, and to realize a desired function.

In this embodiment, the rear half and the front half of the full scanning angle of each of the laser output devices A ₁ and A ₂ are connected to the shielding frame 29.
Although the example in which the shielding is performed by the shielding frames 29a and 29b has been described, the positions of the shielding frames 29a and 29b are not necessarily limited to the positions having the ratio, and two laser beams are not output at the same time. It is sufficient that the barcode 3 to be measured exists at a position where both laser beams can be received. Also, even if there is an area where two laser beams are simultaneously output, there is a means for recognizing this implementation area, for example, facing each polygon mirror 22a, 22b of each laser beam output device A ₁ , A _2. If a sensor such as a potentiometer for detecting an angle is installed and a processing circuit that discards data obtained in this area is used, measurement can be performed.

(Embodiment 2) Next, an embodiment using the apparatus shown in FIG. 6 will be described. In this configuration, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. The structure of the polygon mirrors 22a 'and 22b' is shown in FIG.
And a non-reflective surface 32b for absorbing or scattering laser light
And are alternated.

When an operation start command is input from the controller 28, a laser beam is output from the laser light source 25, and this laser beam is split into two by the spectroscopic mirror 26, as in the first embodiment. Polygon mirror 22
a 'and 22b'. Further, in synchronization with this, the motors 24a and 24b start rotating, and the motor controller 23 controls the motors 24a and 24b so that the rotation of the motors 24a and 24b has a predetermined angular velocity and a predetermined phase difference.
control b. Here, polygon mirrors 22a ', 22
b 'is arranged so as not to simultaneously reflect the laser beam.

That is, the first polygon mirror 22a '
While receiving the laser beam on the reflection surface 32a, the second polygon mirror 22b 'receives the laser beam on the non-reflection surface 32b. Thus, the first and second laser light output devices A ₁ and A ₂ alternately output the scanning laser light.

In the first and second embodiments, a method of controlling the rotation of the motors 24a and 24b by using a rectangular wave and electrically controlling the rotation by the motor controller 23 has been described. Mirror 22
a, 22b, 22a ', and 22b' are prepared as one motor, and the rotation output is transmitted to both polygon mirrors via power transmission means such as gears, drive shafts, and timing belts. Is also good.

(Embodiment 3) Next, an embodiment using the apparatus shown in FIG. 8 will be described. In this configuration, the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. First, second laser beam output device A _1, A ₂ of each of the laser light window 21a, 21b to the liquid crystal shutter 33a, 33b
Was provided. The liquid crystal shutter 33a, 33b of the state H ₁ that transmits a laser beam, and is variably two states of the state H ₂ to this blocking, or scattered. 34
Is a controller for controlling the liquid crystal shutters 33a and 33b to alternately switch between the two states.

In this configuration, the laser light output from the laser light source 25 is split into two by the spectroscopic mirror 26 and applied to the polygon mirrors 22a and 212b, respectively.
The laser light is reflected toward 21b. put it here,
If the controller 34 sets the first liquid crystal shutter 33a in the transmission state (H ₁ ) and the second liquid crystal shutter 33b in the non-transmission state (H ₂ ), laser light is output only from the first laser light window 21a. Then, the laser beams are alternately output from the first and second laser light output devices A ₁ and A ₂ by alternately changing the states of the shutters 33 a and 33 b.

In the third embodiment, the liquid crystal shutters 33a and 33b are used as shutters for selecting the output of the laser beam. This is, for example, as shown in FIGS.
It can also be realized by rotating a disk 36 having a slit 35 by a motor 37. In the third embodiment, an example is shown in which a shutter is provided at a position (laser light window) where the laser light is scanned by the polygon mirror and exits.
b, for example, as shown by the dashed line in FIG. 8, the spectral mirror 26 and the polygon mirrors 22a, 22
2b.

In the first, second, and third embodiments, in order to output laser light to the two polygon mirrors 22a, 22b, 22a ', and 22b', laser light from one laser light source is used by using the spectral mirror 26. Although the example of dividing into two was shown,
This may of course use one laser light source (ie two laser light sources) for each polygon mirror.

(Embodiment 4) Next, an operation example using a carrier equipped with the position measuring device B shown in each of the above embodiments will be described. First, in FIG. 11, a bar code 3 using this position measuring device B is displayed.
A method for measuring the relative distance between the robot and the position measuring device B will be briefly described.

As shown in FIG. 11, an intermediate position between the first and second laser light output devices A ₁ and A ₂ is defined as an origin O, and the X axis is set in a direction parallel to the polygon mirrors 21a and 21b.
The direction perpendicular to the X axis is defined as the Z axis. Angles between the line connecting the point P of the code written on the barcode 3 and the reflecting surfaces of the polygon mirrors 22a and 22b and the Z axis are φ ₁ and φ ₂ respectively.
And The distance between the polygon mirrors 22a and 22b is W. Here, the coordinates of the point P viewed from the origin O are (X,
Z). At this time, from equation (1),
Equation (2) is obtained.

[0047]

(Equation 1)

From the expressions (1) and (2), X and Z are obtained from the expressions (3) and (4). Thereby, the relative position (X) and the relative separation distance (Z) between a certain point on the barcode 3 and the position measuring device B are obtained.

[0049]

(Equation 2)

The point P is described by using the reflection and non-reflection bars existing on the bar code 3, and is represented by decoding the detection pattern. Also, φ ₁ , φ
_The measurement of ₂ can be realized by attaching an encoder or a potentiometer for detecting an angle to the rotation axes of the polygon mirrors 22a and 2b. Alternatively, it is also possible to measure the time from the start of rotation under the condition that the rotational angular velocities of the polygon mirrors 22a and 22b are constant.

Next, an example in which the apparatus according to the fourth embodiment is mounted on an unmanned transport vehicle to perform a cargo handling operation will be described with reference to FIG. The transport vehicle 38 is an unmanned vehicle having a steering function and a traveling function, and has the above-described position measuring device B including two laser light output devices mounted on a side surface thereof. A guide wall 39 indicates the direction in which the transport vehicle 38 travels. The bar code 3 is attached to a side surface on the transport vehicle 38 side. N ₁ ,
N ₂ and N ₃ are load operation fields, respectively, and a bar code 3 is also attached to the side surface thereof. Each bar code 3 has a position code a ₁ ,
a ₂ ,. . . , B ₁ , b ₂ ,. . . c ₁ , c ₂ ,. . .
Is read, and by reading these codes, the current position of the carrier 38 can be confirmed. And each of the front operation field N _1, N _2, N ₃ 40 attaching a bar code that for example _{a 1, b 4, c 5} .

Now, as an example, when the carrier 38 in N ₁ is instructed to receive a load in N ₂ and put a load in N ₃ , the carrier 21 receives this command and sends the following command to the carrier 38. Decompose as follows.

(1) From bar code a1 to bar code a3
Go straight to. (2) Turn to the left at the barcode a3. (3) Go straight from bar code b1 to b4. (4) Stop in front of the bar code b4 and receive the load. (5) Go straight from bar code b4 to bar code b1. (6) Turn left at the barcode b1. (7) Go straight from bar code c1 to bar code c5. (8) Stop at the front of the barcode c5 and put the load.

Upon receiving the work start instruction, the transport vehicle 38 detects the bar code a ₁ by scanning the bar code scanner B, and detects the bar code a ₁ , that is, the wall surface 39 and the transport vehicle 3.
8 distance measurement, travels while maintaining a distance (direction Distance Z relative to the bar code scanner L) of the wall 39 constant at a predetermined speed until the bar code a _8. Once reached the position where the bar code a ₈ are measured by a position measurement apparatus B (X
= 0 is not necessary) lowers the speed, traveling at a low speed until a position measuring device B on the front position of a ₈ (the position of X = 0). performs steering from the time it reaches the front of a _3, to the transport vehicle 38 is turning left. Position measurement device B again after turning
In scanning, advances from the position measuring device B measures the position of the bar code b _1, to b ₄ while keeping the distance between the wall 39 constant. b ₄ decelerates When the transport vehicle 38 to reach the position for detecting, stopped Tara barcode b ₄ brat at the position of X = 0 as viewed from the front that is, the position measuring device B of traveling at a low speed b _4, load receipt of Do the work. The following travel in the same work up bar code b _1, turning to the left, and stopped in front of the bar code c _5, performs a load delivery operation. The given operation can be realized by the above operations. Conventionally, such unmanned vehicles are guided by burying a cable in the floor and detecting the induced magnetic field or attaching a light reflecting tape. It can measure, but cannot measure the distance to the workplace. In addition, there is a monetary advantage that the cost of floor work is eliminated.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing a conventional position measuring device.

FIG. 2 is an explanatory diagram showing a configuration of a position measuring device having two barcode scanners arranged side by side.

FIG. 3 is a flowchart illustrating a method for calculating a position in the Z and X directions.

FIG. 4 is an explanatory diagram showing a configuration and operation in a barcode scanner.

FIG. 5 is a configuration explanatory view showing a first embodiment of the present invention.

FIG. 6 is a configuration explanatory view showing a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a polygon mirror according to a second embodiment of the present invention.

FIG. 8 is a configuration explanatory view showing a fourth embodiment of the present invention.

FIG. 9 is a configuration explanatory view showing another example of the fourth embodiment of the present invention.

FIG. 10 is a perspective view showing a disk having a slit.

FIG. 11 is an explanatory diagram illustrating a measurement method for measuring a relative distance between a barcode and a barcode scanner.

FIG. 12 is an explanatory view showing an embodiment of a carrier using a position measuring device.

[Explanation of symbols]

1, 25 ... laser light source 2, 22a, 22b, 22a ', 22b' ... polygon mirror 3 ... barcode 4a, 4b ... barcode scanner 5 ... 3-bit register for comparison 6 ... laser receiving section 7 ... amplifier 8 ... comparator DESCRIPTION OF SYMBOLS 10 ... Input 3 bit shift register 11 ... Scan angle counter 21a, 21b ... Laser light window 23 ... Motor controller 24a, 24b, 37 ... Motor 26 ... Spectral mirror 27 ... Receiver 28, 34 ... Controller 32a ... Reflection surface 32b ... Non reflecting surfaces 33a, 33b ... liquid crystal shutter 35 ... slit 36 ... disk 38 ... transport vehicle 39 ... induction wall 40 ... load A _1, A ₂ ... laser beam output device B ... position measuring device

Claims (8)

[Claims] 1. A position measuring apparatus for measuring a relative position between a barcode and a barcode scanner by scanning a barcode with a barcode scanner that simultaneously scans at least two laser beams. A position measuring device characterized in that laser light is alternately output from a laser light window. 2. A polygon mirror for scanning and outputting laser light from a laser light source from a laser light window between a laser light source and each of the laser light windows. The polygon mirror is narrowed so as to block a part of the entire scanning angle, and the rotation phase of each polygon mirror is
2. The apparatus according to claim 1, further comprising a controller configured to perform control so that scanning is output from the laser light windows by shifting the laser light windows so as not to be simultaneously output.
The position measuring device as described. 3. A polygon mirror for scanning and outputting laser light from the laser light source from the laser light window between the laser light source and each laser light window, and a reflecting member of each polygon mirror is provided with a reflection surface and a non-reflection surface. And are arranged alternately,
2. A controller according to claim 1, further comprising a controller for controlling the rotation phase of each polygon mirror so that the laser light from each reflection surface is output alternately from each laser light window.
The position measuring device as described. 4. A shutter having two states, a state in which laser light is transmitted and a state in which laser light is blocked, is provided in an optical path between a laser light source and a bar code, and a state in which each shutter is blocked is alternately in the optical path. 2. The position measuring device according to claim 1, further comprising a controller for controlling the position. 5. The position measuring device according to claim 4, wherein a liquid crystal shutter is used as the shutter. 6. The position measuring apparatus according to claim 4, wherein a disk having a slit is used as a shutter, and the disk is rotated so as to alternately block each laser light window. 7. The position measuring apparatus according to claim 1, wherein a laser beam output from one laser light source is irradiated on each polygon mirror via a spectroscope that divides the laser beam into a plurality of laser beams. . 8. A carrier equipped with the position measuring device according to claim 1, wherein the bar code provided on the guide wall is scannable.