JPS6248264B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mark or barcode reading device.

In general, in unmanned vehicles that can automatically travel along a predetermined track, a bar code consisting of a series of bar signs is pasted on the floor so that the unmanned vehicle can detect location information while traveling. , a method is adopted in which an unmanned vehicle reads this mark (barcode) and detects its location information.

Conventional mark reading methods include a parallel reading method, a serial reading method, and a serial reading method such as a timing bit method. Among these, the parallel reading method uses multiple detectors to detect the presence or absence of bars at once by arranging the bars in a direction perpendicular to the direction of movement of the unmanned vehicle, and reading the bar presence/absence information. This method requires the same number of detectors as the number of bits in the barcode, which has the disadvantage of being expensive. In addition, the serial reading method arranges bars in the direction of movement of the unmanned vehicle, detects the bars in series with one detector, counts the number of detected pulses, and reads information from the count value. However, this method requires many circuits such as a scan circuit, a pulse generation circuit, and a counting circuit, making the device complex and expensive. Furthermore, in the timing bit series reading method, for example, two detectors are mounted on an unmanned vehicle in a direction perpendicular to the direction of movement of the unmanned vehicle.
When one detector detects a bar, the other detector detects the presence or absence of a bar and reads the information, but this method has the disadvantage that errors in the direction of movement can sensitively affect reading accuracy. It was hot.

Therefore, the inventor of the present invention proposed a mark reading method that eliminates the above-mentioned drawbacks by arranging first and second bars of different widths in the direction of movement of the moving object and moving the first and second detectors. We have already developed a device that is mounted on the body in an array in the direction of movement, and that determines the type of bar according to the output of the second detector when the first detector detects the starting end of the bar. .

By the way, in the conventional mark reading method, when trying to detect whether reading of a mark has been completed, a mark is separately provided to indicate the completion of reading, and a logic circuit is used to distinguish between this mark and an information mark. The conventional method is to detect the completion of reading, or to provide a dedicated detector to detect the completion mark of reading. However, this method requires a mark other than the information mark, and also requires a complicated logic circuit and a new detector.

This invention was made in view of these conventional problems, and in the mark reading method developed by the present inventor, there is always a gap between the first and second detectors during mark reading. The third detector is arranged and mounted so that the detector detects the bar, and the mark reading completion signal is generated when none of the three detectors detects the presence of the bar. It is an object of the present invention to provide a mark reading device that can easily detect whether or not reading of a mark is completed.

An embodiment of the present invention will be described below with reference to the drawings.

1 to 4 show a mark reading device according to an embodiment of the present invention. In the figure, 1 is a road surface which is an object to be detected, and a bar code (mark) 3 formed by encoding positional information is pasted on the road surface 1. Reference numeral 2 denotes an unmanned carrier (moving object) that travels on the road surface 1 in the direction of arrow A. When the carrier 2 passes over the mark 3, the mark 3 is read to determine its position. Mark 3 above is the width
a The first bar of ₁ (meaning binary “0”),
It is constructed by arbitrarily arranging a second bar (meaning a binary "1") with a width a ₂ (a ₂ > a ₁ ) at an interval b, as shown in Figures 3 and 4. In the example, 4 and 5 are the first bars, and 6 is the second bar. Note that all of these bars are formed using reflective plates.

On the other hand, a detection device 7 is disposed on the bottom of the transport vehicle 2, and the detection device 7 includes a first light receiving sensor (first detector) 8 that detects the starting end of the bar, and a second light receiving sensor (first detector) that detects the presence or absence of the bar. It is composed of third light receiving sensors (second and third detectors) 9 and 10. The detection position 9a of the second light receiving sensor 9 on the road surface 1 is set at a distance d from the detection position 8a of the first light receiving sensor 8 in the direction of arrow A, that is, toward the end of the bar. The detection position 10a of the third light receiving sensor 10 is set at a distance e from the detection position 8a of the first light receiving sensor 8 toward the end of the bar. However, here e<a ₁ <d<a ₁ +b, b
<d< _a2 . The transport vehicle 2 is also provided with a light emitting element (not shown) that emits light downward, and receives outputs from the first and second light receiving sensors 8 and 9, and the first light receiving sensor 8 is connected to the bar. The first light receiving sensor 9 detects the first
The bars detected by the light receiving sensor 8 are the first and second bars.
Discrimination circuit (not shown) that determines which bar it is.
is installed. Furthermore, the transport vehicle 2 receives the outputs of the first, second, and third light receiving sensors 8, 9, and 10, and when any of the three sensors 8, 9, and 10 no longer detects the presence of the bar, A reading completion signal generation circuit (see FIG. 5) for generating a mark reading completion signal is mounted.

FIG. 5 shows the circuit configuration of the reading completion signal generation circuit 16, and in the figure, 11 has three inputs, which are the outputs a, f, and c of the first, second, and third light receiving sensors 8, 9, and 10. OR circuit; 12 is a first pulse generation circuit consisting of a monostable multivibrator that receives the output of OR circuit 11 and generates a pulse signal in synchronization with the rise of the output; 13 receives an inverted signal of the output of OR circuit 11; a second pulse generation circuit consisting of a monostable multivibrator that generates a pulse signal in synchronization with the fall of the output of the OR circuit 11;
14 is an OR circuit having two inputs: the output of the first pulse generating circuit 12 and the external reset signal g;
15 is a flip-flop circuit whose S terminal is connected to the output of the second pulse generation circuit 13, and whose R terminal is connected to the output of the OR circuit 14.

Next, the operation will be explained.

When the transport vehicle 2 is traveling on the road surface 1, its light emitting element always emits light downward, and when the transport vehicle 2 passes over the mark 3, the first and second light receiving sensors 8 and 9 The reflected light from the bars 4 to 6 of the mark 3 is sequentially received. When the first light receiving sensor 8 detects the starting end 4a of the first bar 4, that is, when its detection output rises, the second light receiving sensor 9 detects the road surface because d>a ₁ is set. Since the detection position 9a on the bar 4 has already passed the terminal end 4b of the bar 4 and no bar is detected, the discrimination circuit determines that the bar 4 is the first bar. Similarly, regarding the bar 5, since the second light receiving sensor 9 does not detect the bar when the output of the first light receiving sensor 8 rises, the bar 5 is determined to be the first bar. Furthermore, in bar 6, its width a ₂ is a ₂ > d
Therefore, when the first light receiving sensor 8 detects the starting end 6a of the bar 6, the detection position 9a of the second light receiving sensor 9 is on the bar 6, and the sensor 9 detects the bar. 6 is determined to be the second bar, and in this way, the binary position information of mark 3 consisting of a plurality of bars can be read.

When reading the position information of the mark 3 in this way, the distance d between the first and second light receiving sensors 8 and 9 is d>b, and the first and third light receiving sensors 8 and 10
Since the interval e is set to e< _a1 , at least one of the first, second, and third light receiving sensors 8, 9, and 10 always detects the presence of the bar.
Then, in the read completion signal generation circuit 16,
The output of the OR circuit 11 becomes "1" when the second light receiving sensor 9 starts to detect the presence of the first bar 4, and the first pulse generating circuit 12 synchronizes with the rise of the output of the OR circuit 11. generates a pulse signal,
Since it is applied to the R terminal of the flip-flop circuit 15 via the OR circuit 14, the output of the flip-flop circuit 15 is reset to "O". When the reading of all the marks 3 is completed, the outputs a, f, and c of the first, second, and third light receiving sensors 8, 9, and 10 all become "0", and the output of the OR circuit 11 also becomes "0". Therefore, the second pulse generation circuit 13 generates a pulse signal in synchronization with the fall of the output of the OR circuit 11 and applies it to the S terminal of the flip-flop circuit 15, so the output of the circuit 15 becomes "1'', thereby making it possible to obtain the mark reading completion signal h. In addition, this reading completion signal generation circuit 16
stops generating the mark reading completion signal h when it starts reading a new mark 3 or when it receives a reset signal g from the outside.

In the apparatus of this embodiment as described above, the completion of mark reading is detected when none of the first, second, and third light receiving sensors detect the presence of the bar. Start reading.
There is no need to separately provide a mark indicating completion, and a mark reading completion signal can be generated by simply providing a third detector and a very simple logic circuit.

Although the above embodiment describes a mark reading device that reads position information of an unmanned carrier, the present invention can be similarly applied to a device that reads information such as the type and number of an article transported by a conveyor, vehicle, etc. In this case, a mark is affixed to the article being transported and is read by a detector on the stationary side.
In addition, the widths a ₁ and a ₂ of the bars, the distance b between them, and the distance d and e between the light receiving sensors satisfy the above-mentioned conditions e<a ₁ <d<a ₁ +
As long as b and b<d<a ₂ are satisfied, there may be variations in each of them. Furthermore, as the detector and bar used for mark reading, a metal detector and a metal plate, or a magnetic sensor and a magnet may be used in addition to the above-mentioned light receiving sensor and reflecting plate.

As described above, according to the mark reading device according to the present invention, the first and second bars having different widths are arranged in the moving direction of the moving body, and the first and second detectors are arranged on the moving body. They are arranged in the moving direction, and the type of the bar is determined according to the output of the second detector when the first detector detects the starting end of the bar. A third detector is provided in between, and a mark reading completion signal is generated when none of the first, second, and third detectors detect the presence of a bar, resulting in a simple configuration. This has the effect of easily detecting the completion of mark reading.

[Brief explanation of the drawing]

1 and 2 are a plan view and a side view of a mark reading device according to an embodiment of the present invention, FIGS. 3 and 4 are an enlarged side view of the main part of the device and a plan view of the mark, and FIG. 2 is a circuit configuration diagram of a read completion signal generation circuit of the above device. FIG. 1... Road surface (detected object), 2... Unmanned carrier (moving object), 3... Mark, 4, 5... First bar, 4a,
5a...Starting end, 4b...Terminal end, 6...Second bar, 6a
... Starting end, 8, 9, 10... First, second, third light receiving sensor (first, second, third detector), 8a, 9
a, 10a...Detection position, 16...Reading completion signal generation circuit.

Claims (1)

[Claims] _1. A detected object to which a mark is attached, which is formed by arranging a plurality of first and second bars with widths a 1 and a 2 (a ₁ < _{a 2 )} with a mutual interval b, and the detected object. a movable body that moves relative to the body in the width direction of the bar; a first detector mounted on the movable body that detects the starting end of the bar;
There is a distance d from the detection position of the detector to the end of the bar,
second and third detectors each mounted on the moving body to detect the presence or absence of the bar so as to be located at the position e (e<a ₁ <d<a ₁ +b, b<d<a ₂ ); When the first detector detects the starting end of a bar, the first detector detects whether the bar is the first or second bar depending on the detection signal of the second detector indicating the presence or absence of a bar. a discriminating circuit for discriminating whether the bar is present, and receiving the outputs of the first, second, and third detectors and generating a mark reading completion signal when none of the three detectors detects the presence of the bar. A mark reading device comprising a reading completion signal generation circuit.