JP3256701B2 - Signal phase adjuster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal phase adjusting device, and more particularly, to a communication between a fixed station and a mobile station by connecting a space between the fixed station and the mobile station with light and carrying information on the light. The present invention relates to a novel signal phase adjusting device that adjusts the phase of a carrier wave emitted from a plurality of fixed stations in a spatial light transmission device that performs the following.

[0002]

2. Description of the Related Art For example, when storing articles in a predetermined position in a warehouse or carrying out articles stored in the warehouse to the outside, a truck driven by remote control is driven into the warehouse. There is known a so-called picking system in which goods are transported by a cart. In such a picking system, a so-called spatial light transmission device is used, which connects a fixed station disposed in a warehouse and a ground station provided on a truck with light. An example of such a system is disclosed in Japanese Patent Application Laid-Open No. 64-24529.

In the system described in the above-mentioned publication, a transport cable derived from a computer-structured control device arranged at an appropriate place inside and outside a warehouse is stretched around a ceiling in the warehouse, and is placed at an appropriate location of the transport cable. Provide multiple branch terminals. A fixed station having a transmitter having a light-emitting element and a fixed station having a receiver having a light-receiving element are respectively disposed near the plurality of branch terminals, and include command signals sent from a control device via a carrier cable. The light emitted from the light emitting element is modulated by a modulated wave, which is an electric signal, and emitted toward a receiver provided on a cart.

Light emitted from the ceiling toward the floor is received by a light receiving device of a mobile station provided on a truck traveling on the floor, and a device such as a lift provided on the truck is remotely operated by a demodulated command signal. Then, the picking operation is performed. In a large warehouse, for example, a carrier cable is stretched on the ceiling in a U-shape so as to be able to receive the light projected from the light source of the fixed station, regardless of the position of the bogie. And a branch terminal is provided so that light to be projected exists at any position on the floor surface.

[0005]

According to a first aspect of the present invention, there is provided a spatial light transmission apparatus for receiving, at a moving ground station, the light emitted from a plurality of fixed stations with the same information loaded on the light. A transmission cable that transmits information to be carried on light, and that transmits an electric signal that is provided as a pair of the same length in which the outward path and the return path have a turning point and are close and parallel to each other, and at the starting end side of the transport cable. A control device provided for transmitting a continuous wave of an electric signal to the carrier cable, and a continuous wave provided on a receiving point in the middle of the carrier cable and received from the carrier cable, the same as the receiving point on the outward route. A phase comparator for detecting a phase shift with respect to the continuous wave on the return path received at the point, and calculating a time corresponding to a phase shift interval detected by the phase comparator and halving the time. Calculate the specific delay time of the receiving point And a variable delay circuit that delays an electric signal for optically modulating the light emitted from the light emitting element by the inherent delay time. , The same optical signal is transmitted at the same timing. The invention according to claim 2 of the present application
In addition to the first aspect of the present invention, each fixed station has switching means for switching a timing for setting a specific delay time of each fixed station and a timing for transmitting an optical signal from a light emitting element to a ground station. A signal phase adjustment device is provided. According to a third aspect of the present invention, in addition to the first aspect, a variable delay time is obtained by measuring individual delay times with a plurality of continuous waves having a plurality of frequencies and averaging the obtained results. And a signal phase adjustment device characterized by obtaining According to a fourth aspect of the present invention, in addition to the first aspect, the present invention provides a signal phase adjusting device, wherein the continuous wave is a square pulse wave.

[0006]

The carrier cable used in the above-described system has a capacitance C, an inductance L, and a resistance R distributed in the cable, and serves as a kind of delay circuit. Therefore, if the length of the carrier cable is very long, such as several hundred meters, the modulated wave emitted from the control device will cause a considerable delay from the speed of light when transmitting through the carrier cable. Therefore, the modulated wave reaching the branch terminal provided at the end of the carrier cable arrives later than the modulated wave reaching the branch terminal provided at the base of the U-shaped carrier cable. Therefore, there is a phase difference between the modulated waves radiated on the light from the transmitters provided at these branch terminals. If there is an area where the lights emitted from these fixed stations are illuminated in duplicate, optical signals including modulated signals with different phases will be mixed in that area and installed on the bogie. In the mobile station, there has been a problem that the reception becomes impossible.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the above-mentioned drawbacks of the prior art, and an object of the present invention is to convert a signal being transmitted from the middle of a cable including a delay element during transmission at a predetermined timing. It is an object of the present invention to provide a novel signal phase adjusting device which can be taken out at once.

[0008]

In order to achieve the object of the invention as described above, the present invention provides a method in which the same information is transmitted from a plurality of fixed stations on the light and transmitted to a moving ground station. A spatial light transmission device that receives light transmits information to be carried on light and transmits a continuous wave to the carrier cable provided at a starting end of the carrier cable, the carrier cable being provided with a pair of forward and return paths. And a phase difference between a continuous wave on the forward path received from the carrier cable and a continuous wave on the return path received at the same point as the receiving point of the forward path of the carrier cable, which is provided in the middle of the carrier cable. A phase comparator to calculate a time corresponding to the interval detected by the phase comparator and halving the time to calculate a variable delay time; and halving the interval by the arithmetic circuit. Telecommunications only for the time And a fixed station that delays an electrical signal received from the carrier cable by the variable delay circuit and optically modulates the light emitting element with the signal. The present invention provides a signal phase adjusting device that performs the following.

[0009]

When a new spatial optical transmission device is installed, the signal delay time according to the length of the carrier cable from the signal oscillation source to each fixed station is set in advance for each fixed station, and normal communication is performed. Occasionally, the phases of the optical signals emitted from the fixed stations are shifted by a set delay time, and the optical signals emitted from the fixed stations are simultaneously radiated at a predetermined timing.

[0010]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration block diagram showing the configuration of one embodiment of the present invention. In the figure, CTRL is a control device having a computer configuration. The control device CTRL
Not only accepts operation commands for each bogie input from an input device such as a keyboard not shown in the figure and issues commands to each bogie, but also ascertains the position of the bogie moving in the warehouse and the work state. The control of the operation of the bogie is also performed by grasping it, but here, the command operation to each bogie and the conveyance thereof will be described.

From the control device CTRL, a transport cable SL1 for transporting an electric signal is led out. This transport cable SL1 is stretched around the ceiling in the warehouse. The transport cable SL1 is turned back at the turning point TP, and thereafter, becomes the return transport cable SL2,
1 is wired to the vicinity of the control device CTRL. At the end point TM of the transport cable SL2, the transport cable SL2
A resistor corresponding to the characteristic impedance is connected. BTn are provided at everywhere in the transport cables SL1 and SL2. The distance from each branch terminal to the turning point TP via the transport cable SL1 is equal to the distance via the transport cable SL2. In the vicinity of each branch terminal, fixed stations SS1, SS2, SS3,... SSn are provided. The fixed station is provided with a transmitting unit T that emits light modulated by the command signal in the floor direction and a receiving unit R that receives an optical signal transmitted from the ground station MS provided on each truck BH. The portion indicated by a dotted line in a fan shape from the transmission unit T is the transmission unit T
Fig. 3 shows a light reaching area radiated in the direction of the floor. A response optical signal is sent from the ground station MS of the bogie BH to the nearest fixed station SS. This optical signal is received by the receiving unit R of the fixed station SS, converted into an electric signal inside the fixed station, and then transmitted to the control device CTRL by the receiving carrier cable RL. Each of the above fixed stations is connected to these carrier cables to receive signals from the carrier cables SL1 and SL2.

FIG. 2 shows a transmitting unit T and a receiving unit R of the fixed station SS.
FIG. 3 is a block diagram showing an internal configuration of only the first embodiment. In the figure, SL
1 and SL2 are the same transport cables as those shown in FIG. These transport cables are twisted pair cables in which two cables A and B are twisted as shown in FIG. 3, but for simplification of description, they are shown by one line in FIG. 1 and in FIG. This is indicated by two parallel lines. Figure 2 for explanation
1 is an interface circuit, in which differential type comparators 11 and 12 are provided, and continuous pulse waves (A and A ′ shown in FIG. 4) from the carrier cable SL1 and from the carrier cable SL2. 4 (B and B 'shown in FIG. 4), and when these are received correctly, the continuous pulse waves A and B
To the next stage. Reference numeral 2 denotes a phase comparator, in which a comparator 2
1, an integrator 22, and an analog voltmeter 23 are provided. The continuous pulse wave A sent through the carrier cable SL1 is input, and the traveling carrier cable SL1 is transmitted and the folded carrier cable SL2 is transmitted from the turning point TP. The continuous pulse wave B is input and the phase shift between the two is measured. Reference numeral 4 denotes a variable delay circuit that stores a time instructed by the arithmetic circuit 3 described later, and when a signal is input to the variable delay circuit 4, delays the input signal by the stored time and outputs the delayed signal. The arithmetic circuit 3 divides the time interval measured by the phase comparator 2 by a divider provided therein to reduce the time interval to １ ／, and sends the calculated time as a delay time of the delay circuit 4 to the circuit. Reference numeral 5 denotes a driver circuit which amplifies the signal output from the variable delay circuit 4.
Reference numeral 6 denotes a light-emitting element that converts an electric signal output from the driver circuit 5 into an optical signal and emits the converted signal toward the floor of the warehouse.

Reference numeral 7 denotes a light receiving element for receiving an optical signal transmitted from the ground station MS of the truck BH, and reference numeral 8 denotes an amplifier, which amplifies a signal received by the light receiving element 7 as an electric signal. Reference numeral 9 denotes a demodulator which extracts a signal (modulated wave) including information sent from the ground station from the signal amplified by the amplifier 8 and sends the signal to the interface circuit 10. In the interface circuit 10, the signal sent from the demodulator 9 is converted by a differential comparator 10a into two continuous pulse waves whose phases are shifted by 180 degrees, and these are connected to a receiving carrier cable RL (twisted pair cable). Via the control unit CTRL. ES is an enable switch. When it is turned on, an enable signal is applied to the phase comparator 2 and the arithmetic circuit 3 to start their operation, and when they are turned off, these two circuits stop their operation.

Next, the operation of the above embodiment will be described in detail.
First, in the present invention, the delay time may be set once for the variable delay circuit 4 before the spatial light transmission device is actually used. At the start of the setting operation, first, power is turned on to the entire device from a control panel (not shown) of the control device CTRL. In this state, the phase comparator 2 and the arithmetic circuit 3 of each fixed station SS are not set to the operation state. When the enable switch ES is turned on, these two circuits are also activated. Next, a continuous pulse wave as shown by A and A 'in FIG. 4 is transmitted from the control device CTRL to the carrier cable SL1 at a predetermined frequency, for example, a frequency actually used for communication. (The control device CTRL is provided with a differential line driver that transmits two pulse signals having a phase difference of 180 degrees, and a continuous pulse wave having a phase difference of 180 degrees between the two cables constituting the carrier cable. As described above, since the transport cable SL1 has a delay element, the continuous pulse wave P1 travels through the transport cable SL1 at a speed much lower than the spatial propagation speed of light. Propagate.

FIG. 5 is a block diagram for explaining the operation of the embodiment. FIG. 6 is a time chart for explaining the operation. The continuous pulse wave P1 starting from the control device CTRL is switched at time ta1 to the branch terminal BT1.
Reaches the point a1. This continuous pulse wave P1 is transmitted to the fixed station S
When it is input to the interface circuit 1 of S1 and received correctly without phase loss, the continuous pulse wave A passes through it and is input to the phase comparison circuit 2. On the other hand, branch terminal BT
The continuous pulse wave passing through the point a1 of the carrier signal SL
1 and reaches the turning point TP, and then heads in the transport cable SL2 toward the point a10 of the branch terminal BT1. Then, at time ta10, this continuous pulse wave B is input to the interface circuit 1 of the fixed station SS1, and when correctly received without phase loss, the continuous pulse wave B passes through it and the comparison section 21 of the phase comparison circuit 2 Is input to In the comparing section 21 of the phase comparing circuit 2, the integrator 2 is activated at time ta1 at the rising timing of the continuous pulse wave A.
2 to start the integration operation, and instructs the integrator 22 to end the integration operation at the rising timing of the continuous pulse wave B. During this time, the integrator 22 sets the time ta1 to the time ta1.
The voltage corresponding to the interval time τ until 0 is integrated. The integrated voltage is sent to the analog voltmeter 23, and a voltage τe corresponding to the interval time τ is output and sent to the arithmetic circuit 3.

The arithmetic circuit 3 repeatedly detects the voltage τe corresponding to the interval time τ several times and averages it,
After obtaining the time from the point a1 to the point a10, the obtained time SP1 is divided to obtain (SP1 / 2 = DEL1). The obtained delay time DEL1 is set in the variable delay circuit 4 as a delay time peculiar to the fixed station. That is,
The signal input to the variable delay circuit 4 has a delay time DEL1
It will be output from the variable delay circuit 4 later. In addition,
The continuous pulse wave that has passed through the point a10 is absorbed by the terminal resistance connected to the terminal TM and disappears.

Although only the fixed station SS1 has been described so far, such an operation is performed for each fixed station, and a delay time unique to each fixed station is calculated. The calculated delay time is calculated for each fixed station SS. The variable delay circuit 4 is set. More specifically, FIG. 7 is a block diagram for explaining the operation of the embodiment in which five fixed stations are provided. As can be seen from the figure, the fixed station SS1 obtains the time SP1, the fixed station SS2 obtains the time SP2, the fixed station SS3 obtains the time SP3, the fixed station SS4 obtains the time SP4, and the fixed station SS5. Then, the time SP5 is obtained. Then, these times SP1 to SP5 are halved and DEL1, DEL2, DEL3, DEL4, DEL
5 = 0 is set in the variable delay circuit 4 of each fixed station.

When the above setting operation is completed, the enable switch ES of each fixed station SS is turned off. As a result, the operations of the phase comparator 2 and the arithmetic circuit 3 are stopped.
Thus, the signal input from the transport cable SL2 is ignored thereafter.

Next, the general operation of the spatial light transmission device will be described. From the control device CTRL, a command signal for each carriage BH is continuously sent to the transport cable SL1. This electric signal passes through the interface circuit 1 of each fixed station and is given to the variable delay circuit 4. This signal corresponds to the delay time (DEL1, DEL) set in each fixed station SS.
L2, DEL3, DEL4, DEL5 = 0), and is given to each driver circuit 5 to drive the light emitting element 6,
An optical signal is emitted to each traveling trolley.

At a certain point in time during such an operation, the signal emitted from the control unit CTRL reaches the respective fixed stations at different timings. Are driven with a delay time fixed to the fixed station, so that the light is radiated from the fixed stations in the bogie direction at the same timing at the same time. That is, an optical signal is emitted from each fixed station SS at the same timing. Therefore, as shown in FIGS. 1 and 8, the bogie BH is fixed to the fixed stations SS2 and SS3.
Even if the lights emitted from the crawlers overlap, the received optical signals are at the same timing, so the bogie ground station MS
Then, confusion does not occur in optical reception.

In the above embodiment, the repetition frequency f of the continuous pulse wave is set to the frequency used for the actual communication. However, the length of the carrier cable is increased by design, and the length of the carrier cable from the beginning to the end is increased. When the signal delay becomes one wavelength or more, it is difficult to accurately measure the delay time. In such a case, if the frequency f ′ of the continuous pulse wave is made lower than the frequency f actually used and the wavelength is made longer, (f ′ = (1 / n) * f where n is an integer) The resolution is not limited). Further, the waveform of the continuous wave is not limited to the pulse wave, but may be a sine wave. In addition, if a plurality of continuous pulse waves having different frequencies are used and the variable delay times are measured and averaged in the continuous pulse waves of each frequency, the accuracy is improved. In this embodiment, when performing actual communication, a characteristic impedance resistor must be connected to the terminal TM.

[0022]

As described above in detail, according to the present invention, when a spatial light transmission device is newly installed, the delay time of a signal according to the length of a carrier cable from a signal oscillation source to each fixed station is adjusted. Preset for each fixed station. During normal communication, the phases of the optical signals emitted from each fixed station are shifted by the set delay time, and the optical signals emitted from each fixed station are synchronized at a predetermined timing. , And even if there is a portion where the light emitted from each fixed station overlaps, it has nothing to do with the reception by the ground station. For this reason,
This has the effect of increasing the degree of freedom in designing the arrangement of fixed stations.
Further, the present invention relates to a carrier cable for transmitting information to be carried on light and transmitting an electric signal provided as a pair of the same length in which a forward path and a return path are close to and parallel to each other with a turning point; A control device provided at the starting end of the cable and transmitting a continuous wave of an electric signal to the carrier cable; and a continuous wave provided at a reception point in the middle of the carrier cable and received from the carrier cable; And a phase comparator for detecting a phase shift with respect to the continuous wave on the return path received at the same point as the receiving point, and calculating a time corresponding to a phase shift interval detected by the phase comparator and calculating the time. A plurality of fixed stations each having an arithmetic circuit for calculating the inherent delay time of the receiving point by １ ／, and a variable delay circuit for delaying the electric signal for optically modulating the light emitted from the light emitting element by the inherent delay time; , Having Since the same optical signal is transmitted at the same timing from the light-emitting elements of a plurality of fixed stations, the present invention measures only the phase difference between the round-trip signal and the fixed station-specific signal. Delay time can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of only a transmission unit T and a reception unit R of the fixed station SS.

FIG. 3 is an explanatory view of a transport cable.

FIG. 4 is a time chart for explaining the operation;

FIG. 5 is a block diagram for explaining the operation of the embodiment;

FIG. 6 is a time chart for explaining the operation;

FIG. 7 is a block diagram for explaining the operation of an embodiment in which five fixed stations are provided.

FIG. 8 is a layout diagram showing a positional relationship between a light emitting area and a fixed station.

[Explanation of symbols]

 CTRL: Control device SL1: Transport cable SL2: Transport cable TP: Turnback point TM: Termination BT1, BT2 ... Branch terminal MS ········ ground station BH ··········· trolley SS1, SS2 ··· fixed station RL ·························································································· Ed. 3,21 T ...... Transmitting unit R ...... Receiving unit 1 Interface circuit 2 Phase comparator 3 ········ Arithmetic circuit 4 ······································································· ..Light-receiving element 8... Amplifier 9... Demodulator 10 Interface circuit 10 , 11, 12, ...... differential comparator 21 ....... comparator 22 ....... integrator 23 ....... analog voltmeter

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI H04L 7/02 (56) References JP-A-62-16635 (JP, A) JP-A-61-145995 (JP, A) JP-A-3-222544 (JP, A) JP-A-3-135244 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 10/00-10/28 H04J 14/00- 14/08 H04L 12/28 H04L 7/02

Claims (4)

(57) [Claims] 1. A spatial light transmission device for receiving the same information from a plurality of fixed stations on a light and transmitting the light at a moving ground station, transmitting the information on the light and determining a turning point. A carrier cable for transmitting an electric signal which is provided as a pair of the same length in which the forward path and the return path are close to and parallel to each other, and a continuous wave of the electric signal is provided to the carrier cable provided at the starting end of the carrier cable. A control device that is provided at a reception point in the middle of the carrier cable, and has a phase difference between the continuous wave of the forward path received from the carrier cable and the continuous wave of the return path received at the same point as the reception point of the forward path. A phase comparator for detecting a shift, a calculating circuit for calculating a time corresponding to a shift interval of the phase detected by the phase comparator, and calculating the inherent delay time of the reception point by halving the time; Light-emitting device A plurality of fixed stations having a variable delay circuit for delaying an electric signal to be caused by the inherent delay time, and the same optical signal is transmitted at the same timing from the light emitting elements of the plurality of fixed stations. A signal phase adjustment device characterized by the above-mentioned. 2. The signal according to claim 1, wherein each fixed station has switching means for switching a timing for setting a specific delay time of each fixed station and a timing for transmitting an optical signal from a light emitting element to a ground station. Phase adjustment device. 3. The signal phase adjusting device according to claim 1, wherein individual delay times are measured with a plurality of continuous waves having a plurality of frequencies, and the obtained results are averaged to obtain a variable delay time. . 4. The signal phase adjusting device according to claim 1, wherein said continuous wave is a square pulse wave.