JPH11205231A - Phase adjusting device for space optical transmitter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a variable delay circuit by using general elements and to reduce manufacturing costs by constituting variable delay circuit of plural delay circuits which serially connect elements that have a delay component which delays a signal and plural switch circuits which are switched so as to change the number of plural delay circuits that are serially connected. SOLUTION: A variable delay circuit 14 serially connects elements which have a delay component that delays a signal to a signal line from an outward cable 3. A circuit is configured by connecting six delay circuits D1 to D6 and six switch circuits S1 to S6 which are switched so that the number of serial connections of the circuits D1 to D6 may be changed. When only the circuit S1 is turned on and only the circuit D1 is connected, the delay time of the delay circuits is 5ns and switch operations can set the delay time up to 315ns with 5ns intervals. It is possible to optionally set a delay time of the elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase adjusting device for a transmission signal in a spatial light transmission device which is applied to data transmission of a picking device or the like and emits light to space to transmit data.

[0002]

2. Description of the Related Art For example, as a picking device for articles in a large warehouse, a cart for transporting articles is arranged so as to be able to travel freely in the warehouse, and a fixed station for communication is installed on a ceiling of the warehouse or the like, and the cart is mounted on the cart. 2. Description of the Related Art There is known an apparatus in which a mobile station is attached, a fixed station and a mobile station are connected by spatial light transmission, and picking information of an article is communicated between a cart and a control device by light radiated into a space (for example, Japanese Patent Application Laid-Open No. HEI 9-103572). 7-7474).

When this type of spatial light transmission device is used in a large warehouse, it is necessary to emit light to the entire warehouse.
For this reason, a plurality of fixed stations connected as slaves to the control device serving as a master are dispersedly mounted on a ceiling or the like so as to radiate light to the entire warehouse, and more than a dozen fixed stations are installed. A carrier cable is laid between each fixed station.

[0004] A data signal (for example, a modulated wave) is transmitted from the control device to each fixed station through a carrier cable, and the light emitting elements of each fixed station are operated at the same time, and the data is placed on the light radiated into the space, and the data is transmitted to the mobile station. To the side. However, when the phases of the data signals on the light radiated from each fixed station are different, the mobile station receiving the light from the plurality of fixed stations has to demodulate the data signals with different phases. And accurate data demodulation cannot be performed.

[0005] The transport cable connecting the control device and each fixed station usually has components of capacitance C, inductance L, and resistance R distributed on the cable, forms a kind of delay circuit, and is used for a large warehouse. In the case of a space optical transmission device, the length of the transport cable reaches hundreds of meters,
A non-negligible delay time occurs between the distal end and the distal end.

For this reason, when each fixed station inputs a signal transmitted on a carrier cable having a different length, the light is emitted, and when the mobile station receives light from a plurality of fixed stations simultaneously, the signal is output. Demodulation, a phase difference occurs between signals from different fixed stations, which adversely affects data demodulation.

Therefore, as shown in FIG. 1, a return point is provided at the end of the transport cable connected to the output side of the control device to form a forward cable and a return cable, and a branch terminal is formed on the forward cable and the return cable. Connections are made at intervals and a plurality of fixed stations are connected via each branch terminal.

Each fixed station detects the phase difference (time difference) between the timing pulse input from the forward cable and the timing pulse input from the return cable, calculates 1/2 of the phase difference, and delays the delay. Time, the delay time is set in a variable delay circuit connected to the driver circuit for light emission, the light emission timing when transmitting data is calculated, and the delay is delayed by the delay time. The data signal without phase difference is simultaneously transmitted from each fixed station to the mobile station side by adjusting the timing with the light emission.

[0009]

However, a variable delay circuit used in such a fixed station requires a circuit capable of arbitrarily switching a delay time of several nanoseconds to several hundred nanoseconds. And a CMOS-IC delay line specially manufactured. This CMOS delay line variable delay circuit sets a delay time by switching an external resistor by an analog selector. However, since the variable delay circuit is a dedicated element, the price is high. However, there is a problem that the manufacturing cost increases.

[0010] The present invention has been made in view of the above points, and a variable delay circuit can be manufactured using a general-purpose element, and the phase adjustment of a spatial light transmission device capable of reducing manufacturing costs. It is intended to provide a device.

[0011]

In order to achieve the above object, a phase adjusting apparatus for a spatial light transmission apparatus according to the present invention radiates light from a plurality of fixed stations to a space to a mobile station to simultaneously transmit signals. A spatial optical transmission device for transmitting, in which a carrier cable composed of a forward cable and a return cable is laid to transmit an electric signal from a control device to each fixed station, and each fixed station transmits a pulse signal to the carrier cable. A phase comparator for detecting a time interval between a signal obtained from the forward cable and a signal obtained from the return cable when transmitting, an arithmetic circuit for halving the time interval detected by the phase comparator, and an arithmetic circuit. A variable delay circuit for delaying the pulse signal by the calculated time; and a phase adjusting device of the spatial light transmission device for transmitting the signal delayed by the variable delay circuit from each fixed station by light. The delay circuit includes a plurality of delay circuits in which elements having delay components for delaying signals are connected in series, and a plurality of switch circuits that switch so as to change the number of the plurality of delay circuits connected in series. Features.

[0012]

In the phase adjusting device of the spatial light transmission device having such a configuration, prior to actual use of the transmission device,
A pulse signal is sent from the control device to each fixed station through a carrier cable, a phase comparator and an arithmetic circuit are operated, and a delay time is set in a variable delay circuit according to the distance to each fixed station. At this time, the phase comparator detects the time interval between the signal obtained from the forward cable and the signal obtained from the return cable, and the arithmetic circuit halves the time interval detected by the phase comparator, and divides the time. The delay time is set in the variable delay circuit.

The variable delay circuit includes a plurality of delay circuits formed by serially connecting elements having a delay component for delaying a signal; a plurality of switch circuits configured to switch the number of the plurality of delay circuits connected in series; And a general-purpose and inexpensive element can be used.
-The manufacturing cost of the variable delay circuit can be reduced as compared with that using an IC delay line.

Further, if a plurality of delay circuits are set with delay times that increase in order at predetermined intervals, the delay time can be set in a wider range by a combination thereof.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of a spatial light transmission device in which the present invention is applied to a picking device. This spatial light transmission device is provided between a plurality of fixed stations K1, K2,... Kn arranged at intervals on a ceiling or the like in a warehouse and a mobile station P installed on a bogie traveling in the warehouse. This is a transmission device that carries out two-way communication by putting a signal on light (for example, near-infrared light) emitted to space.

The control device 1 inputs and modulates a data signal such as picking information sent from a terminal device or the like (not shown), outputs the transmission signal to a transmission cable 2 for transmission, and transmits the transmission signal from the mobile station side. Then, the received signals received by the fixed stations K1 to Kn are input through the receiving carrier cable 5.

The transmission carrier cable 2 connected to the control device 1 is composed of a forward cable 3 and a return cable 4 that return at a return point 2a, and a resistor corresponding to a characteristic impedance is connected to the end of the return cable 4. Is done. Branch terminals B1 to Bn are connected to the forward cable 3 and the return cable 4, respectively, and fixed stations K1, K2,... Kn are connected near the branch terminals B1 to Bn. In addition, the distance between the forward cable 3 and the return cable 4 from each of the branch terminals B1 to Bn to the turning point is equal.

Each of the fixed stations K1 to Kn is provided with a fixed station circuit 10 as shown in FIG. The fixed station circuit 10 includes a transmitting unit that transmits a signal transmitted through the carrier cable 2 on light, and a receiving unit that receives light transmitted from the mobile station P and demodulates a received light signal to obtain a transmission signal. Become.

The transmission unit is connected to the outbound cable 3 and the inbound cable 4 for transmission, the interface circuit 11, and transmits a signal (modulated transmission signal) from the outbound cable 3 input through the interface circuit 11 only for a preset time. Variable delay circuit 14 for delaying and variable delay circuit 1
And a driver circuit 15 for inputting the modulated transmission signal through 4 and driving the light emitting element 8. Further, at the time of initial setting, the transmitting unit detects the time interval between the signal from the forward cable 3 and the signal from the return cable 4, and reduces the time interval detected by the phase comparator 12 by 1 /. And an arithmetic circuit (CPU) 13 is provided.
Sets the calculated delay time in the variable delay circuit 14.

The receiving section includes a light receiving element 9 for receiving light emitted from the mobile station P, an amplifier 18 for amplifying a light receiving signal from the light receiving element 9, and a demodulator 1 for demodulating the amplified light receiving signal.
7 and an interface circuit 16 for sending out the demodulated data signal to the receiving carrier cable 5.

FIG. 3 shows a phase comparator 12, an arithmetic circuit 13,
2 shows a detailed configuration diagram of the variable delay circuit 14. The phase comparator 12 includes a comparing unit 20 including a JK flip-flop, an integrator 21 that integrates an output of the comparing unit 20, and an analog signal that converts the signal voltage of the integrator 21 into a digital signal and sends it to the arithmetic circuit 13. It comprises a voltmeter 22. The comparison unit 20 causes the integrator 21 to start the integration operation at the timing of the rising edge of the pulse signal input from the outward cable 3 and end the integration operation at the timing of the rising edge of the pulse signal input from the return cable 4. It works to make it work. As a result, the integrator 21 integrates the voltage corresponding to the time interval between the signal of the forward cable 3 and the signal of the return cable 4, and converts the voltage corresponding to the interval to a digital value by the analog voltmeter 22. Arithmetic circuit 1
Sent to 3.

The arithmetic circuit 13 takes in the phase difference of the signal detected by the phase comparator 12, that is, the time difference between the signal of the forward cable 3 and the signal of the backward cable 4, and calculates the time difference by 、. The time is set in the variable delay circuit 14 as a delay time.

The variable delay circuit 14, as shown in FIG.
For example, six delay circuits D1 formed by serially connecting an element (here, a coil and an inverter) having a delay component for delaying a signal to a signal line from the outward cable 3
To D6 and six switch circuits S1 to S5 for changing the number of series connection of the delay circuits D1 to D6.
And S6. Switch circuits S1 to S
Reference numeral 6 denotes an analog switch whose control terminal is connected to an arithmetic circuit (CPU) 13, which is set to an on or off state at the time of setting.

The delay circuits D1 to D6 have, for example, a delay time of 5 ns, a delay time of the delay circuit D2 of 10 ns, a delay time of the delay circuit D3, and a delay time of 5 ns to 315 ns, for example. The time is 20 ns and the delay time of the delay circuit D4 is 40
ns, the delay time of the delay circuit D5 is 80 ns, and the delay time of the delay circuit D6 is 160 ns.

Thus, when only the switch circuit S1 is turned on and only the delay circuit D1 is connected, the delay time of the delay circuit is 5 ns. When only the switch circuit S2 is turned on and only the delay circuit D2 is connected, the delay time is reduced. The delay time of the circuit is 10 ns. When only the switch circuits S1 and S2 are turned on and only the delay circuits D1 and D2 are connected, the delay time of the delay circuit is 5 ns so that the delay time is 15 ns.
The delay time can be set up to 315 ns at intervals of s.

The delay time of the element can be arbitrarily set according to the number of turns of the coil and the number of inverters. In addition, an element having a delay function such as a resistor can be used. Such a delay circuit including an inverter, a coil, a resistor, and the like, and a switch circuit including an analog switch can be manufactured relatively inexpensively using general-purpose elements.

The output side of the variable delay circuit 14 is connected to a driver circuit 15. The driver circuit 15 inputs the modulated transmission signal sent from the outward cable 3 through the variable delay circuit 14, amplifies the signal, and drives the light emitting element 8 by the signal. The light projecting element 8 is composed of a plurality of light emitting diodes or the like, and emits light (near-infrared light) bearing a signal toward the mobile station P.

Next, the operation of the spatial light transmission apparatus having the above configuration will be described. Prior to the actual use of the transmission equipment, each fixed station K
In 1 to Kn, the delay time of the variable delay circuit 14 of the fixed station circuit 10 is set. In this case, the phase comparator 12 is set to the operating state, and the controller 1 sends a continuous pulse signal to the carrier cable 2. The pulse signal is transmitted from the outbound cable 3 to the inbound cable 4. At this time, each fixed station K
1 to Kn through the interface circuit 11 to the phase comparator 12 of the fixed station circuit
And a pulse signal from the return cable 4 are input.

At this time, the comparing section 20 of the phase comparator 12
Causes the integrator 21 to start the integration operation at the rising timing of the pulse signal input from the outward cable 3 and to end the integration operation at the rising timing of the pulse signal input from the return cable 4. Operate. As a result, the integrator 21 integrates the voltage corresponding to the time interval between the signal of the forward cable 3 and the signal of the return cable 4, and converts the voltage corresponding to the interval to a digital value by the analog voltmeter 22. It is sent to the arithmetic circuit 13.

The arithmetic circuit (CPU) 13 calculates a half of the time interval between the forward path and the return path detected as described above to obtain a delay time, and sets this time in the variable delay circuit 14. For example, when the calculated delay time is 100 ns, the delay time of the delay circuit D3 is 20 ns,
Since the delay time of No. 5 is 80 ns, the arithmetic circuit 13 is set so that only the delay circuits D3 and D5 are turned on. Thus, the delay circuits D3 and D5 are connected in series to the signal lines in the variable delay circuit.

Similarly, the delay time of variable delay circuit 14 in all fixed stations K1 to Kn is set.
Since the distance from the branch terminals B1 to Bn to which each fixed station is connected to the return point 2a, that is, the distance from the return cable 2 to the forward cable 3 and the return cable 4 is equal, the distance is input from the forward cable 3 and the return cable 4. One half of the signal time interval corresponds to the time from the branch terminal of the fixed station to the turning point 2a. Accordingly, if the time calculated for each fixed station is set as the delay time, all the fixed stations can simultaneously emit optical signals at the position of the turning point 2a, that is, from all the fixed stations K1 to Kn.

After the above setting is completed, the operation of the phase comparator 12 is stopped, and in actual use, the modulated transmission signal sent from the outward cable 3 passes from the interface circuit 11 through the variable delay circuit 14. The driver circuit 15 drives the light emitting element 8 to emit light carrying a signal toward the mobile station P. Each fixed station K1 to Kn through the transport cable 2 from the control device 1
The arrival timing of the signals sent to the
In each of the fixed stations K1 to Kn, the driver circuit 15 drives the light emitting element 8 with the delay time set in the variable delay circuit 14 and emits light. The mobile station P can receive an optical signal having a good phase variation.

As described above, since the variable delay circuit 14 can be configured using elements having delay components such as inverters and coils and relatively inexpensive general-purpose elements such as analog switches, a CMOS-IC delay line is used. The manufacturing cost of the variable delay circuit can be reduced as compared with that of the variable delay circuit.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a spatial light transmission device according to an embodiment of the present invention.

FIG. 2 is a configuration block diagram of a fixed station circuit 10.

FIG. 3 is a configuration block diagram of a phase comparator 12 and a variable delay circuit 14.

[Explanation of symbols]

 1-Control device 2-Transport cable 3-Outbound cable 4-Return cable 12-Phase comparator 13-Operation circuit 14-Variable delay circuit K1-Kn-Fixed station D1-D6-Delay circuit S1-S6-Switch circuit

Claims (2)

[Claims] 1. A spatial optical transmission device for transmitting signals simultaneously by radiating light to a mobile station from a plurality of fixed stations and transmitting the signals from the control device to each of the fixed stations. A carrier cable consisting of a cable and a return cable is laid, and when each fixed station transmits a pulse signal to the carrier cable, a time interval between a signal obtained from the forward cable and a signal obtained from the return cable is determined. A phase comparator for detecting, a calculation circuit for halving the time interval detected by the phase comparator, and a variable delay circuit for delaying the pulse signal by the time calculated by the calculation circuit; In a phase adjustment device of a spatial light transmission device that transmits a signal delayed by a variable delay circuit from each fixed station by light, the variable delay circuit connects elements having a delay component that delays a signal in series. A phase adjusting device for a spatial light transmission device, comprising: a plurality of delay circuits; and a plurality of switch circuits for switching the number of series-connected delay circuits so as to change the number. 2. The phase adjusting device for a spatial light transmission device according to claim 1, wherein a delay time that increases sequentially at predetermined intervals is set in each of the plurality of delay circuits.