JPH0541652A - Multibeam sensor system - Google Patents

Abstract

PURPOSE:To eliminate the influence of mutual interference of infrared rays in the multibeam sensor system. CONSTITUTION:A projector driving circuit 2 generates a driving signal SD composed of a start pulse SP and (n) data pulse DPs repeatedly. The start pulse SP and a data pulse DP1 are projected from a projector T1, and start pulses DP2 to DPn are projected from projectors T2 to Tn. When detecting the start pulse P, a start pulse detection circuit 1 successively changes a switch circuit 14 based on the sequence of the driving signal SD, and supplies the only light receiving signal from a light receiver R1 to a data pulse detection circuit 15 when the data pulse DP1 is projected. The output of the data pulse detection circuit 15 is entered in a control circuit 13 to be used for detecting the presence or absence of an ivader.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-beam sensor system in which a plurality of pairs of projectors and receivers are arranged so as to face each other.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, there is known a multi-beam sensor system in which a plurality of pairs of light emitters and light receivers are arranged so as to face each other. In FIG. 3, four projectors T ₁ , T ₂ , T ₃ and T ₄ are attached to the projector mounting column 23, and four projectors T ₁ , T ₂ , T ₃ and T ₄ are mounted on the receiver mounting column 24 facing each other. number of projector _{T 1, T 2, T 3} , T 4 and four photodetectors, each paired _{R 1, R 2, R 3} , R 4 are attached. According to this configuration, since the infrared beam can be projected from a low position to a high position, the warning range can be widened.

[0003]

By the way, in the conventional multi-beam sensor system, each projector projects an infrared beam asynchronously with each other, and the infrared beam projected from this projector is generally large on the receiver side. Have a spread. Since each light receiver is provided with a signal system for processing a light reception signal, in the configuration shown in FIG. 3, for example, the infrared beam projected from the projector T ₁ is not only received by the light receiver R _1. , At the same time receiver R ₂ ,
There is a problem in that the light is also received by R ₃ and R ₄ , causing mutual interference of infrared rays.

Such mutual interference of infrared rays may also be caused by an infrared beam from a projector mounted on a projector mounting column other than the projector column to which the opposing projector is mounted. That is, as shown in FIG. 4, for example, a projector group T _G1 including a plurality of projectors attached to one projector mounting column, and the projector group T _G1.
A projector group T _G2 comprising a plurality of projectors one multi-beam sensor system by the light receiver unit R _G1 which is disposed to face is configured and attached to the other projector mounting braces in _G1, the projector group T _If another multi-beam sensor system is configured by the photoreceiver group R _G2 arranged facing _G2 , the photoreceivers that make up the photoreceiver group R _G1 are Emitter group T _G2
There is a case where an infrared beam from the light projector constituting the above is received, and in such a case, no alarm is output even when the infrared beam from the light projector group T _G1 is blocked.

As described above, in the conventional multi-beam sensor system, the light receiver sometimes receives an infrared beam from a projector other than the facing projector, and the multi-beam sensor system is effectively made by such mutual interference of infrared rays. There was a problem that it might not work.

Further, in the conventional multi-beam sensor system, as described above, each projector is provided with a drive circuit for projecting an infrared beam, and each photoreceiver is provided with a signal processing circuit for processing a received light signal. There is also a problem that the cost becomes high because it has to be prepared.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a multi-beam sensor system capable of eliminating the influence of mutual interference of infrared rays.

[0008]

To achieve the above object, a multi-beam sensor system of the present invention is a multi-beam sensor system in which a plurality of pairs of light emitters and light receivers are arranged facing each other. In the following, the data pulse is sequentially projected in a predetermined order subsequent to the start pulse, and after the start pulse is detected on the side of the light receiver, the data pulse is projected in accordance with the predetermined projection order. The light receiving signal of only the light receiving device facing the light projecting device is obtained.

[0009]

The multi-beam sensor system of the present invention comprises a plurality of light projectors and a plurality of light receivers arranged facing the light projectors. From the light emitter side, first, a start pulse is emitted, and subsequently, a data pulse is emitted. The data pulse is sequentially projected from each projector in a predetermined order. On the light receiver side, first, a start pulse is detected, and on the basis of the detected start pulse, a light receiver for receiving a light reception signal of a data pulse is sequentially selected.

[0010]

Embodiments will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of an embodiment of a multi-beam sensor system according to the present invention. In the figure, 1 is a light projecting unit, 2 is a light emitter driving circuit, 3 is a switch circuit, 10 is a light receiving unit, and 11 is a light emitting unit.
Is an OR circuit, 12 is a start pulse detection circuit, 13 is a control circuit, 14 is a switch circuit, and 15 is a data pulse detection circuit.

As shown in FIG. 1, the multi-beam sensor system according to the present invention comprises a light projecting section 1 and a light receiving section 10. First, the light projecting unit 1 will be described. The light projecting unit 1 includes n projectors T ₁ , T ₂ , T ₃ , ..., T _n, and a projector driving circuit 2
And a switch circuit 3. Floodlights T ₁ , T ₂ , T
₃ , ..., T _n are each composed of a light emitting element that emits infrared light and a projection optical system. The projector drive circuit 2 repeatedly generates the drive signal SD having the sequence shown in FIG. 2 and switches the switch circuit 3.

The drive signal SD includes a start pulse SP and n data pulses DP ₁ , DP ₂ , DP ₃ , ..., DP _n (hereinafter, the data pulses will be simply referred to as DP when collectively referred to). ). The start pulse SP and the data pulse DP are generated by modulating a carrier wave having a predetermined frequency, and the carrier wave frequencies of the start pulse SP and the data pulse DP are selected to have different values. In FIG. 2, both the start pulse SP and the data pulse DP are generated by pulse-amplitude modulating the carrier wave. The carrier frequency of the start pulse SP is f ₁ and the carrier frequency of the data pulse DP is f ₂ (≠ f ₁ ). Has been done. In FIG. 2, the period of the start pulse SP indicated by t ₀ , the first data pulse DP after the start pulse SP indicated by t ₁ is finished.
Data pulse D indicated by t ₂ until ₁ is generated
Period P, and the data pulses shown in _{t 3 DP i (i = 1,2} ,
The period from the end of (..., n-1) to the generation of the next data pulse DP _{i + 1} can be arbitrarily set as necessary, but the multi-beam sensor system is used for intruder detection. In the case of use, since the time for which the human being shields the infrared beam is about 50 msec at the shortest, it is preferable to set it to 20 to 30 msec from the start of the start pulse SP to the end of the last data pulse DP _n . By doing so, the sequence of the drive signal SD shown in FIG. 2 can be repeated about twice while the intruder is blocking the infrared beam, so that the intruder can be detected well. ..

When the projector drive circuit 2 generates the start pulse SP, it supplies the start pulse SP to a preset projector, for example, the projector T ₁ via the switch circuit 3, and then generates the data pulses DP ₁ and DP _2. , DP ₃ , ..., DP
_{As for n} , T ₁ , T ₂ ,
T _3, ..., sequentially supplies to T _n. As a result, the start pulse SP and the data pulse DP ₁ are projected from the projector T ₁ , and the data pulse DP ₂ is projected from the projector T ₂ .
The data pulse DP _n is projected from the projector T _n . When the last data pulse DP _n is supplied to the projector T _n , the projector drive circuit 2 repeats the operation of generating the drive signal SD shown in FIG. 2 again and supplying the drive signal SD to each projector after a lapse of a predetermined time.

Next, the light receiving section 10 will be described. The light receiving unit 10 includes n light receivers R ₁ , R ₂ , R ₃ , ..., R _n arranged to face the n light projectors T ₁ , T ₂ , T ₃ , ..., T _n. There is. It goes without saying that each light receiver is composed of a light receiving element for receiving infrared rays and a light receiving optical system. Light reception signals output from these light receivers are supplied to the OR circuit 11 and the switch circuit 14. The switch circuit 14 selects only the light-reception signal output from the light-receiver facing the light-emitter that is currently emitting light from the light-reception signals output from all the light-receivers, and supplies it to the data pulse detection circuit 15. Therefore, when the data pulse DP _i is being projected from the projector T _i, only the light reception signal of the light receiver R _i is supplied to the data pulse detection circuit 15 via the switch circuit 14. The switching of the switch circuit 14 is performed by the control circuit 1 including a microcomputer or a logic circuit.
In order to perform the above switching, the control circuit 13 needs to detect that the data pulse DP _i is currently being projected from the projector T _i in the projector unit 1. The start pulse SP is used for this purpose. That is, the start pulse SP is used as a synchronization signal for switching the switch circuit 14.

The start pulse SP is detected as follows. The light reception signals from all the light receivers are OR circuits 11
Is input to the start pulse detection circuit 12 via. The start pulse detection circuit 12 is composed of a filter for extracting the carrier frequency component used in the start pulse SP, a detection circuit for detecting the output of the filter, a pulse generation circuit for generating a pulse at the rising edge of the detection output, and the like. It Therefore, when the start pulse SP is emitted from the light projecting unit 1, the start pulse SP is detected by the start pulse detecting circuit 12 of the light receiving unit 10, and the pulse is output. The control circuit 13 uses the drive signal SD shown in FIG.
If the rising edge of the pulse output from the start pulse detection circuit 12 is detected,
This is recognized as the start of the drive signal SD, and (t
_The switch circuit 14 is switched so that the light reception signal from the light receiver R ₁ is supplied to the data pulse detection circuit 15 when the time ₀ + t ₁ ) has elapsed.

The reason for taking the logical sum of the light receiving signals from all the light receivers in detecting the start pulse SP is as follows. That is, the start pulse SP is generated based on only the light reception signal from a specific light receiver, for example, the light receiver R _1.
Needless to say, the start pulse SP cannot be detected when the photodetector R ₁ fails, and as a result, the switch circuit 14 is switched in synchronization with the sequence of the drive signal DS. Since it becomes impossible to perform the above, it is possible to detect the start pulse SP if there is at least one normal photodetector by taking the logical sum of the photodetection signals from all photodetectors as described above. Of.

As described above, when the data pulse DP ₁ is being projected from the projector T _1, only the light receiving signal from the light receiver R ₁ is supplied to the data pulse detecting circuit 15. When the period of the data pulse DP ₁ ends, the control circuit 13 switches the switch circuit 14 so that no signal is supplied to the data pulse detection circuit 15. As a result, it is possible to prevent the noise signal from being mixed in during the period between the data pulses.

Then, the control circuit 13 causes the data pulse DP
_When t ₃ hours have passed since the end of ₁ , the receiver R
_The switch circuit 14 is switched so that only the light reception signal from ₂ is supplied to the data pulse detection circuit 15. By repeating the above operation, when the data pulse DP _i is projected from the projector T _i , the projector T
Only the light reception signal output from the light receiver R _i facing _i is supplied to the data pulse detection circuit 15.

The data pulse detection circuit 15 includes a filter for extracting the carrier frequency component used for the data pulse DP, a detection circuit for detecting the output of the filter, and a pulse having a predetermined time width at the rising edge of the detection output. It is composed of a pulse generation circuit and the like. Then, the output of the data pulse detection circuit 15 is input to the control circuit 13 and used for determining the presence or absence of an intruder.

As described above, the control circuit 15 performs the switching control of the switch circuit 14 and the process of detecting an intruder based on the output from the data pulse detection circuit 15. The presence or absence of an intruder is determined by performing signal processing. As described above, the control circuit 13 recognizes the sequence of the drive signal SD shown in FIG. 2, and therefore, by detecting the level of the signal output from the data pulse detection circuit 15 during each data pulse DP, It is possible to judge whether the infrared beam projected from the projector is blocked, and if the position and / or the number of the blocked infrared beam satisfy the preset alarm condition, reception not shown The alarm signal KS is output to the container. This alerting condition can be set arbitrarily, for example, an alarm signal KS can be output when even one infrared beam is blocked, and an alarm is issued only when all infrared beams are blocked at the same time. It is also possible to output the signal KS.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications can be made. For example, when the multi-beam sensor system of the present invention is applied to the case as shown in FIG. 4, the light emitter group T _G1 and the light projector group T _G2 have different carrier frequencies of the start pulse SP and the data pulse DP. Mutual interference can be prevented. Further, in the above embodiment, the pulse amplitude modulation is performed as the modulation, but it is clear that appropriate modulation such as frequency modulation can be performed.

[0022]

As is apparent from the above description, according to the present invention, since the data pulse is projected from the projector in a time-division manner and the predetermined modulation is performed, the mutual occurrence of the light which has been conventionally generated. Interference can be eliminated, and as a result, many light emitters and light receivers can be arranged. Further, as a signal system for projecting light in the light projecting section and a signal system for receiving light in the light receiving section, it is sufficient to dispose only one signal system shared by all the projectors and the light receivers, so that it is inexpensive. Can be configured.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a multi-beam sensor system according to the present invention.

FIG. 2 is a diagram showing an example of a drive signal.

FIG. 3 is a diagram showing a schematic configuration example of a conventional multi-beam sensor system.

FIG. 4 is a diagram for explaining a problem of a conventional multi-beam sensor system.

[Explanation of symbols]

1 ... Projector, 2 ... Projector drive circuit, 3 ... Switch circuit,
10 ... Light receiving part, 11 ... OR circuit, 12 ... Start pulse detection circuit, 13 ... Control circuit, 14 ... Switch circuit, 15
... Data pulse detection circuit.

Claims (3)

[Claims] 1. In a multi-beam sensor system in which a plurality of pairs of light emitters and light receivers are arranged so as to face each other, on the light emitter side, following a start pulse, data pulses are sequentially emitted in a predetermined order and received. The multi-beam sensor system is characterized in that after detecting the start pulse, the light receiving signal of only the light receiving device facing the light projecting device for projecting the data pulse corresponding to the predetermined light projecting order is obtained on the device side. .. 2. The multi-carrier according to claim 1, wherein both the start pulse and the data pulse are generated by subjecting a predetermined carrier frequency to a predetermined modulation, and the carrier frequencies are different from each other. Beam sensor system. 3. The multi-beam sensor system according to claim 1, wherein the start pulse is detected on the side of the light receiver based on the light reception signals of all the light receivers.