JPH0258168B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus and method for detecting whether a specific event occurs within a predetermined time frame in a certain process, and more particularly, to The present invention relates to an apparatus and method for detecting warp tears.

On large non-metallic endless conveyor belts used to transport bulk materials, there is a possibility that the belt may tear due to sharp objects falling onto the belt in the loading section. . It is desirable to detect such tears immediately and stop the conveyor belt, thereby minimizing damage to the belt. One such warp tear detection device is disclosed in US Pat. No. 3,792,459. In such a warp tear detection device,
Multiple antennas, which may be a single electrical conductor,
They are embedded in the belt at intervals perpendicular to the length of the belt. One electrical signal is coupled to each built-in antenna as it passes through the tear detection station, and the antenna is capacitively coupled to a transmitter and a receiver, respectively, located near opposite edges of the belt. to combine. However, a severed antenna, for example in the area where the belt is split, will not couple the signal through the receiver to the transmitter and therefore will not send a signal to the detection circuit. At that time, the detection device determines that a warp tear has occurred based on the absence of a signal. The detection circuit in such patents detects a predetermined amount of time corresponding to the time it takes for a predetermined number of disconnected antennas to pass through a tear detection station without coupling the transmitter signal to the receiver. After the expiration, it is activated to output a signal to energize the warning device and/or de-energize the drive of the conveyor belt.

A drawback associated with the system of the '459 patent is the lack of accurate tear detection during belt acceleration and deceleration. If an attempt is made to increase the accuracy of the detection function when the belt is operating at low speed, the detection function during full speed operation will be degraded. Such conventional techniques due to long waiting times to check whether the next antenna is detected after one antenna is not acquired and/or to accommodate the longest spacing between adjacent antennas. The undesirable inaccuracy of tear detection devices means that relatively long and expensive to repair tears may occur before the conveyor belt is stopped. . Moreover, since conveyor belts are known to stretch during use by, for example, 20%, the above-mentioned waiting times will be even longer if the belt is stretched, thus reducing the accuracy of detection as well as the immediacy of stopping. It decreases more and more.

The antenna in the belt becomes worn and, in some cases, no longer produces a reliable signal. For example, an antenna may have a cut in the middle, but sometimes the cut ends touch each other, coupling a weak signal between the transmitter and the receiver.
Also, in some cases the ends do not touch each other. Such antennas are unreliable and cause unnecessary and laborious belt stoppages.

Some of the drawbacks associated with conventional warp tear detection systems are described in commonly owned U.S. Patent No.
This problem was overcome by the apparatus and method disclosed in No. 4,228,513. In such a warp rip detection system, the position of each antenna in the belt is electronically stored as a function of the position of the belt as sensed by, for example, a tachometer.
If the expected antenna is not sensed at the detection station (which contains the transmitter and receiver), such non-detection is sensed and used to stop the conveyor belt. Each time a valid antenna passes the detection station, information regarding the actual position of that antenna is updated, thereby compensating for belt stretch. In addition, information regarding the location of cut or worn antennas in normal belt sections (no warp tears) is allowed to be erased from memory.

In particular, a signal detection circuit for warp tear detection is disclosed in U.S. Patent Application No. 871,664 (U.S. Pat.
No.). Such a circuit avoids falsely responding to noise signals as an indication that the antenna is present. Such a circuit also performs waveform modification of the signal properly received from the antenna to optimize the response of the detection circuit thereto.

The above is the background of the present invention, and a summary of the present invention will be described below. One installation area for warp tear detection equipment where warp tears most frequently occur is the cargo area. A loading area is the location in a conveyor system where ore or other conveyed material is loaded onto the conveyor for conveyance downstream. In the present invention, tear detection protection is provided for a single area, such as the loading area of a conveyor belt, and the protection includes:
It is made in a general or real time frame independent manner while retaining sensing accuracy for conveyor belt speed changes. In other words, the time frame during which the present invention operates is variable as determined by the actual belt speed. As a result, inaccuracies associated with conventional time-dependent warp tear detection systems are eliminated.

Simply stated, three detection stations and one electronic logic and control device are employed in accordance with the present invention. The three detection stations detect respective antennas in the conveyor belt. The first two detection stations are
A third detection station is located upstream of the loading area for the conveyor belt, and a third detection station is located downstream of the loading area. The relative spacing of each detection station is predetermined or predetermined. Upon sensing that the antenna has passed the first and second detection stations, the logic device can predict when the antenna will reach the third detection station. If no such arrival is detected, it is determined that a warp tear has occurred in the load.

According to the present invention, a method for detecting a tear in a conveyor belt including means for indicating the health of the conveyor belt and means for activating the conveyor belt means allows the events indicative of the health of the conveyor belt to be mutually recognized. A time interval between detection times of events detected by the first detecting means and the second detecting means in the first, second and third detecting means respectively arranged at a predetermined distance. and setting a time frame having a range within which the event is expected to be detected in the third detection means based on the time interval; A mutually predetermined method for detecting a tear in a conveyor belt comprising the step of sensing an apparent lack of health of the conveyor when the event is not detected, and a means for indicating the health of the conveyor belt. first, second, and third detection means arranged at a distance from each other, and detecting the time interval between respective detection times of events detected by the first detection means and the second detection means. means for setting a time frame having a range within which the event is expected to be detected by the third detection means based on the time interval; and means for sensing an apparent defect in the conveyor when said event is not detected, wherein:
The detection information from each detection means may include, for example, an electronic input to the control device, within which the above detection time interval is calculated;
A highly accurate conveyor belt tear detection device is provided by setting a time frame, determining whether or not an event is detected by the third detection means, and further instructing the device to take subsequent appropriate measures based on this. Ru.

Furthermore, according to another aspect of the present invention, in the process of a specific event occurring subsequently, a first detection means for detecting the event; and the event detected by the first detection means. A second detection means is arranged at a predetermined distance from the first detection means to detect the event at a certain time interval, and the event detected by the second detection means is detected at a time interval. a third detecting means arranged at a predetermined distance from the second detecting means, and each of the events detected by the first detecting means and the second detecting means; means for sensing a detection time interval and sensing the movement speed of the process based on the time interval and the relative distance between the first detection means and the second detection means; 2
means for setting a time frame having a range within which the event is expected to be detected in the third detection means based on the relative distance between the detection means and the third detection means; detecting means for detecting the apparent absence of said event when said event is not detected within said time frame; Apparatus is provided for detecting whether or not the occurrence of a problem occurs as expected. Here, the detection information from each detection means is inputted into, for example, the aforementioned electronic logic and control device to determine the detection time interval and the actual speed of the process, to set a time frame, and to ensure that the event occurs in the third detection means as expected. It is possible to instruct the detection device to determine whether or not to do so, and to perform subsequent operations associated with this determination.

According to another aspect of the invention, the conveyor belt is a non-conductive endless conveyor belt, and the means for actuating the conveyor belt is a conveyor belt for driving the conveyor belt for transporting the conveyance from a loading point to an unloading point. The belt device includes antenna means disposed within the conveyor belt for indicating the normality of the conveyor belt, and first and second antenna means disposed along the moving direction of the conveyor belt for detecting the presence or absence of the antenna means. 2 and a third antenna means detecting means, the first detecting means and the second detecting means being arranged upstream of the loading point with respect to the direction of travel of the conveyor belt and at a predetermined distance from each other from the loading point. arranged in sequence,
and a third detection means is disposed downstream of the loading point and further communicated with the first, second and third detection means, the antenna means being effectively detected by said first and second detection means. detect whether or not the
calculating the actual speed of the conveyor belt when validly detected, establishing a time window having a range within which the validly detected antenna means is expected to be detected at the third detection means; In response to the status of whether detected within the time frame,
A conveyor belt rip detection apparatus is provided that includes an apparatus for detecting the presence or absence of a rip in a conveyor belt. The detection information from the first, second and third detection means is sent to a suitable, e.g. electronic logic and control device, where the operations described above are carried out. If the antenna is not detected by the third detection means at the expected time, it is determined that a vertical tear has occurred and the control means stops the conveyor belt. It will function to minimize damage to the belt.

With the above in mind, the main objective of the present invention is to detect subsequent events, and more particularly to detect means (antennas) contained within the belt to indicate its health. This is to monitor the normality of the conveyor belt.

Another objective is to provide accurate tear detection protection over a wide range of speeds, such as conveyor belts, while reducing the complexity and bulk of the software and hardware traditionally required. be.

Another purpose is to semi-mechanically detect the speed of a conveyor belt, etc., and to detect any tears that may occur therein.

Yet another object is to provide time independence for the endless conveyor belt tear detection system by using the speed of the conveyor belt to establish a time frame independent of real time.

Still other purposes are when the belt accelerates, decelerates,
or to provide accurate tear detection protection for the belt, such as during constant speed operation.

Yet another object is to provide an accurate tear detection function for a conveyor belt tear detection device at a predetermined location along the conveyor belt.

Yet another object is to provide an improved system for detecting cyclic events in a time-independent cyclic process at a predetermined location.

Yet another purpose is to indicate the distance between valid tear detection sensors (antennas) within the conveyor belt.

Yet another objective is to minimize the reduction in accuracy of warp detection and protection as the warp tear detection sensors wear out or become useless.

These and further objects of the invention will be more clearly understood as the description proceeds.

To complete the description of the foregoing and related objects, the invention consists of the features particularly pointed out in the following specification and particularly pointed out in the claims. The following description and the accompanying drawings, which describe in detail one embodiment of the invention, are but one of various aspects to which the principles of the invention may be applied.

Embodiments of the present invention will be described in detail below with reference to the drawings.

First, FIG. 1 shows a warp tear detection system according to the present invention for monitoring the health of a conveyor belt of a conveyor belt system, generally designated as 3, and for sensing warp tears in particular. Device 1 is shown. The conveyor belt system 3 includes two or more wheels or pulleys 4,5, which are connected to, for example, a motor or other prime mover 6 connected to a drive shaft 7 attached to the wheels 5. A conveyor belt 2 is mounted on the wheels or pulleys so that the belt moves as it is rotated. At a loading point 8 ore or other material is loaded onto the belt 2 in a conventional manner;
Such conveyance is then typically discharged from the belt at an unloading point 9 at or near the downstream end of the belt 2, in the vicinity of the wheel 4 as the belt turns around the wheel 4. or other evacuation means may be provided to remove the conveyed material from the belt.

The belt 2 includes a plurality of means 10 for indicating the health of the belt at specific locations thereof. Such means 10, in accordance with a preferred embodiment or best mode of the invention, are elongated wire electrical conductors substantially embedded in the material of the belt 2, the material of the belt 2 being preferably non-conductive. of materials such as rubber or rubber-like substances. Preferably, the antenna 10 is made of an elongated electrically conductive material of the type disclosed in US Pat. No. 3,792,459. Of course, other types of antennas may be used as belt health indicators. A preferred such antenna 10 is one capable of capacitively coupling to the transmitter and receiver of the detection station as also disclosed in such patents. Each time an antenna passes a detection station, a transmitter adjacent to one side of the belt capacitively couples one electrical signal to the antenna; In the absence of fatigue, such an antenna will reliably couple such signals capacitively to a receiver located on the other side of the belt. Receipt of such a signal at the receiver is taken as an indication of sufficient health of the conveyor belt. The belt 2 includes one or preferably a plurality of such antennas 10, the spacing of which (spacing between the antennas) being according to the economics of the belt construction as well as the desired level of preferred tear detection protection. It is determined.

Basically, the warp tear detection device 1 comprises first, second and third detection stations 11, 12, 1
May contain 3. The respective stations are of the type disclosed in US Pat. No. 3,792,459, the disclosure of which is incorporated herein by reference. The first and second detection stations are located upstream from the loading point 8, which is the loading point, with respect to the traveling direction of the belt 2, and the third detection station 13 is located immediately downstream of the loading point 8. are doing. The relative positions or spacings of the detection stations 11-13 are predetermined or known. Each detection station has transmitters 11T, 12T, 13T
and receivers 11R, 12R, and 13R. Although the station transmitters and receivers are shown along the belt in a single plane in the drawings, in reality the transmitters and receivers shown therein at each station are on opposite sides of the belt. located near the end or side. The warp tear detection device 1 also includes an electronic device 14 . Regarding the device 14,
It will be described in more detail below.

By using three detection stations and their known relative spacing, the warp tear detection device 1 can be used in a real-time independent mode of operation, thereby detecting warp tears. The accuracy of the detection function can be maintained at a high level. The high degree of accuracy depends on the antenna spacing and detection station spacing, which sets the relative time window for antenna detection as a function of belt speed. Therefore, the real-time period had to be long enough to accommodate belt stretching, disconnected antennas, belt starts and stops, etc., and as a result of the tear detection function. The inaccuracies inherent in conventional devices, which had substantial inaccuracies, are avoided.

More specifically, during operation of the warp tear detection system 1, one antenna, e.g.
When a passes the first detection station 11,
The first electrical signal (Figure 2A) is preferably DC
It occurs in the form of a pulse at time _t1 . When the antenna 10a passes the second detection station 12, a second signal pulse 21 occurs at time _t2 . Since the spacing between detection stations 11, 12 is known, the period of time _tx (FIG. 2B) between times _t1 and _t2 is a proportional representation of the belt speed. second and third detection stations 12,
Since _the distance between 13 and the magnitude of said time interval _t It is possible to predict or calculate the expected time t ₃ to occur with relatively high accuracy. Such a detection (detection at the third station) indicates sufficient health of the belt 2, and if no detection occurs by time t ₃ or a short time thereafter, it indicates a tear. as an indication of non-detection of the antenna, in which case the electronic device 14 is automatically actuated, for example by deenergizing the motor 6 and/or applying a suitable braking action. Stop belt 2.

Thus, the warp tear detection device 1 functions independently in real time. Rather, system 1
The time frame in which the belt is activated is a function of the speed of the belt 2. The accuracy of the warp tear detection function is therefore determined by the spacing of the antenna 10 in the belt 2 and the spacing of the detection stations 11-13. Typically, exact information regarding the location of all antennas in the belt 2 is not required. In the simplest form of the warp tear detection device 1 of the invention, the spacing between the antennas 10 may be such that one antenna per cycle covers the sensing area. 23, that is, at one position along the belt between the first and third detection stations 11, 13. However, smaller spacing between antennas may be employed if desired. In this case, means must be provided to inform the warp detection device 1 that there may be more than one antenna at a time in the sensing area 23. A severed or substantially fatigued antenna in the belt 2 in an area of the belt where no warp tear has occurred will not be detected by the first and/or second detection station; Therefore, no search for the antenna (antenna detection) by the third detection station 13 will take place, thus avoiding troublesome stoppages.

The operation of the warp tear detection device 1 according to the invention is based on the assumption that the area where belt tears can occur is the loading point 8. The operation of each warp detection cycle is therefore initiated by the passage of a valid antenna 10 past both the first and second detection stations 11,12. Device 1 is
In the process of specific events occurring sequentially, i.e. the passage of the antenna 10 past several detection stations, or other events, such events are themselves a function of the speed of operation of the process. It operates to detect whether it occurs within some suitable time period.

Referring now to FIG. 3, the electronic device 14 shown therein in accordance with a preferred embodiment of the invention, and in accordance with the best mode of the invention, utilizes a microprocessor 30. The microprocessor 30 includes a set of program instructions contained in a read-only memory (ROM) 31 directly associated therewith, as well as for use in conventional purposes associated with the microprocessor 30. Random access memory (RAM) 32 is included and is utilized for the operation of electronic device 14. Each detection station 11,1
Transducers or receivers 11R, 12R, 13R at 2, 13 receive signal pulses 20,
21 and 22 are coupled to supply microprocessor 30 via signal conditioning circuit 33. The signal conditioning circuit 33 is described in U.S. patent application no.
871,664 (U.S. Pat. No. 4,229,735), such a circuit may be individually associated with each transducer 11R-13R. The circuit 33 may also have the ability to distinguish between valid antenna signals and noise. A conventional clock signal generator 34 provides clock pulses 35 to the microprocessor 30.

Output line 40 from microprocessor 30
is coupled to a conventional stop control circuit 41.
The stop control circuit 41 is, for example, a deenergizing solenoid mechanism for deenergizing the motor 6, which circuit is also adapted to actuate a braking system for the conveyor belt system 3 when a warp tear is detected. Good too. Output line 42 from microprocessor 30 is coupled to a warp tear indicator 43, which provides, for example, a visual display to indicate that a warp tear has been detected. Additionally, an output line 44 from the microprocessor is coupled to a distance indicator 45.
The indicator displays the distance between adjacent antennas in the belt, as described below.

During operation of the warp tear detection device 1 associated with the conveyor belt system 3, the electronic device 14 monitors the passage of each antenna 10 by means of the detection stations 11-13. If a tear is detected, electronics 14 will operate to stop the conveyor belt, minimizing belt tear damage. Such operation will be described below in accordance with the computer program summary illustrated by the flowchart of FIG. The flowchart may be converted by one of ordinary skill in the computer arts into the machine language program statements necessary for control of the entire electronic device by a microprocessor 30 or other central processing unit. Dew. Such a computer program is stored in the ROM 31 and will be used to effect the entire operation of the electronic device 14 after the device operator manually closes the start switch 46.

Referring in detail to FIG. 4, the flowchart 50 is shown in which, when the start switch 46 is closed, the electronic device 14 is activated in a conventional manner, e.g. Block 5
It is initialized as indicated by 1. The initialization will include an automatic check of parts of the electronics 14, activation of the clock signal generator to generate constant frequency clock pulses 35, and activation of the detection stations 11-13.
The initialization step may also include suitably activating the stop control circuit 41 to energize the motor 6 to drive the belt 2.

Thereafter (after initialization), a circular loop is entered from block 52 in which it is determined whether the first antenna signal 20 is present, for example at the first detection station 11, and whether it Questions are asked to sense whether there is a level of acceptance that indicates a presence. If a fatigued or otherwise damaged antenna (an incomplete antenna) passes through the station 11, the signal 20 is at a level that is too low.
, circuit 33 will act as a discriminator to treat such a signal as if it were noise, and the waiting loop will continue until a valid antenna is sensed according to line 53.

When the presence of a valid antenna is sensed in block 52, it is detected in block 55 according to line 54.
, at which time an internal clock mechanism is started within microprocessor 30, thereby beginning to count pulses from clock signal generator 34.
Such a clock pulse is detected during an interrogation at block 56 to sense whether a second signal 21 of a sufficiently large level (acceptance level) is present at the second detection station 12. Medium, continued. Initially no such second signal will be sensed; therefore line 5
7 leads to block 58 where it is determined whether the value of a first clock, e.g. the number of clock pulses counted by the first internal clock of microprocessor 30, exceeds a predetermined value. Questions are asked to answer questions. If such predetermined value has not yet been reached, line 59 is passed until signal 21 is detected at block 56 or such predetermined value is exceeded at block 58. The process then returns to block 56. If such predetermined value is exceeded in block 58, the first signal 20 detected in block 52 will be treated as a noise signal and not a valid antenna signal. , line 60 returns to block 52. Therefore, if the signal sensed in block 52 is due to a tired antenna,
If the transmitter of the first detection station 11 and the receivers 11T, 11R are coupled by chance, but the coupling is no longer sufficient at the second detection station 12, the vertical tear is detected. For this purpose, such an antenna is ignored throughout subsequent cycles of the conveyor belt system 3.

When the second signal 21 is detected in block 56, it follows line 62 to block 63 where the second internal clock of the microprocessor 30 is set to zero and the clock signal generator 3
It will start counting clock pulses 35 from 4. The current value of the first clock will then be stored in block 64 and the first clock will be stopped. The distance between the second and third detection stations 12, 13 is known;
Since the time required for the antenna to travel from the first station to the second station is also known (stored in block 64), the time required for the antenna to reach the third detection station is also known. t ₃ is calculated in block 65.

Thereafter, an inquiry is made in block 66 as to whether the third signal appears at the third detection station within the required time t _y at an acceptable level. If it does appear (detected), it returns along line 67 to block 52 and waits in the first detection station 11 for the detection of the presence of the next antenna. However, if the answer to the question asked in block 66 is negative (no antenna detected within the required time), then it is likely that the antenna was caused by a tear in the belt. A tear indication is provided at block 68 to indicate that this may be due to a cut. Microprocessor 30 then operates stop control circuit 41 (FIG. 3) to stop belt 2. The warp tear indicator 43 may also be activated to indicate on the control panel that the belt has stopped. The operator will then inspect the belt, request repairs if necessary, and restart the belt. If no warp tear is found upon inspection of the belt, the appearance of a warp tear indication in block 68 is due to a damaged antenna, for example, and the operator then operates switch 46 again. This will restart the detection system 1 and the conveyor belt system 3.

Referring to blocks 71, 72, and 73 of FIG. 4, they are provided to provide a display of the expected passage time of the antennas in the belt or the physical distance between the antennas.
For example, during initialization at block 51, a third clock is initialized to zero. When the first antenna is detected at the second detection station 12 (this is represented by a positive response in block 56), line 74 is followed to block 71, as shown therein. , the third clock value is stored in memory, RAM32. Thereafter, in block 72, the third clock starts again from 0, and in block 73, the previously stored third clock value, i.e. the value stored in block 71, is displayed on the distance display. 45 (FIG. 3).
The third clock continues running until the next antenna is detected by the second detection station 12. When the next antenna is detected, the current value of the third clock is stored in block 71 and the third clock is restarted from zero in block 72. The now stored third clock value is then displayed in block 73. This means that at a given belt speed,
It represents the time between the detection of the first antenna and the next antenna at the second detection station. Such information may be converted to distance information, if desired, by conventional techniques such as a tachometer, or to obtain the current speed of the belt. The information can also be directly related to the distance between the antennas by having the clock signal generator 34 itself generate clock pulses at a frequency that is directly proportional to the actual speed of the belt.

Furthermore, by making the frequency of the clock signal pulse 35 directly proportional to the belt speed,
The accuracy of the warp tear detection device 1 can be maximized. However, the detection station 11~
Even if the intervals of 13 are appropriately approached and the frequency of the clock signal pulse is fixed at a constant, appropriately high frequency, the degree of change in belt speed is not that large, so the accuracy of the warp tear detection device 1 is sufficient. It would be practical. In any case,
Accuracy of tear detection capability is achieved over a wide range of belt operating conditions, such as during belt acceleration, deceleration, or constant speed operation.

The electronic circuit in the above description and explanation is
Although a microprocessor control circuit using a computer program is used for its control operations, the overall operation of the present invention is also functionally equivalent to the previously described preferred embodiment of electronic device 14. Hard-wired logic and timing circuits may be used to perform physical and control operations.

In using the warp tear detection device 1 of the present invention to detect whether or not the event occurs appropriately in the process of a specific event occurring subsequently, the occurrence of the event is first detected. It is detected by the detection station 11 in a first position. The subsequent occurrence of an event occurs at a second location, i.e. a detection station 1 located at a predetermined distance from the first location.
Detected at 2. Subsequent detection occurs at a third location, i.e. at a third detection station 13 at a predetermined distance relationship from the second detection station.
In the process, we search for the occurrence of events. The time between the first and second detections is sensed as being indicative of the speed of the process, and depending on the magnitude of such time (period) and the positional relationship of the second and third detection stations, An event is expected to occur at the third detection station1
A time frame (within which the event is expected to occur) is set.

More particularly, a first, The presence of the antenna is detected at the second and third locations. The time between the first and second detection is one of the times by which the third detection is expected to occur.
used to set a time frame (time period). If such third detection does not occur as expected, assuming there is a tear or other damage, operation of the process or conveyor belt may be stopped or other appropriate action may be taken. is taken.

From what has been described above, it can be seen that the present invention can be applied for conveyor belt tear detection and, more broadly, for real-time detection of subsequent events in a process as a function of the actual speed of the process. ), it will be appreciated that it can be applied to monitor independently of

[Brief explanation of drawings]

FIG. 1 is a diagrammatic illustration of a conveyor belt warp tear detection device according to the invention. 2nd A,
2B and 2C are graphical representations of the signals occurring at the first, second and third detection stations of the warp tear detection apparatus of FIG. FIG. 3 is a schematic electrical circuit block diagram of the electronics associated with the warp tear detection apparatus of FIG. FIG. 4 is a flowchart of a computer program illustrating the operation of the electronic device of FIG. 3 in the tear detection apparatus of FIG. 1 for detecting warp tears in a conveyor belt. 1... Warp tear detection device, 3... Conveyor belt system, 8... Loading point (loading point), 9... Unloading point,
10, 10a... Antenna, 11... First detection station, 12... Second detection station, 13
...Third detection station, 14...Electronic device, 2
0, 21, 22...Signal waveform.

Claims (1)

[Scope of Claims] 1. A plurality of wire-shaped electrical conductors that generate a signal indicating the normality of the conveyor belt when the conveyor belt is in a normal state with no warps present therein, and the conveyor belt A method for detecting a tear in a conveyor belt, the method comprising: means for activating a signal indicating the normality of the conveyor belt generated by the electrical conductor; the first and second detection means arranged at a distance from each other, and the third detection means arranged downstream of the loading point, the first detection means and the second detection means detecting a time interval between detection times of each of said signals detected by said third detection means, and based on said time interval, a time frame having a range in which said signal is expected to be detected at said third detection means; and sensing an apparent lack of conveyor belt health when the signal is not detected within the time frame in the third detection means. 2. A tear detection device for a conveyor belt apparatus comprising a non-conductive conveyor belt and means for driving said conveyor belt for conveying a conveyed material from a loading point to an unloading point, wherein said conveyor belt is antenna means disposed within the conveyor belt for generating a signal indicating the normality of the conveyor belt when the conveyor belt is in a normal state with no warps present; and a signal generated by the antenna means. first and second detection means arranged at a predetermined distance from each other upstream of the loading point along the direction of travel of the conveyor belt; and a third detection means arranged downstream of the loading point. a detection means, coupled to the first, second and third detection means, for sensing whether or not the signal generated by the antenna means is effectively detected by the first and second detection means; calculating the actual speed of the conveyor belt when detected and setting a time frame having a range within which a validly detected antenna means signal is expected to be detected at said third detection means;
and a device for detecting the presence or absence of a tear in the conveyor belt in response to whether a signal of the antenna means is detected at the third detection means within the time frame. Rip detection device.