JPS6181200A - Disconnection detector of coil - Google Patents

Abstract

PURPOSE:To readily detect the disconnection of a coil and the shortcircuit by discriminating the output of a comparator for comparing a voltage of a connecting point of the coil with a switching element with a reference voltage immediately after the switching element is interrupted. CONSTITUTION:A processor 100 applies a signal of high level to the base of a transistor 6 during a period W to energize a coil 5. Immediately after the transistor 6 is interrupted, i.e., at a time t2, the voltage of a connecting point 7 of the coil 5 with the transistor 6 becomes a high level by the forward voltage V1 of a diode D from a power source voltage VB. A comparator 10 outputs a signal of low level when the voltage of the point 7 is smaller than the reference level signal from a reference level setter 12. Thus, the disconnection of the coil 5 is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for detecting whether a coil of a motor or solenoid is disconnected or short-circuited.

BACKGROUND ART For example, an electric circuit of an electromagnetic clutch used to reciprocate the document table of a copying machine is shown in FIG. One end of the electromagnetic coil 1 that disturbs the clutch is connected to the power supply +VBK, the dragon end is connected in series to a transistor 2 as a switching element, and the emitter side of the transistor 2 is grounded. When the transistor 2 is cut off, a back electromotive force is generated at both ends of the electromagnetic coil 10 immediately after #i is cut off, and the transistor 2 is destroyed or damaged by this back electromotive force. Therefore, a diode D as a voltage drop element is connected in parallel to both ends of the electromagnetic coil 1. This diode D absorbs the back electromotive force generated across the electromagnetic coil 1, and even if a transistor caused by the back electromotive force is connected in series with the electromagnetic coil l, the back electromotive force is absorbed by the diode D. Therefore, it is possible to prevent leakage from occurring between the contacts a and b of the relay switch 3, thereby preventing damage to the contacts a and b and generation of noise.

Problems that 98 Man tries to solve In the above prior art, even though the electromagnetic filter 1 has been secured and the control circuit of the copying machine has commanded the electromagnetic clutch to drive, the desired IK Hara Makidai When it became impossible to move, it was impossible to determine whether the failure was caused by a break in the electromagnetic coil 1, and it took a great deal of time and effort to repair the 1φ.

An object of the present invention is to solve the above-mentioned technical problems and provide a coil fold detection device in which the acupuncture needle is simplified.

Means for Solving the Problems The present invention provides a coil, a switching cable connected in series to the coil, a voltage drop element connected in parallel to the coil, and a connection point between the coil and the switching element. It includes a comparison circuit connected to one input terminal, a reference level setting circuit for providing a reference level to the other input terminal of the comparison circuit, and means for determining the output from the Hinu circuit immediately after the switching element is disconnected. , the reference level is lower than the voltage applied to the one input terminal due to the back electromotive force of the coil immediately after the switching element is evaluated, and the voltage applied to the one input terminal is lower than the voltage applied to the one input terminal in a steady state in which the switching element is being dialyzed. This is a coil disconnection detection device that detects a voltage exceeding Kfi as a special fault.

According to the present invention, there is provided a comparison circuit in which the connection point between the coil and the switching element is connected to one input terminal, a reference level throwing circuit that applies a reference level to the other input terminal of the comparison circuit, and By working with the means for determining the output of the comparator circuit immediately after the cut-off, coil breakage and standard are easily detected, and the time required for processing etc. is significantly shortened.

Actual Relaxation Example FIG. 1 is a return loop diagram of the folding line device 52 according to Zero's brother Akira. A coil 5 and a transistor 6 as a switching element are connected in series between the 2-in-4 of the +4 source VB and the ground line 4a of the low frequency band. Diode D as a voltage drop element across the coil 5/'i
are connected in parallel.

Connection point 7 between diode D and collector of transistor 6
For example, it is grounded via resistors R1 and R2.

The connection point 8 between the resistors R1 and R2 is connected via a line 9 to one input terminal AiC4IAa of the comparator circuit 10.

The other input terminal B of the comparator circuit 10 is connected via a line 11 to a reference level setting circuit 12 which provides a reference level signal to an input terminal BK. The reference level installation circuit 12 is
Voltage dividing resistors R3 and R4 connect the power line 50 and the ground line 5.
The potential of terminal A connected in series with 1 is the potential of input terminal B.
When the potential of the input terminal A is higher than the potential of the input terminal B, it is a low level equal to the potential of the ground line 51, and when the potential of the input terminal A is higher than the potential of the input terminal B, it is a high level equal to the line 4 on the high side of the electromagnetic +VB. It is. The output of this comparison circuit 10 is connected via a line 13 to a processing circuit 100 realized by a microcomputer or the like. Processing circuit 100 is connected to the base of transistor 6 via line 14 .

Assume that the coil 5 is not disconnected. Processing circuit 1
00 inputs a high level signal to the base of the transistor 60 during the period W between times t1 and t2. At this time, as shown in FIG. 2 (1) of the transistor 61d, the period W
The coil 5 is energized during this period W.

When the coil 5 is not bent, the voltage at the anode seen from the cathode side of the diode D, that is, the voltage at the connection point 7, is the voltage at the node 7 of the transistor 6, as shown in FIG.
2+J−−F m immediately after folding, that is, after time t2
n/l+”v-r/=4*-h M
n74- If? /'l 'f#'
The level becomes high by 71 times the forward voltage of S-rD. This voltage v1 is, for example, 0.5 to 0.7v. '4 voltage V immediately after crystallization of this transistor 6
B+V1 is connected from line 9 to comparator circuit 1 via resistor R1.
0 to one input terminal A. The other input terminal BK of the comparison circuit 10 is supplied with a reference level signal V2 from the reference level setting circuit 12. As shown in Figure 3g2 (3), this reference level signal v2 is lower than the nominal pressure VB+V1 applied to one input terminal A of the comparator circuit 10, and the transistor 6 is cut off in a steady state. The voltage VB is selected to be higher than the current voltage VB. Therefore, if the signal of the transistor 6 applied to the input terminal A immediately after one cut-off becomes larger than the reference level signal applied to the input terminal B, the comparison circuit 10 immediately after the cut-off of the transistor 6
The output from the processing circuit 100 becomes high level as shown in FIG.
It is determined that the coil 5 is normal.

Assuming that the coil 5 is exposed in some places, due to the disconnection of the coil 5, the transistor 6 connected to # becomes m l'JT.
Even if it is, a back electromotive force may be generated from the coil, so the voltage on the anode side of diode D remains at O■. Therefore, one input terminal AK of the comparison circuit 10
is given a low level signal equal to the ground potential, which is compared with the reference level signal from the reference level setting circuit 12 given to the other input terminal B, the output from the comparison circuit 10 becomes low level, and in the processing circuit 100 coil 5
It is determined that the wire is disconnected. In this way, disconnection or short circuit of the coil 5 is determined depending on whether the output from the comparator circuit 10 is high level or low level.
rratt detection of the coil 5 can be easily performed.

FIG. 3 shows a disconnection detection device 52 according to another embodiment of the present invention.
It is an electric circuit diagram of a. 43 is similar to the configuration of FIG. 1, and corresponding parts are given the same reference numerals. What should be noted is that the cathode of the Zener diode ZD and the cathode of the diode D are connected to form a series circuit, and this series circuit is connected in parallel to the coil 5. By connecting the Zener diode ZD, the gray voltage V2 (for example, 5 V) due to the Zener diode ZD is added to the forward voltage v1 of the diode D and is applied to the comparator circuit 10. Therefore, in FIG. The voltage from the connection point 7 immediately after the release 11T of the transistor 6 shown in FIG. Comparison with the reference level signal is extremely easy. This prevents the voltage across the diode D from being too small and making comparison by the comparator circuit 10 difficult due to the S/N ratio of No. IS.

FIG. 5 is an electrical circuit diagram of still another embodiment of the present invention. FIG. 5 is similar to the structure of FIG. 1, and corresponding parts are given the same reference numerals. In this embodiment, a plurality of coils 5, 5a
The disconnection detection is performed by the relatively soft circuit 10, and one or both of the coils 5 and 5a are detected at the same time.

When the conduction is interrupted, if the coils 5 and 5a are both short-circuited, the comparator circuit 10 outputs a high level signal, as in the case of the previous embodiment. Therefore, the processing circuit 100 can identify the disconnected or short-circuited coil 5 by simply determining which coil is the cause of the output of the comparator circuit 10. In this way, even if there are several tens of coils 5, only one comparator circuit 10 is required, and a very inexpensive and useful disconnection detection can be achieved.

In another embodiment of the present invention, the transistor 6 may be replaced with a switching element such as a relay switch. (9) terms in the claims of the preceding patent;
Heavy pressure drop elements include (a) a diode, (b) a combination of a diode and a Zener diode, and (c)
) It must be interpreted to include the concept of other elements that cause a drop in vehicle pressure.

The coil disconnection detection device according to the present invention is not limited to applications such as copying machine motors and electromagnetic clutches, but can be implemented in other technical fields.

Effects As described above, according to the present invention, the coil, the switching cable connected in series to the coil, the cage pressure drop cable connected in parallel to the coil, and the coil and switching cable are connected to each other in parallel. A comparator circuit whose connection point is connected to one input terminal, a standard level setting circuit that provides a reference level to the other input terminal of the comparator circuit, and means for determining the output of the comparator circuit immediately after the switching circuit is shut off. By providing this, disconnections and short circuits in the coil can be easily detected, and the time and labor required for repairs etc. can be significantly saved.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of a coil disconnection detection device 52 according to the present invention, FIG. 2 is a waveform diagram of signals at various parts of the coil disconnection detection device 52, and FIG. 3 is a diagram of a coil disconnection detection device 52 according to another embodiment of the present invention. Electrical circuit diagram of the fold line detection device d52a, Figure 4 is the 3rd
FIG. 5 is an electric circuit diagram of still another embodiment of the present invention, and FIGS. 6 and 7 are electric circuit diagrams for explaining the prior art. 1.5, 5a...Coil, 2,6...Transistor,
lO... Comparison circuit, 12... Reference level setting circuit,
52.52a...Disconnection detection device agent Patent attorney Keiichi Shikyo 6 +VB Figure 2 B Shin /, lliZ

Claims (1)

[Claims] A coil, a switching element connected in series to the coil, a voltage drop element connected in parallel to the coil, and a connection point between the coil and the switching element connected to one input terminal. a reference level setting circuit that applies a reference level to the other input terminal of the comparison circuit; and means for determining an output from the comparison circuit immediately after the switching element is shut off, the reference level being determined by the output of the switching element. The voltage is selected to be lower than the voltage applied to the one input terminal due to the back electromotive force of the coil immediately after the switching element is cut off, and higher than the voltage of the one input terminal in a steady state where the switching element is cut off. Characteristic coil disconnection detection device.