JPH0422310Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a disconnection detection circuit for detecting disconnection of a coil, a resistor, etc.

Background Art FIG. 3 is a typical prior art electrical circuit diagram. A low-level signal is sequentially derived from one of the output terminals a, b, c, ..., n of a processing circuit 1 realized by a microcomputer, etc., and a high-level signal is derived from the remaining terminals. signals remain derived. For example, when a low level signal is derived from output terminal a, the transistor
Qa is cut off, and the remaining output terminals b, c, ..., n
A high level signal is derived from , and transistors Qb, Qc, ..., Qn are conductive. When the coil La, which is the load corresponding to the transistor Qa, is not disconnected and is conducting, the collector of the transistor Qa is at a high level, and therefore the collector of the transistor Qa is connected to the transistor Q through the diode D11.
A high level signal is applied to the base of the . This makes transistor Q conductive and input terminal p
becomes low level. If the load La is disconnected, the collector of the disconnected transistor Qa is at a low level, the transistor Q is disconnected, and the input terminal p is at a high level. Similarly, the coils Lb, Lc and the load resistance R
wire breakage can be detected.

Problems to be solved by the invention In such prior art, the coil which is the load
Other diodes D21, D22, and D23 are required to absorb surges of La, Lb, and Lc.
Therefore, there is a problem that the number of parts increases.

An object of the present invention is to provide a circuit for detecting disconnection, etc., which can reduce the number of parts.

Means for Solving the Problems The present invention connects one end of the inductive detected element to the first
Commonly connected to the power supply line, the other end is connected to the second power supply line via individually provided switching elements, one of the switching elements is sequentially cut off, and the remaining switching elements are made conductive. control means;
a level discrimination circuit that discriminates the level at the other end of the detected element, and detects a disconnection or the like of the detected element based on the discrimination result of the level discrimination circuit, the circuit comprising: and the first power supply line, a first diode is arranged individually for each detected element, and a second diode is provided commonly for each detected element.
and a diode are connected in series so as to be in a forward direction with respect to the surge current generated from the detected element, and the level discrimination circuit discriminates the level at the other end of the detected element via the first diode. This is a circuit for detecting wire breakage, etc., which is characterized in that it is configured to do so.

Effect According to the present invention, one end of each inductive detected element such as a plurality of coils is commonly connected to the first power supply line, and the other end is connected to an individually provided switching element. The second power supply line is connected to the second power supply line via the second power supply line. The switching elements are individually controlled to be turned on/off by a control means.
Therefore, when the control means conducts a switching element, a drive current flows to the detected element corresponding to the switching element, and the detected element acts as a load.

The other end of the detected element, that is, the connection point with the switching element is connected to a level discrimination circuit via a first diode. The control means sequentially shuts off one of the switching elements and conducts the remaining switching elements, and detects disconnection or short circuit of the detected element based on the discrimination result of the level discrimination circuit in each switching state. is detected.

Further, a second diode common to the first diode is connected between the other end of the detected element and the first power supply line.
A diode is provided, and this second diode is interposed between each first diode and the first power supply line so as to be in the forward direction of the surge current generated when the current of the detected element is cut off. Therefore, the number of components can be reduced by using the second diode for surge absorption in common for each detected element.

Embodiment FIG. 1 is an electrical circuit diagram of an embodiment of the present invention. The detected elements as loads are referenced La, Lb, Lc.
It is a coil as shown in . This coil La,
Lb, Lc and one end of a resistor R, which is another load, are commonly connected to line 2. coil
The other end of La, Lb, Lc and resistor R is line la,
Transistors Qa, Qb, Qc, ..., which are switching elements, are connected individually through lb, lc, ..., ln.
Each is connected to a Qn collector. The bases of these transistors Qa, Qb, Qc, ..., Qn are connected to output terminals a, b, c, ..., n of a processing circuit 1 realized by a microcomputer or the like.
A control signal is given from Coil La, Lb, Lc
The other end of the resistor R is connected in the forward direction to the anode, which is one end of the diodes D31, D32, D33, . . . , D3n. The first of these
Diodes D31, D32, D33, ..., D3
The other end of n, the cathode, is commonly connected to line 3. This line 3 is connected to resistors R1 and R2. A connection point 4 between resistors R1 and R2 is connected to the base of a transistor Q for level discrimination. The collector of the transistor Q is pulled up by a resistor R3, and its output is applied to the input terminal p of the processing circuit 1. First diode D31,D
A second diode D30 is connected to the line 3 to which 32, D33, ..., D3n are commonly connected, and to the line 2 to which the coils La, Lb, Lc and resistor R are commonly connected for surge absorption. is connected.

The processing circuit 1 has second output terminals a, b, c, and n.
The control signals shown in FIGS. 1-2 and 4 are provided. For example, when a low level signal is applied to output terminal a, high level signals are applied to the remaining output terminals b, c, . . . , n. In this way, low level signals are sequentially applied to output terminals a to n, and the remaining output terminals are kept at high level. For example, when a low level signal is applied from output terminal a, transistor Qa is cut off, and the remaining transistors Qb, Qc, ..., Qn
is conducting. When the coil La is not disconnected and conductive, a high level signal is applied to the line 31 via the first diode D31. Note that the remaining transistors Qb, Qc, ..., Qn
is conductive, and at this time, the remaining first diodes D32, D33, ..., D3n are turned off, so line 3 is connected to the first diode D as described above.
It remains at a high level due to the function of 31. Therefore, the transistor Q becomes conductive, and the output terminal p becomes a low level regardless of the action of the resistor R3. When the coils La, Lb, Lc and the resistor R are not disconnected, the signal shown in FIG. 2 is input to the input terminal p. In this way, the processing circuit 1 can detect that the coils La, Lb, Lc and the resistor R are not disconnected.

Assume that coil La is disconnected. At this time, even if only the output terminal a is at low level, line 3 does not go to high level, so transistor Q is cut off. As a result, the input terminal p is kept at a high level by the action of the resistor R3. When the remaining coils Lb, Lc and resistor R are not disconnected, the signal shown in FIG. 26 is applied to the input terminal p. In this way the coil
It is possible to detect that La is disconnected.

It can also be detected that line la is grounded. For example, when the output terminal a is at a low level and the line la is grounded, the line 3 does not go to a high level, the transistor Q remains cut off, and the input terminal p is at a high level. Therefore, when the input terminal p is at a high level while the output terminal a is at a low level, it is possible to detect a disconnection of the coil La or a grounding of the line la.

Resistors may be used instead of the coils La, Lb, and Lc. Further, the resistor R may be replaced with a coil.
In place of the level discrimination means constituted by the resistors R1, R2 and the transistor Q, level discrimination means having another structure may be provided.

Effects As described above, according to the present invention, it is possible to reduce the number of parts as much as possible and detect disconnection or grounding of the detected element.

[Brief explanation of the drawing]

Fig. 1 is an electrical circuit diagram of one embodiment of the present invention;
The figure is a waveform diagram for explaining the operation of the embodiment shown in FIG. 1, and FIG. 3 is an electric circuit diagram of the prior art. 1... Processing circuit, La, Lb, Lc... Coil, R
...Resistor, Qa, Qb, Qc, ..., Qn ... Switching transistor, Q ... Level discrimination transistor, D31, D32, D33, ..., D3n
...First diode, D30...Second diode.

Claims (1)

[Claims for Utility Model Registration] One end of an inductive detected element is commonly connected to a first power supply line, and the other end is connected to a second power supply line via an individually provided switching element. , control means for sequentially shutting off one of the switching elements and conducting the remaining switching elements;
a level discrimination circuit that discriminates the level at the other end of the detected element, and detects a disconnection or the like of the detected element based on the discrimination result of the level discrimination circuit, the circuit comprising: and the first power supply line, a first diode is arranged individually for each detected element, and a second diode is provided commonly for each detected element.
and a diode are connected in series so as to be in a forward direction with respect to the surge current generated from the detected element, and the level discrimination circuit discriminates the level at the other end of the detected element via the first diode. A detection circuit for detecting disconnection, etc., characterized in that the circuit operates as follows.