JPS6247092Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an operation detection circuit that detects the operating state of a circuit that includes a drive element that becomes conductive when a drive signal is applied to its input terminal, thereby enabling current to flow through the driven element.

Conventionally, there are various kinds of motion detection circuits of this type, and for example, there is one as shown in FIG. That is, one end of the winding 1 of the electromagnet, which is a driven element, is connected to the power source V, and the other end is connected to a so-called fuse 3 with an alarm terminal equipped with an alarm terminal 2.
The other end is connected to the collector of a drive transistor 4, which is a drive element whose emitter is grounded, and when a drive signal _S1 is applied from an input terminal 5 to the base of the drive transistor 4, the drive transistor 4 becomes conductive and the winding 1 becomes conductive. The electromagnet is activated. When excessive current flows through the fuse 3 due to a short circuit in the winding 1 or other causes, the fuse 3 blows out, the alarm terminal 2 closes, and an alarm is output from the detection terminal 6.

However, in such a conventional example, although it is possible to detect if the fuse blows, winding 1
If the wire itself breaks, it is impossible to detect it, and therefore, there are inconveniences such as consecutive commands being issued one after another without being able to detect it even though it is in an inactive state.

This invention was made to eliminate these drawbacks, and by repeatedly checking the current status while and after the current is flowing through the electromagnet windings and other elements, various abnormalities can be reliably detected. Its purpose is to make it possible.

Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

A in the figure is a circuit whose operation is checked. The motion detection circuit of the present invention is mainly composed of a detection section B, a comparison section C, and a control section D. First, each configuration will be explained.

For convenience, the circuit A whose operation is to be checked applies a drive signal _S1 to the input terminal 5 of the drive transistor 4, which is a drive element, and makes it conductive, thereby energizing the winding 1 of the electromagnet, which is a driven element. I have chosen it. Note that 7 is just a fuse for safety.

The detection unit B outputs a continuity detection signal _S2 at one of two levels depending on whether the drive transistor 4 is conductive or not, that is, whether the winding 1 is energized. connects the collector of the drive transistor 4 to the detection transistor 9 via the resistor 8.
The collector potential of this detection transistor 9 is used as the output value of the continuity detection signal _S2 . In the figure, 10 is a diode and 11 is a resistor, which are provided to absorb back electromotive force.
12 is a resistor, and _V2 is a power supply.

The comparison unit C compares the continuity detection signal _{S 2} and the drive signal S ₁ and outputs _the operation detection signal S ₃ only when they match. is input to the exclusive OR gate 13, its output is inverted by the inverter 14, and the output of the inverter 14 is further input to the AND gate 15 together with a timing pulse from the control section D, which will be described later, to have a logical product of these. The motion detection signal S3 is generated using the motion detection signal _S3 .

The control section D generates synchronized first and second check pulses immediately after the leading edge and immediately after the trailing edge of the drive signal _S1 , and applies these to the comparison section C as detection timing pulses. drive signal S ₁
Approximately 25μS from the leading edge of the drive signal _S1 , taking into account the rise and fall characteristics of S1 and the response characteristics of the drive transistor 4.
The first check pulse 16 is delayed, and the drive signal
A second check pulse 17 is generated with a delay of about 100 μS from the trailing edge of _S1 , and is sent to the comparison section C as described above.
The voltage is applied to the AND gate 15 of .
Note that these first and second check pulses 16, 17
Since a well-known method can be used as the generating means itself, a description thereof will be omitted.

Next, the action will be explained.

First, the normal operation will be explained. The drive transistor 4 receives a drive signal of H at a binary level to the input terminal 5.
When S ₁ is applied, conduction occurs and current flows through winding 1, activating the electromagnet. At this time, the collector potential of the drive transistor 4 becomes L → the detection transistor 9 is cut off → the collector potential [continuity detection signal S ₂ ] H.
A coincidence signal is input, and the output becomes L → the inverter output H. This state is sampled by the first check pulse 16 generated immediately after the leading edge of the drive signal _S1 , and the output of the AND gate 15 [operation detection signal _S3 ] becomes H, indicating that the circuit is normal. Figure 3 T ₁ part].

When the drive signal _S1 becomes L from this state, the drive transistor 4 is cut off, and no current flows through the winding 1, and the electromagnet becomes inactive. At this time, the collector potential H of the drive transistor 4 → the detection transistor 9
Continuity → collector potential [continuity detection signal S ₂ ] becomes L, so the exclusive OR gate 13
The matching signals of L and L will be input to the .
In other words, this continuity detection signal _S2 is always a drive signal during normal operation.
It is output in agreement with L and H of _S1 . As a result, the output of the exclusive OR gate 13 changes from L to the inverter output H. This state is sampled by the second check pulse 17 generated immediately after the trailing edge of the drive signal _S1 , so the output of the AND gate 15 [operation detection The signal S ₃ ] becomes H, indicating that the circuit is normal. [Fig. 3 T ₂ section] This operation detection circuit performs the basic function as described above during normal operation, and when an abnormality occurs, the continuity detection signal S ₂ and drive signal S ₁ , which were the same during normal operation, do not match. Detection is performed by
That is, due to these mismatches, exclusive OR gate 1
The output of S3 becomes H → the output of the inverter 14 becomes L, and this L is sampled by the first check pulse 16 or the second check pulse 17 through the AND gate 15, and the operation detection signal _S3 becomes L, that is, abnormal. This is to let you know that there is. Examples of detected abnormalities include the following:

[Abnormalities detected by the first check pulse] (a) Disconnection of winding 1 (b) Melting of fuse 7 (c) Open failure of drive transistor 4 These are all factors that cause the continuity detection signal _S2 to go low. This causes a mismatch with H of the drive signal _S1 , and an abnormality is detected. [Part _T3 in Figure 3] [Abnormalities detected by the second check pulse] (a) Short circuit to ground in winding 1 (b) Short circuit in drive transistor 4 Both of these cause the continuity detection signal _S2 to become H. This causes a mismatch with L of the drive signal _S1 , and an abnormality is detected.

In this way, not only possible abnormalities can be detected reliably, but also the cause of the abnormality can be estimated to some extent depending on which check pulse the abnormality was detected. In addition, if there is a failure in the operation detection circuit itself, such as a failure in the detection transistor 9, poor contact at each contact, failure in the power supply _V2 , etc., it will always appear as an abnormality in one of the check pulses, so the operation detection will be delayed. It is possible to detect the operation of circuits as well.

Note that how to use the motion detection signal _S3 can be freely determined depending on the characteristics of the circuit A whose motion is to be detected. Specifically, this can activate a warning buzzer or lamp, or can be used as a drive signal.
It is conceivable to guide the signal to the generation system of _S1 and stop subsequent drive commands.

In order to make this motion detection circuit function,
Prior to the drive signal, a semi-drive signal S 1 ' with a width of about 50 μS, for example, is applied to the drive element (drive transistor 4 in this case) to an extent that is insufficient to operate the driven element (in this case, the winding ₁ of the electromagnet). By inserting it into the input terminal, it is possible to perform operation detection in exactly the same manner as described above at this stage, and it is possible to check for failures before putting the circuit whose operation is actually detected into operation. figure〕. Therefore, if a preliminary check is performed using the semi-drive signal S ₁ ' as described above, and the operation detection signal S ₃ (in this case, the output of the AND gate 15) is inputted as a suppression signal to the drive signal generation system, It is possible to prevent a situation in which a subsequent drive signal is sent to the drive element when there is an abnormality. [Figure 4 T ₄ section]. Furthermore, in the case of a device having a plurality of circuits whose operation is to be checked, in addition to immediately before the drive signal S ₁ , this type of semi-drive signal S ₁ ' is applied immediately after turning on the power of the device. If the signal is applied to the circuit to be checked, it is extremely rational because it is possible to completely check for abnormalities in the entire device before using the device. In addition, even if an abnormality occurs during use of the device, a high level of safety can be expected since a preliminary check can be made using the semi-drive signal S ₁ ' issued immediately before the drive signal S ₁ .

As explained above, according to this invention, almost all conceivable abnormalities in the circuit whose operation is being checked can be reliably checked, and even if a failure occurs in the operation detection circuit itself, one of the check pulses will always be detected. Since it can be detected, the operation detection circuit itself can be self-diagnosed, and the circuit whose operation is checked can be used with extremely high reliability. Furthermore, by effectively applying semi-drive signals, abnormalities can be checked in advance, and a more rational operation detection circuit can be developed.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an example of a conventional motion detection circuit, FIG. 2 is a circuit diagram showing an embodiment of the motion detection circuit according to this invention, and FIG. 3 is an explanatory diagram showing waveform time charts of various parts. FIG. 4 is an explanatory diagram showing waveform time charts of various parts when a semi-drive signal is applied. A...Circuit to be checked for operation, B...Detection section, C...Comparison section, D...Control section, _S1 ...Drive signal, _S2 ...Continuity detection signal, _S3 ...Operation detection signal,
S' ₁ ...Semi-drive signal, 1...Winding (driven element), 4...Drive transistor (drive element), 5...
...Input terminal, 9...Continuity detection signal, 13...Exclusive OR gate, 16...First check pulse (timing pulse), 17...Second check pulse (timing pulse).

Claims (1)

[Claims for Utility Model Registration] In an operation detection circuit that detects the energization state of a circuit including a drive element that becomes conductive when a drive signal is applied to an input terminal and enables energization of a driven element, the above drive A detection unit that outputs a continuity detection signal at one of two levels depending on whether the element is conductive or not, and compares this continuity detection signal with the above drive signal and outputs an operation detection signal only when they match. and a control unit that generates synchronized first and second check pulses immediately after the leading edge and immediately after the trailing edge of the drive signal, and applies these as detection timing pulses to the comparing unit. A motion detection circuit characterized by: