JPH0241617A - Protective circuit - Google Patents

Abstract

PURPOSE:To reduce damage due to the suspension of an equipment by installing a plurality of interrupting devices having different ratings in parallel, detecting the interruption of at least the interrupting device, voltage of which is lowered, and giving a warning. CONSTITUTION:When load 13 is brought to the state of overload, the temperature of a heat dissipating section 15 beings to rise. Since the input level of a non-inverting input terminal for a comparator 21 normally represents a level acquired by dividing voltage applied to load by resistors R1, R2 and the input level of an inverting input terminal voltage applied to a resistance R3 through a second temperature fuse 17 in an interruption detector 18, an output from the comparator 21 is at 'L' and a warning generator 19 is not operated. When the temperature of a heat dissipating section 15 is brought to the rated temperature Ta of the temperature fuse 17, the temperature fuse 17 is cut, the inverting input terminal voltage of the comparator 21 is brought to 0, and an output level is changed to an 'H' and the warning generator 19 is worked, thus giving a warning. When the temperature of the heat dissipating section 15 rises and exceeds the rated temperature Ta of a first temperature fuse 16, the temperature fuse 16 is cut, thus stopping power supply to the load 13.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a protection circuit using multiple disconnection devices.

[Prior Art] Generally, various types of electrical equipment are equipped with a fuse that cuts off and protects the equipment when a short circuit or other abnormal current flows.

The above fuse is installed in one power supply line of the equipment (if the fuse is a current fuse, it controls the current flowing through that line, or if the fuse is a temperature fuse, it is driven by the power supply). Touch the temperature fuse to a part of the circuit that needs to be controlled by temperature, such as a heat generating part,
I am protecting the equipment.

[Problems to be Solved by the Invention] In the conventional technology, a current exceeding the capacity of the power supply flows in the power supply line for which the fuse should be cut off, or the heat dissipation part of the power supply section exceeds the rating by 4□1 degrees. Or, if the cooling device for the power supply section or the heat dissipation section of the load malfunctions, and the heat dissipation section reaches a temperature higher than the rated temperature, the fuse will blow, cutting off the power line and minimizing damage to the equipment. . However, in medical equipment, such as endoscope equipment, when an endoscope is inserted into a patient and the endoscope image is observed on a monitor, if a fuse blows, the endoscope image being observed on the monitor suddenly disappears, causing the patient to When pulling out the inner mirror, it has to be done blindly, which poses a problem in that it can cause damage to the fool.

On the other hand, if a fuse is provided in addition to the power line,
For example, in Japanese Utility Model Application Publication No. 54-41126, a protective fuse is provided between the load signal line of the power supply and the ground wire in contact with the housing to prevent overheating and burnout of electrical components.

In the conventional example disclosed in the above-mentioned publication, if an excessive current flows through the load within the casing rather than due to a short-circuit accident in which the load comes into contact with the casing, the operation will be similar to the conventional example described above.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a protection circuit that can issue a warning and inform of an abnormality in the equipment before the fuse blows and the equipment stops functioning.

Means and Effects for Solving Problems L In the conceptual diagram of an electronic equipment device 1 shown in FIG. The circuit breaker includes a plurality of circuit breaker devices 2b, 2c, . 2a, and connected in series between the interrupting devices 2b, 2c, . . . 2n and the interrupting device 2a.
Connect m. The cutoff detection circuits 5a, . . . , 5m are connected to a warning generating device 6.

In the electronic device 1, when the load 4 becomes different, the state of the electronic device 1 starts to increase toward the rated value. Then, the conditions match those of the cutoff devices 2b, . . . 2n, starting from the lowest rating, and the power supply line is cut off. 5a, . . . 5m detect the interruption of the power line L and generate a interruption detection signal.The warning generating device 6 includes:
The cutoff detection circuit 5a, . . . , 5m receives each cutoff detection signal and issues a warning according to the signal. Therefore, emergency measures can be taken from this warning.

[Example] Hereinafter, the present invention will be specifically explained with reference to the drawings.

2 and 3 relate to a first embodiment of the present invention, FIG. 2 shows the configuration of the first embodiment, and FIG. 3 shows a specific configuration.

The electronic equipment device 11 shown in FIG.
2, and a protection circuit 14 of the first embodiment installed in the middle of one power supply line 1-1 (on the non-ground side).

In the protection circuit 14, a first temperature fuse 16 having a temperature Ta rated for a heat radiation section 15 provided in the electronic device 11 is connected in series between the power supply 12 and the load 13.
At the same time, one end of a second temperature fuse 17 having a rated temperature Tb lower than the rated temperature Ta of the first temperature fuse 16 is connected to the power supply side terminal of the first temperature fuse 16. The other end of the humidity fuse 17 is connected to one end of the cutoff detection circuit 18.
The other end is connected to the load side terminal of the first temperature sensor 16.

The cutoff detection circuit 18 detects when the second temperature sensor 17 is cut off and outputs a detection signal from an output terminal, and one warning generating device is connected to this output terminal.

Above 1st. The second temperature fuse 16.17 is connected to the heat dissipation section 1
5. Avoid thermal contact.

By the way, the configuration of the above-mentioned cutoff detection circuit 18 is shown in FIG.

As shown in FIG. 3, one end of a resistor R1 is connected to the load side terminal of the first temperature fuse 16, and the other end is connected to a resistor R1.
2 and is connected to the non-inverting input terminal of the comparator 21. The inverting input terminal of this comparator 21 is connected to the first temperature fuse 1 via the second temperature fuse 17.
It is connected to the power supply side terminal of No. 6 and grounded via a resistor R3. Also, this inverting input terminal is connected to diode 2
The cathode of this diode 22 is connected to the connection point between the load 13 and the first reservoir 16.

The output terminal J of the axis ratio device 21 is connected to the input terminal of one warning generating device composed of buzzers 1-[D and the like.

The operation of the first embodiment configured in this way will be described below.

The first temperature fuse 16 and the second fuse have a rated temperature a that is approximately the same as the permissible temperature limit value of the heat radiation part 15 at which circuit components thermally connected to the heat radiation part 15 will not be thermally destroyed.
The temperature fuse 17 has a rated temperature Tb lower than the rated temperature Ta of the first temperature fuse 16.

When the load 13 becomes overloaded, the power consumption of the electronic device 11 increases and the humidity of the heat radiation section 15 begins to rise. In the cutoff detection circuit 18, the input level of the non-inverting input terminal of the comparator 21 is normally the level obtained by dividing the voltage applied to the load 13 by the resistors R1 and R2, and the input level of the inverting input terminal is the second level.
This is the voltage applied to the resistor R3 via the temperature fuse 17 of One doesn't work. When the temperature of the heat sink 15 reaches the rated temperature Ta of the temperature fuse 17, the temperature fuse 17 is disconnected, the voltage applied to the inverting input terminal of the comparator 21 becomes O, and the non-inverting input terminal level becomes higher than the inverting input terminal level. and the output level is high (“H”).
), the warning generating device 19 is operated and a warning is issued. Thereafter, when the temperature of the heat radiation section 15 rises and exceeds the rated temperature Ta of the first temperature fuse 16, this temperature fuse 16 is cut off and power supply to the load 13 is stopped.

In this way, there are two types of temperature fuses 16 with different rated temperatures.
．． By connecting the fuses 17 in parallel and providing cutoff detection means on the temperature fuse 17 side with a low rated temperature Tl), the load 13
Since a warning is issued before the power supply to the device is cut off, the user of the device can detect an abnormality before the device stops functioning, and can prevent damage caused by the device stopping.

FIG. 4 shows a second embodiment of the present invention. Note that the same components as in FIG. 2 are not designated by the same reference numerals.

A first temperature fuse 16 is connected in series between the protective power supply 12 and the load 13, and one end of a second temperature fuse 17 having a rated humidity Tb lower than the rated temperature la of the temperature fuse 16 is connected to the first temperature fuse 16. This second temperature fuse 17 is connected to the terminal connected to the power supply side of the temperature fuse 16.
The terminal on the left side is connected to one end of a cutoff detection circuit 18, and the other end of this cutoff detection circuit 18 is connected to the load side terminal of the first thermal fuse 16. Further, the output terminal of this cutoff detection circuit 18 is connected to one bamboo warning generator.

The first and second humidity fuses 16 and 17 are connected to the power supply 12.
This is the contact rippling with the heat dissipation part 15 of.

By the way, in this second embodiment, a cooler 31 is provided to constantly cool the heat radiating section 15. This cooler 31
is formed by a fan, for example, and directs air (wind) to the heat dissipation section 15.
I'm trying to cool it down by blowing it.

The operation of this second embodiment will be explained below.

When the cold FDL device 31 malfunctions and the temperature of the heat radiation section 15 begins to rise and exceeds the rated temperature of the second temperature fuse 17, this temperature fuse 17 is blown. Then,
Since no signal is input to the inverting input terminal of the comparator 21 in the cutoff detection circuit 18, the output of this comparator 21 (,
The signal becomes 1 high, and the warning generating device 19 is activated to issue a warning. Thereafter, the temperature of the heat dissipating section 15 continues to rise ('J1) and exceeds the rated temperature 7a of the heat source 16, which causes the temperature fuse 16 to break and the supply of power to the load 13 to stop.

The effects of this second embodiment are similar to those of the first embodiment.

FIG. 5 shows a third embodiment of the invention.

This third embodiment is applied to, for example, a light source mounting 41 for an endoscope.

In this embodiment, the lighting circuit 42 is used as the load 13 in the first embodiment. This lighting circuit /I-2 supplies a dotted electric horn to the light source lamp /'I3.

The light from this light source lamp 43 passes through a condenser lens 44 and is condensed and irradiated onto a light guide connector 45 of an endoscope (not shown) connected to this light source device 41 .

By the way, the output terminal of the cutoff detection circuit 18 is connected to the control terminal of the relay drive circuit 46 as well as the warning generating device 19.
When a high signal is applied to the control end of this relay drive circuit/I6, it enters an operating state (a state in which it outputs a drive current) and performs an operation of switching the relay switch 47.

In other words, the lighting circuit 42 is normally maintained in a state where it supplies lighting current to the lamp 43 via contact a;
When the switch 47 turns on the contact a, a current smaller than that of the contact a is supplied to the lamp 43, so that the light emitting state is reduced and the amount of heat generated is also reduced.

Also, in this embodiment, the first. Second humidity fuse 16.1
7 is in thermal contact with a heat radiation part 48 provided on the light source lamp/13 side.

The first humidity fuse 16 has a rated humidity of the lamp 4.
3 is used, while the second temperature fuse 17
The one with a lower rated temperature than this temperature rating is used.

In this third embodiment, if some abnormality occurs during normal use and the temperature of the heat dissipation section 48 becomes close to the maximum allowable rated temperature, the second temperature fuse 18
is disconnected, and the warning generating device 19 issues a warning. At the same time, the relay drive circuit /'16 operates to switch the relay switch 47 to reduce the amount of light emitted and the amount of heat generated from the lamp 43. For this reason, the subsequent rise in temperature of the heat dissipation section 48 is suppressed, and the first 1 degree fuse 16 is prevented from breaking, and it takes a relatively long time to break.

Although the amount of illumination light is reduced by switching the relay switch 47, it is possible to carry out emergency treatment, pulling out the endoscope, etc. without difficulty.

In this embodiment, it is possible to more reliably prevent the light emitting function from being stopped, and therefore damage caused by this function stoppage can be effectively prevented.

In each of the above embodiments, two fuses are used, but it is also possible to provide three or more fuses, each with its own cut-off detection circuit. It is also possible to detect the disconnection of each fuse with a single disconnection detection circuit.

Further, although a temperature fuse is used in each of the above embodiments, a current fuse or a breaker may be used. Further, the cutoff detection circuit and the warning generating device may be operated for a while using a backup power source even when all fuses are blown.

[Effects of the Invention] As described above, according to the present invention, a plurality of cut-off devices with different ratings are installed in parallel (), and a warning is issued by detecting the cut-off of at least the cut-off device with a lower rating. Therefore, it is possible to know the abnormality in advance before the function of the device stops, making it easier to deal with the damage caused by the stoppage of function.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of the present invention, FIGS. 2 and 3 show a first embodiment of the present invention, FIG. 2 is a configuration diagram of an electronic device equipped with the first embodiment, and FIG. FIG. 4 is a circuit diagram showing a specific configuration of the cutoff detection circuit, FIG. 4 is a configuration diagram of a second embodiment of the present invention, and FIG. 5 is a configuration diagram of a third embodiment of the present invention. 1... Electronic equipment devices 2a, 2b,..., 2n... Cutoff device 3... Power source 4... Loads 5a, 5b,..., 5
m... Cutoff detection circuit 6... Warning generating device

Claims (1)

[Scope of Claims] An electronic device equipped with a cutoff device that cuts off the supply of power, comprising: a first cutoff device having a predetermined rating, and a first cutoff device provided in parallel with the first cutoff device in the power supply line. one or more shutoff devices set to different ratings, lower than the predetermined rating, and different in the case of two or more shutoff devices; shutoff detection means for detecting shutoff of the shutoff devices; and shutoff of the shutoff detection means. A protection circuit characterized by comprising a warning generation means for issuing a warning based on a detection signal.