JPH07280855A - Voltage detecting circuit - Google Patents

Abstract

PURPOSE:To provide a voltage detecting circuit in which the insulation from the circuit on the receiving circuit is ensured and the size of circuit can be reduced while suppressing generation of heat. CONSTITUTION:The voltage detecting circuit comprises a unit 1 which emits light upon conduction for delivering a detection signal, a group 2 of a plurality of series LEDs 23 connected in series with the unit 1, and a resistor element 3 connected in series with the LED group 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a voltage detection circuit for detecting the presence or absence of a power supply voltage of V system or higher, detecting the operation of a relay, a motor, etc., and detecting the disconnection of a motor coil.

[0002]

2. Description of the Related Art As a first conventional example, there is one that detects the presence or absence of a voltage by the open / closed state of a contact of a voltage relay.
As a second conventional example, as shown in FIG. 10, an optical link element 5 for transmitting a detection signal is provided to a resistance element 50 that limits a current.
Some have connected 1 to perform detection. Reference numeral 52 is an optical fiber whose one end is connected to the light emitting portion of the optical link element 51, and 53 is an input side optical link element in the receiving circuit 54. P and N are power supplies.

[0003]

However, since the first conventional example is of the relay type, it requires an operating time of several msec to detect the presence / absence of a voltage, and the problem of insulation from the receiving side circuit and the mechanical problem. There was a problem of life expectancy. The second conventional example is the first
However, there is a problem of heat generation when it is applied to a DC 100V circuit system or a voltage circuit system higher than that. That is, since a voltage obtained by subtracting the forward voltage of the optical link element 51 from the power supply voltage is applied to the current limiting resistance element 50, when the necessary forward current of the optical link element 51 is considered to be constant, the power supply voltage is large. The amount of heat generated increases. Therefore, there is a defect that the resistance element 50 for securing the rated power is increased in size due to safety against heat generation.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a voltage detecting circuit which can ensure insulation from a receiving side circuit and can reduce the size of the circuit and suppress heat generation.

[0005]

A voltage detection circuit of the present invention comprises a light emitting device for transmitting a detection signal which emits light when energized,
A light emitting diode group consisting of a plurality of light emitting diodes connected in series to each other and connected in series to the light emitting device,
The light emitting diode group is provided with a resistance element connected in series.

[0006]

According to the structure of the present invention, when a voltage is applied to the voltage detecting circuit, a current flows through the light emitting device for transmitting the detection signal, the light emitting diode group and the resistance element, and the light emitting device and the light emitting diode for transmitting the detection signal. The group emits light, and the optical signal of the light emitting device for transmitting the detection signal is transmitted to the receiving side circuit through, for example, the optical connector and the optical fiber connected to the light emitting device, and is detected. In this case, the voltage applied to the voltage detection circuit is divided and divided by the light emitting device, the light emitting diode group, and the resistance element. However, since the light emitting diode group shares the voltage, the burden of the voltage of the resistance element is suppressed. The heat generation amount of the resistance element is suppressed as compared with the example.
On the other hand, the light emitting diode group emits light but hardly generates heat. Therefore, since the detection signal is light, electrical insulation from the receiving side circuit can be ensured, heat generation of the resistance element can be suppressed, and the size of the voltage detection circuit can be reduced.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. That is, this voltage detection circuit is used in the light emitting device 1.
And a light emitting diode group 2 and a resistance element 3. The light emitting device 1 is for transmitting a detection signal and emits light when energized. The light emitting device 1 of the embodiment uses the optical link element shown in FIG. 7 (for example, DF 1701 / T manufactured by Sumitomo Electric Industries, Ltd .; rating 5V, 70 mA, transmission distance 40 m). Figure 7
In, 4 is a TTL buffer, 5 to 9 are transistors, 10 is a resistance element, 11 is a light emitting diode, 12 is a case, IN is an input terminal, Vcc is a power terminal, PC is a light emitting diode power control terminal, and GND is a ground terminal. Reference numeral 13 is an optical connector for receiving the light of the light emitting diode 11, to which an optical fiber 14 is connected and is connected to a receiving circuit (not shown). The input terminal IN is fixed to the optical link power supply potential, and the power control terminal PC is directly connected to the power supply terminal Vcc. The current and voltage used for this optical link device is a forward current of 30 mA in consideration of stability.
Although the forward voltage is set to about 3.8 V, it may be about 10 mA if the transmission distance is about 5 m.

The light emitting diode group 2 comprises a plurality of light emitting diodes 23 connected in series with each other and is connected in series with the light emitting device 1. Example Light-Emitting Diode Group 2
Prepares a 20V type configured by a collective element formed by connecting 10 chips of the light emitting diode 23 in series, and a 10V type configured by connecting 5 chips of the light emitting diode 23 in series. 2 shows a light emitting diode 23
A cylindrical package 1 of a 20V type connected in series and having a diameter of about 5φ as shown in FIGS. 3 and 4.
It is arranged and housed in a substantially ring-like shape in FIG. Reference numeral 16 is a transparent cover, and 17 is a lead wire. FIG. 5 shows a 10V type in which five light emitting diodes 23 are connected in series,
As shown in FIG. 6, it is housed in the package 15 in a substantially semicircular shape. The side view of the package 15 is similar to that of FIG.

Since the forward voltage of the light emitting diodes 23 is about 2V, the voltage of the light emitting diode group 2 when the number of the light emitting diodes 23 is 10, for example, is about 20V. As described above, the value of the forward voltage of about 2 V of the light emitting diode 23 is about three times as high as that of the diode, but the temperature rise is hardly seen even when the rated current continues to flow. Therefore, by using the light emitting diode group 2, The load of the voltage applied to the current limiting resistance element 3 can be efficiently reduced in terms of mounting space.

The resistance element 3 is connected in series with the light emitting diode 2 and also serves as a current limiting function of the light emitting diode 2. In addition, P and N are power supplies. According to this embodiment, when a voltage is applied to the voltage detection circuit, a current flows through the light emitting device 1 for transmitting the detection signal, the light emitting diode group 2, and the resistance element 3, and the light emitting device 1 and the light emitting diode for transmitting the detection signal. The group 2 emits light, and the optical signal of the light emitting device 1 for transmitting the detection signal is connected to the light emitting device 1 by the optical connector 1.
3 and the optical fiber 14 to be transmitted to a receiving side circuit (not shown) and detected.

In this case, the voltage applied to the voltage detection circuit is
The light-emitting device 1, the light-emitting diode group 2 and the resistance element 3 share and divide the voltage. However, since the light-emitting diode group 2 shares the voltage, the load of the voltage of the resistance element 3 is suppressed. The calorific value of 3 is suppressed. On the other hand, the light emitting diode group 2 emits light but hardly generates heat. For example, the circuit voltage V, the forward voltage V _LINK of the optical link element of the light emitting device 2, the power consumption W _R1 of the resistance element 50 of the conventional example, the forward voltage V _{LED of} the light emitting diode 2, the number n of the elements of the light emitting diode 2, Assuming the power consumption W _R2 of the resistance element 3 in the example,
The power consumption ratio W _R2 / W _R1 is: W _R2 / W _R1 = {V− (V _LINK + V _LED × n)} / (V−
V _LINK ).

In the case of a 100V system circuit, the resistance element 3
Burden voltage + forward voltage of the light emitting device 1 = about 10 V,
When the remaining 90V is applied to the light emitting diode group 2,
4 of the above-mentioned 20V type light emitting diode groups 2 and 1
A total of five 0V type light emitting diode groups 2,
The resistor element 3 and the light emitting device 1 are connected in series. At this time, V = 100V, V _LINK = 3V, V _LED × 45 = 90
Since it is V, W _R2 / W _R1 = 1 / 13.9. Then, assuming that the forward current I _H of the optical link element is 30 mA,
W _R1 = 2.91 W and W _R2 = 0.21 W.

Therefore, since the detection signal is light, electrical insulation from the receiving side circuit can be ensured and the resistance element 3
Therefore, it is possible to suppress the heat generation and to downsize the voltage detection circuit. Also 10V type and 20
By preparing the light emitting diode group 2 corresponding to various voltages by changing the number of elements like the V type light emitting diode group 2, it becomes possible to easily cope with different voltages and generate heat according to the voltage class to be detected. A suppression type voltage detection circuit can be configured.

Further, by using a device in which the chips of the light emitting diodes 23 forming the light emitting diode group 2 are assembled in the package 15 to form a collective element, the efficiency of the mounting space can be increased. For example, when the total number of the light emitting diode groups 2 is 5, the mounting area can be reduced to about 2 cm square. As a result, this example
It is possible to provide various highly reliable voltage detection circuits that are compact, operate at high speed, have high insulation, and have no contacts.

FIG. 8 shows an example applied to a relay operation detecting circuit using this voltage detecting circuit. Reference numeral 19 is a normally open contact of a relay (not shown), which is connected to the voltage detecting circuit A in series. In the voltage detection circuit A, 20 is a reverse voltage protection element connected in series, and 21 is an eight series overvoltage protection diode connected in parallel to the light emitting device 1. When the normally-open contact 19 is turned on, a current flows through the voltage detection circuit A, so that the light emitting device 1 emits light and the signal is transmitted to the reception circuit to detect the operation of the relay.

FIG. 9 monitors the operation of a motor rated at 5 A. A normally open contact 22 is connected in series to a motor coil 23, and a voltage detection circuit is connected in parallel to the normally open contact 22. In this case, about 30 mA flows to the voltage detection circuit A, but since it does not affect the motor coil 23, no malfunction occurs,
The voltage detection circuit A detects both contact operation and coil breakage.

In the present invention, the light emitting device 1 may be a photo coupler in addition to the optical link element.

[0018]

According to the voltage detection circuit of the present invention, the voltage applied to the voltage detection circuit is divided and divided by the light emitting device, the light emitting diode group and the resistance element. Since the voltage load on the resistance element is suppressed, the amount of heat generated by the resistance element is suppressed as compared with the conventional example. On the other hand, the light emitting diode group emits light but hardly generates heat. Therefore, since the detection signal is light, electrical insulation from the receiving side circuit can be ensured, heat generation of the resistance element can be suppressed, and the voltage detection circuit can be downsized.

[Brief description of drawings]

FIG. 1 is a voltage detection circuit diagram of an embodiment of the present invention.

FIG. 2 is a circuit diagram of a light emitting diode group including ten light emitting diodes.

FIG. 3 is a plan view showing a state where the light emitting diode group is housed in a package.

FIG. 4 is a side view thereof.

FIG. 5 is a circuit diagram of a light emitting diode group including five light emitting diodes.

FIG. 6 is a plan view of the package housed state.

FIG. 7 is a circuit diagram of an optical link device.

FIG. 8 is a relay operation detection circuit diagram.

FIG. 9 is a circuit diagram of a motor operation detection and motor coil disconnection detection circuit.

FIG. 10 is a voltage detection circuit diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light emitting device 2 Light emitting diode group 3 Resistance element 14 Optical fiber 23 Light emitting diode

Claims (1)

[Claims] 1. A light emitting device for transmitting a detection signal which emits light when energized, a light emitting diode group consisting of a plurality of light emitting diodes connected in series to each other, and a light emitting diode group connected in series to the light emitting device, A voltage detection circuit including a resistance element connected in series.