JP4399313B2 - Voltage detector - Google Patents

Description

  The present invention relates to a battery-type voltage detector that obtains an operating power supply from a built-in battery (battery), and more particularly to a battery check technique.

  The voltage detector has a sensor (electrode plate in short) that is capacitively coupled to the line to be detected, and is used to measure whether or not current flows by bringing the sensor close to, for example, an outlet or a power cord. .

  That is, when an electric current is flowing, an electric field is generated around the current, so that an AC output is obtained by the sensor, thereby detecting a live line. The distinction between a live line and a non-live line is normally displayed as a live line when turned on by a light emitting diode (LED) and as a non-live line when turned off.

  Since the voltage detector is carried and used, it is often driven by a battery. However, when the LED is turned off, it cannot be distinguished whether it is due to a non-live line or due to a dead battery. For this reason, for example, in the invention described in Patent Document 1, a test switch is provided separately from the power switch to check whether the measurement circuit operates normally before measurement, including the state of the battery.

Microfilm of Japanese Utility Model No. 57-200004 (Japanese Utility Model Publication No. 59-104083)

  However, it is not only cumbersome to operate the test switch every time measurement is performed, but it may be forgotten by carelessness. In addition, even if it is confirmed that the test switch operates normally, the battery may run out in the middle of walking around many measurement points with the power switch turned on. . Then, unless the test switch is operated again, as described above, it cannot be distinguished whether the LED is turned off due to a non-live line or due to the battery running out.

  Therefore, a problem to be solved by the present invention is to provide a voltage detector that can always perform a battery check without requiring a special operation if a power switch is turned on.

In order to solve the above-mentioned problem, the invention according to claim 1 of the present application has a sensor that is capacitively coupled to the detected line, and is based on the output of the sensor. In a battery-type voltage detector for displaying the difference between the above, a power switch including a first light emitting diode for displaying normality / abnormality of a built-in battery and a second light emitting diode for displaying a live / inactive line of the detected line Display means connected to the battery via the sensor, detection means for monitoring the output of the sensor and outputting either a live signal or a non-live signal, the voltage of the battery and the output from the detection means Display control means for controlling the display means based on the display control means, wherein the display control means causes the battery voltage to be equal to or higher than the forward voltage of the first light emitting diode and the output of the detection means is a non-live signal. In the case of Lighting light diode, the second light emitting diode is extinguished, when the voltage of the battery output of the forward voltage over and the detection means of the first light emitting diode is hot signal the first light When the diode is turned off, the second light emitting diode is turned on, and the battery voltage is less than the forward voltage of the first light emitting diode, both the first and second light emitting diodes are turned off. It is a feature.

  The invention described in claim 2 of the present application is characterized in that, in the above-mentioned claim 1, the emission color of the first light emitting diode is a safe color, and the emission color of the second light emitting diode is a dangerous color. Here, safe colors are green, blue, and white colors, and dangerous colors are orange, red, and yellow colors.

  The invention according to claim 3 of the present application is the logic IC according to claim 1 or 2, wherein the detection means inputs the output of the sensor superimposed on a bias voltage obtained by dividing the voltage of the battery by a predetermined value. A rectifier circuit including a resistor and a capacitor connected in parallel, the input side being connected to the output side of the amplifier circuit via a diode connected in the reverse direction when viewed from the output side, and the output of the rectifier circuit The display control means includes a switching element that is connected to the drive current path of the second light emitting diode and is turned on / off by the output of the comparison circuit. The drive current path of the first light emitting diode is connected to the output side of the comparison circuit.

  The invention according to claim 4 of the present application is characterized in that, in claim 1, 2 or 3, the forward voltage of the first light emitting diode is higher than the minimum operating voltage of the detecting means.

  According to the present invention, it is understood that the battery is normal (within the effective voltage range) when the power switch is turned on and, for example, the green first light emitting diode is lit. As a result of bringing the sensor closer to the detected line, the first light-emitting diode is turned off, and instead, for example, the red second light-emitting diode is turned on, it is understood that it is a “live line”. On the other hand, if the first light emitting diode is lit and the second light emitting diode is not lit, it is understood that it is a “non-live line”.

  In this way, if any one of the light emitting diodes is lit, it can be seen that the battery is within the effective voltage range during that time, and if the first light emitting diode does not light from the beginning or two light emitting diodes are being measured. When both are turned off, it can be seen that the battery has run out, so the test switch for checking the battery itself can be dispensed with.

  Next, an embodiment of the present invention will be described with reference to the circuit diagram of FIG. 1, but the present invention is not limited to this. FIG. 2 is a flowchart when using the voltage detector of the present invention.

  As shown in FIG. 1, the voltage detector 10 is a battery-type voltage detector having a sensor 10B and operated by a built-in battery 10A, and includes two light emitting diodes 11 and 12 as display means. One light-emitting diode 11 displays the voltage state (normal or abnormal) of the battery 10A. In this example, green light-emitting diodes of green, blue, and white that are said to be safe colors are used. In the description, it is referred to as “green LED”.

  On the other hand, the other light emitting diode 12 indicates whether the detected line is a live line or a non-live line. In this example, a red light-emitting diode of orange, red, or yellow is called a dangerous color. Since it is used, it is referred to as “red LED” in the following description.

  In order to control the green LED 11 and the red LED according to the output from the sensor 10B and the voltage state of the battery 10A, the voltage detector 10 includes a bias circuit 20, an amplifier circuit 30, a rectifier circuit 40, a comparison circuit 50, and a display control circuit 60. ing. These circuits including the LEDs 11 and 12 are connected in parallel between the positive and negative lines of the battery 10A, and a power switch 10C of the battery 10A is provided on the positive line side.

  In this example, the forward voltage of the green LED 11 is 2.1V, and the forward voltage of the red LED 12 is 1.9V. This forward voltage difference is preferably 0.2 V or more. The sensor 10B may be a known sensor having an electrode plate that is capacitively coupled to a detected line (for example, a commercial power line) X shown in the chain line, and when the current is flowing through the detected line X, An AC signal induced by an electric field is output.

  The bias circuit 20 includes two voltage dividing resistors 21 and 22 that divide the voltage of the battery 10A (hereinafter, simply referred to as a power supply voltage), and supplies the divided voltage to the amplifier circuit 30 as a bias voltage. The AC output signal of the sensor 10B is superimposed on the bias voltage and input to the amplifier circuit 30. In this example, the power supply voltage is divided by the bias circuit 20 to a voltage slightly lower than ½. For example, when the power supply voltage is 3V, the voltage division ratio is set to be about 1.4V.

  Both the amplifier circuit 30 and the comparison circuit 50 use output inversion logic ICs (inverters). The recommended operating voltage of this logic IC is 2 to 5.5 V, and in this example, the input threshold is set to 1/2 of the power supply voltage, that is, 1.5 V if the power supply voltage is 3 V. The logic IC used for the amplifier circuit 30 and the comparison circuit 50 may be a non-inverting type.

  The rectifier circuit 40 is composed of a CR circuit including a capacitor 41 and a resistor 42 connected in parallel to the positive line of the battery 10A. The input side of the rectifier circuit 40 is connected to the output side of the amplifier circuit 30 via a diode 43. ing. The diode 43 is connected in the reverse direction when viewed from the output side of the amplifier circuit 30. The output side of the rectifier circuit 40 is connected to the input side of the comparison circuit 50.

  In the display control circuit 60, the anode side of the green LED 11 is connected to the positive line of the battery 10 </ b> A via the load resistor 11 a, and the cathode side is connected to the output side of the comparison circuit 50. The anode side of the red LED 12 is also connected to the positive line of the battery 10A through the load resistor 12a, while the cathode side is connected to the negative line of the battery 10A through the switching element 61 controlled by the comparison circuit 50. ing.

  In this example, an NPN transistor is used as the switching element 61, its collector-emitter is included in the drive current path of the red LED 12, and the base is connected to the output side of the comparison circuit 50. An FET (field effect transistor) or a mechanical switch may be used as the switching element 61.

  Here, an example of the operation of the voltage detector 10 according to the present invention will be described on the assumption that the power supply voltage of the battery 10A is 3 V obtained when two AAA batteries, for example, 1.5 V are connected in series.

  First, a case where the detected line X is in a non-live line state will be described. When the power switch 10C is turned on, the output of the sensor 10B is 0, so that only the bias voltage of about 1.4 V divided by the voltage dividing resistors 21 and 22 is input to the amplifier circuit 30. Since the input threshold value of the amplifier circuit 30 is 1.5V, the input level is regarded as Lo and the output is Hi.

  Since the output of the amplifier circuit 30 is Hi, the input side of the rectifier circuit 40 is also Hi, so that the output side of the rectifier circuit 40 is also Hi. Since the Hi output of the rectifier circuit 40 is input to the comparison circuit 50, the output becomes Lo (approximately 0V).

  Accordingly, the transistor 61 is kept off and the red LED 12 is not lit. At this time, if the power supply voltage of the battery 10A is 2.1 V or more, the positive electrode side of the battery 10A passes through the green LED 11 toward the output side of the comparison circuit 50. Since the current flows, the green LED 11 is turned on.

  As described above, since the forward voltage of the green LED 11 is 2.1 V, which is higher than 2 V, which is the recommended minimum operating voltage of the logic IC used in the amplifier circuit 30 and the comparison circuit 50, the green LED 11 is lit. In the meantime, it can be seen that the power supply voltage is within the normal voltage range in which the circuit operates properly.

  On the other hand, if the green LED 11 does not light even when the power switch 10C is turned on, it can be seen that the power supply voltage is less than 2.1V and is below the circuit operating range, that is, the battery is dead. Further, even when the green LED 11 is initially turned on when the power switch 10C is turned on, it is understood that the battery is dead because the green LED 11 is turned off when the power supply voltage becomes less than 2.1 V during the measurement.

Next , a case where the detected line X is in a live line state will be described. When the power switch 10C is turned on and the sensor 10B is brought close to the detected line X, the detected line X and the sensor 10B are capacitively coupled, so that an AC signal is output from the sensor 10B. This AC signal is superimposed on the above-described bias voltage of about 1.4 V and input to the amplifier circuit 30.

  When this input signal swings in the + and-directions with the input threshold value of 1.5 V as the boundary of the amplifier circuit 30 as a boundary, a square wave that repeats Hi and Lo appears on the output side of the amplifier circuit 30 accordingly. This square wave is rectified by the rectifier circuit 40. Since the rectifier circuit 40 is a circuit pulled up to the Hi side by the resistor 42, when the square wave is input, it becomes the Lo level due to the difference in impedance.

  As a result, Lo is input to the comparison circuit 50 and its output becomes Hi. Accordingly, the driving current does not flow to the green LED 11 and the green LED 11 is turned off. Instead, the transistor 61 is turned on, and the red LED 12 is turned on. Thereby, it turns out that the to-be-detected track | line X is a live-line state. When the power switch 10C is off, no power is supplied, so both the green LED 11 and the red LED 12 are turned off.

  By the way, when the power supply voltage of the battery 10A is lowered to, for example, 1.9 V in the live line detection state, malfunction may occur because it is lower than the recommended operation voltage of the logic IC used in the amplifier circuit 30 and the comparison circuit 50. There is sex.

  However, even if the red LED 12 is lit due to a malfunction, the green LED 11 is not lit because the power supply voltage is lower than the forward voltage of the green LED 11. Therefore, the live line state is not determined as the non-live line state, and the user is not exposed to the risk of electric shock.

  Referring to the flowchart of FIG. 2, according to the present invention, the battery 10A is normal if the green LED 11 is lit when the power switch 10C is turned on for measurement, and the battery is dead if not lit. And the power switch 10C is turned on again.

  When the green LED 11 is lit and the sensor 10B is brought close to the detected track X, the red LED 12 is not lit. On the other hand, when the green LED 11 that has been lit is turned off, and the red LED 12 is lit instead, it is understood that it is a live line. Although not shown in FIG. 2, it can be seen that the battery has run out when both the green LED 11 and the red LED 12 are turned off during the measurement.

The circuit diagram for demonstrating embodiment of the voltage detector by this invention. The flowchart at the time of using the said voltage detector.

Explanation of symbols

10A battery 10B sensor 10C power switch 11 first light emitting diode (green LED)
12 Second light emitting diode (red LED)
20 Bias circuit 30 Amplifier circuit 40 Rectifier circuit 50 Comparison circuit 60 Display control circuit 61 Switching element (transistor)

Claims (4)

In a battery-type voltage detector having a sensor capacitively coupled to the detected line, and displaying whether the detected line is a live line or a non-live line based on the output of the sensor,
Display means connected to the battery via a power switch, including a first light emitting diode for displaying normality / abnormality of a built-in battery and a second light emitting diode for displaying a live line / non-live line of the detected line; Detecting means for monitoring the output of the sensor and outputting either a live signal or a non-live signal, and display control for controlling the display means based on the voltage of the battery and the output from the detecting means Means,
When the voltage of the battery is equal to or higher than the forward voltage of the first light emitting diode and the output of the detecting means is a non-live signal, the display control means turns on the first light emitting diode and the second light emitting When the diode is turned off, the voltage of the battery is equal to or higher than the forward voltage of the first light emitting diode , and the output of the detecting means is a live signal, the first light emitting diode is turned off, and the second light emitting diode When the battery is turned on and the voltage of the battery is less than the forward voltage of the first light emitting diode, both the first and second light emitting diodes are turned off.   2. The voltage detector according to claim 1, wherein an emission color of the first light emitting diode is a safety color, and an emission color of the second light emitting diode is a dangerous color.   The detection means includes an amplifying circuit composed of a logic IC in which the output of the sensor is superimposed on a bias voltage obtained by dividing the voltage of the battery by a predetermined voltage, and a resistor and a capacitor connected in parallel. The display control means comprising: a rectifier circuit connected to the output side of the circuit via a diode connected in a reverse direction when viewed from the output side; and a comparator circuit comprising a logic IC connected to the output side of the rectifier circuit. Has a switching element connected to the drive current path of the second light emitting diode and turned on and off by the output of the comparison circuit, and the drive current path of the first light emitting diode is connected to the output side of the comparison circuit. The voltage detector according to claim 1, wherein the voltage detector is provided.   4. The voltage detector according to claim 1, wherein a forward voltage of the first light emitting diode is higher than a minimum operating voltage of the detecting means.

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