JP4085853B2 - Electronics - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic device that is connected to a commercial power source and used in a general home.
[0002]
[Prior art]
2. Description of the Related Art In recent years, capacitors that avoid unnecessary radiation such as high-frequency noise, usually called across-the-line capacitors (hereinafter referred to as X capacitors), are connected to AC power supply lines of electronic devices.
[0003]
On the other hand, with the advancement of technology, higher frequency of DC power supply circuit that generates DC power supply from AC power supply, and higher speed operation of microcomputers, etc., high frequency high frequency noise is generated in the AC power supply line, The capacity of the X capacitor is large.
[0004]
On the other hand, the power saving of the DC circuit operated by the DC power supply is achieved, and the impedance after the DC power supply circuit (hereinafter referred to as secondary load) viewed from the AC power supply is increased.
[0005]
For these reasons, for example, an electronic device that operates at 100 V of a commercial power supply and consumes several watts or less (in other words, the secondary load is several hundred kΩ or more) has a discharge resistor connected in parallel to the X capacitor. Has been.
[0006]
When the so-called AC power source is turned off, such as when the power plug of the electronic device is pulled out from the outlet or when the power switch provided in the electronic device is turned off, the AC voltage is applied to the X capacitor when the AC power source is turned off. Since the corresponding charge is accumulated, the charge is discharged through the discharge resistor.
[0007]
As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-306160
[Problems to be solved by the invention]
However, in the above-described conventional electronic device, while the device is operating and AC power is being supplied, the discharge resistor connected in parallel with the X capacitor is energized and always consumes power, and the power consumption is low. Since the resistance value of the discharge resistor is relatively large for the purpose, there is a problem that the discharge time is long.
[0010]
The present invention solves such a conventional problem, and an object thereof is to provide an electronic device that eliminates the discharge resistance and shortens the discharge time of the charge accumulated in the X capacitor.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an across-the-line capacitor (X capacitor) connected to an AC power supply to avoid high-frequency noise and a parallel connection to the across-the-line capacitor (X capacitor). An energization element for energizing the load, a drive means for turning on and off the energization element, a control means for controlling the drive means, rectifying and smoothing the AC power supply, and at least the control means, the drive means, and the A DC power supply for supplying power to the energization element, the DC power supply operates at a high frequency, the control means detects a power supply synchronization signal of the AC power supply output from the power supply synchronization signal generation means , and the control means detecting the power-supply sync signal the AC power-off by the presence or absence of output from the power-supply sync signal generating means, said control means voltage remaining of the DC power supply Upon detecting the off of the AC power by turning on a predetermined time the current element, the charge accumulated in the across-the-line capacitor, which has been configured to discharge through the load, the As a measure against noise caused by high frequency DC power supply, even if the capacity of the across-the-line capacitor is increased, the discharge resistance can be abolished by giving the load a function of discharge resistance. In addition to being able to avoid high frequency noise .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0013]
(Embodiment)
1 is a circuit diagram of an electric pot as an electronic apparatus according to an embodiment of the present invention, FIG. 2 is a circuit diagram of the DC power supply, FIG. 3 is an operation waveform diagram of the main part, and in FIG. The AC power source 2 is connected to the AC power source 1 and emits unnecessary radiation such as high frequency noise entering the electronic device superimposed on the AC waveform of the AC power source 1 and high frequency noise output from the electronic device to the outside of the electronic device. This is an X capacitor for avoidance.
[0014]
Reference numeral 3 denotes a relay contact as an energization element, and reference numeral 4 denotes a load such as a heater that is connected to the AC power source 1 and that turns off the AC power source 1 when the relay contact 3 is opened and closed.
[0015]
Here, the relay contact 3 is opened and closed by a control means 7 such as a microcomputer driving a transistor 6 as a drive means, and the relay coil 5 is turned on and off.
[0016]
Further, a DC power supply 8 for rectifying and smoothing the AC power supply 1 supplies the generated predetermined DC voltage to the secondary load 100 such as the control means 7, and 9 generates a signal synchronized with zero volts of the AC power supply 1. It is a power supply synchronizing signal generation means.
[0017]
Reference numeral 10 is incorporated in the control means 7 as a program, and the on / off of the AC power supply 1 is detected by the power supply synchronization signal 9a of the power supply synchronization signal generating means 9, and when the AC power supply 1 is turned off, the relay contact 3 is closed for a predetermined time. An electric pot 200 is constituted by the discharge driving means to be held.
[0018]
Next, as shown in FIG. 2, the rectification circuit 8a that rectifies the AC power supply 1 and the rectification waveform rectified by the rectification circuit 8a are smoothed by a smoothing circuit 8b composed of a diode 81 and a capacitor 82 connected in parallel. A DC power supply 8 is configured.
[0019]
The rectifier circuit 8a is a single-wave rectifier circuit that rectifies only the positive waveform of the AC power supply 1, but is not limited thereto, and may be a full-wave rectifier circuit that rectifies both positive and negative waves of the AC waveform. .
[0020]
Regarding the electric pot 200 configured as described above, the normal operation when energized will be described below.
[0021]
First, in FIG. 1, when water is stored (not shown) in the electric pot 200 energized by the user, the control means 7 detects the water temperature with a temperature sensor (not shown) or the like, When it is determined that the temperature is lower than or equal to the temperature, a control program (not shown) is activated to output an ON signal to the transistor 6.
[0022]
Then, when the transistor 6 is turned on, the relay coil 5 is turned on, the relay contact 3 is closed, and the heater 4 as a load is energized with the AC power supply 1 to perform a water heating operation.
[0023]
Further, when the control means 7 detects the boiling temperature, it outputs an off signal to the transistor 6, the heater 4 is turned off, and the operation of boiling water is stopped.
[0024]
Next, in order to maintain a predetermined hot water temperature that is convenient for use after the boiling operation, the control means 7 detects the hot water temperature and outputs a short on / off signal to the transistor 6, and the relay contact 3 opens and closes. Accordingly, the heater 4 is turned off and performs a heat retaining operation so as to keep the hot water temperature at a predetermined temperature.
[0025]
Here, in any of the operation states described above, when the AC power supply 1 is turned off when a power plug (not shown) of the electric pot 200 or a magnet plug (not shown) using a magnet is pulled out, Since the electric charge accumulated in the X capacitor 2 is exposed at both ends of these plugs, it is necessary to take measures so that a user or the like can safely touch the plug.
[0026]
Hereinafter, the discharge operation of the charge accumulated in the X capacitor 2 of the present invention will be described with reference to FIG.
[0027]
First, as shown in FIG. 3A, when the AC power supply 1 is turned off at the point a1, the AC voltage of the AC power supply 1 supplied to the electric pot 200 becomes zero volts, but the X capacitor 2 has an AC power supply 1 The charge corresponding to the AC voltage at the time of turning off is accumulated and remains as it is.
[0028]
Here, the AC power supply 1 is turned off at any time, and the maximum charge is accumulated in the X capacitor 2 at the positive and negative peak points of the AC waveform.
[0029]
Next, as shown in FIG. 3 (b), the power supply synchronization signal generating means 9 outputs a rectangular wave power supply synchronization signal 9 a synchronized with zero volts of the AC power supply 1 to the control means 7 when the AC power supply 1 is on. However, the output of the power supply synchronizing signal 9a stops after the point a1 when the AC power supply 1 is turned off.
[0030]
On the other hand, as shown in FIG. 3C, the output of the DC power supply 8 is not lost immediately after the AC power supply 1 is turned off from the ON state, but the capacitance values of the diode 81 and the capacitor 82 shown in FIG. Is appropriately selected, it is possible to secure the operating voltage V1 at which the secondary load 100 operates normally for a predetermined ta time.
[0031]
For example, when the DC voltage VD is 5 v, the operating voltage V1 at which the secondary load 100 operates normally is 4.5 v, the current of the secondary load 100 is 10 mA, and the capacitance value of the capacitor 82 is 100 μF, the discharge of the capacitor 82 From the characteristics, the time ta from when the AC power supply 1 is turned off (point a1) until the DC voltage VD becomes the operating voltage V1 is approximately 5 ms.
[0032]
As described above, even if the AC power supply 1 is turned off, the secondary load 100 operates for the ta time.
[0033]
Incidentally, the impedance of the secondary load of the electric pot 200 is 200 kΩ.
[0034]
When the control means 7 of the present invention detects that the AC power supply 1 is turned off by the signal of the power supply synchronization signal 9b as shown in FIG. 3 (d1), the control means 7 outputs an on signal to the transistor 6. The discharge driving means 10 is driven to operate to output an on signal (6a) to the transistor 6 for a predetermined time (from td1 to ta).
[0035]
Further, as shown in FIG. 3 (d2), the control means 7 stops the off signal and drives the discharge driving means 10 when the off signal is output to the transistor 6 when the AC power source 1 is turned off. Then, the transistor 6 operates to output an ON signal (6a) to the transistor 6 for a predetermined time (from td2 to ta).
[0036]
Here, the times td1 and td2 are times necessary for discharging the electric charge accumulated in the X capacitor 2 to the heater 4, and differ depending on the electronic equipment and are stored in the discharge driving means 10 by experiments or the like.
[0037]
As described above, the control means 7 connects the energizing element 3 and the heater 4 to the X capacitor 2 for a predetermined time determined by the discharge driving means 10 after the AC power source 1 is turned off, thereby forming a discharge path. The electric charge accumulated in 2 is discharged through the heater 4.
[0038]
Next, the discharge characteristics due to the difference in the discharge resistance (or load resistance) with the X capacitor 2 of FIG. 4 as 1 μF will be described.
[0039]
First, the discharge resistance R shown in FIG. 4A is infinite when the discharge path is not formed in the X capacitor 2, and only the self-discharge of the X capacitor 2 takes a long discharge time.
[0040]
Next, FIG. 4B shows the case where the discharge resistance R connected in parallel to the X capacitor 2 is 100 kΩ, as in the case of the prior art, and the charge accumulated in the X capacitor 2 is 100 kΩ of the discharge resistance R. The discharge time at that time is approximately 100 ms.
[0041]
FIG. 4C shows the case where the load resistance R according to the present invention is 10Ω, for example, the case where the heater 4 of the electric pot 200 is 1000 W (the load resistance R is 10Ω), and is accumulated in the X capacitor 2. The discharged electric charge is discharged through 10Ω of the load resistance R, and the discharge time at that time is approximately 10 μs.
[0042]
In other words, the electric pot 200 of the present invention eliminates the need for a discharge resistor, and the discharge time of the charge accumulated in the X capacitor 2 can be shortened to 1/10000 of the conventional example, which can be shortened significantly.
[0043]
As described above, according to the present embodiment, the control means detects that the AC power supply is turned off, turns on the energization element while the voltage of the DC power supply remains, and discharges the charge accumulated in the X capacitor via the load. Thus, since the load functions as a discharge resistor, the discharge resistor can be eliminated and an inexpensive electronic device can be obtained.
[0044]
In the present embodiment, the load is described as the heater 4. However, the present invention is not limited to this, and can be implemented as long as it is a resistive load such as a motor or a light bulb.
[0045]
Further, although the electronic device has been described as an electric pot, the embodiment of the present invention is not limited to this, and a device main body itself such as a video device may be used as a load.
[0046]
For example, when the device main body is a television device and the power consumption of the television device is 100 W, the charge stored in the X capacitor 2 can be discharged using the television device as a load, and the discharge time is 100 μs. Become.
[0047]
Furthermore, although the energizing element has been described as the relay contact 3, it is not limited to the relay contact or the power switch, and the present invention can be implemented as long as it is an energizing element such as a thyristor or FET that can energize the AC power supply 1 bidirectionally. is there.
[0048]
【The invention's effect】
As described above, according to the present invention, while the voltage of the DC power supply remains after the AC power supply is turned OFF, the control means detects the AC power supply OFF to drive the discharge driving means, and loads the X capacitor for a predetermined time. By connecting and forming a discharge path, there is an advantageous effect that a discharge resistor is not required and an inexpensive electronic device can be obtained.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an electric pot as an electronic device according to an embodiment of the present invention. FIG. 2 is a circuit diagram of the DC power source. FIG. 3 is an operation waveform diagram of the main part. Schematic diagram [Explanation of symbols]
1 AC power supply 2 X capacitor 3 Energizing element (relay contact)
4 Load 5 Relay coil 6 Drive means (transistor)
7 Control means 8 DC power supply 9 Power supply synchronization signal generation means 10 Discharge drive means

Claims (1)

An across-the-line capacitor (X capacitor) that is connected to an AC power supply to avoid high-frequency noise, and a current-carrying element that is connected in parallel to the across-the-line capacitor (X capacitor) to energize the load; Drive means for turning on and off the energization element; control means for controlling the drive means; rectifying and smoothing the AC power supply; and at least a DC power supply for supplying power to the control means, the drive means, and the energization element The DC power supply operates at a high frequency, and the control means detects the power supply synchronization signal of the AC power supply output from the power supply synchronization signal generation means , and the control means outputs the power supply output from the power supply synchronization signal generation means. the presence or absence of the synchronization signal detected off of the AC power source, when the control means detects the off of the AC power while the voltage remaining the DC power supply A constant time the energizing element is turned on, the charge accumulated in the across-the-line capacitor, an electronic apparatus to be discharged through the load.

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