JP2759506B2 - Load abnormality detection circuit in air purifier - Google Patents

Description

The present invention relates to a load abnormality detection circuit in an air purifier.

(Prior Art) An air purifier applies a high voltage between a charge electrode and a dust collection electrode to charge the dust collection electrode, and adsorbs dust and the like to purify air. The electrode and the dust collecting electrode are made into a cassette, which is detached from the air washer body so that it can be cleaned. For this reason, the cassette may be forgotten to be mounted, and the dust collecting electrode may be bent during cleaning or the like, so that if the dust collecting electrode and the charge electrode come close to each other, a short circuit occurs between them. In this case, if any of them is left, the air cleaning function is not performed. Therefore, conventionally, these are detected as abnormalities.

(Problems to be Solved by the Invention) However, in the conventional detection of this type, since signals are detected according to causes, when the signals are processed in hardware or software, different signals must be processed according to causes. There is a problem that processing is troublesome.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an inverter type switching regulator circuit including an insulating transformer and a transistor, wherein the insulating transformer is provided with a primary winding for input and a primary winding for output. In a self-excited type in which a tertiary winding is provided in addition to the secondary winding and the transistor is turned on and off by an output from the tertiary winding, the insulating transformer has a square-shaped characteristic. In addition, a signal extraction circuit is provided in the switching regulator circuit via an insulating transformer.

(Operation) In the detection circuit configured as described above, a load is connected to the secondary winding side, and when the load is normal, the transistor is repeatedly turned on and off. A predetermined signal can be extracted to the extraction circuit. However, when the load resistance is extremely large on the secondary winding side, for example, when the dust collecting electrode is forgotten to be attached as described above, no current flows through the secondary winding, and accordingly, the transistor does not turn off. , A predetermined signal cannot be extracted from the signal extraction circuit.
Also, when the load resistance of the secondary winding is extremely small, for example, as described above, when the dust collecting electrode and the charge electrode are short-circuited, as shown in FIG. A current does not flow through the secondary winding, and similarly, a predetermined signal cannot be extracted from the signal extraction circuit.

(Example) An example of the present invention will be described with reference to a separate drawing. In the drawing, reference numeral 1 denotes an inverter type switching regulator circuit including an insulating transformer 2 and a transistor 3, and the insulating transformer 2 has a tertiary winding in addition to a primary winding 2a for input and a secondary winding 2b for output. 2c, and the switching regulator circuit 1 is of a self-excited type in which the transistor 3 is turned on and off by an output from the tertiary winding 2c.

According to the present invention, the switching transformer circuit 1 is provided with a signal extracting circuit 5 via a separate insulating transformer 4 and the switching transformer circuit 1 is provided with a square character. More specifically, the switching regulator circuit 1 is a flyback type in which the secondary winding 2b and the secondary winding 2b are reversely connected to the primary winding 2a. Resistor 7 for
And the primary winding 2a and the transistor 3 are connected to a power supply, and the pace 3a of the transistor 3 is connected to the power supply via a Zener diode 8, a diode 9a and a diode 9b, and is also connected to the tertiary winding 2c. ing.

Reference numeral 10 denotes a diode interposed in the circuit 11 connecting the tertiary winding 2c and the load 12, and reference numeral 13 denotes a circuit for securing the transistor 3.

 Next, the operation of this circuit will be described.

When the load is correctly connected to the secondary winding 2b, when the power switch 6 is turned on, the starting resistor 7, the Zener diode 8, the diode 9a, the tertiary winding 2c, the diode 9b
, The base current of the transistor 3 flows, and the transistor 3 is turned on.

Then, a current corresponding to the winding resistance of the primary winding 2a flows as a collector current of the transistor 3. At this time, a voltage corresponding to the turn ratio is generated in the tertiary winding 2c, the base current of the transistor 3 is further increased, and the conduction state of the transistor 3 is maintained. Also, since the secondary winding 2b is reversely connected to the primary winding 2a, a reverse voltage is applied to the diode 10 connected to the secondary winding 2b, and no current flows through the secondary winding 2b, Is stored in the primary winding 2a.

Although the base current of the transistor 3 is maintained by the voltage generated by the tertiary winding 2c, the increase of the base current cannot follow the rapid increase of the collector current, and the transistor 3 is cut off. At this time, the energy stored in the primary winding 2a is generated in the secondary winding 2b as a reverse voltage and supplies power to the load 12. After a certain time, a surge voltage is generated in the secondary winding 2b, which is induced in the tertiary winding 2c, and the transistor 3 is turned on again. By repeating this operation, constant power is supplied to the load 12 and a signal is extracted to the signal extracting circuit 5.

However, when the resistance of the load 12 connected to the secondary winding 2b is extremely large, for example, when the collector electrode a3 is forgotten to be attached, the energy accumulated in the primary winding 2a is not sufficiently released, and the transistor When 3 is turned on, current flows in each of the windings 2a, 2b, 2c with a bias. As a result, the magnetic flux of the transformer increases and eventually saturates, so that the current flowing through each of the windings 2a, 2b, 2c itself decreases. Therefore, a signal of a sufficient voltage cannot be extracted from the signal extracting circuit 5.

Further, when the resistance of the load 12 is extremely small, for example, as described above, when the dust collecting electrode and the charge electrode are short-circuited, the current flowing through the secondary winding 2b increases and the primary winding 2a
Releases more energy than is necessary to be stored. As a result, the voltage generated in the secondary winding 2b decreases, and the voltage generated in the primary winding 2a and the tertiary winding 2c decreases (characteristics in a square shape). Therefore, the transistor 3 cannot obtain a sufficient base current and stops transmitting. As a result, a signal of a sufficient voltage cannot be extracted from the signal extraction circuit 5.

3 to 5 show an air purifier A provided with the detection circuit. The air purifier A is a cassette type in which a charging electrode a2 and a collector cell a3 are detachably attached to an air purifier main body a1. The operation of removing the charged electrode a2 and the collector cell a3 and removing dust adhering to the collector cell a3 is performed. At this time, the user forgets to attach them, or
As shown by a chain line in the figure, the collector cell a3 is bent to approach the charged electrode a2.

In such a case, however, by providing the detection circuit,
If both inconveniences occur, this can be easily detected.

It is needless to say that a forward type switching regulator circuit of the forward type described in connection with the flyback type can be used for the above-mentioned type.

(Effects of the Invention) Since the present invention has the above-described configuration, the following effects can be obtained.

When the load resistance is extremely large on the secondary winding side, for example, when the dust collecting electrode is forgotten to be attached as described above, and when the load resistance of the secondary winding is extremely small, for example, as described above, the dust collecting electrode In either case where the signal and the charge electrode are short-circuited, this can be extracted as the same signal, and there is an effect that the processing of the signal is simple.

[Brief description of the drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a circuit diagram, FIG. 2 is a characteristic diagram thereof, FIG. 3 is a slope diagram of an air purifier to which the circuit is applied, and FIG. FIG. 5 is an enlarged view of a part of the cutaway side view. 1 Switching regulator circuit 2 Insulation transformer 3 Transistor 4 Separate insulation transformer 2a Primary winding 2b Secondary winding 2c Tertiary winding

Claims (1)

(57) [Claims] 1. An inverter type switching regulator circuit comprising an insulating transformer and a transistor, wherein the insulating transformer includes a tertiary winding in addition to a primary winding for input and a secondary winding for output. In a self-excited type in which the transistor is turned on and off by an output from a tertiary winding, the insulating transformer has a square-shaped characteristic, and a signal is output to the switching regulator circuit through the insulating transformer. Abnormal load detection circuit in an air purifier equipped with a circuit.