JPH01250204A - Load voltage switching circuit - Google Patents

Abstract

PURPOSE:To set a load to a proper value according to a supplied alternating current voltage by converting the alternating current to a direct current and disposing a SCR, a voltage division resistance, a constant current conductive element and a change over switching element at a direct current power source to form a circuit. CONSTITUTION:In case a power source is 100V, since the potential of the connecting part P of a voltage division resistances 29, 30 is low and a constant voltage conductive element 31 is not caused to be conductive, a SCR 28 is not conductive, a first and a second heaters 11, 12 are respectively connected in parallel to the contact of the first switching element 20 and the second switching element 21 of a first and a second relays 15a, 15b to lower a synthesized resistance and it is connected to a power supply terminals 19a, 19b. In case the power source is 200V, the potential of the connecting part P of the voltage division resistances 29, 30 is raised, when it reaches above Zener voltage of the constant voltage conductive element 31, the conductive element is made conductive to make the SCR 28 conductive, respectively energize the first and the second relays 15a, 15b, open the first switching element 20, switch the variable contact piece 21a of the second switching element 21, connect the first heater and the second heater serially and increase all the synthesized resistance value of the heater.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a load voltage switching circuit suitable for portable appliances such as hair dryers.

(b) Conventional technology Although commercial voltages in various countries around the world currently vary,
Generally speaking, countries are divided into countries with a rated voltage of 100V and 200V.

In addition, the number of overseas travelers has increased recently, and these travelers have begun to carry small hair dryers, irons, etc. as necessities, but in general, hair dryers and irons used in Japanese paintings are It has the disadvantage that it cannot be used in Europe and other countries where the commercial voltage is different from that in Japan. For this reason, for example, Utility Model Publication No. 58-18 filed by the same applicant.
As disclosed in Publication No. 804, when the commercial voltage is 100V, multiple loads (heaters) are connected in parallel to the power supply using a changeover switch, and when the commercial voltage is 200V, multiple loads are connected in parallel to the power supply. The configuration is connected in series. As shown in Figure 2 of the above-mentioned prior art, a specific means for this study is to provide a convex movable contact piece (no drawing number) on the changeover switch (11), and connect each load in parallel to the power supply. If you do (
100V) is connected to the power supply at both ends of each load using two movable contacts, and when connecting each load in series, 1
This is done using two movable contact pieces.

Although the above-mentioned switching means can easily connect multiple loads in parallel or series with a single changeover switch, it is necessary to check whether the AC voltage being supplied is 100 or 200. It is necessary to manually operate the changeover switch, which makes checking and operation troublesome, and if the AC power source is connected without sufficiently checking the AC voltage, sufficient heat generation may not be obtained. On the other hand, the heater overheats, creating a risk of fire or the like, and the heater wire may break.

(C) Problems to be Solved by the Invention The present invention automatically changes the combined resistance value of the load connected between the AC power supply terminals in accordance with the commercial AC voltage supplied to the AC power supply terminals. It is designed to generate heat according to the rating, and in particular, to change the combined resistance value of the load in sufficient response even if the AC voltage supplied to the AC power supply terminal fluctuates higher or lower than the rated voltage. purpose.

(D) Means for Solving the Problems The present invention provides at least two
at least one set of loads, and an operating circuit that changes a combined resistance value of the two sets of loads connected between the AC power supply terminals according to a voltage applied between the AC power supply terminals, the operating circuit , a DC circuit that converts the AC power applied between the AC power supply terminals into DC, an SCR connected between the DC power supply by the DC circuit, and a series of a plurality of voltage dividing resistors connected in parallel to the SCR. a circuit, a constant voltage conduction element connected between the gate of the SCR and the connection portion of each of the voltage dividing resistors, and a circuit that increases the combined resistance value of the load when the SCR is conductive and combines the loads when the SCR is not conductive; It consists of a switching element that reduces the resistance value.

(E) Function If the commercial AC voltage supplied between the AC power supply terminals has a rated voltage of 200V, for example, the SCR of the operating circuit becomes conductive, increasing the combined resistance of the load, and if the rated voltage is 100V, the SCR becomes non-conducting. It enters a conductive state, reduces the combined resistance value, and makes it possible to set the load to an appropriate value according to the supplied AC voltage.

(F) Embodiment An embodiment of the present invention will be described based on the drawings. Figure 1 is a side view of the main body of the hair dryer when it is installed in the hair dryer.
5) and a discharge port (7) consisting of a discharge grille (6). (8) is a motor that drives a fan (9) provided on the intake port (5) side in the main body; (lO) is a fan unit provided on the discharge port (7) side in the main body; As shown in FIG. 2, it has a first load [1] (hereinafter referred to as the first heater) and a second load (12+ (hereinafter referred to as the second heater)), and the first heater (11) is Heating heater (ll
a) and the step-down heater (llb) of the motor (8).
We are doing a division. (13) is a printed circuit board stored and fixed in the empty space (3) of the handle (4), (14) is a relay (15a) (15b) stored in the lower part of the empty space (3).
(16) is a push-button power switch placed between the printed circuit board (13) and the mounting board (14) in the space (3), (17) is a power cord, (18) is a A cord protector for the power cord.

Figure 2 shows the basic electrical circuit diagram, (19a) (1
9b) is the power supply terminal, (20) is the first switching element, (21) is the movable contact piece (21a) and the first fixed contact +2
a second switching element having a second fixed contact (21c) and a second fixed contact (21c), which is electrically interlocked with the first switching element (20); The first heater (11) has one end connected to one of the power supply terminals (19a) and the other end connected to the movable contact piece (21a) of the second switching element (21). On the other hand, one end of the second heater (12) is connected to the other terminal of the supply terminal (<19b), and the other end is connected to the second fixed contact (21C) of the second switching element (21).
). Also, the first switching element of the second switching element
The fixed contact (21b) is connected to the other terminal (19) of the supply terminal.
b), and the first switching element (20) connects one terminal (19a) of the supply terminals and the second heater (1
2) Connected to the other end.

Next, the operation will be described based on the basic electrical circuit diagram shown in FIG. Now, for example, if the supplied AC power is 100V, the first and second switching elements (20), (2
1) Switch to the position indicated by the solid line. This turning off operation is performed by operating an operating circuit (22) as shown by the broken line. Due to the position of the switching element (201 (211) as described above, the first heater (!l) is connected to the supply terminal (19al) via the movable contact piece (21al) of the second switching element (20) and the first fixed contact (21b). (19b) and the second
The heater (12) is connected to the closed first switching element (20).
) is connected to the supply terminal (19al (19b)). That is, each heater is connected in parallel, and the parallel circuit is connected to a commercial Power is applied.

The power consumption (Pl) in this case is the resistance value (Ro) of the first heater (11), the resistance value (R2) of the second heater (12),
If the commercial AC power source (E) is used, and if the supplied commercial power source has a rated voltage of 200V, the operating circuit (22) connects the movable contact (21al) of the second switching element (21) to the second fixed contact ( 2
1c) and release the first switching element (20). Due to the operation of the switching elements as described above, the first heater (11) and the second heater (12) are connected to the movable contact piece (21a) of the second switching element (21) and the second fixed contact (2).
1b+, and a 200V commercial power supply is applied to this series circuit via the supply terminals (19a) and (19b).

The power consumption (P2) in this case is therefore, if R, = 20Ω, R2 = 20Ω, P
1=P2=1000W, which is the same whether the supply voltage is 100■ or 200■.

FIG. 3 embodies the operating circuit (22) shown in FIG. 2, and the electrical circuit diagram and its operation will be briefly explained. (23) and (24) are step-down resistors and diodes connected in series, and (25) is the diode (24).
(26) is a Zener diode for constant voltage, and (27) is a smoothing capacitor connected in parallel to the diode.

The first and second relays (15a) and (15b) are connected in parallel, and the first relay (15a) opens the first switching element (20) when energized, and the second relay (15b) opens the first switching element (20) when energized. By energizing, the movable contact (21a) of the second switching element (21) is switched and connected to the second fixed contact (21c), thereby forming a switching element (SW). The first relay (15al) and the second relay (+
5b) is connected in series to SCR (28),
This series circuit is connected in parallel to the smoothing capacitor (27). (29) and (30) are the diodes (
They are connected in series by a voltage dividing resistor connected between the cathode side of 24) and the other power supply terminal ++9b). (31
) is the gate of the SCR (28) and the resistor (29)
, (30) is a constant voltage conduction element connected to the connection part (P), and is set to a value such that it becomes conductive depending on the potential of the connection part (P) when the supplied AC power supply voltage is about 150 to 160V. ing. (32) is a full-wave rectifier that applies DC voltage to the motor (8), and is connected to both ends of the step-down heater (llbl). (33) is a full-wave rectifier that applies DC voltage to the motor (8). 19al (19b), and is provided at an appropriate position in the heater unit (10).

If the current commercial power supply is 100cm, the potential of the connecting part (P) of the voltage dividing resistors (29) and (30) is low and the constant voltage conduction element (31) does not conduct, so the SCR (
28) is non-conductive and the first and second relays (15at
The contact points of the first switching element (20) and the second switching element (21) in (15b) are at the solid line positions shown in FIG. 3, and the first and second heaters (11) and (12) are connected in parallel. The combined resistance value becomes small and is connected to the power supply terminal (19al (19b).Here, when the power switch (16) is closed, 100V is applied to each heater.
When the voltage is applied, the motor (8) rotates and the fan (9) blows air.

If the commercial power supply is 200V, the voltage dividing resistor (2
9), when the potential of the connection part (P) of (30) becomes high and reaches the Zener voltage value or higher of the constant voltage conduction element (31), the conduction element becomes conductive and the SCR (28) becomes conductive. and the second relay (15a) (15bl) are energized. With this energization, the first switching element (20) opens and the second switching element (21) closes its movable contact piece (2).
1a) from the first fixed contact (21b) to the second fixed contact (2
1c), the first heater (111) and the second heater (12) are connected in series, increasing the combined resistance value of the entire heater.

In the present invention, an operating circuit in which the first switching element opens and closes and the second switching element switches are electrically interlocked has been described. The same applies even if it can be compared.

Further, the first heater and the second heater need not be switched in series and parallel, but one of the two heaters connected in series may be short-circuited depending on the voltage.

(G) Effects of the Invention As described above, the present invention automatically changes the combined resistance value of the load connected between the AC power supply terminals in accordance with the commercial AC voltage supplied to the AC power supply terminals, and always maintains the rated value. (100V or 200V), especially when the AC voltage supplied to the AC power supply terminal is rated 100V or 200V, the voltage fluctuation is higher or lower than the rated voltage, respectively. Even if there is, the timing of conduction/non-conduction of the SCR is determined by the constant voltage conduction element. Therefore, even if a rated voltage of 100V is supplied and the voltage rises due to voltage fluctuations, the circuit will switch to the rated 200V side, or even if a rated voltage of 200V is supplied and the circuit drops due to voltage fluctuations, the operating circuit will not change. Because it operates accurately, the rated voltage is 100Vffl due to malfunction.
! There is no inconvenience such as switching to the I circuit, and dangers such as fire can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a side view of a hair dryer equipped with the load voltage switching circuit of the present invention with one case removed, Fig. 2 is a basic electric circuit diagram of the present invention, and Fig. 3 is a specific electric circuit diagram of the same. be. (11)--First load, (12)-Second load, (
19a) (19b)...AC power supply terminal, (22
)...Operating circuit, (28)...5CR1+291
(30)...Voltage dividing resistor, (sW)...Switching switching element. Applicant: Sanyo Electric Co., Ltd. and one other representative Patent attorney Takuji Nishino (two others) Figure 1 1゜

Claims (1)

[Claims] (1) Combining at least two or more sets of loads connected between AC power supply terminals and the two sets of loads connected between the AC power supply terminals according to the voltage applied between the AC power supply terminals. an actuation circuit that changes a resistance value, the actuation circuit comprising: a DC circuit that converts AC power applied between the AC power supply terminals into DC; an SCR connected to the DC power side of the DC circuit; A series circuit of a plurality of voltage dividing resistors connected in parallel to the SCR, a constant voltage conduction element connected between the gate of the SCR and the connection part of each of the voltage dividing resistors, 1. A load voltage switching circuit comprising a switching element that increases a combined resistance value and reduces the combined resistance value of the load when non-conducting.