JP3398062B2 - Power supply circuit for electronic equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device such as an audio device, and more particularly to a power supply circuit thereof. 2. Description of the Related Art In recent years, many electronic devices are equipped with a microcomputer circuit, and control the functional operation of the device. Considering home audio equipment as an example, various operations such as turning on / off the power, adjusting the volume and sound quality, selecting a source, and playing / fast-forwarding a compact disc or cassette tape can be easily performed. [0003] In such a device,
For example, even in a standby state in which listening to music is completed and the power of the device is turned off, at least the microcomputer circuit continues to operate in preparation for turning on the power when a remote control operation or timer recording from the user is performed. It is necessary. [0004] Although the power consumed by the microcomputer circuit is small, the power transformer itself consumes power. Even if the secondary side of the power transformer is not loaded, power of several W to several tens of W is consumed. That is, if such totally wasteful energy consumption is contrary to the purpose of global environmental conservation,
It is a global problem. To solve such a problem, there is a circuit as shown in FIG. 3, for example. In the figure, reference numeral 21 denotes a power transformer for supplying power to a subsequent circuit (not shown);
22 is a power switch, 23 is a high-voltage secondary winding of the power transformer 21, 24 is a low-voltage secondary winding of the power transformer 21, and 25 is a power transformer 21.
26A is a rectifier / smoothing circuit for high voltage, 26A
B is a rectifying / smoothing circuit for low voltage, 27 is a microcomputer circuit, 2
8 is a power on / off controlled by the microcomputer circuit 27.
The off relays 29A and 29B are relay contacts for supplying / non-supplying power to the subsequent circuit. Normally, the power supply of the apparatus is turned on / off by a relay 28 controlled by a microcomputer circuit 27, and the low voltage side and the high voltage side are turned on / off by relay contacts 29A and 29B, respectively. When the device is not used, the power switch 22 provided on the primary side of the power transformer 21 can be directly mechanically turned off by hand. In this circuit, when the power switch 22 is turned off, the power transformer 21 is completely cut off from the commercial AC power supply, so that the power consumption when the equipment is not used can be completely reduced to zero, and the standby state can be achieved. Although it is most effective in reducing the useless power consumption of the state, it is very troublesome to operate the mechanical power switch 22 each time, and the convenience of precious microcomputer control is lost,
For example, there is a problem that it is not possible to use the infrared remote control remotely to turn on the device or use the timer function to automatically turn on the device and start operation at a certain time using the timer function is there. In addition, as shown in FIG. 2, there is another type in which a dedicated small sub power transformer 5 is separately provided for the microcomputer circuit 17. In the figure, reference numeral 11 denotes a main power transformer for supplying power to a subsequent circuit (not shown), and 13 denotes a high voltage 2 of the main power transformer 11.
The secondary winding 14 is also the same as the main power transformer 11.
, The secondary winding for low voltage, 16 is the main power transformer 1
1, a primary winding, 17 a microcomputer circuit, 18 a power ON / OFF relay controlled by the microcomputer circuit 17, 12 a power switch relay contact controlled by the relay 18, and 15 a power switch relay contact. The secondary winding of the sub power transformer, 20 is the primary winding of the sub power transformer,
19A is a rectifying / smoothing circuit for high voltage, 19B is a rectifying / smoothing circuit for low voltage, and 19C is a rectifying / smoothing circuit for a microcomputer circuit. In this circuit, a relay 18 controlled by a microcomputer circuit 17 is used to turn on and off the power of the device.
Accordingly, the primary side of the main power transformer 11 is turned on / off by the contact 12 of the relay 18. When the device is turned off, that is, during a standby state, the main power transformer 11 is completely cut off from the commercial AC power by the contact 12 of the relay 18, and the power consumption during this period is reduced by the sub power transformer 5.
And only the power on the microcomputer circuit side, the power consumption can be suppressed to less than several W, and at the same time, since the microcomputer circuit 17 is always energized, even if the device is turned off,
It is possible to avoid losing convenience by microcomputer control. However, in order to equip the sub power transformer, it is necessary to secure a space for the inside of the device, and there is a problem that an increase in the price of the device cannot be avoided. According to the present invention, there is provided a transformer for converting a voltage of a commercial AC power supply.
A rectifying / smoothing circuit for rectifying and smoothing the converted voltage of the transformer to generate a DC voltage; and receiving a voltage via the rectifying / smoothing circuit to operate the electronic device in an operation state or a standby state.
And a control circuit for switching between the two states. The transformer has a primary winding, a first secondary winding, and a second secondary winding. A smoothing circuit, a first rectifying / smoothing circuit connected to a first secondary winding of the transformer, and a second rectifying / smoothing connected to a second secondary winding of the transformer; A circuit;
The third rectification / smoothing circuit provided in parallel with the rectification / smoothing circuit of
A smoothing circuit, wherein the control circuit includes a first electric circuit connecting the commercial AC power supply and the primary winding via a capacitor, and a commercial AC power supply and the primary winding without a capacitor. And a second relay for switching connection between the first rectifying / smoothing circuit and the third rectifying / smoothing circuit. When the electronic device is in a standby state, the first relay is connected to the first electric circuit, and the second relay is connected to the third rectifying / smoothing circuit. No circuit is provided. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a power supply circuit to which the present invention is applied. In FIG. 1, reference numeral 1 denotes a power transformer for supplying power to a subsequent circuit (not shown);
Reference numeral 3 denotes a high-voltage secondary winding of the power transformer 1, 4 denotes a low-voltage secondary winding of the power transformer 1, 30 denotes a primary winding of the power transformer 1, 7 denotes a microcomputer circuit, 8 Are relays turned on / off by the microcomputer circuit 7,
A and 2B are relay contacts turned on and off by the relay, 10 is a capacitor provided between the relay contact 2A and the primary side of the power transformer 1, and 9A is a rectifier for high voltage.
A smoothing circuit, 9B is a rectifying / smoothing circuit for low voltage, 9C is a rectifying / smoothing circuit for microcomputer circuit, and 6 is a diode provided between the rectifying circuit 9B for low voltage and the microcomputer circuit 7. The power on / off of the device is controlled by contacts 2A and 2B of a relay 8 controlled by a microcomputer circuit 7. First, when the device is operating with the power on, the contact 2A of the relay 8 is on the A side and the power transformer 1
The secondary side is connected to the commercial AC power supply and the contact 2 of the relay 8
B is also on the A side, and the high voltage secondary winding 3 is connected to the high voltage rectifying / smoothing circuit 9A. Furthermore, 2 for low voltage
Since the secondary winding 4 is always connected to the low-voltage rectifying / smoothing circuit 9B, power is supplied from this output to the microcomputer circuit 7 through the diode 6. Next, when the power supply is turned off, that is, in a standby state, the microcomputer circuit 7 causes each contact 2A of the relay 8 to be turned off.
And 2B are switched to the B side, the primary side of the power transformer is connected to a commercial AC power supply through a capacitor 10, and the secondary winding 3 for high voltage is connected to a rectifying / smoothing circuit 9C for a microcomputer circuit. As shown in the figure, a small-capacity capacitor 10 (for example, 0.2) is connected in series with the primary side of the power transformer 1.
.mu.F to 0.5 .mu.F), a low voltage of several volts appears on the high voltage secondary winding 3 which normally has a voltage of several tens of volts.
Therefore, by using this low voltage, it is possible to supply the minimum power required to operate the microcomputer circuit 7. In general, the larger the power transformer, the greater the loss. Even if all the secondary sides are open, the power transformer alone consumes power of several W to several tens of W. However, as in the present invention, a small-capacity capacitor is connected in series to the primary side, and a low voltage of several volts that appears in a winding that normally has a voltage of several tens of volts is used, so that power consumption of less than 1 W is achieved. It is possible to As a result, the microcomputer circuit can be operated even in the standby state of the device, and at the same time, the power consumption can be significantly reduced. As described above, according to the present invention, it is possible to greatly reduce power consumption in the standby state of equipment, reduce wasteful energy consumption, and contribute to global environmental conservation. It is. Even when the device is in a standby state, the convenience unique to the microcomputer circuit control device such as a remote control operation or power-on by a timer function is maintained. Furthermore, since a sub-power transformer as in the conventional circuit is not required, no space is required for it, the weight does not increase, and component materials (resources)
And cost can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit block diagram showing a configuration of a power supply circuit of the present invention. FIG. 2 is a circuit block diagram showing a configuration of a conventional power supply circuit. FIG. 3 is a circuit block diagram showing a configuration of a conventional power supply circuit. [Description of Signs] 1 Power transformer 2A Relay contact 2B Relay contact 3 Secondary winding for high voltage (first secondary winding) 4 Secondary winding for low voltage (second secondary winding) 6) Diode 7 Microcomputer circuit 8 Relay 9A High voltage rectification / smoothing circuit (first rectification / smoothing circuit) 9B Low voltage rectification / smoothing circuit (second rectification / smoothing circuit) 9C Rectification / smoothing for microcomputer circuit Circuit (third rectifier / smoothing circuit) 10 Capacitor 30 Primary winding

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 7/06 G06F 1/26 H02J 9/06

Claims (1)

(1) A transformer for converting a voltage of a commercial AC power supply, a rectifying / smoothing circuit for rectifying and smoothing the converted voltage of the transformer to generate a DC voltage, In a power supply circuit of an electronic device having a control circuit that receives a supply of voltage via a smoothing circuit and switches the electronic device between an operating state and a standby state, the transformer includes a primary winding and a first winding. 1 secondary winding and the second winding
A rectifying / smoothing circuit connected to a first secondary winding of the transformer, and a second secondary winding of the transformer. A second rectifying / smoothing circuit connected to the side winding; and a third rectifying / smoothing circuit provided in parallel with the first rectifying / smoothing circuit. The control circuit includes a capacitor. A first electric circuit connecting the commercial AC power supply and the primary winding via the first circuit, and a second electric circuit connecting the commercial AC power supply and the primary winding without the use of the capacitor.
A first relay for switching connection with an electric circuit of the
Rectifier / smoothing circuit and a second relay for switching the connection between the third rectifier / smoothing circuit, and when the electronic device is in a standby state, the first relay is connected to the first electric circuit. A power supply circuit for an electronic device, wherein the second relay is connected to the third rectifying / smoothing circuit.