JPH048167A - Power supply to be mounted on electronic machine - Google Patents

Abstract

PURPOSE:To simplify the constitution and to reduce the weight by feeding a full-wave rectified output from a main power supply section to main and sub-circuit sides when a power switch is turned ON whereas connecting the half-wave rectifying circuit at a sub-power supply section to the sub-circuit side when the power switch is turned OFF. CONSTITUTION:When a signal for turning a relay contact 14b ON is applied on the relay coil 14a of a power switch 14, AC power supply side is connected with a full-wave rectifying circuit 8 which thereby full-wave rectifies in AC power supply. The full-wave rectified output is then smoothed through a smoothing capacitor 10 and fed to a main power supply section 2 and a sub- power supply section 4. When a signal for turning the relay contact 14b OFF is fed from a microcomputor, full-wave rectified output is not fed to the stabilizing DC power supply section 12 in the main power supply section 2 and the AC power supply is half-wave rectified through the half-wave rectifying circuit 22 in the sub-power supply section 4.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a power supply circuit installed in an electronic device such as a television receiver. The present invention relates to a power supply circuit having a main power supply section for a main circuit driven by a microcomputer, and a sub power supply section for a subcircuit driven at a relatively low voltage, such as 5V, such as in a microcomputer.

(Prior Art) FIG. 2 is a circuit diagram of this type of power supply circuit. The conventional power supply circuit shown in FIG. 2 includes a main power supply section 2, a sub power supply section 4
It has

The main power supply unit 2 is for a main circuit (not shown) driven at a relatively high voltage such as 120V in a television receiver, and includes a current limiting resistor 6, a full-wave rectifier circuit 8, and a smoothing capacitor 10. , and stabilized DC power supply section 12
have.

The full-wave rectifier circuit 8 is connected between the power plug 16 (commercial AC power supply side of 100 Va, c) and the main circuit side via the power switch 14, and the power switch I4 is in the on state. Full-wave rectification of the AC power supplied through the This full-wave rectified output is smoothed by a smoothing capacitor 10, converted into a stabilized DC power source by a stabilized DC power supply section 12, and then supplied to the main circuit side.

Here, the power switch 14 is composed of a relay coil 14a and a relay contact 14b, and the relay coil 14
When a is excited, relay contact 14b closes (turns on)
It looks like this.

The sub power supply unit 4 is a power supply for a microcomputer, which is a sub circuit equipped with electronic equipment, and includes a current limiting resistor 14, a full-wave rectifier circuit 16, a smoothing capacitor I8, and a stabilized DC power supply unit 20. .

The full-wave rectifier circuit 16 is connected between the AC power source side and the microcomputer side, and performs full-wave rectification of the AC power source regardless of whether the power switch 14 is turned on or off. This full-wave rectified output is smoothed by a smoothing capacitor 18, converted into a stabilized DC power supply by a stabilized DC power supply section 20, and then supplied to the microcomputer side.

(Problems to be Solved by the Invention) In the conventional power supply circuit having the above configuration, when the power switch I4 is turned off, the main power supply unit 2 is connected to the main circuit side.
Even if the supply of 20V power is stopped, 5V power is supplied to the microcomputer from the sub power supply section 4, or the configuration of the sub power supply section 4 is the same as that of the main power supply section 2. It has become.

By the way, with a heavy load such as the main circuit, the ripples in the power supply increase, so it is necessary to reduce the ripples by using a full-wave rectifier circuit 8 as shown in Figure 2. Since the ripple is small under such a light load, it is considered that there is no need to use the full-wave rectifier circuit 16 as shown in FIG.

In this case, if the full-wave rectifier circuit 16 is not used for the microcomputer, if the main circuit and the microcomputer are driven at the same time, the microcomputer will be supplied with power with a lot of ripple. Conventionally, even in a light-load microcomputer with little ripple, a complex power supply configuration similar to that of the main power supply section 2 has been used in the sub power supply section 4.

However, since two such complicated power supply configurations are used, there are problems in that the manufacturing cost of the power supply circuit is high and it is also heavy.

Therefore, it is an object of the present invention to simplify the configuration of a power supply for a subcircuit such as a microcomputer, thereby reducing its manufacturing cost and weight.

(Means for Solving the Problems) In order to achieve such an object, the electronic device-mounted power supply circuit of the present invention has a main power supply section, a sub power supply section, and a power supply switching element. The power supply section is for the main circuit of the electronic device and has a full-wave rectification circuit, and the full-wave rectification circuit is connected to the AC power supply side and the main circuit side via the power switch. connected between, and
The alternating current power supplied through the power switch in the on state is full-wave rectified and output to the main circuit side, and the sub power supply section is a power supply for the sub circuit equipped with electronic equipment, and The half-wave rectifier circuit is connected between the AC power source and the sub circuit side, and rectifies and outputs the AC power source regardless of whether the power switch is turned on or off to output the AC power to the sub circuit side. The power source switching element is characterized in that it connects the full-wave rectifier circuit to the sub-circuit side when the power switch is on.

(Function) When the power switch is on, the full-wave rectifier circuit of the main power supply section applies its full-wave rectified output to the main circuit side through the power switch, and at the same time pressurizes the AC power supply to the main circuit side through the power switch. It is also output to the sub-circuit side via.

When the power switch is off, the half-wave rectifier circuit is connected to the sub-circuit side.

Therefore, when the power switch is turned on and power is supplied to the main circuit side, which has a heavy load, and the ripple component of the power supply increases, on the sub circuit side with a light load such as a microcomputer, the ripple component is suppressed. On the other hand, when the power switch is turned off and power is not supplied to the heavily loaded main circuit side, and therefore the ripple component of the power supply is reduced, The output of the wave rectifier circuit, that is, the half-wave rectifier output in which ripples are not removed like in the aftereffect rectifier circuit, is given to the sub-circuit side.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram of an electronic device-mounted power supply circuit according to an embodiment of the present invention, in which parts corresponding to those in FIG. A detailed explanation will be omitted.

The characteristic configuration of the power supply circuit of this embodiment is that the configuration of the sub-power supply section 4 is simplified compared to that shown in FIG. 2, and that a diode 24 as a power supply switching element is newly added.

The other configurations are the same as the conventional example.

In this embodiment, the sub power supply section 4 includes a half-wave rectifier circuit 22 instead of the full-wave rectifier circuit 16 of the conventional example. The diode 24 is connected between the output part of the full-wave rectifier circuit 8 of the main power supply part 2 and the input part of the stabilized DC power supply part 20 on the side of the sub power supply part 4, and when the power switch I4 is turned on. In this case, connect the output part of the full-wave rectifier circuit 8 to the input parts of the stabilized DC power supply part I2 of the main power supply part 2 and the stabilized DC power supply part 20 of the sub power supply part 4, and make sure that the power switch 14 is turned off. In this case, the output section of the half-wave rectifier circuit 22 is connected to the input section of the stabilized DC power supply section 20.

In the above configuration, when a signal for turning on relay contact +4b is given from a microcomputer (not shown) to relay coil 14a of power switch 14, relay contact 1
4b turns on. This connects the AC power source and the full-wave rectifier circuit 8, so the full-wave rectifier circuit 8 performs full-wave rectification of the AC power source.

After being smoothed by the smoothing capacitor IO, this full-wave rectified output is input to the stabilized DC power supply section I2 of the main power supply section 2, while being inputted to the stabilized DC power supply section I2 of the sub power supply section 4 via the diode 24. It will also be input to section 20.

The full-wave rectified output input to the stabilized DC power supply unit 12 of the main power supply unit 2 is converted into a stabilized DC power supply and supplied to the main circuit side, and then to the stabilized DC power supply unit 20 of the sub power supply unit 4. Similarly, the human-powered full-wave rectified output is converted here into a stabilized DC power supply and supplied to the microcomputer side. As a result, a stabilized power supply with less ripple is supplied to the microcomputer side.

On the other hand, when a signal is given from the microcomputer to turn off the relay contact 14b, the power switch 14 is turned off, and thereby the stabilized DC power supply section 12 of the main power supply section 2
On the other hand, the AC power supply is half-wave rectified by the half-wave rectifier circuit 22 of the sub-power supply IE4, smoothed by the smoothing capacitor 18, and then stabilized by the stabilized DC power supply section 2o. It is converted into power and supplied to the microcomputer side. In this case, since the load is light, there is less power supply ripple, and even if the half-wave rectified output is converted to a stabilized DC power source instead of the full-wave rectified output and output to the microcomputer, it will affect the operation of the microcomputer. There is no impact.

(Effects of the Invention) As should be clear from the above explanation, according to the present invention, when the power switch is on, the full-wave rectifier circuit of the main power supply section converts its full-wave rectified output into While the AC power is output to the main circuit side through the power switch, it is also output to the sub circuit side via the power switching element. When the power switch is off, the power switching element switches the half of the sub power supply A wave rectifier circuit is connected to the sub-circuit side.

Therefore, when the power switch is turned on and power is supplied to the main circuit side, which has a heavy load, and the ripple component of the power supply increases, on the sub circuit side with a light load such as a microcomputer, the ripple component is suppressed. On the other hand, when the power switch is turned off and power is not supplied to the heavily loaded main circuit side, and therefore the ripple component of the power supply is reduced, Since the output of the wave rectifier circuit side is given to the sub circuit side, the sub power supply section does not require a complex full wave rectifier circuit like the main power supply section, resulting in a simplified configuration. , it has become possible to reduce the manufacturing cost and weight.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an electronic equipment-mounted power supply circuit according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional electronic equipment-mounted power supply circuit. 2... Main power supply section, 4... Sub-power supply section, 8... Full wave rectifier circuit, 14... Power switch, 22... Half wave rectifier circuit. Applicant Sharp Co., Ltd.

Claims (1)

[Claims] (1) It has a main power supply part (2), a sub power supply part (4), and a power supply switching element (24), and the main power supply part (2) is for the main circuit of an electronic device, and a full-wave rectifier circuit (8), the full-wave rectifier circuit (8) being connected between the AC power source side and the main circuit side via a power switch (14), Further, the AC power supplied through the power switch (14) in the on state is full-wave rectified and outputted to the main circuit side, and the sub power supply section (4) is a sub circuit equipped with electronic equipment. The half-wave rectifier circuit (22) is connected between the AC power source and the sub-circuit side, and is connected to the power switch ( The power supply switching element (24) rectifies and outputs the alternating current power supply to the sub-circuit side regardless of the on/off status of the power supply switching element (24).
When the power switch (14) is on, the full-wave rectifier circuit (8
) is connected to the sub-circuit side.