JPH08308220A - Stabilized power source - Google Patents

Abstract

PURPOSE: To prevent emitted switching noise without increase of the cost. CONSTITUTION: Coils 14 and 19 are mounted together so that the directions of windings are opposite to one another. Accordingly, the direction of lines of magnetic force generated from the coil 14 becomes entirely opposite to the direction of the lines of magnetic force generated from the coil 19 in the direction for cancelling each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to reduction in size and weight of a magnetic recording / reproducing apparatus such as a camera-integrated type, and low power consumption
In particular, it relates to a stabilized power supply device equipped with a switching power supply.

[0002]

2. Description of the Related Art In recent years, a magnetic recording / reproducing apparatus having a small size, a light weight, and a low power consumption, such as a camera integrated type, has been rapidly developed, and a magnetic recording / reproducing apparatus having a low power consumption has been developed. Development is progressing rapidly, and a switching power supply is indispensable for lowering power consumption. On the other hand, switching miniaturization requires countermeasures against switching interference.

An example of the above-described conventional stabilized power supply device will be described below with reference to the drawings.

In FIG. 4, reference numeral 1 is a battery input terminal. Reference numeral 2 is a switching transistor, and 3 is a switching pulse input terminal for controlling the switching transistor 2. Reference numerals 4 and 5 are coils and capacitors that form an LC filter that smoothes the output of the switching transistor 2. Reference numeral 6 is an output terminal of a DC voltage which is switched and smoothed. At the same time, 7 is a switching transistor, and 8 is a switching pulse input terminal for controlling the switching transistor 7. Reference numerals 9 and 10 are a coil and a capacitor that form an LC filter that smoothes the switching transistor 7. Reference numeral 11 is an output terminal of the switched and smoothed DC voltage. The operation of the conventional stabilized power supply device configured as described above will be described below.

An unstabilized DC voltage of 7V DC (here, 7V) from the battery input terminal 1 is supplied to the emitter of the switching transistor 2. A switching pulse input 3 supplies a switching pulse of about 500 KHZ to the base of the switching transistor 2. The switching transistor 2 is turned on and off by the switching pulse and the power is smoothed by the coil 4
And stabilized DC voltage of 5V supplied to capacitor 5
Is output from the DC output terminal 6. Similarly, the unstabilized DC voltage of 7V is also supplied to the emitter of the switching transistor 7 for the pair. The switching pulse input 8 supplies a switching pulse of about 500 KHZ to the base of the switching transistor 7. The switching pulse turns the switching transistor 7 on and off, and the power is supplied to the smoothing coil 9
And DC voltage of 5V stabilized and supplied to capacitor 10
Is output from the DC output terminal 11.

Here, as shown in FIG. 5, the coil 4 connected to the collector of the switching transistor 2 and the coil 9 connected to the collector of the switching transistor 7 are disturbed by the switching pulse noise in the recording / reproducing video signal. Printed circuit board 1 to prevent the occurrence
When mounted on 2, it is composed of the above-mentioned parts. The switching power supply circuit section is shielded by a completely covered shield case 13 (made of a tin plate or the like).

[0007]

However, the above-mentioned structure has a problem that the shielding effect of the smoothing coil 4 or 8 is not sufficient and the recording / reproducing video signal is disturbed particularly when the size is reduced. Was.

In view of the above problems, the present invention forms a pair of coils for switching smoothing, and applies them to the other coil having a winding direction that is completely opposite to the winding direction of one winding. By reducing the outflow of magnetic field lines from each other,
It is intended to provide a stabilized power supply device for a magnetic recording / reproducing device which prevents switching noise.

[0009]

In order to solve the above-mentioned problems, a stabilized power supply device of the present invention comprises an even number of chopper type switching power supplies each composed of a switching transistor, a coil for smoothing a switching voltage, and a capacitor. A pair of coils are arranged in diametrically opposite winding directions, and the coils are arranged side by side and mounted on a printed circuit board.

[0010]

According to the present invention, by virtue of the above-described structure, the strong magnetic lines of force generated from each of the pair of coils are made opposite in the winding directions of the coils, so that the directions of generation of the magnetic lines of force are made opposite. Therefore, the amount of magnetic force lines generated from the coil portion is mutually reduced, and the magnetic field region is reduced. As a result, even if a small-sized magnetic recording / reproducing apparatus is configured, it is possible to prevent beats from occurring in the recording / reproducing video signal due to interference from the coil.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A stabilized power supply device according to an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 11 is a battery input terminal. Reference numeral 12 is a switching transistor, and 13 is a switching pulse input terminal for controlling the switching transistor 12. Reference numerals 14 and 15 are coils and capacitors that form an LC filter that smoothes the switching transistor 12. Reference numeral 16 is an output terminal for switching and smoothing a DC voltage of 5V. Similarly, 17
Is a switching transistor, and 18 is a switching pulse input terminal for controlling the switching transistor. Reference numerals 19 and 110 are coils and capacitors that form an LC filter that smoothes the switching transistor. 111 is a switched and smoothed DC voltage 5
V output terminal. The operation of the stabilized power supply device of this embodiment configured as described above will be described below.

Here, as shown in FIG. 2, a coil 14 connected to the collector of the switching transistor 12 or a coil 19 connected to the collector of the switching transistor 17 has magnetic lines of force that interfere with the recording / reproducing video signal due to switching pulse noise. Is occurring. Further, the above-mentioned components are mounted on the printed circuit board 22, and in order to prevent switching noise radiated from the coil, a shield case (constituted by a tin plate or the like) 21 is provided with a shield case. However, particularly in a camera-integrated magnetic recording / reproducing apparatus, which is becoming extremely miniaturized, the shielding effect is not sufficient only with the shield case 21.

Therefore, as shown in FIG. 3, the coil 14 and the coil 19 are mounted so as to be in contact with each other, and the winding directions are opposite to each other. Therefore, the direction of the magnetic lines of force generated from the coil 14 and the coil 1
The directions of the magnetic force lines generated from 9 are completely opposite to each other and cancel each other.

Therefore, the amount of magnetic lines of force generated from the coil portion is reduced and the magnetic field region is reduced, which works to obtain a sufficient shielding effect.

Further, it has a great effect on miniaturization of the apparatus.

[0017]

As described above, according to the present invention, a pair of coils for switching smoothing is formed, and a winding that is exactly opposite to the direction of one winding is applied to the other coil, and the lines of magnetic force are mutually generated. By reducing the outflow of each other, the radiated switching noise can be greatly reduced, and it is possible to prevent interference with the recording / playback video signal when it is small and lightweight.
This is an excellent stabilized power supply device that can be realized without increasing costs.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a stabilized power supply device according to an embodiment of the present invention.

FIG. 2 is a perspective view of the stabilized power supply device according to the embodiment.

FIG. 3 is a cross-sectional view of a stabilized power supply device according to the same embodiment.

FIG. 4 is a circuit diagram of a conventional stabilized power supply device.

FIG. 5 is a perspective view of a conventional stabilized power supply device.

[Explanation of symbols]

 11 Battery Input Terminal 12, 17 Switching Transistor 13, 18 SW Pulse Input Terminal 14, 19 Coil 15,110 Capacitor 16,111 Output Terminal 21 Shield Case 22 Printed Circuit Board

Claims (1)

[Claims] 1. A first chopper type switching power supply composed of a switching transistor, a first coil provided for smoothing a switching voltage, a smoothing capacitor, and a winding of the first coil. A second coil composed of a winding wire in a direction opposite to the winding direction and a second chopper type switching power supply composed of a smoothing capacitor are provided, and magnetic lines of force of the first coil and the second coil. 1. A stabilized power supply device, characterized in that it has a configuration in which the directions are opposite and parallel.