JPH1152903A - Switching power source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source device of the frequency-multiplied synchronization system which allows a wide operating range in horizontal frequency, maintains the highest operating frequency of the switching power source circuit at an optimum value even when the highest horizontal frequency rises and can reduce the skin effect loss of the switching transformer, the switching loss of switching elements, etc., in the case of a multi-scan display monitor by improving the precision of the multi-scan display monitor while holding the effect which reduces the screen disturbance caused by the switching power source circuit. SOLUTION: This device is constituted so that the pulse signals of the horizontal frequency detected by a horizontal deflection circuit 4 are frequency- converted by automatically switching the multiplication factor in accordance with the value of horizontal frequency in a multiplying circuit 2 and the switching power source circuit 3 operates synchronously with the pulse signals outputted from the multiplying circuit 2. By this the operating frequency range is narrowed and the highest operating frequency of the switching power source circuit 3 is set at an optimum value range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiply synchronous switching power supply used for a multi-scan display monitor using a CRT (CRT).

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a conventional switching power supply used for a multi-scan display monitor capable of processing image signals having different horizontal frequencies. As shown in FIG. 2, the conventional switching power supply includes a switching power supply circuit 30 that supplies power to the horizontal deflection circuit 40 and the like, and a detection circuit unit that detects the horizontal frequency pulse signal f _H (Hz) of the horizontal deflection circuit 40. 10
It is composed of The horizontal frequency pulse signal f _H (Hz) detected by the detection circuit unit 10 is input to the switching power supply circuit 30, and the switching power supply circuit 30 is configured to operate in synchronization with the horizontal frequency pulse signal f _H (Hz). The switching power supply circuit 30 uses a semiconductor device as a switch element and stabilizes the output voltage of the switching power supply device by controlling the duty ratio in the on / off time, and is conventionally used for a multi-scan display monitor. It had been. In the conventional switching power supply device configured as described above, since the switching power supply circuit 30 is configured to operate in synchronization with the horizontal frequency pulse signal f _H (Hz), noise generated by the switching operation of the switching power supply circuit 30 is performed. Screen interference was prevented.

[0003]

Conventionally, in a switching power supply circuit used in a multi-scan display monitor and synchronized with the horizontal frequency of a horizontal deflection circuit,
If the maximum horizontal frequency is set high and the horizontal frequency range during operation is expanded, the operating frequency of the switching power supply circuit operates up to the maximum horizontal frequency.
In such a case, the loss due to the skin effect of the switching transformer in the switching power supply circuit, the switching loss of the switching element, and the like increase, and it is difficult to take measures against heat radiation of these components. Further, in another conventional switching power supply circuit, the horizontal frequency is multiplied by the same multiplication factor in the entire horizontal frequency range of the multi-scan display monitor, and the switching power supply circuit is operated in synchronization with the multiplied signal, so that the switching power supply is switched. There was a method for setting the maximum operating frequency of the circuit to an optimum value. However, this method cannot be configured so that the entire operating frequency range of the switching power supply circuit is in an appropriate frequency range, and thus there is a problem that reduction in size of components such as a switching transformer is restricted.

The present invention relates to a switching power supply for a multi-scan display monitor, which maintains synchronization with a horizontal deflection circuit to maintain the effect of reducing screen disturbance caused by the switching power supply circuit while maintaining a high level. By increasing the definition, the operating range of the horizontal frequency is expanded, and even if the maximum horizontal frequency is increased, the loss due to the skin effect of the switching transformer and the loss of the switching element can be achieved by optimizing the maximum operating frequency of the switching power supply circuit. It is an object of the present invention to obtain a switching power supply of a multiple synchronous system capable of reducing switching loss and the like.

[0005]

In order to solve the above-mentioned problems, a switching power supply according to the present invention is a switching power supply used for a multi-scan display monitor, comprising a pulse signal synchronized with horizontal deflection of a horizontal deflection circuit. And a pulse signal synchronized with the output pulse signal of the detection circuit unit, which receives an output pulse signal of the detection circuit unit, switches a multiplication rate according to a horizontal frequency value of the horizontal deflection circuit, A multiplying circuit for outputting the signal; and a switching power supply circuit operating in synchronization with an output pulse signal of the multiplying circuit. For this reason, the switching power supply device of the present invention can be configured so that the entire operating frequency range of the switching power supply circuit is in an appropriate frequency range, and it is possible to achieve miniaturization of components such as a switching transformer.

[0006] The switching power supply of the present invention comprises:
The multiplying circuit is configured to determine an output pulse signal of the detection circuit unit by comparing it with a threshold value and switch to a desired multiplying factor. Further, the switching power supply device of the present invention is configured such that the multiplying circuit determines the output pulse signal of the detection circuit unit by comparing it with at least two or more threshold values, and switches to a desired multiplying factor. Therefore, in the switching power supply of the present invention, by setting the threshold frequency and the multiplication factor to appropriate values, the highest operating frequency of the switching power supply circuit can be set to the optimum value, and the operating frequency range can be narrowed.

[0007]

DETAILED DESCRIPTION OF THE INVENTION

<< Embodiment 1 >> Hereinafter, Embodiment 1 which is an embodiment of a switching power supply of a multiplication synchronous system of the present invention will be described with reference to FIG. In FIG. 1, the switching power supply of the first embodiment includes a horizontal deflection circuit 4, a detection circuit 1, a multiplying circuit 2, and a switching power supply 3. The detection circuit unit 1 detects a synchronization pulse signal having a horizontal deflection frequency from the horizontal deflection circuit 4. The multiplication circuit 2 to which the output pulse signal of the detection circuit unit 1 is input
The multiplication rate is switched between a case where the horizontal deflection frequency value is higher than the threshold frequency f _T and a case where the horizontal deflection frequency value is lower than the threshold frequency f _T , and each outputs a different power supply synchronization pulse signal f _p (Hz) to the switching power supply circuit 3. . Switching power supply circuit 3
Performs a switching operation in synchronization with the output pulse signal of the frequency multiplier 2.

In the multiplying circuit 2, the threshold frequency f _T and the multiplying factor are set to appropriate values, thereby narrowing the operating frequency range of the switching power supply circuit 3 of the first embodiment and setting the highest operating frequency to an optimum value. Thus, loss of electronic components such as switching elements in the switching power supply circuit 3 can be reduced, and appropriate electronic components can be used. Further, in the multiplying circuit 2, by setting another threshold value and increasing the number of switching points of the multiplying factor, it is possible to cope with a further increase in the frequency of the horizontal deflection. As described above, the switching power supply of the multiplication synchronous system of the present invention converts the pulse signal of the horizontal frequency detected from the horizontal deflection circuit by automatically switching the multiplication factor according to the horizontal frequency value in the multiplication circuit, and converting the frequency. By configuring the switching power supply circuit to operate synchronously with the pulse signal output from the multiplier circuit, the operating frequency range can be narrowed and the maximum operating frequency of the switching power supply circuit can be set to the optimum value range.

[0009]

As described above, according to the switching power supply device of the present invention, by maintaining synchronization with the horizontal deflection circuit, it is possible to maintain the effect of reducing screen disturbance caused by the switching power supply circuit while maintaining a multi-scan display. As a result, the maximum operating frequency of the switching power supply circuit can be set to an optimum value even if the maximum horizontal frequency increases. For this reason,
ADVANTAGE OF THE INVENTION According to this invention, the loss increase by the skin effect of the switching transformer in a switching power supply circuit and the switching loss of a switching element can be reduced, and the heat dissipation countermeasure can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a switching power supply according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a conventional switching power supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detection circuit part 2 Multiplier circuit 3 Switching power supply circuit 4 Horizontal deflection circuit

Claims (3)

[Claims] 1. A switching power supply device used for a multi-scan display monitor, comprising: a detection circuit unit for detecting a pulse signal synchronized with horizontal deflection of a horizontal deflection circuit; and an output pulse signal of the detection circuit unit, A multiplying circuit that switches a multiplication factor according to a horizontal frequency value of the horizontal deflection circuit and outputs a pulse signal synchronized with an output pulse signal of the detection circuit unit; and a switching device that operates in synchronization with an output pulse signal of the multiplication circuit. And a power supply circuit. 2. The switching power supply according to claim 1, wherein the multiplying circuit is configured to determine an output pulse signal of the detection circuit section by comparing it with a threshold value and to switch to a desired multiplying rate. 3. The multiplying synchronous system according to claim 2, wherein the multiplying circuit is configured to determine the output pulse signal of the detecting circuit section by comparing it with at least two or more threshold values and switch to a desired multiplying factor. Switching power supply.