JPH07107319A - High pressure generating circuit - Google Patents

Abstract

PURPOSE:To synchronize a high pressure generating part with horizontal deflection in any mode, and to realize the same brightness, high pressure regulation performance, and low noise, in a television receiver corresponding to two kinds of horizontal scanning frequency modes fH and 2fH such as a high-vision and a double-speed high-vision. CONSTITUTION:Return pulses Hp and Hp from a horizontal deflection outputting part 13 and a horizontal synchronizing pulse generating circuit 14 are 1/2 frequency-divided by a 1/2 frequency-dividing circuit 16, and an obtained Hp' is inputted to a synchronization switching circuit 17. A synchronizing signal HD 11 of the two kinds of input sources fH and 2fH is inputted to a frequency discriminating circuit 15, and the frequency of an output signal from the synchronization switching circuit 17 is always set as fH by a discrimination signal HFS, so that the driving of a high pressure generating circuit consisting of circuits 18, 19, and 20 can be attained under a constant condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high voltage generating circuit for a television receiver, and more particularly to a first horizontal scanning frequency fH and second horizontal scanning frequencies 2fH and fH which are twice the first horizontal scanning frequency fH. The present invention relates to a high-voltage generation circuit of a television receiver that has a large horizontal scanning frequency of about ± 3 kHz with respect to 2 fH and is compatible with two horizontal scanning frequencies.

[0002]

2. Description of the Related Art In recent years, in order to improve the image quality of a television receiver, an interlaced signal is converted into a non-interlaced signal by digital signal processing, and horizontal deflection driving is performed at a frequency twice the horizontal scanning frequency. Some John receivers have been put to practical use.

In recent years, high-definition televisions have been put into practical use as a favorite of high-definition televisions, and there are many cases of commercialization. However, HDTV is an interlaced system,
In the future, there is also a trend to seek high-speed double-speed scanning for high-definition images with the aim of achieving higher image quality, mainly for business purposes.

Further, in the computer market, the demand for higher performance is increasing, and workstations which require a monitor at a horizontal scanning frequency of around 60 kHz to 70 kHz are occupying a large position.

From the background described above, the so-called multi-scan type television receivers corresponding to an arbitrary scanning frequency within a specific scanning frequency range are mainstream as a television receiver corresponding to the above-mentioned application, and are commercially available. Is also big. On the other hand, considering high-definition and its double speed, the horizontal scanning frequency is 33.75 kHz and 67.5 kHz.
Specialized products may also be used in terms of higher brightness and higher image quality.

The prior art of the high voltage generation system of the two types of television receivers corresponding to a plurality of horizontal scanning frequencies will be described.

First, a system in which horizontal deflection scanning and high voltage generation driving are synchronized will be described with reference to FIG. Horizontal sync signal HD
11 is input to the horizontal deflection jungle unit 12 and also to the frequency detection circuit 21. Frequency detection circuit 21
In general, frequency detection is performed by counting input pulses in a fixed time, and an output signal for controlling the self-oscillation frequency of the horizontal deflection jungle unit 12 is output from the horizontal oscillation frequency control circuit 22 according to the detection result. R. The synchronizing pulse signal HD ′ generated by the horizontal deflection jungle unit 12 is subjected to waveform shaping and is input to the horizontal deflection output unit 13 so that a sawtooth wave current is passed through the horizontal deflection yoke.

In the horizontal deflection output section 13, a pulse voltage is generated in the collector of the output transistor, the pulse voltage is divided by a choke transformer or the like, and the horizontal synchronizing pulse generating circuit 1
4 outputs the synchronizing pulse Hp. Hp is fed back to the horizontal deflection jungle unit 12 as a return pulse and is input to the HD 11 and A of the horizontal deflection jungle unit 12.
Phase detection is performed in the FC circuit for synchronization. Also Hp
Is also input to the high-voltage drive circuit 18, and is CR by the FBT (flyback transformer) drive circuit 19 and FBT 20.
A high voltage is applied to the T anode. In this case, the FBT of the high voltage generator is always driven at the same frequency as the horizontal scanning frequency.

Next, a method in which the horizontal deflection scanning and the high voltage generation driving are asynchronous will be described with reference to FIG. The horizontal deflection unit is the same as in the case of FIG. The drive pulse of the high voltage generation circuit uses the pulse signal from the oscillation circuit 31 as the reference synchronization signal. Generally, the oscillator circuit 31 is composed of a crystal having a natural vibration frequency and a multistage frequency divider. The configuration and operation of the high voltage drive circuit 18, the FBT drive circuit 19, the FBT 20, and the CRT anode are the same as those in FIG. 2 except that the pulse signal output from the oscillation circuit 31 is used as the reference synchronization signal of the high voltage generation circuit.

[0010]

However, the conventional techniques shown in FIGS. 2 and 3 have the following problems.

First, in the case of FIG. 2, the inductance of the winding of the FBT is basically used to always drive the FBT at the same frequency as the horizontal scanning frequency, and the horizontal scanning frequency is designed according to the maximum scanning frequency. There is a need. This is necessary to prevent magnetic saturation of the FBT in the high frequency range. As its adverse effects, first of all, the heat loss inside the FBT increases in order to use it at a high frequency, and the output power at the same core size becomes lower than that of an FBT for exclusive use at a low frequency. It is disadvantageous in terms of brightness of the television receiver.

Secondly, since the FBT must be designed with reference to the high frequency, the regulation characteristic is greatly deteriorated when the FBT is used at the low frequency.

Next, in the case of FIG. 3, since high voltage is driven asynchronously with respect to the horizontal scanning frequency, ringing components and the like in the high voltage output section are likely to appear on the screen as asynchronous noise, so that image quality deterioration is likely to occur.

The present invention is intended to solve the above-mentioned problems, and the first horizontal scanning frequency fH and the second horizontal scanning frequencies 2fH and fH, 2fH which are twice the first horizontal scanning frequency fH.
On the other hand, in a television receiver corresponding to two horizontal scanning frequencies with large horizontal scanning frequencies of about ± 3 kHz and ± 6 kHz, respectively, the maximum output power as an FBT is obtained even in any of the two modes. It is an object of the present invention to provide a bright and high-quality television receiver by securing and removing an asynchronous noise component.

[0015]

In order to achieve this object, a high voltage generating circuit of the present invention detects a horizontal scanning frequency from a horizontal synchronizing signal and outputs L / L depending on fH or 2fH.
The horizontal pulse signal from the frequency discriminating circuit 15 that outputs the H-level frequency discriminating signal HFS and the horizontal pulse signal from the horizontal deflection circuit 1 /
It has a configuration including a 1/2 divider circuit 16 that divides the frequency by 2 and a synchronization switching circuit 17 that switches the original signal of the horizontal pulse signal and the 1/2 divider signal by the divider circuit.

[0016]

With this configuration, the input signals are fH and 2f.
In either case of H or the horizontal scanning frequency near each of them, the high voltage generating circuit can operate at a constant drive frequency fH synchronized with the horizontal scanning frequency.
The maximum output power is generated as the FBT in any of the various modes, and a high performance of the high voltage regulation characteristic can be ensured. Also, asynchronous noise components can be removed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, a double speed NTS is used as an input source.
C (fH = 31.5kHz), HDTV (3
3.75 kHz), double-speed HDTV (67.5 kHz, same)
A television receiver corresponding to 3 modes of (Hz) will be described as an example. In this case, fH and 2fH described in claim 1
Is fH = 33.75 kHz, 2fH = 67.5 kHz. In FIG. 1, 11 is an input source horizontal synchronizing signal HD, which is input to the horizontal deflection jungle unit 12 and the frequency determining circuit 15. The frequency discriminating circuit 15 counts and calculates the number of synchronizing pulses of the horizontal synchronizing signal for a certain period with a counter, and outputs the frequency discriminating signal HFS corresponding to the horizontal scanning frequencies fH and 2fH by comparing with the frequency discriminating threshold voltage. To do. HFS outputs L level when fH is input and H level when fH is input.

The HFS is a horizontal deflection jungle unit 12,
Switch the self-oscillation frequency. With the above configuration, the horizontal deflection jungle unit 12 outputs the self-oscillation frequency pulse HD 'which is substantially equal to the input synchronization signal HD11. The horizontal deflection output unit 13 amplifies the self-oscillation frequency pulse HD ′ and supplies a sawtooth wave current to the horizontal deflection coil. The horizontal synchronizing pulse generation circuit 14 detects the horizontal collector pulse generated in the collector electrode of the output transistor of the horizontal deflection output unit 13 as a low-voltage pulse signal in the secondary winding of the choke transformer, and further controls the horizontal deflection jungle unit 12. Then, level conversion and impedance conversion are performed to a voltage value suitable for the operation, and a return pulse Hp is created.

The Hp is input to the horizontal deflection jungle unit 12 and compared in frequency and phase with the input synchronizing signal HD11 to synchronize the horizontal deflection with HD11.

The above is the basic configuration and function of the horizontal deflection circuit. The features of the high voltage generation circuit of the present invention will be specifically described below with reference to embodiments. The synchronizing signal Hp output from the horizontal synchronizing pulse generating circuit 14 is first input to the synchronizing switching circuit 17 as it is and secondly to the 1/2 frequency dividing circuit 1.
6 is output as a synchronizing signal Hp ′ whose frequency is divided by ½ of Hp, and is input to the synchronization switching circuit 17.

Here, the input synchronizing signal HD1 is 33.75k.
In the case of Hz, the frequency of Hp is 33.75 kHz, and the frequency of Hp 'obtained by dividing Hp by 1/2 is 16.875 kHz. When the input synchronization signal HD1 is 67.5 kHz, the frequency of Hp is 67.5 kHz, and the frequency of Hp 'obtained by dividing Hp by 1/2 is 33.75 kHz.

As described above, the frequency discriminating circuit 15 outputs the frequency discriminating signal HFS corresponding to the frequency mode of the input synchronizing signal HD11 to control the output signal of the synchronization switching circuit 17. Here, when HFS is L, the synchronization switching circuit 1
7 output signal is Hdp = 33.75 kHz, and in case of H, Hdp = 2fH / 2 = 67.5 kHz / 2 = 33.
The synchronization switching circuit 17 operates so that the frequency becomes 75 kHz.

Due to the above configuration, the frequency of the output signal Hdp from the synchronization switching circuit 17 is basically always 3
It becomes 3.75 kHz. Therefore, the high voltage drive circuit 18,
FBT drive circuit 19 and FBT 20 are always 33.75 kH
It is driven by z and is always synchronized with the horizontal deflection circuit.

As described above, according to this embodiment, the high voltage generating circuit is always f in any input frequency mode.
It operates stably at H = 33.75 kHz, is capable of generating the maximum output power of the FBT, and has a constant regulation characteristic. Secondly, since the horizontal deflection circuit and the high voltage generation circuit are synchronized with each other, unnecessary noise due to the asynchronous operation of the high voltage generation circuit with respect to the horizontal deflection circuit can be prevented from appearing on the display screen, and high image quality can be stably displayed.

[0026]

As described above, according to the present invention, by providing the frequency discriminating circuit 15, the 1/2 frequency dividing circuit 16, and the synchronous switching circuit 17, the horizontal scanning frequency of the input source is fH, 2f.
In each of the H modes, the output power of the FBT is maximized by synchronizing with the scanning frequency and operating at the fixed driving frequency fH (and near fH), and the constant regulation characteristic is maintained, and the asynchronous noise is eliminated. Does not occur.

Therefore, a bright and high-quality television receiver can be realized in terms of both high-definition and double-speed high-definition compatibility.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a block configuration according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a block configuration of a first conventional example.

FIG. 3 is a block configuration explanatory diagram of a second conventional example.

[Explanation of symbols]

 15 frequency discrimination circuit 16 1/2 frequency divider circuit 17 synchronization switching circuit

Claims (2)

[Claims] 1. A horizontal scanning frequency of about ± 3 kHz and a horizontal scanning frequency of about ± 6 kHz with respect to a first horizontal scanning frequency fH and second horizontal scanning frequencies 2fH and fH, 2fH that are twice the first horizontal scanning frequency fH, respectively. In the television receiver corresponding to two types of horizontal scanning frequencies, the horizontal scanning frequency is detected from the horizontal synchronizing signal, and fH or 2f is detected.
A frequency discriminating circuit for outputting a frequency discriminating signal of L / H level according to H, a frequency dividing circuit for dividing the horizontal pulse signal from the horizontal deflection circuit by 1/2, an original signal of the horizontal pulse signal, and the frequency dividing circuit. A high voltage which is synchronized with the horizontal scanning frequency in both the fH and 2fH modes and operates at a fixed driving frequency fH and fH in the vicinity by a configuration provided with a synchronous switching circuit for switching the 1/2 frequency-divided signal. Generator circuit. 2. A high-definition horizontal scanning frequency of 33.75 kHz is applied as fH, a high-definition double-speed scanning frequency of 67.5 kHz is applied as 2fH, and an NTSC double-speed scanning is applied as a horizontal scanning frequency near fH. 31.5 kHz, HD-MAC 31.25
A high-voltage generation circuit characterized by being applied to kHz as well.