KR900005950Y1 - Mis operating protecting circuit for stereo and multi-sound television - Google Patents

Abstract

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Description

Stereo and bilingual selection malfunction prevention circuit when channel tuning

1 is a block diagram showing the present invention.

2 is a circuit diagram specifically showing the first diagram.

* Explanation of symbols for main parts of the drawings

1: voice intermediate frequency detection circuit 2, 4: buffer

3: mute output driving circuit 5: pulse shaping circuit

6: Bilingual Demodulation and Carrier Detector Integrated Circuit

7: Stereo demodulation and pilot detector integrated circuit

8: frequency synthesis and clock pulse generator

The present invention prevents stereo and bilingual selection malfunctions during channel tuning for stable operation of the designated channel during auto search tuning in stereo or bilingual function display and mode operation of a frequency-synthesis tuning system. It is about a circuit.

In the related art, when the channel is tuned by Auto Search, accurate synchronization is not performed, so that the synchronization is weak, resulting in transient phenomenon.

This phenomenon directly affects the audio output, which adversely affects stereo, pilot detection LED display and mode switching, bilingual LED and mode operation. That is, this effect has caused the display LED to flicker and the mode operation to malfunction.

Therefore, the present invention aims to make the stable operation by muting the transient phenomenon to solve the conventional problems.

Another object of the present invention is to enable the use of an output voice mute in a circuit with a fixed voice output terminal.

The present invention provides an audio intermediate frequency detection circuit for detecting an audio synthesis signal at an audio intermediate frequency in an image amplification signal, a buffer for amplifying an input signal, a frequency synthesizing device for generating clock pulses during channel up / down or various key inputs. A waveform generating circuit which buffers a clock generating circuit, an output signal of the frequency synthesizing and clock generating circuit and filters the waveform in a desired band, and demodulates a bilingual broadcasting signal and outputs it according to a user's desired mode. On the other hand, a bilingual demodulation and carrier detector integrated circuit for detecting a carrier output, and a stereo demodulation and pilot detector for detecting a stereo signal of L + R, L-R, and a pilot signal to drive an LED.

Hereinafter, with reference to the drawings of the present invention will be described in detail.

1 is a block diagram showing the present invention, where 1 is a voice intermediate frequency (SIF) detection circuit, 2 is a buffer of the output signal of the voice intermediate frequency detection circuit 1, and 3 is a mute output driving circuit. , Symbol 8 is a frequency synthesis and clock pulse generator (FS) that generates clock pulses during the initial 350ms when a channel UP / DOWN or various key inputs are performed by a built-in clock generator, and symbol 5 is a signal output from the FS (8) device. Is a waveform shaping circuit for driving the mute output driving circuit (3) after detecting the DC component through the low frequency filter, and the code 6 is a bilingual demodulation and carrier detector, the code 7 is a stereo demodulation and pilot detector, and the code 4 is It is a buffer that amplifies and buffers so that a sufficient output can be obtained from a bilingual demodulation and carrier detector 6 and a stereo demodulation and pilot detector 7.

The SIF detector 1 separates the 4.5 MHZ subcarrier from the image intermediate frequency VIF and buffers and amplifies it in the buffer 2, and in the frequency synthesizer and the clock pulse generator 4, a user selects a selection key. Press to generate a pulse.

The signal is input to the waveform shaping circuit 5 to detect a DC component while passing the low pass filter to drive the mute output driving circuit 3. At this time, the bilingual demodulation (6) or stereo demodulation circuit (7) mutes the cause signal from transients occurring during carrier or pilot detection, and prevents malfunctions. The output is buffered and amplified in the buffer (8). Get the output.

FIG. 2 is a circuit diagram specifically showing the block diagram of FIG. ₁ , wherein R ₁ to R ₁₂ are resistors, C ₁ to C ₁₂ are capacitors, Q ₁ to Q ₄ are transistors, and B ₁ to B ₂ are buffers. , D ₁ is diode, FS is voice synthesizer and clock pulse generator, SIF is voice intermediate frequency detector, DUM is bilingual demodulation and carrier detector, STM is stereo and pilot detector.

The SIF corresponds to the symbol (1), the portion composed of the resistor (R ₁₁ ) and the buffer (B ₁ ) corresponds to the buffer (2), and the portion composed of the resistor (R ₁₀ ) and the transistor (Q ₄ ) is muted. Corresponding to the drive circuit 3, the FS device corresponds to the symbol 4, and includes resistors R ₁ to R ₉ , capacitors C ₁ to C ₄ , transistors Q ₁ to Q ₃ , and diode D. ₁ ) the portion constituted by the waveform shaping circuit 5 corresponds to the waveform shaping circuit 5, the DUM corresponds to the sign 6, the STM corresponds to the sign 7, the resistor R ₁₂ , the capacitor C ₁₂ , and the buffer ( The portion constituted by B ₂ ) corresponds to the shock absorber 8.

Therefore, in the implementation of the present invention, the audio intermediate frequency detector of the SIF (1) detects the image from the television image detection (VIF), separates the 4.5MHZ subcarrier through the 4.5MHZ ceramic filter, and then amplifies and limits the complex audio signal. Becomes

This signal is a capacitor (C ₅₎ and a resistor (R _11), a buffer (B ₁₎ affected by each sub-circuit when the detected after the shock absorber (2) configured to be become one of the audio-wave component and weakening the amplification buffer capacitor (C ₁₅ ), A buffer amplified by a buffer (8) consisting of a resistor (R ₁₂ ) and a buffer (B ₂ ) and detects a carrier wave according to the mode selection in a bilingual demodulation circuit (DUM), and displays the broadcasting status according to the mode selection. A light emitting diode (LED) is driven and outputs a left, right, and a foreign language, both a left and a native language, and a right and a native language, both left and right, according to a user's selection.

The stereo demodulation circuit STM detects a pilot signal to drive a light emitting diode LED, and detects and selectively outputs a difference (L-R) signal and a sign (L + R) signal. By the way, when the mode is selected, if the key is pressed according to the user's selection in the frequency synthesis and clock generation circuit FS, the frequency is generated in the built-in clock generator to select the channel up or down. During input, a clock pulse is generated during the initial 350ms and input to the base of the transistor Q ₁ .

The signal is buffered in transistor Q ₁ to remove external noise generated by an external FS device when the current of the clock pulse is driven. The signal is passed through the resistors R ₃ , capacitor C ₁ , and resistor ( When a low pass filter composed of two stages of R ₄ ) and capacitor C ₂ is passed, a DC component is detected and input to transistor Q ₂ , and “high” is input. The transistor Q ₂ is turned on, and a "low" is output to the collector of the transistor Q ₂ , the high frequency component is bypassed by the capacitor C ₃ , and the protection resistor R ₈ of the transistor Q ₃ is increased. Transistor Q ₃ is turned on.

Therefore, when the channel is turned up and down, the collector of transistor Q ₂ is subjected to a "low" voltage, thereby turning on transistor Q ₃ , where a discharge path of capacitor C ₄ is formed, which is applied to the base of transistor Q ₄ . A signal is applied to turn on the transistor Q ₄ so that a ground path is formed through the transistor Q ₄ at A. Therefore, the stereo demodulator (STM) integrated circuit or bilingual demodulator (DUM) integrated circuit mutes the abnormality caused by transient phenomenon during the detection of the pilot or carrier, and prevents the malfunction of the diode (D ₁ ). The charge charged in the capacitor C ₃ during the off serves to discharge quickly.

Therefore, as described above, abnormal transients occurring during channel selection and key operation can be prevented, and malfunctions of LEDs and modes can be prevented, and circuits with fixed voice output terminals can be used as output voice mutes. .

Claims (1)

Audio intermediate detection circuit (1), capacitor (C ₅ ), and resistor (R ₁₁ ) for detecting the audio intermediate frequency in stereo or bilingual function display and mode selection circuit of a frequency multiplexed TV receiver. the collector of the buffer the buffer (2), a transistor (Q _4), consists of a resistance (R _10), a transistor (Q ₄₎ is composed of (B ₁₎ for amplifying an output of the audio intermediate frequency detection circuit (1) A mute output driving circuit (3) for amplifying the output of the buffer ( ₂ ), consisting of a capacitor (C ₂ ), a resistor (R ₁₂ ), a buffer (B ₂ ) 4, a resistor (R ₁ ~ R _2), buffer resistor consisting of a transistor (Q ₁₎ (R ₃ ~ R _4), a capacitor (C ₁ ~ C ₂₎ DC component detecting a two-stage low-pass filter composed of the transistors (Q ₂ ~ Q _3), a resistance (R ₆ ~ R _9), a capacitor (C _3), diode (D ₁₎ connected to the sum frequency as a logic circuit comprised of And a waveform shaping circuit 5 for shaping an output waveform of the clock generation circuit FS and applying a switching signal to the mute output driving circuit 3, a stereo demodulation and pilot detector (DUM) integrated circuit 6, and Channel demodulation, comprising a national demodulation and carrier detector (STM) integrated circuit (7), a frequency synthesizing device and a clock generating circuit (8) in which frequencies are generated from channel UP / DOWN or various key inputs. Stereo and bilingual selectable tamper proof circuit.