JPH05191823A - Tv receiver - Google Patents

Abstract

PURPOSE:To maintain a stable reception by stabilizing a frequency characteristic and a phase characteristic for the status change of an antenna in a TV receiver. CONSTITUTION:In a TV receiver composed of an antenna 1, a tuner 2, a SAW filter 3, a video intermediate frequency amplifier circuit 4, a video detection circuit 5, a color subcarrier wave level detection circuit 6 and a video frequency amplitude correction circuit 7, a color subcarrier amplitude detection signal in accordance with the amplitude level is obtained by detecting the amplitude level of the color subcarrier wave of a signal passing the video detection circuit 5 in the color subcarrier wave level detection circuit 6. By impressing this signal on the video frequency amplitude correction circuit 7 and performing a feedback, a frequency characteristic and a phase characteristic are stabilized and the stable video is maintained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency characteristic control circuit and a phase characteristic control circuit of a television receiver.

[0002]

2. Description of the Related Art FIG. 4 shows a circuit block diagram of a conventional television receiver. 1 antenna, 2 tuner, 3
SAW filter, 4 video intermediate frequency amplifier circuit, 5
It consists of a video detection circuit. The transmitted signal is one antenna,
The signal is passed through the tuner 2 and the SAW filter 3 and the image intermediate frequency amplification circuit 4 and is detected by the image detection circuit 5. However, the detected signal has a drawback that the frequency characteristic and the phase characteristic are likely to be in an abnormal state depending on the reception condition of the antenna.

[0003]

SUMMARY OF THE INVENTION In a television receiver, the frequency characteristic and the phase characteristic are stabilized against a change in the status of the antenna.

[0004]

In a television receiver, a color subcarrier amplitude is detected, and a video amplitude correction and phase correction circuit is controlled by the detected level.

[0005]

According to the present invention, a stable image is maintained in a television receiver by the above-mentioned structure.

[0006]

FIG. 1 shows a first embodiment of the present invention. 1 antenna, 2 tuner, 3 SAW filter, 4 video intermediate frequency amplification circuit, 5 video detection circuit, 6 color subcarrier level detection circuit, 7 video frequency amplitude correction circuit. The operation will be described below.

The signal that has passed through the video detection circuit of 5 detects the amplitude level of the color subcarrier of the signal in the color subcarrier level detection circuit of 6 and obtains a color subcarrier amplitude detection signal matching the amplitude level. This signal is applied to the video frequency amplitude correction circuit 7 and feedback is applied to stabilize the frequency characteristics.

FIG. 2 shows a second embodiment of the present invention. 1 antenna, 2 tuner, 3 SAW filter, 4
The video intermediate frequency amplification circuit 5, the video detection circuit 5, the color subcarrier level detection circuit 6, and the phase correction circuit 8. The operation will be described below.

The signal passed through the video detection circuit 5 is obtained by the color subcarrier level detection circuit 6. This signal is 8
The phase characteristic is stabilized by applying it to the phase correction circuit of and applying feedback.

FIG. 3 shows a third embodiment of the present invention. 1 antenna, 2 tuner, 3 SAW filter, 4
Video intermediate frequency amplifier circuit, 5 video detection circuit, 6 color subcarrier level detection circuit, 7 video frequency amplitude correction circuit,
8 phase correction circuits. The operation will be described below.

The signal passing through the video detection circuit 5 detects the amplitude level of the color subcarrier of the signal in the color subcarrier level detection circuit 6 to obtain a color subcarrier amplitude detection signal corresponding to the amplitude level. This signal is sent to the video frequency amplitude correction circuit of 7,
The frequency characteristics and the phase characteristics are stabilized by applying them to the phase correction circuits 8 and 8 and applying feedback.

[0012]

As described above, according to the present invention, a television receiver can receive stably in frequency characteristics and phase characteristics, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a block diagram of a second embodiment of the present invention.

FIG. 3 is a block diagram of a third embodiment of the present invention.

FIG. 4 is a block diagram of a conventional example.

[Explanation of symbols]

 1 Antenna 2 Tuner 3 SAW Filter 4 Video Intermediate Frequency Amplifier Circuit 5 Video Detection Circuit 6 Color Subcarrier Level Detection Circuit 7 Video Frequency Amplitude Correction Circuit 8 Phase Correction Circuit

Claims (3)

[Claims] 1. A television receiver characterized in that a color subcarrier amplitude level is detected to control the frequency characteristic in order to stabilize the video frequency characteristic. 2. The television receiver according to claim 1, wherein the video frequency characteristic is a phase characteristic. 3. The television receiver according to claim 1, wherein the video frequency characteristic is a video frequency characteristic and a phase characteristic.