JPH0638140A - Portable television receiver - Google Patents

Abstract

PURPOSE:To improve the reception sensitivity at the reproduction of an audio signal only by selecting a characteristic of a detection transformer or a surface acoustic wave(SAW) filter of an intermediate frequency amplifier circuit at the reproduction of the audio signal only in the portable television receiver having a function of reproducing only the audio signal in addition to the usual TV reception function. CONSTITUTION:When only an audio signal is desired to be reproduced, a TV reproduction-audio only reproduction changeover switch 1 is thrown to the position of the audio reproduction only. In this case, SAW filter changeover switches 2, 3 are thrown to the position of audio only reproduction SAW filter 8 in interlocking with the switch 1. Then a TV signal received by an antenna 5 is selected and amplified by a tuner 6, amplified and detected via the audio only reproduction SAW filter 8 and outputted as a video output and an audio output. Since the video quality is not taken into account for the audio only reproduction SAW filter 8 in use, it is not required to attenuate an audio carrier and the audio sensitivity is remarkably improved by it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable television receiver having a function of reproducing only sound in addition to a normal television receiving function.

[0002]

2. Description of the Related Art In recent years, liquid crystal television receivers (hereinafter referred to as
The miniaturization of portable TVs such as TVs)
Even things that are in your pocket have been commercialized. Since it is a TV, it is natural to play video and audio at the same time,
It is very convenient for actual use when it is difficult to view the video in a crowded train, or when the function to play back only the voice is added to extend the battery life.
V is also commercialized. In the conventional portable TV,
The video function is turned off by means such as turning off the video signal when reproducing only the sound, or turning off the backlight for a liquid crystal TV or the like that requires a light source.

[0003]

However, in the conventional portable TV, since the receiving circuit is designed with an emphasis on improving the display quality of the image, for example, the surface wave filter of the intermediate frequency amplifying circuit (hereinafter, As an abbreviated SAW filter), an audio carrier attenuated by about 20 dB with respect to the video carrier is used to reduce the audio beat and to balance the video sensitivity and the audio sensitivity. Therefore, even when only the audio is reproduced, the audio sensitivity determined by the video-oriented receiving circuit must be satisfied. That is, there is a problem that only the same sensitivity as when receiving a normal TV can be obtained even when only audio is reproduced.

Therefore, in the present invention, the characteristic of the SAW filter is switched at the time of reproducing only the voice, or the characteristic of the detection transformer of the intermediate frequency amplifier circuit is switched, so that the receiving sensitivity is greatly improved at the time of reproducing the voice only. With the goal.

[0005]

A portable television receiver of the present invention having a function of reproducing only audio in addition to a normal television receiving function of simultaneously reproducing video and audio reproduces only audio. In this case, a means for improving the receiving sensitivity is provided.

Further, the improvement of the reception sensitivity is realized by switching the characteristics of the surface wave filter of the intermediate frequency amplifier circuit.

Further, the improvement of the reception sensitivity is realized by switching the characteristics of the detection transformer of the intermediate frequency amplifier circuit.

[0008]

1 is a block diagram showing a first embodiment of a portable TV according to the present invention. In FIG. 1, during normal TV reproduction, the TV reproduction / audio only reproduction changeover switch 1 is set to T.
Defeat to the V playback side. At this time, the SAW filter changeover switches 2 and 3 are interlocked with the switch 1 and are connected to the SA for TV reproduction.
It is switched to the W filter 4 side. In FIG. 1, the TV signal received by the antenna 5 is tuned and amplified by the tuner 6, amplified and detected by the intermediate frequency amplification circuit 7 via the SAW filter 4 for TV reproduction, and output as video output / audio output. It The SAW filter used here has a characteristic in which the audio carrier is attenuated by about 20 dB with respect to the video carrier, which balances the video sensitivity and the audio sensitivity and reduces the audio beat to improve the video quality. Next, when only the sound is to be reproduced, the TV reproduction / sound-only reproduction changeover switch 1 is set to the sound-only reproduction side. At this time, the SAW filter changeover switches 2 and 3 are switched to the SAW filter 8 side for reproducing only the sound in conjunction with the switch 1. In FIG. 1, the antenna 5
The TV signal received at is selected and amplified by the tuner 6,
Although only the sound is amplified and detected by the intermediate frequency amplifier circuit 7 through the SAW filter 8 for reproduction, and output as a video output / audio output, the video output is not reproduced but only the audio output is reproduced. Since the SAW filter used here does not need to consider the image quality, it is not necessary to attenuate the voice carrier, and the voice sensitivity can be greatly improved accordingly. Moreover, the voice quality is improved by reducing the voice buzz. It should be noted that the filter in this case may be usable as a simple transformer instead of the SAW filter if the adjacent channel interference does not cause a problem.

FIG. 2 is a block diagram showing a second embodiment of the portable TV of the present invention. In FIG. 2, the TV reproduction / sound only reproduction changeover switch 1 and the detection transformer changeover switch 9 of the intermediate frequency amplifier circuit 7 are interlocked. Figure 2
At the time of normal TV reproduction, the TV reproduction detection transformer 10 that is tuned to the video carrier is used to perform an operation focusing on the video quality. Next, when only the sound is reproduced, the sound-only reproduction detection transformer 11 synchronized with the sound carrier is used, and the sound sensitivity can be improved although the image quality is sacrificed.

The basic receiving operation is the same as in FIG.

The methods shown in FIGS. 1 and 2 may be used together.

In any case, when only the sound is reproduced, the image sensitivity is relatively deteriorated as compared with the sound sensitivity, or the audio beat is increased and the image quality is deteriorated. At this time, however, the image is not displayed at all. It doesn't matter.

[0013]

As described above, in the portable TV having the function of reproducing only the sound in addition to the normal TV receiving function of simultaneously reproducing the image and the sound according to the present invention, when the sound is reproduced, the intermediate The voice sensitivity can be significantly improved by a simple means of switching the characteristics of the SAW filter or the detection transformer of the frequency amplification circuit. In addition, voice quality such as voice buzz reduction is improved. Therefore,
According to the present invention, the audio-only reproducing function, which is sufficiently considered as a function of using a portable TV, has the great appeal of improved sensitivity and improved sound quality, and the commercialability of the portable TV is dramatically improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a portable TV of the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of the portable TV of the present invention.

[Explanation of symbols]

 1 TV reproduction / audio only reproduction changeover switch 2, 3 SAW filter changeover switch 4 TV reproduction SAW filter 5 Antenna 6 Tuner 7 Intermediate frequency amplification circuit 8 Audio only reproduction SAW filter 9 Detection transformer changeover switch 10 TV reproduction detection transformer 11 Detection transformer for audio playback only

Claims (3)

[Claims] 1. In a portable television receiver having a function of reproducing only audio in addition to a normal television receiving function of simultaneously reproducing video and audio, the receiving sensitivity is improved when only audio is reproduced. A portable television receiver comprising means. 2. The portable television receiver according to claim 1, wherein the improvement of the reception sensitivity is realized by switching the characteristics of the surface wave filter of the intermediate frequency amplifier circuit. 3. The portable television receiver according to claim 1, wherein the improvement of the reception sensitivity is realized by switching the characteristics of the detection transformer of the intermediate frequency amplifier circuit.