JPH0576012A - Infrared wireless transmission receiver - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to satisfactorily transmit video signals of a plurality of systems when video signals are transmitted using an infrared wireless transmission system. In an infrared wireless transmission receiver used in a system for transmitting a video signal by FM using infrared rays, a means 5 for detecting a sync signal of the video signal to detect a determination, and a plurality of low-pass filters 3, 4 And a switching means 6 for switching and outputting the outputs of the low-pass filters 3 and 4, and determining means 5 for determining the video signal system.
It is characterized in that a low-pass filter for band-limiting the demodulated video signal is selected according to the output of.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared wireless transmission device for transmitting a video signal using infrared light.

[0002]

2. Description of the Related Art In recent years, wireless devices for AV devices and other electronic devices have been developed, and infrared wireless transmission of audio signals has been put into practical use, and video signals are about to be put into practical use.

An example of an infrared wireless transmission receiver constituting a conventional video signal infrared wireless transmission device will be described below with reference to the drawings.

FIG. 2 is a block diagram of an example of a conventional infrared wireless transmission receiver. In FIG. 2, reference numeral 1 is a light receiving portion for converting an incident infrared signal into an electric signal, and 2 is an F
M is a demodulator, 7 is a video signal output terminal, and 8 is a low-pass filter.

Now, consider the case where an infrared signal intensity-modulated by an electric signal obtained by frequency-modulating a transmission video signal is incident on the light-receiving surface of the light-receiving unit 1 (FIG. 2). The light receiving unit 1 outputs a signal whose frequency is modulated by the transmission video signal. This signal is F
It is demodulated by the M demodulator 2, band-limited to the required band by the low-pass filter 8, and output to the video signal output terminal 7. As described above, the video signal is delivered by infrared wireless transmission.

[0006]

However, when transmitting an image signal using the infrared wireless transmission receiver configured as described above, there are cases where it is necessary to transmit an image signal of a different system. For example, it is a case of transmitting a high-definition signal band-compressed by the MUSE system (hereinafter referred to as MUSE baseband signal) in a system transmitting an NTSC system video signal.

In such a case, it is necessary to use a low-pass filter adapted to a system having the widest band. In the case of NTSC and MUSE baseband, M
It is a low-pass filter with a band of USE baseband signal of 8.1 MHz. However, since the band of the NTSC signal is generally 5 MHz or less, the use of this low-pass filter will increase the noise in the high frequency band. In infrared wireless transmission, since a video signal is often transmitted by frequency modulation, high-frequency noise due to triangular noise is large, and the influence of the characteristic difference of the low-pass filter is very large.

Therefore, the present invention is intended to enable transmission with good quality even when transmitting a plurality of different types of video signals.

[0009]

In order to achieve this object, an infrared wireless transmission receiver according to the first aspect of the present invention detects a sync signal of a video signal and determines a video signal system by its cycle. And a plurality of low-pass filters and a means for switching and outputting the outputs of the low-pass filter, wherein the low-pass filter for band-limiting the demodulated video signal is switched according to the video signal system. is there.

An infrared wireless transmission receiver according to a second aspect of the present invention detects a sync signal of a video signal and determines a video signal system according to its format, a plurality of low-pass filters and outputs of the low-pass filter. And a means for switching and outputting, and a low-pass filter for band-limiting the demodulated video signal is switched according to the system of the video signal.

[0011]

With this configuration, the infrared wireless transmission receiver of the present invention can enable transmission with good quality even when transmitting a plurality of video signals of different systems.

[0012]

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

FIG. 1 is a block diagram showing the configuration of an infrared wireless transmission receiver according to an embodiment of the present invention. In the figure, 1 is a light receiving unit for converting an incident infrared signal into an electric signal, 2 is an FM demodulator, 3 is a low pass filter having a pass band of 5 MHz or less, 4 is a low pass filter having a pass band of 8.1 MHz or less, 5 Is a synchronization determination circuit that detects a synchronization signal to determine the system, 6 is a switching circuit, and 7 is a video signal output terminal.

Now, consider the case where the infrared wireless transmission receiver receives the video signal transmitted by infrared rays. Infrared rays are incident on the light receiving unit 1, and the video signals FM-demodulated by the FM demodulator 2 are input to the synchronization determination circuit 5, the low-pass filter 3, and the low-pass filter 4, respectively.
The synchronization determination circuit 5 detects the synchronization frequency, and outputs 15.75.
If kHz, output of low-pass filter 3, 33.75
If it is kHz, the switching circuit 6 is controlled to output the output of the low pass filter 4 to the video signal output terminal 7.

In this way, the NTSC signal, MUSE
It is possible to demodulate and output with good quality regardless of which infrared signal of the baseband signal is incident.

In the above embodiment, the method of the video signal is determined by the sync frequency. However, the shape of the sync signal may be different depending on the video signal. It is also effective to determine the signal system. For example, NTSC signal is negative binary synchronization, and MUSE baseband is positive and negative three-value synchronization.
This combination is sufficiently effective.

[0017]

As described above, according to the present invention, good transmission quality can be obtained even when a plurality of video signals of different systems are transmitted using the infrared wireless transmission system.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an infrared wireless transmission receiver according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional infrared wireless transmission receiver.

[Explanation of symbols]

 1 Light-receiving part 2 FM demodulator 3 Low-pass filter 4 Low-pass filter 5 Synchronization determination circuit 6 Switching circuit 7 Video signal output terminal

Claims (3)

[Claims] 1. An infrared wireless transmission receiver used in a system for transmitting a video signal by FM using infrared rays, means for detecting a synchronizing signal of a video signal and determining a system, and an output signal of an FM demodulating means. A plurality of low-pass filters each having an input and switching means for switching one of the output signals of the low-pass filter and outputting one of the output signals. Infrared wireless transmission receiver characterized by switching a low-pass filter for band limiting the generated video signal. 2. The infrared wireless transmission receiver according to claim 1, wherein the means for detecting the synchronizing signal of the video signal and detecting the method has a structure for detecting the method according to the cycle of the synchronizing signal. 3. The infrared wireless transmission receiver according to claim 1, wherein the means for detecting the sync signal of the video signal and detecting the method has a structure for detecting the method according to the format of the sync signal.