JPH01261091A - Television receiver - Google Patents

Abstract

PURPOSE:To use a D/A converter, a low pass filter and an amplifier or the like in common for an existing television receiver and a high definition television receiver by connecting a selector connecting a sampling frequency conversion circuit for an HNTSC signal and switching a clock in response to the input signal to an HNTSC signal processing section. CONSTITUTION:The HNTSC signal is inputted to frequency conversion circuits 1-3, the sampling frequency is converted and inputted to a selector 4 and the selector 4 selects the HNTSC signal and an HDTV signal. The signal selected by the selector 4 is inputted to D/A converters 5-7, where the signal is converted into an analog signal and the changeover of the clock of D/A converters 6-7 is applied by the selector 8, which selects a clock corresponding to the input signal. Thus, the D/A converters 5-7, low pass filters 9-11 and amplifiers 12-14 are used in common for the receiver in common use of existing TV signal and high definition signal.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a D/A converter, a low-pass filter,
This relates to a system in which amplifiers and the like are shared.

[Conventional technology]

Figure 4 (a) shows a conventional television (hereinafter the scan conversion circuit for television, (11 is ma) IJ Lux path, α7)
.

(G), ae is a digital/analog (D/A") converter for red (R), green (Q, blue (G)), wire, (2
), (Foundation) is a low-pass filter, (E), G! 4,
) is an amplifier section (hereinafter referred to as amplifier).

FIG. 4 (1)) is a block diagram showing an example of the output part of a high-definition television receiver, in which (E) is a matrix circuit, @ and @ are D/A converters, ), (2) is a low-pass filter, (to), ? 34,0I19 is an amplifier section.

Next, the operation will be explained. In FIG. 4(a), the NTSC signal sampled at four times the color subcarrier frequency (4f・C) input to the scan conversion circuit (2) is 8
It is converted into a progressive scanning signal sampled at twice the fmc. Hereafter, on this day - this sequential scanning signal is converted to HNT8.
C! Signal. This HN'rSO signal is then input to matrix circuit QQ. Here, input luminance signal Y and R-Y, B-Y color difference signals are converted into R, G, B
Convert to signal. Then the R,G.

The B signal is sent to the R, G, and B D/A converters αη and [phase], respectively.

It is input to the q-wound and subjected to D/A conversion. The D/A converted analog R, G, and B signals each have approximately 10
A low-pass filter with a cutoff frequency of MH2,
Qυ, @ through the amplifier section 1124. It is amplified and output in (c).

In FIG. 4 (1)), an input high-definition television signal (hereinafter referred to as an HDTV signal) is converted into a luminance signal Y and a color difference signal format of R-Y and B-Y by a matrix circuit (e). It is converted into G and B signals. Next, these R2O, B signals are input to D/A converters @, (to), @, respectively, and after being D/A converted, a low pass filter (7) with a cutoff frequency of about 20MH21, 0υ, (To), is amplified by the amplifier section (To), (B), and (2) and is output.

In the current TV/high-definition TV shared receiver, the output section has two built-in circuits shown in Figure 4 (a) and Figure 4 (1)), and the two circuits can be switched depending on the signal to be received. use.

[Problem to be solved by the invention]

Since the conventional current TV/high-definition TV receiving device is configured as described above, it requires a D/A converter, a low-pass filter, an amplifier, etc. on both the current TV receiving side and the high-definition TV receiving side. There were issues such as an increase in circuit scale.

This invention was made to solve the above-mentioned problems, and its purpose is to obtain 48 receivers using a set of D/A converters, low-pass filters, amplifiers, and the like.

[Means to solve the problem]

The receiving device according to the present invention has an HNTSO signal processing unit that
Connect the NTSO signal sampling frequency conversion circuit,
In addition, a selector that switches the clock according to the input signal is connected to the current TV receiving side.

The D/A converter, low-pass filter, amplifier, etc. on both high-definition television receiving sides are shared.

(Function) The HNTBO signal sampling frequency conversion circuit of the present invention converts the sampling frequency of the HNT80 signal, and thereby converts the sampling frequency of the HNTBO signal into D/A converters, low-pass filters, amplifiers, etc. of both current televisions and high-definition television receivers. It becomes possible to share.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram of an embodiment of the present invention. In FIG. 1, tl), +21, and (3) are frequency conversion circuits, (4) is a selector that switches between the HNTSO signal and HDTV signal, and (5), (6), and (7).
) is a D/A converter, (8) is a selector that switches the clock of the D/A converter according to the signal input to selector (4), (9), (11).

(b) is a low-pass filter with a cutoff frequency of about 20 MHss, and (6), (2), and Q4) are amplifiers.

Next, the operation of the embodiment of the present invention will be explained. The HN'rSC signal sampled at a frequency of 09fsc is converted into frequency conversion circuits (1), +2), (31
is input to.

Here, from 8fsc (approximately 28.6MHz) to 12f
The sampling frequency is converted to sc (approximately 42.9 MHgi). This is because the cutoff frequency of the low-pass filter used after the D/A converter is 20MHz.
If the signal is passed through the low-pass filter, aliasing components will remain in the band as shown in FIG. 2 if the 8 fsc signal remains as it is. Therefore, the sampling frequency is converted from 13 fsc to 12 fmc, and the aliasing component can be removed using a 20 MHz low-pass filter as shown in FIG.

The sampling frequency conversion circuit is a well-known interpolation filter having low-pass filtering characteristics.

The signal whose sampling frequency has been converted to 12 fsc is then input to the selector (4). In selector (4), 1
Select HN'r 80x of 2fsc and HDTV signal. This selector uses HNT80 signal and HDTV
This is used to switch between signals.

The signal selected by the selector (4) is sent to the D/A converter (5)
.

16) , (input to 71 and converted to an analog signal. The clock of the D/A converter varies depending on the input signal.
It is necessary to switch between each. This clock switching is performed by a selector (8), which selects the clock corresponding to the input signal.

The analog signal converted by the D/A converter is 20M
Low pass filter with cutoff frequency of Hz +91
, fil, passes through the α force, amplifier section (2), (to),
α → is amplified and output.

Note that in the above embodiment, the sampling frequency conversion circuit 11
) , +21 , (In 31, an example of converting an 8fsc input signal to a 12fsc signal was shown, but this sampling frequency conversion from 8fsc to 16fsc
It may be 1 or 8 f@c to 10 fsc.

〔Effect of the invention〕

As described above, according to the present invention, a D/A converter can be used in a current television/high-definition television common receiver.

Since the configuration is such that the low-pass filter, amplifier, etc. can be shared, the device can be made inexpensive and the circuit can be made small.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a frequency spectrum diagram showing aliasing components, Fig. 3 is a frequency spectrum diagram when sampling frequency conversion is performed, and Fig. 4 is a diagram of the conventional method. FIG. 2 is a block diagram illustrating the respective output portions of a current television and a high definition television. In the figure, +1), +2), (31 is the sampling frequency mantissa conversion circuit, (4) is the selector, (5),
(61, (7) is D/A conversion 5.191 m ttn
*α power is a low pass filter.

Claims (1)

[Claims] (1) A sampling frequency conversion circuit that converts the sampling frequency of the digitized first television signal, and either the output signal of this sampling frequency conversion circuit or the digitized second television signal. a selector for selecting, a digital-to-analog converter for converting the digital signal selected by the selector into an analog signal, and a digital-to-analog converter that uses the bandwidth of the second television video signal as a cutoff frequency. a low-pass filter to which the outputs of the first and second filters are input;
A television receiver that uses a common output path for television signals.