JPH02271786A - Television signal converter - Google Patents

Abstract

PURPOSE:To obtain a TV signal converter with simple constitution able to inform the name of the signal during reception to the user by providing an AND circuit ANDing an output of a synchronizing processing circuit and an output of a keyed AFC pulse generating circuit. CONSTITUTION:When a TV signal deflecting device receives a standard signal, a signal from a standard TV signal input terminal 12 is outputted to a television receiver from a video signal output terminal 13 by closing a switch 7 between terminals a and c. When a high quality TV signal is received, terminals b, c of a switch 7 are closed to convert a high quality TV signal from a tuner into a digital signal by an A/D converter 1 and a signal processing circuit 2 converts the result into an aspect ratio and a scanning line number. Moreover, an AND circuit 8 ANDing a synchronizing processing circuit 3 and a keyed AFC pulse generating circuit 4 is provided to the TV signal converter and its output is outputted from a keyed AFC pulse output terminal 14 to the tuner. Then the keyed AFC pulse is outputted to the tuner by the normal operation when the high quality TV signal is received.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a television signal conversion device for converting a television signal different from a current standard television signal into a current standard television signal.

BACKGROUND OF THE INVENTION In recent years, television signals such as high-definition television, which have a transmission method different from conventional television signals, have been developed and come into use. Accordingly, a need has arisen for a television signal converter that can convert high-definition television signals into standard television signals and reproduce them on conventional television receivers.

Figure 3 shows a schematic block diagram of a conventional television signal conversion device. In Figure 3, 1 is an A/D that converts the video detection signal, which is an analog signal from a tuner/detection circuit (not shown), into a digital signal. A converter, 2 is a signal processing circuit for various processing of the gibtal signal from the A/D converter 1, 3 is a synchronization processing circuit that detects the synchronization of the video detection signal and generates a standard television signal, and 4 is a keyed AFC. Keyed AFC to output to tuner that generates pulses
a pulse generation circuit; 5 a D/A converter that converts the digital signal processed by the signal processing circuit 2 into an analog signal;
6 is an NTSC converter for converting the analog signal from the D/A converter 5 into a current standard television signal;
is a switch that automatically or manually switches between the first signal, which is the current standard TV signal from the tuner, and the second signal obtained by converting the high-definition TV signal, and outputs the signal to the TV receiver. A terminal a inside the switch 7 is connected to a first signal, a terminal A is connected to a second signal, and a terminal C is connected to a television receiver. Here, 1) is a high-quality television signal input terminal, 12 is a standard television signal input terminal, 13 is a video signal output terminal, and 14 is a keyed AFC pulse output terminal.

Regarding the television signal converter configured as above,
The operation will be explained below.

By closing terminals a and C of the switch 7 when receiving a standard television signal, the first signal, which is the standard television and video signal output from the tuner, is output as is to the television receiver.

Further, when receiving a high-definition television signal, terminals A and C of the switch 7 are closed, the high-definition television signal obtained from the tuner is converted into a digital signal by the A/D converter 1, and the signal processing circuit 2 converts the high-definition television signal obtained from the tuner into a digital signal. Convert aspect ratio and number of scanning lines. At the same time, a keyed AFC pulse is output to the tuner. Further, the synchronization processing circuit 3 detects a synchronization signal of a high-quality television signal, generates a synchronization signal of a standard television signal, and outputs it to the NTSC encoder 6.

The digital signal output from the signal processing circuit 2 is converted into an analog signal by the D/A converter 5, and then the NT
The SC encoder 6 converts it into a standard television signal. The second signal, which is a standard television signal obtained by converting the high-definition television signal in this way, is sent to the terminal of the switch 7.
Since the interval c is closed, the signal will be output to the television receiver.

Problems to be Solved by the Invention However, in the operation when receiving a standard television signal,
As can be seen from the configuration of the conventional example, the keyed AFC pulse is
It is outputted to the tuner from the keyed AFC pulse generation circuit 4 for receiving high-definition television signals. the result,
There is a problem in that when receiving a standard television signal, the AFC circuit of the tuner malfunctions, causing an abnormality in the clamp level.

SUMMARY OF THE INVENTION Based on these problems, it is an object of the present invention to provide a television signal converter having a simple configuration and a function of inhibiting the output of keyed AFC pulses when receiving a current standard television signal. This is the purpose.

Means for Solving the Problems The television signal conversion device of the present invention includes an AD converter, a signal processing circuit, a synchronization processing circuit, a keyed AFC pulse generation circuit, and an A that calculates the logical product of the keyed AFC pulse and the synchronization signal.
It is characterized by being provided with an ND circuit, a DA converter, an NTSC encoder that converts the output of the DA converter into a current standard television signal, and a switch that switches between a signal obtained by converting a high-definition television signal and a current standard television signal.

Function: According to the television signal conversion device of the present invention, by being equipped with an AND circuit that takes an AND of a synchronization processing circuit and a keyed AFC pulse generation circuit, when receiving a current standard television signal, the pulse generated from the synchronization processing circuit and the keyed AFC pulse generation circuit are combined. The keyed AFC pulse is not generated by ANDing the pulses output from the AFC pulse generation circuit, and malfunction of the tuner can be prevented.

Example Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic block diagram according to an embodiment of the present invention.

In this figure, parts common to those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. In this configuration, an AND circuit 8 that performs an AND operation between the synchronization processing circuit 3 and the keyed AFC pulse generation circuit 4 is provided, and its output is outputted to the tuner as a keyed AFC pulse.

In this way, by ANDing the output of the synchronization processing circuit 3 and the output of the keyed AFC pulse generation circuit 4, a keyed AFC pulse is output to the tuner in normal operation when a high-definition television signal is received, and the current standard When a television signal is received, synchronization is disabled by the synchronization processing circuit 3, and a pulse for inhibiting keyed AFC pulse generation is generated from the synchronization processing circuit 3. By ANDing with the keyed AFC pulse, the keyed AFC pulse is activated by the tuner. will not be output.

Next, other embodiments of the present invention will be described. FIG. 2 shows another embodiment of the present invention. In this embodiment, in addition to the configuration shown in FIG. 1, an output for automatic switching is provided from the synchronization processing circuit 3 to the switch 7, and the received signal is Connect ROM9 of the screen display diagram that stores the name of to the output terminal of switch 7 and N
It is provided between the output end of the TSC encoder 6 and the current standard television signal input terminal 12.

In the television signal processing circuit configured in this way, when receiving a high-quality television signal, the keyed AFC pulse operates in the same manner as in the first embodiment, and the output generated from the synchronization processing circuit 3 is used to switch 7. The signal name can be displayed on the television receiver using the screen display ROM 9. Also, when receiving the current standard TV signal, the key A
Regarding the FC pulse, the same operation as in the first embodiment is performed, and the output generated from the synchronization processing circuit 3 controls the switch 7 to close between the terminals a and c, so that the video signal is directly transmitted to the TV receiver. It will be shown on screen. Also RO
Data indicating the current standard television signal is output from M9,
The name of the signal is displayed on-screen on the cathode ray tube,
In addition, in this implementation, an AND circuit is used to perform keyed AF.
Although the output of the C pulse is controlled, other configurations than the above may be used as long as the output of the keyed AFC pulse is controlled.

Effects of the Invention As described above, according to the present invention, the output of the keyed AFC pulse can be controlled even though the configuration is simple with only an AND circuit inserted, and the ROM for screen display can be controlled.
By including this, it is possible to provide a television signal conversion device that can inform the user of the name of the signal being received, and this invention can be said to have excellent practical effects.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of a television signal converter according to one embodiment of the present invention, FIG. 2 is a schematic block diagram of a television signal converter according to another embodiment of the present invention, and FIG. 3 is a conventional television signal converter. FIG. 2 is a schematic block diagram of the device. 2...Signal processing circuit, 3...Synchronization processing circuit, 4...Keyed AFC pulse generation circuit, 7
...Switch, 8...AND gate,
9...ROM.

Claims (3)

[Claims] (1) Keyed AFC is used when converting a second signal of a different format from the first signal, which is the current standard television signal, into the first signal.
Outputs a pulse, and when receiving the first signal, keyed AFC
A television signal converter with a function to prohibit pulse output. (2) The television according to claim (1), which has a function of controlling the output signal depending on the presence or absence of a keyed AFC pulse and switching the signal processing path between when receiving the first signal and when receiving the second signal. Signal converter. (3) The television according to claim (1), which has a function of displaying the name of the television signal being received on the screen and notifying the user when receiving the first signal and the second signal. Signal converter.