JPH0537586Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention reproduces either a signal having a luminance signal, a carrier color signal related to this signal, or a received and demodulated composite color video signal. The present invention relates to a display device.

(Prior Art and its Problems) Conventionally, in the field of consumer display devices, such as so-called display devices for personal computers, a signal having a luminance signal and a carrier color signal related to this signal are input, respectively. There was a display device to play it.

However, this display device cannot input a composite color video signal received and demodulated by a tuner, a signal having a luminance signal supplied from a video cassette recorder, etc., and a carrier color signal related to this signal. However, there was a problem in that two dedicated display devices were required to view these two reproduced images.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a display device with a first signal having a luminance signal, a carrier chrominance signal associated with this first signal, and a demodulator. A display device for reproducing either one of the first signal and the composite color video signal, the display device comprising: a first switching means for selecting one of the first signal and the composite color video signal; a second switching means that selects either the signal selected by the switching means or a carrier color signal related to the first signal and supplies the selected signal to a carrier color signal band filter;
A trap means for attenuating a carrier color signal superimposed on a luminance signal among the signals selected by the first switching means, and a control means for interlocking the trap means and the first and second switching means. and has
Activation of the control means in one direction reproduces the first signal and a carrier color signal associated with the first signal, and operation of the control means in the other direction reproduces the composite color video signal. Configured.

(Embodiment) The present invention is a signal (first signal) having a composite color video signal received and demodulated by a tuner and a luminance signal supplied from a video cassette recorder or the like.
And a carrier color signal related to this signal can be reproduced by one display device.

FIG. 1 is a block diagram of an embodiment of a display device according to the present invention, and FIG. 2 is a frequency characteristic diagram of a trap circuit 8. In FIG.

In the circuit configuration shown in FIG. 1, 1 is an antenna, 2 is a high frequency amplification circuit, 3 is a video detection circuit, and 4 is an antenna.
- 6 are buffer circuits, 7 is an input switching control circuit (control means), 8 is a trap circuit (trap means), 9
is a carrier color signal band filter (BPF), 10 is a color signal amplification circuit, 11 is a CRT drive circuit, and 12 is a
13 is a delay line (DL), 14 is a video amplification circuit, S1 and S2 are switches (first and second switching means), and a to f are contacts. Trap circuit 8 includes NPN transistor Q1 and diode D.
1, Resistance R1 to R4, Coil L1, Codenser C1
Consisting of

The switches S1 and S2 are controlled by an input switching control circuit 7. That is, when reproducing a composite color video signal received and demodulated by the television tuner, the input switching control circuit 7 is operated to the other side to switch between contacts a and c of switch S1 and between contacts d and f of switch S2. are connected together.

Also, a signal having a luminance signal supplied from a video cassette recorder or the like and applied to the external input terminal Y, and a carrier color signal related to the signal applied to the external input terminal C and applied to the external input terminal Y. When playing at the same time, the input switching control circuit 7
is operated in one direction between contacts b and c of switch S1,
Contacts e and f of switch S2 are connected together.

(1) When reproducing a color television broadcast, the television broadcast signal is applied to the high frequency amplifier circuit 2 via the antenna 1, where it is high frequency amplified, and then supplied to the video detection circuit 3 where it is video detected. A demodulated composite color video signal is obtained. The composite color video signal obtained here is supplied to the buffer circuit 4 and amplified, and then applied to the contact a of the switch S1. In this case, contact a- of switch S1
Since the terminals c are connected, the composite color video signal applied to contact a is sent to switch S via contact c.
2 and the delay line 13. The delay line 13 delays the composite color video signal for a predetermined period of time in order to compensate for the delay in the color signal caused by the difference in signal passage between the composite color video signal and the carrier color signal that can be separated from the composite color video signal. This is a circuit for

On the other hand, the composite color video signal applied to the contact d of the switch S2 is supplied to the carrier color signal band filter 9 via the contact d, where the carrier color signal band component is extracted, and then the color signal is amplified in the next stage. circuit 10
A color difference signal is obtained by reproducing the color signal. This color difference signal is supplied to the CRT drive circuit 11.

On the other hand, the composite color video signal supplied to the delay line 13 is delayed for a predetermined time to make the time difference with the color signal zero, and then supplied to the next stage trap circuit 8, where the coil L1 and capacitor are connected. C1 attenuates the carrier color signal component superimposed on the luminance signal of the composite color video signal.

The operation of the trap circuit 8 at this time will be explained below. When a voltage of, for example, zero volts is applied from the input switching control circuit 7 to the input terminal A of the trap circuit 8, the NPN transistor Q1 changes from the on state to the off state, and the current from the power supply Vcc no longer flows through the NPN transistor Q1. , resistance R3, R
4 through diode D1.

In this way, one end of the capacitor C1, which is continuously connected to the coil L1, is grounded through the diode D1, thereby trapping the carrier color signal superimposed on the luminance signal of the composite color video signal applied to the point E. be done.

This trap frequency is =1/2π√L1・C1 , and 3.58MHz was selected.

The frequency characteristics of the composite color video signal applied to point E at this time are the characteristics shown by the solid line in Figure 2.
It is greatly attenuated around 3.58MHz.

Thereafter, the composite color video signal with the carrier color signal trapped is supplied to the video amplification circuit 14, where the horizontal synchronization signal and vertical synchronization signal are separated and the luminance signal is amplified.
is supplied to the CRT12 along with the color difference signal mentioned above.
The image is played back.

As described above, the input switching control circuit 7 connects the contacts a and c of the switch S1, connects the contacts d and f of the switch S2, and applies a voltage of zero volts to the input terminal A of the trap circuit 8. By performing these steps in conjunction, it is possible to reproduce the composite color video signal received and demodulated by the television channel.

(2) When reproducing a signal having a luminance signal supplied from a video cassette recorder etc. and a carrier color signal related to this signal, the signal having a luminance signal applied to the external input terminal Y is applied to the buffer circuit 5. After being amplified here, it is applied to contact b of switch S1. In this case, since the contacts b and c of the switch S1 are connected, the signal having the luminance signal applied to the contact b is supplied to the contact d of the switch S2 and the delay line 13 via the contact c. The delay line 13 has a luminance signal in order to compensate for a delay in the color signal caused by a signal passage path difference between the signal having the luminance signal and the color signal obtained from the carrier color signal applied to the external input terminal C. This is a circuit for delaying a signal by a predetermined time.

On the other hand, since the contacts e and f of the switch S2 are connected, the signal applied to the contact d of the switch S2 is not supplied to the carrier color signal band filter 9. Furthermore, the carrier color signal applied to the external input terminal C is applied to the buffer circuit 6, where it is amplified and applied to the contact e of the switch S2, so the carrier color signal applied to the contact e is applied to the contact f. The carrier color signal is supplied to the bandpass filter 9 via the carrier color signal. After the carrier color signal band components are extracted here, the carrier color signal is applied to the next stage color signal amplification circuit 10 to reproduce the color signal, thereby obtaining a color difference signal. This color difference signal is supplied to the CRT drive circuit 11.

On the other hand, the signal containing the luminance signal supplied to the delay line 13 is delayed for a predetermined time to make the time difference with the color signal zero, and then supplied to the trap circuit 8 at the next stage. The signal is supplied to the video amplification circuit 14 without being affected by the coil L1 and capacitor C1, where it is amplified, and then supplied to the CRT drive circuit 11, where the image is reproduced on the CRT 12 together with the color difference signal described above.

The operation of the trap circuit 8 at this time will be explained below. When a voltage of V ₁ volt is applied from the input switching control circuit 7 to the input terminal A, this voltage is applied to the input terminal A through the resistors R1 and R2 whose resistance value is set to sufficiently turn on the NPN transistor Q1. Transistor Q
1 changes from off state to on state.

In this way, the current from the power supply Vcc flows between the collector and emitter of the transistor Q1, and the current flows through the coil L1.
Since one end of the capacitor C1 connected in cascade to the capacitor C1 is grounded via the high resistance R4 and the transistor Q1, there is no trapping by the coil L1 and capacitor C1, and the luminance signal applied to point E is almost attenuated. The video signal is supplied to the video amplification circuit 14 without being affected.

At this time, the frequency characteristic of the luminance signal at point E becomes the characteristic shown by the broken line in FIG. 2, and is not attenuated around 3.58 MHz and has a flat frequency characteristic.

As mentioned above, the input switching control circuit 7 connects the contacts b and c of the switch S1, connects the contacts e and f of the switch S2, and applies a voltage of V ₁ volt to the input terminal A of the trap circuit 8. By applying these signals in conjunction with each other, it is possible to reproduce a signal having a luminance signal supplied from a video cassette recorder or the like and a carrier color signal associated with this signal.

In the case of (2) above, only the luminance signal can be reproduced in a wide band, and the chrominance signal cannot be widened at all. The improvement in image quality is much greater than that achieved by widening the bandwidth of the luminance signal, and especially in small color television receivers, widening the bandwidth of only the luminance signal is sufficient.

The present invention is aimed at achieving low cost playback of video tape recorders and the like that separate and output color signals and luminance signals.

In the configuration shown in FIG. 1 described above, a terminal Y for video signal separation input (a first signal having a reproduced luminance signal) and a terminal C for a carrier color signal are shown as external input terminals. However, if a normal composite input terminal is added to these, it is of course possible to easily accommodate this by adding the circuit configuration of a well-known display device. The circuit configuration includes a video signal separation input terminal Y and a carrier color signal terminal C.
Of course, even if multiple numbers are added, this can be handled.

(Effects of the Invention) As described above, the display device according to the present invention receives a composite color video signal received by a tuner and demodulated, and a signal (first signal) including a luminance signal supplied from a video cassette recorder or the like. and the reproduction of the carrier color signal associated with this signal can be performed in one display device, thereby:
You can play high-quality videos.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a display device according to the present invention, and FIG. 2 is a frequency characteristic diagram of a trap circuit 8. In FIG. 7... Input switching control circuit (control means), 8...
Trap circuit (trap means), 9... carrier color signal band filter, S1... switch (first switching means), S2... switch (second switching means).

Claims (1)

[Scope of utility model registration request] A display device for reproducing one of a first signal having a luminance signal, a carrier color signal associated with the first signal, and a demodulated composite color video signal, the display device comprising: a first signal having a luminance signal, a carrier color signal associated with the first signal; a first switching means for selecting one of a composite color video signal; and a first switching means for selecting either one of the signal selected by the first switching means and a carrier color signal related to the first signal. a second switching means for supplying the carrier color signal to the carrier color signal band filter; a trap means for attenuating the carrier color signal superimposed on the luminance signal among the signals selected by the first switching means; means, control means for interlocking said first and said second switching means, and when said control means is operated in one direction, said first signal and a carrier color signal associated with said first signal. A display device characterized in that the display device is configured to play back the composite color video signal when the control means is operated on the other side.