JP3503747B2 - TV video signal receiver - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television which continuously displays the video signal written in the memory when the electric field of the received video signal fluctuates or when the electric field at the receiving point falls below a certain value. The present invention relates to a video signal receiving device .

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a conventional television receiver. That is, the antenna 1 receives the RF signal of the television wave and inputs it to the television tuner 2. The TV tuner 2 receives an RF signal of TV radio waves from the antenna 1 and outputs a video signal to the synchronization / ghost detection circuit 3, the video memory circuit 4, and the video switching device 5. The synchronization
The ghost detection circuit 3 detects the synchronization level of the video signal input from the TV tuner 2, the presence or absence of a ghost, etc., and if the result of the detection indicates that the reception condition is good, a control signal is sent to the video memory circuit 4 and the video switching device 5. Output. The video memory circuit 4 receives the control signal from the synchronization / ghost detection circuit 3, and if the reception state is good from the detection result of the synchronization / ghost detection circuit 3, the video signal input from the TV tuner 2 is stored in the memory frame by frame. At the same time as writing, the video signal written in the memory is output to the video switching device 5 for synchronization /
If the reception state is bad from the detection result of the ghost detection circuit 3, writing to the memory is stopped. The video switching device 5 receives the control signal from the sync / ghost detection circuit 3 and the detection result of the sync / ghost detection circuit 3 indicates that the video signal input from the TV tuner 2 is displayed on the display unit 6 if the reception condition is good. The video is output to display the video, and if the reception state is bad from the detection result of the synchronization / ghost detection circuit 3, the video signal input from the video memory circuit 4 is output to the display unit 6 to display the video. The video switching device 5 has a timer,
When the video signal is switched to the video memory circuit 4, it is automatically switched to the video signal of the TV tuner 2 in a fixed time of, for example, about 0.1 second.

[0003]

In the conventional television receiver, in the detection of the reception state, the video data written in the memory only at the time when the synchronization level is below a certain electric field strength or when the ghost level is above a certain level. Is output to the display unit to display the image. Therefore, the following problems occur.

(1) If the receiving point is a weak electric field and the electric field is always lower than a certain electric field strength, the synchronization / ghost detection circuit does not operate, and the image data is stored in the memory. It is impossible to display the video by stopping the writing of the data and continuously outputting the video data written in the memory to the display unit.

(2) When the signal is abruptly deteriorated in a state where the electric field is relatively strong, the writing of the image data to the memory is stopped and the image data written in the memory is continuously output to the display section. Can not be displayed.

The present invention has been made in view of the above circumstances, and the display of the video data written in the memory on the display unit is stopped while the writing of the video data in the memory is stopped, and the display is good with respect to the reception state. TV video signal receiver
The purpose is to provide storage .

[0007]

In order to solve the above problems, the present invention provides a television video signal receiving apparatus for displaying a received video signal on a display unit, in which a memory for writing the received video signal and an electric field are deteriorated. When the deterioration fluctuation speed detected by the detecting means is less than a predetermined value, the image is stored in the memory.
Writing data, deterioration detected by the detection means
When the fluctuation speed is equal to or higher than a predetermined value, writing of video data in the memory is stopped, and the deterioration fluctuation speed equal to or higher than the predetermined value
The video data written in the memory is continuously displayed on the display unit immediately before is detected . Further, the detecting means may detect the deterioration fluctuation speed by using a differentiating circuit. Further, the detecting means further includes means for detecting that the electric field has become a predetermined value or less, and the deterioration detected by the detecting means.
The fluctuation speed is less than the specified value and the electric field is less than the specified value.
If it is not detected, the video data is stored in the memory.
Writing, deterioration fluctuation speed detected by the detection means
Is greater than or equal to a predetermined value, or when the detection unit detects that the electric field is less than or equal to a predetermined value, writing of video data in the memory is stopped, and video data already written in the memory is deleted. You may make it display on a display part continuously.

[0008]

The present invention detects abrupt deterioration of a received video signal or a weak electric field at the receiving point, stops writing the video signal to the memory, and displays the video signal written in the memory on the display unit. By displaying, a good image can be obtained for the reception state.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. That is, the RF signal of the television radio wave is received by the antenna 7 and input to the television tuner 8. The television tuner 8 receives the RF signal of television radio waves from the antenna 7 and outputs the video signal to the 1-field memory circuit 12 and also outputs the IF AGC voltage 10 of the video signal to the electric field deterioration variation detection circuit 9. The 1-field memory circuit 12 operates as a delay circuit when the electric field deterioration variation detection circuit 9 does not detect the deterioration of the electric field, the video signal input from the television tuner 8 is written, and immediately read out to be displayed on the display unit 13. Is input to and the image is displayed. The electric field deterioration variation detection circuit 9 receives the IF AGC voltage 10 from the television tuner 8 and outputs the electric field deterioration signal 11 to 1 when the electric field of the electric field fluctuation signal generated from the IF AGC voltage 10 becomes a predetermined value or less.
When the electric field of the IF AGC voltage 10 becomes a certain value or less and the electric field at the receiving point becomes a certain value or less, the electric field deterioration signal 11 is output to the one field memory circuit 12. When the electric field deterioration signal 11 is input from the electric field deterioration variation detection circuit 9, the 1-field memory circuit 12 stops writing the video signal input from the television tuner 8 and stops writing the video signal written in the 1-field memory circuit 12. Is read and input to the display unit 13 to display an image.

FIG. 2 is a circuit diagram showing an example of the electric field deterioration variation detection circuit 9 of FIG. That is, in the operational amplifier 15, the IF AGC voltage 10 is input to the non-inverting input terminal and the inverting input terminal is connected to the output terminal. The output terminal of the operational amplifier 15 is connected to the non-inverting input terminal of the comparator 14 and the non-inverting input terminal of the amplifier 23 via the capacitor 20. The inverting input terminal of the amplifier 23 is grounded via the resistors 37, 26 and 27 in series. The connection point of the resistors 37 and 26 is connected to the output terminal and the inverting input terminal of the operational amplifier 16 and the amplifier 2 via the resistor 21.
3 non-inverting input terminal. The operational amplifier 16
The non-inverting input terminal of is grounded via a resistor 18 and a capacitor 38 in parallel, and is +5 via a resistor 17, for example.
It is connected to a power source Vcc such as V. The output terminal of the amplifier 23 is connected to the non-inverting input terminal of the comparator 29 and also to the inverting input terminal of the amplifier 23 via the variable resistor 39. The inverting input terminal of the comparator 29 is the resistance 2
The output terminal is connected to one input terminal of the AND gate 35. The inverting input terminal of the comparator 14 is connected to a power source Vcc of + 5V or the like via a resistor 31 and is grounded via a resistor 32,
The output terminal of the comparator 14 is connected to the other input terminal of the AND gate 35. Each of the operational amplifiers 15 and 16, the amplifier 23, and the comparator 29 has a power source V of, for example, + 5V.
It is connected to cc and is also grounded.

The IF AGC voltage 10 input from the TV tuner 8 is impedance-converted by the operational amplifier 15. The operational amplifier 16 impedance-converts the voltage divided by the resistors 17 and 18 to obtain a reference voltage (Va).
19 is generated. The output of the operational amplifier 15 is differentiated by a differentiating circuit composed of a capacitor 20 and a resistor 21 and the deterioration variation of the electric field is detected, and a first electric field variation signal 22 having the DC potential as the reference voltage 19 is input to the amplifier 23.
This amplifier 23 amplifies the first electric field fluctuation signal 22 and
The electric field fluctuation signal 24 is generated and input to the non-inverting input terminal of the comparator 29. A reference voltage (VthA) 28 obtained by dividing the reference voltage 19 by the resistors 26 and 27 is input to the inverting input terminal of the comparator 29. Therefore, the comparator 2
9 generates an electric field deterioration fluctuation signal (FR1) 30 and outputs it to the AND gate 35. The output of the operational amplifier 15 is compared with the voltage (VthB) divided by the resistors 31 and 32 by the comparator 14, and a weak electric field signal (FR2) 34 is generated and output to the AND gate 35. The AND gate 35 receives the electric field deterioration variation signal (FR1) 3 input from the comparator 29.
0 and the weak electric field signal (FR2) 3 input from the comparator 14
An electric field deterioration signal 11 is generated by taking the logical product with 4 and is output to the 1-field memory circuit 12.

FIG. 3 is a timing chart showing an example of the operation of the electric field deterioration variation detection circuit 9 of FIG. The electric field deterioration fluctuation signal (FR1) 30 is generated when the electric field of the second electric field fluctuation signal 24 generated from the video signal is significantly deteriorated in both the strong electric field and the medium electric field at the receiving point, and the electric field deterioration fluctuation signal (FR1) 30 is generated. When a constant time ta determined by the time constant of the differentiation circuit composed of the capacitor 20 and the resistor 21 is exceeded, the electric field deterioration signal (low level active) 11 automatically becomes high level and is output to the 1-field memory circuit 12. The 1-field memory circuit 12 operates as a delay circuit when the electric field deterioration signal 11 from the electric field deterioration variation detection circuit 9 becomes high level, the video signal input from the television tuner 8 is written, and immediately read out and displayed. Thirteen
Is input to and the image is displayed. At this time, IF AGC
Since the DC value of the voltage 10 is always higher than the reference voltage (VthB), the weak electric field signal (FR2) 34 does not become low level. On the other hand, when the receiving point is no electric field or weak electric field, I
The DC value of the FAGC voltage 10 becomes the minimum value and the voltage Vth
Since it is below B, the weak electric field signal (FR2) 34 becomes low level, and the electric field deterioration signal (low level active) 11
Goes low and outputs to the 1-field memory circuit 12. When the electric field deterioration signal 11 from the electric field deterioration variation detection circuit 9 becomes low level, the 1-field memory circuit 12 stops writing the video signal input from the television tuner 8 and stops the video written in the 1-field memory circuit 12. The signal is read and input to the display unit 13 to display an image.

As described above, the IF AGC voltage of the IF block of the TV tuner 8 is differentiated by the differentiating circuit to detect the variation in the deterioration of the electric field. When the reception condition is significantly deteriorated, the electric field deterioration signal 11 from the electric field deterioration variation detection circuit 9 becomes low level, and the writing of the video signal input from the television tuner 8 to the 1 field memory circuit 12 is stopped and the 1 field is stopped. Memory circuit 1
The video signal written in 2 is read and the display unit 1
3 is input and an image is displayed. Further, when the reception state becomes good immediately after the deterioration, the electric field deterioration signal 11 from the electric field deterioration variation detection circuit 9 becomes high level,
The 1-field memory circuit 12 operates as a delay circuit,
The video signal input from the television tuner 8 is written, immediately read, and input to the display unit 13 to display the video. Furthermore, when the reception state deteriorates and remains for a certain period of time, a timer is not required and the electric field deterioration signal 11 from the electric field deterioration variation detection circuit 9 automatically becomes high after the time determined by the time constant of the differentiating circuit has elapsed. Level 1
The field memory circuit 12 operates as a delay circuit, in which the video signal input from the television tuner 8 is written,
It is immediately read out and input to the display unit 13 to display an image.

When the electric field is cut off like in a tunnel and the IF AGC voltage is at the minimum value (weak electric field), the electric field deterioration signal 11 from the electric field deterioration variation detection circuit 9 becomes low level, The writing of the video signal input from the television tuner 8 to the 1-field memory circuit 12 is stopped, and the video signal immediately before the electric field written in the 1-field memory circuit 12 is cut off is read and displayed on the display unit 13. The image is input and the image continues to be displayed. Therefore, annoying images such that the snow noise continues to move are not displayed. In this case, if the detection signal at the time of the weak electric field is input to the blue back control terminal of the chroma circuit, it is possible to display the blue back at the time of the weak electric field.

[0016]

As described above, according to the present invention, the rapid deterioration of the received video signal or the weak electric field at the receiving point is detected, and the writing of the video signal to the memory is stopped and then written to the memory. By displaying the video signal being displayed on the display unit, a good video can be obtained in the receiving state.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of an electric field deterioration variation detection circuit of FIG.

3 is a timing chart showing an example of the operation of the electric field deterioration variation detection circuit of FIG.

FIG. 4 is an explanatory diagram showing a configuration of a conventional television receiving device.

[Explanation of symbols]

7 ... Antenna, 8 ... TV tuner, 9 ... Electric field deterioration variation detection circuit, 12 ... 1 field memory circuit, 13 ... Display part, 14, 29 ... Comparator, 15, 16 ... Operational amplifier, 1
7, 18, 21, 26, 27, 31, 32, 37 ... Resistors, 20, 38 ... Capacitors, 23 ... Amplifiers, 39 ... Variable resistors.

Claims (3)

(57) [Claims] 1. A television video signal receiving device for displaying a received video signal on a display unit, comprising: a memory for writing the received video signal; and a detection means for detecting a deterioration fluctuation speed when an electric field is deteriorated. The deterioration fluctuation speed detected by this detection means is not a predetermined value.
When full, write video data to the memory,
When the deterioration variation speed detected by the detection means is equal to or higher than a predetermined value, the video data is stopped from being written to the memory, and the video image written to the memory immediately before the deterioration fluctuation speed equal to or higher than the predetermined value is detected . A television video signal receiving device characterized by continuously displaying data on a display unit. 2. The television video signal receiving apparatus according to claim 1, wherein the detecting means detects the deterioration fluctuation speed by using a differentiating circuit. 3. The detecting means further includes means for detecting that the electric field has become equal to or lower than a predetermined value, and the deterioration fluctuation speed detected by the detecting means has not reached a predetermined value.
It is not detected that it is full and the electric field is below the specified value.
In this case, the video data is written in the memory, and the deterioration fluctuation speed detected by the detecting means is equal to or more than a predetermined value.
In the above case or when it is detected by the detecting means that the electric field becomes equal to or lower than a predetermined value, writing of the video data in the memory is stopped and the video data already written in the memory is continued. The television video signal receiving device according to claim 1 or 2, wherein the television video signal receiving device displays the image on a display unit.