JPH09312813A - Tv receiver for traveling object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce image size fluctuation caused by electric field intensity fluctuation and multipath transmission by registering, operating and storing based on the existence and nonexistence of an EDTV II identification signal and size of an electric field intensity signal and performing aspect ratio convers ion. SOLUTION: A signal from an ANT is converted into visual and audio intermediate frequency signals via a front end part l and outputted to a visual intermediate frequency amplifier part 2 and an audio intermediate frequency amplifier part 6. An audio signal is amplified, detected and outputted to a speaker 8 via a voltage amplifier 7. On the other hand, a visual signal is amplified and detected by an automatic control AGC and outputted to an image demodulation part 3 and an EDTV II signal identification part 4. Also, an AGC output is digitized as an electric field intensity signal output and outputted to a microcomputer 10 which controls an image aspect ratio. Here, this output is registered, operated and stored according to the existence and nonexistence of an EDTV II identification signal and size of the electric field intensity signal, and is shown in a display device via an aspect ratio conversion part 3. Thereby, fluctuation of an electric field intensity and an image size is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TV receiver for a mobile body which copes with fluctuations in electric field strength.

[0002]

2. Description of the Related Art Generally, the display screen of a conventional moving body such as a vehicle-mounted TV receiver has an aspect ratio of 4: 3, and recently, an aspect ratio of 16: 9 has been used. TV
The receiver has been put to practical use as a stationary type for home use. The TV receiver having the expanded aspect ratio is in the process of being widely used by using the MUSE system and the EDTVII system, which are techniques for improving image quality.

The MUSE system is a system for performing band compression by sampling in order to transmit a high-definition signal (base band of 20 MHz) having an information amount about 5 times that of the current TV signal on one channel of satellite broadcasting. It has not yet been put to practical use for moving bodies that require a large scale and small size. On the other hand, the EDTVII system is a second generation system of EDTV (Clear Vision), which is a system for expanding the aspect ratio, improving the image quality, and improving the sound quality in the current TV signal (6 MHz baseband). The ghost elimination signal, which is one of the above, is transmitted by inserting it in the vertical blanking period of the TV signal, and the multi-path distortion due to the multiple propagation of radio waves that is a factor of the ghost at the receiving side is a signal based on the original ghost elimination signal. This is a method of processing and removing ghost waves.

However, a signal processing time for performing the signal processing for removing the ghost is long and it is difficult to follow the vehicle speed. However, a display screen having an aspect ratio of 16: 9 has attractive advantages such as improved visibility for vehicle use, and this wide screen is promising for displaying information other than TV broadcasting such as map information.

[0005]

Therefore, an EDTVII signal (aspect ratio 16: 9) and a current NTSC signal (aspect ratio) which emphasize the visibility are used by using a display device having an aspect ratio of 16: 9 for a mobile body. As a result of studying the case of realizing a mobile TV receiver capable of supporting both aspect ratios of 4: 3), the following was found.

That is, while the vehicle as a moving body is running, the TV
When receiving an image, a fading phenomenon of broadcast radio waves may occur due to multiple propagation of radio waves (multipath) due to reflection and diffraction of valleys of high-rise buildings and buildings. When receiving an EDTVII signal due to such a sudden change in the electric field strength of TV broadcasting or a ghost radio wave, the displayed image changes, and as shown in the display size example of the screen of FIG. From a wide screen (displays an image with an aspect ratio of 16: 9 and spreads over the entire display screen) to a narrow screen (a thick non-light emitting frame appears on four sides of the display screen and the image is displayed small in the center of the screen) There was a drawback that it was very difficult to see, because the screen was suddenly switched and then returned to the original wide screen.

Therefore, an object of the present invention is to realize a TV receiver for a mobile body in which the size of the display screen is stable even with the abrupt change of the broadcast electric field state as described above.

[0008]

The present invention provides an electric field strength detecting means for detecting electric field strength in a mobile TV receiver for changing the aspect ratio of a display screen based on an aspect ratio identification signal received from the outside. And an aspect ratio control means for controlling a change in the aspect ratio of the display screen based on the aspect ratio identification signal according to the magnitude of the electric field strength detected by the electric field strength detection means. To do. Further, in a mobile TV receiver that changes the aspect ratio of a display screen based on an aspect ratio identification signal received from the outside, an electric field intensity detecting means for detecting an electric field intensity and a multiplex for detecting multipath propagation of broadcast radio waves. Based on the magnitude of the electric field strength detected by the path propagation detecting means and the electric field strength detecting means,
When the electric field strength is small, the change of the aspect ratio of the display screen is prohibited, and when the electric field strength is large, based on the aspect ratio identification signal included in the multipath propagation detection result of the multipath propagation detecting means, Aspect ratio control means for changing the aspect ratio of the display screen.

Further, the electric field strength detecting means detects the signal level of the video intermediate frequency amplified by the video intermediate frequency amplifying means, and detects the electric field strength based on the signal level. It is characterized by comprising means. Further, the video intermediate frequency signal level detecting means is characterized by using an automatic gain adjustment signal for automatically adjusting an intermediate frequency amplification gain for performing the video intermediate frequency amplification.

The electric field strength detecting means detects the signal level of the sound intermediate frequency amplified by the sound intermediate frequency amplifying means, and detects the electric field strength based on the signal level. It is characterized by comprising means. Further, the audio intermediate frequency signal level detecting means is characterized by using an electric field strength output signal which is output in the audio intermediate frequency amplifying means in accordance with the electric field strength.

The multipath propagation detecting means includes an amplitude modulation detecting means for detecting an amplitude modulation component of the audio intermediate frequency signal in the audio intermediate frequency amplifying means for amplifying the audio intermediate frequency, and at least the amplitude modulation detecting means. Aspect ratio control means for controlling the aspect ratio of the display screen based on the amplitude modulation detection result used.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the structure of an embodiment of the present invention. Reference numeral 1 denotes a front end (F / E) section, which is generally used in electronic tuning to receive each TV channel in the VHF band and the UHF band, and an input tuning circuit for inputting a TV broadcast signal from the antenna ANT. An RF amplifier including a semiconductor such as an ultra-high frequency transistor and its peripheral circuits, a local oscillator, a frequency converter, and the like, and a TV broadcast signal input to the antenna ANT is converted into an intermediate frequency signal by the frequency converter, and an intermediate frequency amplification unit. 2 is output.

An image intermediate frequency (IF) amplification and detection unit 2 includes an intermediate frequency bandpass filter having an image signal bandwidth, a semiconductor integrated circuit for intermediate frequency amplification, an intermediate frequency amplification circuit and an automatic gain control circuit ( AGC), a video detection circuit, etc., and is configured to output a composite video signal. A video signal demodulation and aspect ratio conversion unit 3 includes a video signal demodulation semiconductor integrated circuit, an aspect ratio conversion semiconductor integrated circuit, etc., and a luminance signal and a chromaticity signal are demodulated from an input composite video signal, and signal processing is performed. The aspect ratio of a display screen for displaying an image is processed based on an input signal from the unit (microcomputer) 10 and output to the display unit 5.

Reference numeral 4 denotes an EDTVII signal discriminating section which comprises a signal discriminating semiconductor integrated circuit and the like, and which has a video intermediate frequency amplifying and detecting section 2.
The identification signal separation circuit for separating the EDTVII identification signal unique to the EDTVII system from the composite video signal output from the device. 5 is a display unit, which is an LCD or CRT
And its peripheral circuits, etc., and the horizontal to vertical dimension ratio (aspect ratio) of the display screen is 16: 9. Since it is mounted on the interior panel of a vehicle, etc.
The D or CRT is housed with the vibration resistant material.

Reference numeral 6 denotes an audio intermediate frequency amplification / detection unit for audio intermediate frequency ceramic filter, intermediate frequency amplification (including envelope detector for detecting electric field intensity and amplitude modulation component as necessary) and FM detection. It is provided with a semiconductor integrated circuit and the like, and is configured to demodulate an audio signal such as stereo. 7
Is a power amplifier, which includes a semiconductor integrated circuit for power amplification and its peripheral circuits, etc., and is configured to amplify the demodulated audio signal and output it to the speaker 8.

Reference numeral 9 denotes an analog-digital converter (A / D converter) which is composed of a semiconductor integrated circuit of integration type or comparison type and peripheral circuits thereof, and the like, and is used for the video intermediate frequency amplifying section 2 or the audio intermediate frequency amplifying section 6. It is configured to convert a direct current signal corresponding to the electric field strength output from the digital signal into a digital signal.
A signal processing unit (microcomputer) 10 is composed of a microprocessor and its peripheral circuits and the like, and registers and calculates an EDTVII identification signal output from the EDTVII signal identification unit 4 and a digital signal output from the A / D converter 9. Then, it is stored and configured to output an aspect ratio signal to the aspect conversion unit 3.

Next, the operation will be described. The TV broadcast signal output from the antenna (ANT) is input to the front end unit 1, converted into a video intermediate frequency signal and an audio intermediate frequency signal, and output to the video intermediate frequency amplification unit 2 and the audio intermediate frequency amplification unit 6, respectively. To be done. The audio intermediate frequency signal input to the audio intermediate frequency amplification unit 6 is amplified by the amplitude limiting amplifier and FM-detected, and the audio signal is output to the power amplifier 7, where it is power amplified and output to the speaker 8. Sound is output from the speaker.

The voice intermediate frequency signal may be, if necessary,
Electric field strength signal output (also called signal meter output) that correlates with electric field strength of TV radio waves as shown in FIG.
Is output to the A / D converter 9 (a part surrounded by a chain line). Alternatively, instead of the electric field intensity signal output, the amplitude modulation component is superimposed on the frequency modulation wave of the audio due to the multipath propagation of TV radio waves, and the amplitude modulation component signal from which the amplitude modulation component is detected is A / D. It may be output to the converter 9 (a part surrounded by a chain line).

On the other hand, the video intermediate frequency signal input to the video intermediate frequency amplifier 2 is amplified by a video intermediate frequency amplifier whose amplification degree is automatically controlled (AGC) based on this signal level,
Then, the detected composite signal is output to the video demodulation unit 3 and the EDTVII signal identification circuit 4. The video intermediate frequency signal is detected, and the AGC output used for controlling the AGC circuit is an A / D converter 9 as an electric field strength signal output having a correlation with the electric field strength of TV radio waves as shown in FIG. Is output to.

The AGC output or the signal meter output is digitally converted by the A / D converter 9,
The digitized electric field strength signal is output to the signal processing unit 10 that controls the aspect ratio of the display screen. Here, the description of FIG. 2 is inserted. FIG. 2 is a diagram showing an antenna input level that correlates with the electric field strength and an AGC output level and a signal meter (S meter) output level that are detected and output in the configuration of the embodiment. .

From the left to the right of the horizontal axis, the antenna input level changes from low to high, while the vertical axis indicates the AGC output voltage and the signal meter output voltage. Although the AGC output voltage tends to decrease as the antenna input level increases, while the signal meter output voltage tends to increase, the signal processing unit 10 can invert the digital voltage. It suffices that the intensity and the value of the result of detecting this correspond to each other.

The electric field strength (antenna input level)
For example, the signal processing unit 1 is a means for detecting A or B.
It can be provided by setting the program to 0. Next, returning to FIG. 1, in the signal processing unit (microcomputer) 10, conditions separately defined based on the presence or absence of the EDTVII identification signal and the magnitude of the digitized electric field strength signal (the antenna input shown in FIG. Registration, calculation, storage, etc. are performed at levels A and B), and as a result, the aspect ratio signal is output to the aspect ratio conversion unit 3.

The aspect ratio signal and the video composite signal are input to the video signal demodulation section and the aspect ratio conversion section 3, where both input signals are processed and a display drive output corresponding to the input is displayed on the display 5. And a color image is displayed on the display 5. The above is the general operation of the present embodiment. Furthermore, using the screen processing flow chart based on the EDTVII signal and the electric field strength signal shown in FIG. 3, a screen according to the signal processing procedure of the signal processing unit (microcomputer) 10 is displayed. The display operation will be described.

In step S1, the TV receiver of this embodiment starts receiving a TV broadcast image. And step S
In 2, the presence / absence of the EDTVII signal input to the microcomputer 10 from the EDTVII signal identifying section is detected and monitoring is performed to make a determination. Then, in step S3, the ED
Whether or not there is a TVII signal, that is, whether or not it is an EDTVII broadcast is determined. If it is the EDTVII broadcast (YES), the process proceeds to step S4, and if it is not the EDTVII broadcast (NO), the process returns to step S2.

Then, in step S4, monitoring is performed to detect and determine the magnitude of the electric field strength signal input from the A / D converter 9 to the microcomputer 10. Next, in step S5, the magnitude of the electric field strength signal is A of the antenna input level (correlation with electric field strength) shown in the example of FIG.
If it is larger than A (YES), the process proceeds to step S6, and if smaller than A (NO), the process returns to step S2.

Then, in step S6, the wide screen signal for displaying an image on the entire display screen is output to the video demodulation and aspect ratio conversion section 3 to widen the display screen of the display unit 5. In this state, the process next proceeds to step 7, and similarly to step 2, the presence / absence of the EDTVII signal input to the microcomputer 10 from the EDTVII signal identifying portion is detected and monitoring is performed to determine the same.

Then, in step S8, the EDTV is
Whether or not there is an II signal, that is, whether or not it is an EDTVII broadcast is determined. If it is not the EDTVII broadcast (NO), the process proceeds to step S9, and if it is the EDTVII broadcast (YES), the process returns to step S7. Then, in step S9, similarly to step 4, the magnitude of the electric field strength signal input from the A / D converter 9 to the microcomputer 10 is detected and monitoring is performed to make a determination.

Next, in step S10, it is judged whether or not the magnitude of the electric field strength signal is smaller than B of the antenna input level (correlated with the electric field strength) shown in the example of FIG. 2, and it is larger than B (NO). If it is smaller than B (YES), the process proceeds to step S12. Then, in step S11, the EDTVII signal cannot be detected (determined that it is not EDTVII broadcasting in step S8), even though the electric field strength is larger than A and further larger than B. The reason is that the electric field strength is complicated. It is not a malfunction due to a loss of the EDTVII signal due to the multipath distortion or the like, and it is recognized that the EDTVII broadcast is not sure, and the output of the wide screen signal to the video demodulation and aspect ratio conversion unit 3 is stopped. , Release the wide state of the display screen.

On the other hand, in step S12, the electric field strength is B
Since it is smaller than the above, it is expected that the EDTVII signal is lost due to the complicated fluctuation of the electric field strength and the multipath distortion, so that the wide state of the display screen is maintained. Then, in step S13, whether the time during which the EDTVII broadcast signal is not detected (determined in step S8) is over the specified time (C seconds) (YES) or not (NO).
(If it is determined that the EDTVII broadcast signal is detected even at an instant within the specified time, it is determined that it does not exceed), and if the specified time (C seconds) is exceeded (YES), the process proceeds to step S11.
When the prescribed time (C seconds) is not exceeded (NO), the wide state of the screen is maintained and the process returns to step S7.

In the flow of FIG. 3, the content of the EDTVII broadcast is first checked and then the magnitude of the electric field strength is detected. However, the present invention is not limited to this, and the magnitude of the electric field strength is detected first and the electric field strength is detected. When the intensity is above a certain level, the screen is switched according to the presence or absence of EDTVII broadcasting, and when the intensity is below a certain level, EDTV
Processing may be performed such that screen switching is prohibited regardless of the presence or absence of II broadcasting.

As described above, according to the present embodiment, it is possible to reduce the malfunction due to the omission of detection of the EDTVII signal due to the electric field variation during the reception of the EDTVII broadcast and the variation in the screen size of the TV image reception. In addition, the signal processor (microcomputer) is mainly used without using a special circuit or circuit element.
It is possible to implement at low cost by adding or changing the program.

[0032]

As described in detail above, according to the present invention, a mobile TV for reducing the fluctuation in the screen size of the EDTVII type TV image due to the fluctuation of the electric field strength of the broadcast radio wave, the multipath propagation and the like. A receiver can be realized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a relationship diagram of electric field strength and AGC and signal meter output level.

FIG. 3 is a screen processing flow chart based on an EDTVII signal and an electric field strength.

FIG. 4 is a diagram showing a display size example of a screen when an EDTVII system image is received.

[Explanation of symbols]

 1 ... Front-end section (F / E) 2 ... Video intermediate frequency amplification and video detection section 3 ... Video demodulation and aspect ratio conversion section 4 ... EDTVII signal identification 5: Display 6: Audio intermediate frequency amplification and audio detection 7: Power amplification 8: Speaker 9: Analog-digital converter ( A / D converter) 10 ... Signal processor (microcomputer)

Claims (7)

[Claims] 1. In a mobile TV receiver for changing the aspect ratio of a display screen based on an aspect ratio identification signal received from the outside, an electric field intensity detecting unit for detecting an electric field intensity, and an electric field intensity detecting unit for detecting the electric field intensity. A TV receiver for a mobile body, comprising: an aspect ratio control means for controlling a change of an aspect ratio of the display screen based on the aspect ratio identification signal. 2. In a mobile TV receiver for changing the aspect ratio of a display screen based on an aspect ratio identification signal received from the outside, an electric field intensity detecting means for detecting an electric field intensity and multipath propagation of broadcast radio waves are provided. On the basis of the magnitude of the electric field strength detected by the multipath propagation detecting means for detecting and the electric field strength detecting means, when the electric field strength is in a small state, the aspect ratio of the display screen is prohibited from being changed, and in the large state. And a aspect ratio control means for changing the aspect ratio of the display screen based on the aspect ratio identification signal included in the multipath propagation detection result of the multipath propagation detection means. TV receiver for body. 3. The image intermediate frequency signal level detection means for detecting the signal level of the image intermediate frequency amplified by the image intermediate frequency amplifying means, and detecting the electric field intensity based on the signal level. The TV receiver for a mobile body according to claim 1 or 2, characterized by comprising means. 4. The video intermediate frequency signal level detecting means uses an automatic gain adjustment signal for automatically adjusting an intermediate frequency amplification gain for performing the video intermediate frequency amplification. The TV receiver for a mobile body described. 5. The audio intermediate frequency signal level detecting means for detecting the signal level of the audio intermediate frequency amplified by the audio intermediate frequency amplifying means, and detecting the electric field strength based on the signal level. The TV receiver for a mobile body according to claim 1 or 2, characterized by comprising means. 6. The moving body according to claim 5, wherein the audio intermediate frequency signal level detecting means uses an electric field strength output signal which is output according to the electric field strength in the audio intermediate frequency amplifying means. TV receiver for TV. 7. The multipath propagation detecting means includes an amplitude modulation detecting means for detecting an amplitude modulation component of an audio intermediate frequency signal in an audio intermediate frequency amplifying means for amplifying the audio intermediate frequency, and at least the amplitude modulation detecting means. 3. An aspect ratio control means for controlling the aspect ratio of the display screen based on the amplitude modulation detection result used.
The TV receiver for a mobile body described.