JPH01202076A - On vehicle television receiver - Google Patents

Abstract

PURPOSE:To obtain an always clear image by storing an excellent image obtained before deteriorating a receiving state, and at the time of deteriorating the receiving state, displaying the stored static image. CONSTITUTION:When the received image is excellent, the image concerned is directly displayed on an image display means 6 and stored in an image storing means 4, and when the received image is defective, the defective image is switched to the excellent image stored in the image storing means 4 before deteriorating the image and the switched image displayed. Consequently, an always clear image can be displayed. Since the period of the defective image is extremely short in travelling, a feeling of disorder is not applied to an observer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an in-vehicle television receiver, and more particularly, to selective display of video on a video display means by determining whether the reception state of a video signal is good or bad. Regarding.

[Prior art and its problems] +lj With the Sagawa TV receiver, the reception status of TV radio waves fluctuates as the heavy vehicle travels, and when driving between buildings, etc., the radio wave interference, etc. Receipt letter IE or worsened by
This had the disadvantage that ghosts and flickering of the image occurred due to multipath and loss of synchronization, making the image difficult to see.

In order to solve such problems, conventionally, different directivity was set as 1. It was equipped with two extended antennas and adopted a diversity reception method that selected the best signal, making it a considerable improvement, although it was far from perfect. You can also stop displaying images when reception conditions deteriorate.
This method is disclosed in Jitsutikaishu No. 60-68758, but it does not attempt to alter the actual video.

[Purpose of the Invention] The Kinei 11 was developed in view of the above-mentioned background, and its purpose is to provide an in-vehicle television receiver that can obtain clear images even in areas with poor reception conditions. shall be.

[Structure of the Invention] In order to achieve the above object, the in-vehicle television receiver according to the present invention includes a video display means for displaying received video, a reception state detection-L stage for detecting whether the reception state of the video is good or bad. , a video storage means for storing the received video when the reception state is determined to be good by the reception state detection means, and a video storage means for storing the video to be displayed on the video display means when the reception state is determined to be poor by the reception state detection means. and video switching means for switching to the video stored in the video.

With the above configuration, when the received video is good, the video display means directly displays the video and stores it in the video storage means, and when the received video is defective, it is stored in the video storage means. The image will be switched and displayed to show the good image immediately before it becomes defective. This allows clear images to be displayed at all times. Furthermore, since the time during which the image becomes defective is extremely short while the vehicle is running, it does not cause any discomfort to the viewer.

[Embodiments of the Invention] Hereinafter, embodiments of 1j1 will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the overall configuration of a preferred embodiment of an in-vehicle television receiver according to the present invention. In the figure, 1 is an antenna, 2 is a TV tuner, and 3 is a receiver that monitors multipath distortion and synchronization value V) based on the video quality from the TV tuner 2 to detect whether the video reception condition is good or bad. A synchronization/ghost detection circuit 4 as a state detection means stores a good video signal from the TV tuner 2 for one screen (-frame), for example, when the synchronization/ghost detection circuit 3 determines that the video reception condition is good. A video memory circuit 5 serves as a video storage means for displaying the received video, and a video memory circuit 5 determines whether the video displayed by the CBr 4 as a video display means for displaying the received video is the video from the TV tuner 2 or the video stored in the video memory circuit 4. whether to do it,
Selected based on the judgment result of synchronization/ghost detection circuit 3 °C
This is a video switching circuit as video switching means for switching.

TV waves received by antenna L are sent to TV tuner 2.
A synchronization/ghost circuit 3 detects whether the video signal from the television tuner 2 is in good condition or not. Here, if the received video signal is good, the good video is stored in the video memory circuit 4, and the latest video received by the TV tuner 2 via the video switching circuit 5 is connected to the CBr 4 through TIX connection. Hide table.

- On the other hand, if the received video signal is determined to be defective, it is not stored in the video memory circuit 4, but is stored in the video memory circuit 4 (good video signal immediately before the video signal becomes defective).
A still image is displayed on the CBr 4 by the image switching circuit 5. When the video becomes good again, it is stored in the video memory circuit 4 and the display on the CBr 4 is switched again to the video from the TV tuner 2 side.

In this way, while the vehicle is running, there is only a very short period of time when the image reception condition is poor, so even if the displayed image is a temporarily still image, it will be viewed as a continuous image for the viewer. Actual II! It is possible to provide clear images without ghosts or flickering, even in valleys between buildings where reception conditions tend to deteriorate.

In the above embodiment, the time for returning the video displayed on the CBr 4 from that of the video memory circuit 4 to that of the TV tuner 2 is set to the time when the video is restored, or the time is forcibly restored using a timer or the like. You can do it like this.

FIG. 2 is a diagram showing an example of signal strength data of television radio waves received when a vehicle is driven in a city area.

Moreover, FIG. 3 is a partial enlargement [-J] of the signal strength graph of the television radio waves shown in FIG.

The received radio wave strength in the city while the vehicle is running fluctuates as shown in FIG. Then, the fluctuation period of the received radio wave is
When expressed as the traveling distance of the vehicle as shown in 1'A, and if this is d, then d is proportional to the wavelength λ of the received radio wave. Here, for wavelength input, the frequency of the radio wave is f, and the propagation speed is c.
= (3XlO'1m1sec).

Since input = c / f, the fluctuation period d of the received radio wave is inversely proportional to the frequency f.

Therefore, when the video is forcibly returned to its original state using a timer or the like, the display time t for displaying the still video from the video memory circuit 4 is changed in inverse proportion to the frequency f of the received radio wave, as shown in the 4th UA. , it is possible to reduce the sense of discomfort compared to operating for a constant period of time.

In addition, the display time t is determined according to the vehicle speed V instead of the receiving frequency f.
may be changed. That is, the time required to travel through the above-mentioned fluctuation period d of the received radio wave becomes shorter as the vehicle speed V increases, and the fluctuation period d of the received radio wave and the vehicle speed V are inversely proportional to each other.

Therefore, in this case as well, it is preferable to change the display time t in inverse proportion to the vehicle speed V, as shown in FIG. In this case, when the speed is extremely low, the 5 display time t becomes too long and becomes unrecognizable as a moving image, giving the viewer a sense of discomfort. It is best to set it to 9 etc.

Note that the signal strength of the received radio waves when determining the video signal from the TV tuner 2 as defective by the synchronization/ghost detection circuit 3 varies depending on the reception sensitivity of the TV tuner 2, but in this implementation In the example, when the signal strength decreases by 10 dB compared to its peak, the video to be displayed on the CRT 6 is switched to a static video stored in the video memory circuit 4.

[Effects of the Invention] As explained above, according to the present invention, a good image immediately before the reception condition deteriorates is stored, and when the reception condition deteriorates, a static image that is stored is displayed. Since the configuration is such that there is no ghosting or loss of synchronization, it is possible to always have a clear image.Moreover, the display time of the above-mentioned still image is extremely short during the run, so it does not cause any discomfort to the viewer. It is something that cannot be given.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of a preferred embodiment of the in-vehicle television receiver according to the present invention, and FIG. 2 shows signal strength data of television radio waves received when a vehicle is driven in a city area. A graph showing an example, FIG. 3 is a partially enlarged view of the signal strength graph of TV radio waves shown in FIG. 2, and FIG. The fifth [-4 is a diagram showing the relationship between the display time t of the still video stored in the video memory circuit 4 and the vehicle speed V. l...Antenna 2...TV tuner 3...Synchronization/ghost detection circuit (reception state detection means) 4...Video memory circuit (video storage means) 5...Video switching circuit (11' image switching means) 6...-CRT (video display means)

Claims (1)

[Claims] A video display means for displaying the received video, a reception state detection means for detecting whether the reception state of the video is good or bad, and a video storage for storing the received video when the reception state is determined to be good by the reception state detection means. and video switching means for switching the video displayed on the video display means to the video stored in the video storage means when the reception state detection means determines that the reception state is poor;
An in-vehicle television receiver featuring: