JPH0548984A - Tv receiver for vehicle - Google Patents

Abstract

PURPOSE:To automatically follow up a channel capable of receiving a desired broadcasting corresponding to the movement of a vehicle. CONSTITUTION:Under the control of a control part 19, a first TV tuner 6 receives the desired broadcasting, a second TV tuner 9 searches a channel, a checking part 11 compares a specific part including a test signal line for the video signals received with the first TV tuner 6 and the second TV tuner 9 and discriminates whether or not these broadcasting is the same one. In the case of the same broadcasting, a receiving state comparison circuit 17 compares the receiving state between the first TV tuner 6 and the second TV tuner 9 and when the receiving state of the second TV tuner 9 on the search side is better, the control part 19 changes over the receiving channel of the first TV tuner 6 to the search channel of the second TV tuner 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-vehicle TV receiver, and more particularly to an on-vehicle TV capable of automatically tracking a audible channel of a desired broadcast according to the movement of the vehicle.
Receiving device

[0002]

2. Description of the Related Art In recent years, an AV system combining audio and visual has been developed for the purpose of enhancing the car life. In-vehicle TV is the center of the visual system
This is a receiving device, and by adopting a liquid crystal panel or the like, a space saving and high quality receiving device has been developed. The service area of one TV broadcasting tower is considerably smaller than that of radio broadcasting, but the same content is broadcast from multiple TV broadcasting towers, so the user can continue to make desired broadcasting regardless of the movement of the vehicle. You can watch it.

[0003]

By the way, TV broadcasting towers that broadcast the same contents are assigned different channel frequencies because ghosts appear on the screen when the frequencies are made the same. Therefore, when the user travels across the service areas of a plurality of TV broadcasting towers performing the same broadcast, in order to continue watching the broadcast of the same content,
On the way, there is a problem that the operation is troublesome because it is necessary to switch to another channel frequency that is performing the same broadcast from the TV band extending from the VHF band to the UHF band.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an in-vehicle TV receiver capable of automatically tracking a audible channel of a desired broadcast according to the movement of the vehicle.

[0005]

According to the present invention, there are provided two TV tuners for receiving a desired broadcast on the one hand and a channel search on the other hand, and a video signal received by the two TV tuners. Collating means for comparing specific portions including a test signal line and collating whether or not they are the same broadcast;
The receiving state comparing means for comparing the receiving states of the two TV tuners, the desired broadcast is received by one of the two TV tuners, and the channel search is performed by the other of the two TV tuners. This is achieved by providing the control means for switching the desired broadcast receiving channel to the search side channel when the comparing means determines that the TV tuner on the search side has a better reception state.

[0006]

According to the present invention, one of the two TV tuners receives a desired broadcast, and the other TV tuner performs a channel search, so that a specific portion including a test signal line is included in a video signal received by the two TV tuners. Are compared to see if they are the same broadcast.
The receiving states of the tuners are compared, and when the TV tuner on the search side has a better receiving state, the desired broadcast receiving channel is switched to the search side channel. As a result, when the audible channel of the desired broadcast changes due to the movement of the vehicle, the receiving channel is automatically switched by tracking it, so that the user can continue the desired broadcast without switching the channel. You can watch it.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram of a vehicle-mounted TV receiving apparatus according to an embodiment of the present invention.

In the figure, 1-4 are four antennas and 5
Is a diversity circuit, which inputs a video signal from a first tuner (to be described later), periodically switches the antennas in order within a short time, compares the reception states, and selects the antenna with the best reception state. select. Reference numeral 6 is a first tuner, which outputs a first video signal and audio signal in synchronization with the desired broadcast. Tuning control for the first tuner 6 is performed by a control unit described later. Reference numeral 7 is a video output terminal V- for amplifying the first video signal output from the first tuner 6.
A first video amplifier circuit to be output from OUT to the outside, 8 is an audio amplifier circuit that amplifies the audio signal output from the first tuner 6 and outputs to the outside from the audio output terminal A-OUT, 9
Is a second tuner which outputs a second video signal while searching for TV channels assigned to TV bands of VHF band and UHF band. The channel search control for the second tuner 9 is performed by the control unit.
Reference numeral 10 denotes an amplifier circuit that amplifies the second video signal output from the second tuner 9. A monitor TV is connected to the video output terminal V-OUT, and an amplifier is connected to the audio output terminal A-OUT.

Reference numeral 11 is a collating unit, which includes the first tuner 6,
A specific portion including a test signal line is compared with the first video signal and the second video signal received by the second tuner 9 to check whether the broadcast contents are the same. Reference numeral 12 denotes a sync separation / timing generation circuit, which separates horizontal / vertical sync signals from the first video signal output from the first video amplifier circuit 7, and uses these sync signals to compare the first to the first for comparison timing. 3 window pulses (refer to WP ₁ to WP _{3 in} FIG. 2) are generated. In this example, the first window pulse is 17
The entire H period, the second window pulse is a 1H / 5 period relating to the central portion of 130H, and the third window pulse is the 1H / 5 period relating to the central portion of 131H.

As shown in FIG. 2, 17H carries a test signal in the VITS signal used for adjusting the broadcasting equipment on the station side, and the central portions of 130H and 131H correspond to the normal center of the screen. A part of the video signal is on.
If the broadcast is the same, the test signals are the same regardless of the difference of the channels. In 130H and 131H, the video signals are likely to be greatly different if the broadcasts are different. In this respect, the video signals for 1H at the edge of the screen are not necessarily significantly different even if the broadcast contents are different because of the background or the like.

Reference numeral 13 denotes a video comparison circuit, which has a first window period for the first video signal and the second video signal (a period in which the first window pulse WP ₁ is H, the same applies hereinafter), a second window period. The window period and the third window period are compared. Video comparison circuit 1
3 is specifically configured as shown in FIG. Reference numeral 13a is an adder circuit for adding a constant level to the first video signal to create an upper reference signal, 13b is a subtraction circuit for subtracting a constant level from the first video signal to create a lower reference signal, and 13c is an upper reference signal. And a second video signal are compared with each other, 13d is a second comparator for comparing the second video signal with the lower reference signal, and 13e is a first to third window pulse WP _{1 to} W.
An OR circuit that takes the OR of P ₃ and 13f is the NA of the output of the first and second comparators 13c and 13d and the OR circuit 13e.
It is a NAND circuit that takes ND. The video comparison circuit 13 configured as described above makes continuous video comparisons in the first to third window periods. For example, in the first window period, when the level of the second video signal is kept within a certain width with respect to the first video signal, the comparison signal becomes a continuous L level, and if it deviates from the certain width, the comparison signal is deviated. It becomes H level during the operation. In the periods before and after the first window period, the first window pulse WP
_{Since 1} becomes L level, the comparison signal becomes H level. The same applies to the other second and third window pulses WP ₂ and WP ₃ .

Reference numeral 14 designates the output of the video comparison circuit 13 as 0 (= L
A / D sampling to level) or 1 (= H level)
A conversion circuit 15 is a counter that counts the number of sampling values 0 in the A / D conversion circuit 14, and performs a counting operation while the window pulse is at the H level after being cleared at the rising edge of the window pulse. 16 is a determination unit is biased to a first fall of the window pulse WP ₁ by entering the count value WD ₁ in the first window period from the counter 15, when a predetermined reference value C ₁ or more, the 1, 17H of the second video signal are determined to be the same as each other, are biased by the falling edge of the second window pulse WP _{2 and} the count value WD ₂ in the second window period is input from the counter 15 to a predetermined value. When the reference value C ₂ or more, it is determined that 130H of the first and second video signals are the same, and the counter 15 counts in the third window period by being urged by the falling edge of the third window pulse WP _3. Enter the value WD ₃ and enter the predetermined reference value C
_{When 3} (= C ₂ ) or more, 13 of the first and second video signals
1H is determined to be the same as each other. And 17H, 130
When it is determined that all H and 131H are the same, it is determined that the broadcast related to the first video signal and the broadcast related to the second video signal are the same.

Here, in this embodiment, the reference value C ₁ is the first value.
During the window period of, the comparison signal is set to 9/10 of WC ₁ when it was at the L level all the time, and similarly,
The reference value C ₂ (C ₃ ) is maintained during the second window period (third period).
During the window period), WC ₂ (WC ₃ ) when the comparison signal is at the L level all the time is set to 9/10.

By having the above-mentioned configuration, the collating unit 11 has a certain allowable range on the signal level and on the time axis, and is related to the broadcast relating to the first video signal and the second video signal. It is possible to check whether the broadcasts are the same.

Reference numeral 17 denotes a reception state comparison circuit, which is a first T
From the V tuner 6 and the second TV tuner 9, respectively, the first
The second video signal and the second video signal are input, the reception states are compared, and the result is output to the control unit. Reference numeral 18 denotes an operation unit, which allows the user to manually select a channel. Reference numeral 19 denotes a control unit which, when a channel selection operation is performed by the operation unit 18, causes the first TV tuner 6 to be tuned to the channel to receive a desired broadcast. Further, while the second TV tuner 9 is searching for each channel in the TV band, the output of the determination unit 16 for each search channel is checked,
If it is determined that the same broadcast is being performed, the second TV tuner 9 is kept tuned to the search channel, the output of the reception state comparison circuit 17 is checked, and the first TV tuner 6 receives the signal. If the state is good, the switching control of the receiving channel for the first TV tuner 6 is not performed, and the channel search control for the second TV tuner 9 is restarted. On the contrary, if the receiving condition of the second TV tuner 9 is better, the receiving channel of the first TV tuner 6 is switched to the receiving channel of the second TV tuner 9 at that time, and the second receiving channel of the second TV tuner 9 is changed. The channel search control for the TV tuner 9 is restarted.

Reference numeral 20 denotes a controller having a microcomputer configuration, which fulfills the functions of the judging section 16 and the control section 19.

FIG. 4 is a flow chart showing the operation of the controller 20, which will be described below with reference to this figure.

When the power switch is turned on, the control unit 19 of the controller 20 performs a predetermined initialization process, and based on the reception channel data j immediately before the previous power-off, for example, if j = 4, the number of channels is changed to four. The first TV tuner 6 is tuned (step 101 in FIG. 4). Therefore,
The screen of the reception channel 4 immediately before the power is turned off is displayed on the monitor TV, and the sound is played from the speaker. When the user operates the operation unit 18 to switch to a desired channel, for example, 6 channels, the control unit 19 tunes the first TV tuner 6 to 6 channels and sets j = 6 (steps 102 to 104). The current position of the vehicle is 6
If the broadcast service area of the channel is in a region with a relatively high electric field strength, the desired broadcast is clearly displayed on the screen, and the sound is played from the speaker. At this time, the diversity circuit 5 selects the optimum antenna for receiving the 6-channel broadcast, so that the screen is not disturbed.

The control unit 19 repeatedly performs channel search control for the second TV tuner 9 when the operation unit 18 does not perform a channel selection operation. In this search control,
The control unit 19 sets i indicating the search channel to 1 (step 105), and on the condition that i is different from the receiving channel on the first TV tuner 6 side, the second channel is set to the second lowest channel of the TV band. The TV tuner 9 is tuned (steps 106 and 107). Then, the controller 20 waits for a certain period of time until the second TV tuner 9 stabilizes (step 108). After step 108, the determination unit 16 of the controller 20 is biased by the falling edge of the first window pulse WP ₁ , and first inputs the count value WC ₁ of the counter 15 in the first window period (step 109). ), And compare with the reference value C ₁ (step 11
0). If the current position of the vehicle is within the broadcasting service area of channel 1, the second video amplifier circuit 10
The second video signal is output from the first video signal from the first video amplifier circuit 7 and the second video signal is output from the first video amplifier circuit 7 in the video comparison circuit 13 for each of the first, second, and third window periods. , The comparison signal is sampled by the A / D converter 14 to 0 (when the comparison signal is at the L level) or 1 (when the comparison signal is at the H level) at a predetermined sampling frequency for each window period. , Counter 15
At, the number of sample values 0 is counted.

However, when the VITS signals of the first video signal and the second video signal are completely different, the comparison signal output in the first window period is H during most of the period.
Since it is a level, WC ₁ <C ₁ . At this time, the determination unit 1
6 determines that 17H of the first and second video signals are not identical to each other, and determines that the broadcast related to the first video signal and the broadcast related to the second video signal are not identical (NO in step 110), The determination result is output to the control unit 19.

In this case, the control unit 19 does not control the switching of the receiving channel for the first TV tuner 6, and i
Determine if is the top channel of the TV band (step 11
1) and NO, i is incremented to 2 (step 112). Since i is not the same as the reception channel of the first TV tuner 6, the tuning channel of the second TV tuner 9 is set to 2 (step 106). , 107). Then, the controller 20 waits for a certain period of time until the second TV tuner 9 stabilizes (step 108). Second TV
When the tuner 9 tunes to a new channel, the second TV tuner 9 does not output the second video signal unless the current position of the vehicle is within the broadcasting service area of channel 2. Therefore, the video comparison circuit 13 The comparison signal of is, in any of the first to third window periods,
The determination unit 16 determines NO in step 110 because it remains at the H level or remains at the L level for a very short period due to the influence of noise. At this time, since the control unit 19 is not yet the search channel or the top channel of the TV band, it increments i (N at step 111).
O, 112), the controller 20 returns to step 102 and performs the same processing thereafter.

After that, for example, the second channel up to channel 15
When the TV tuner 9 of is tuned in order (however,
Channel 6 is excluded. If NO in step 106), the current vehicle position is not in the broadcast service area in any channel, or even if it is in the broadcast service area, the broadcast is completely different from channel 6 and the test signal is also different. Therefore, the determining unit 16 determines that the first window period is not the same, and the broadcast relating to the first video signal and the broadcast relating to the second video signal are not the same. Channel switching is not controlled.

The second TV tuner 9 displays the next 16 channels
When tuned to the
In the 16-channel broadcasting service area
16 channels are different from 6 channels
Happened to send the same test signal at 17H
When the video comparison circuit 13 is in the first window period,
Almost only L level is output. Therefore, cow
Value WC obtained by counting the number of sampled values 0 by the computer 15
₁Is getting bigger C₁Over. The determination unit 16 is the first
Indian Wpulse WP₁Counseled by the fall of
15 to count value WC₁Enter C₁Compare with
But WC₁≧ C₁Therefore, the determination unit 16 determines that the first video signal
And 17H of the second video signal are determined to be the same (step
109, 110). However, if the test signals are the same,
, The broadcast may be different, so the determination unit 16 continues.
Second window pulse WP₁Urged to fall
From the counter 15 in the second window period
Count value WC₂Enter C ₂Compare with (step
113, 114).

However, since the 16-channel broadcast is different from the 6-channel broadcast, the 130H video signal is completely different, and the output of the video comparison circuit 13 is almost at the H level during the second window period. Will only be. Therefore, the count value WC ₂ of the counter 15
Becomes very small, and WC ₂ <C ₂ , so that the determination unit 16 determines that the first video signal and the second video signal are not the same at 130H, and the broadcast related to the first video signal and the second video signal are not performed.
It is determined that the broadcasts related to the video signal of are not the same (step 1
No in 14).

Therefore, the control unit 19 does not control the switching of the receiving channel for the first TV tuner 6, but does not control the second channel.
The channel of the TV tuner 9 is upgraded (steps 111, 112, 107). After that, for each of channels 17 to 34, if it is determined that the first video signal and the second video signal are not the same, the reception channel of the first TV tuner 6 is not switched. When the second TV tuner 9 is tuned to the next 35 channels, the current vehicle position is in the 35 channel broadcasting service area together with 6 channels,
When the broadcasts are the same, the test signals of 17H, 130H, and 131H are all the same. in this case,
The comparison signal output by the video comparison circuit 13 in each of the first to third window periods is almost at the L level during each period,
Count value CW _{1 to} CW of the counter 15 in each period
₃ is larger than C _{1 to} C ₃ , respectively.

In this case, the determination unit 16 is first urged by the falling edge of the first window pulse WP ₁ to cause the counter 15 to output the count value W relating to the first window period.
Enter the C _1, compared with C _1. Here, WC ₁ ≧ C
_{Since it is 1} , it is determined that 17H of the first video signal and 17H of the second video signal are the same as each other (steps 109 and 110). However, since the broadcast may be different if the test signals are the same, the determination unit 16 is urged by the trailing edge of the second window pulse WP _{2 to} cause the counter 15 to perform the second window period. The count value WC ₂ is input and compared with C ₂ (steps 113 and 114). Here again, since WC ₂ ≧ C ₂ , it is determined that the first video signal 130H and the second video signal 130H are the same. If 17H and 130H are the same as each other, the possibility of the same broadcast is extremely high. However, as a precaution, the determination unit 16 further
The third is biased to the falling of the window pulse WP _3, the counter 15 inputs the count value WC ₃ in the third window period, compared with C ₃ (Step 1
15, 116). Again, since WC ₃ ≧ C ₃ , the first
Of the first video signal and the broadcast of the second video signal are determined to be the same, and the determination result is determined by the control unit 1.
Output to 9.

Upon receiving the determination result indicating that the two broadcasts are the same, the control unit 19 inputs the comparison result of the reception states of the first TV tuner 6 and the second TV tuner 9 from the reception state comparison circuit 17. Then, it is determined which one has a better reception state (step 117). Here, if the current position of the vehicle is in a place where the electric field strength is still relatively strong in the 6-channel broadcasting service area, on the other hand, in a place where the electric field strength is relatively weak in the 35-channel broadcasting service area. Therefore, if the first TV tuner 6 is in a better receiving state, it is sufficient to continue to receive 6 channels, and therefore the receiving channel for the first TV tuner 6 is not switched. At this time, since the control unit 19 is not yet the search channel or the top channel of the TV band, i
After incrementing (NO in step 111, 1
12), the controller 20 returns to the step 102 side,
Channel up control for the second TV tuner 9 is performed in the same manner as described above.

Hereinafter, during the channel search, the broadcasting service area is located at the current position of the vehicle, but there is no channel broadcasting the same as channel 6, or a channel broadcasting the same as channel 6. However, if the reception condition is not good, the search channel is returned to the bottom of the TV band and the same processing is repeated when the channel up to the top of the TV band is finished (YES in step 111, 105). Here, for simplicity, 3
It is assumed that only channel 5 is broadcasting the same as channel 6.

After that, when the vehicle approaches the edge of the 6-channel broadcasting service area and enters the 35-channel broadcasting service area to some extent, the first TV tuner 6
The image quality and sound quality of the screen received by will gradually deteriorate.
In this case, when the control section 19 sets the search channel of the second TV tuner 9 to 35 channels, the video comparison circuit 13 causes the first to third channels in the same manner as described above.
The first video signal and the second video signal in the window period are compared, and the number of sample values 0 of the comparison signal is counted by the counter 15. However, since 17H is the same, the count value in the first window period is Since WC ₁ exceeds C ₁ and both 130H are the same, the count value WC _{2 in} the second window period exceeds C ₂ and 131H are the same, so the count value WC in the third window period WC
₃ exceeds C ₃ . Therefore, the determination unit 16 determines that the broadcast related to the first video signal and the broadcast related to the first video signal are the same (steps 110 to 116).

At this time, the control unit 19 controls the reception state comparison circuit 17 to receive the first TV tuner 6 and the second TV tuner 9 from each other.
The comparison result of the reception status is input to check which tuner has the better reception status (step 117). However, since the comparison result of the reception status is better for the second TV tuner 9 here, The control unit 19 switches the receiving channel of the first TV tuner 6 to the search channel 35 of the second TV tuner 9 at that time (step 118). As a result, even if the vehicle position deviates from the 6-channel broadcast service area, the user can continue to watch the desired broadcast on an appropriate channel without performing any operation for switching the receiving channel.

When the first TV tuner 6 is tuned to the 35th channel, the first video signal output from the first TV tuner 6 is changed to that for the 35th channel.

After step 118, the control section 19 changes j to 35 which is the receiving channel on the first TV tuner 6 side (step 119), and returns to step 105 to set 1 on the second TV tuner 9 side. The channel search from the channels is restarted, and the determination unit 1
6 determines whether the second video signal output from the second TV tuner 9 is the same as the first video signal related to the 35th channel, and if the determination result is not the same, the control unit 19 simply determines the search channel. If the up control is performed and the determination result is the same, the reception state comparison signal is checked to determine which tuner has a better reception state. If the first TV tuner 6 is better, The receiving channel of the TV tuner 6 is not switched. As a result,
As long as the vehicle travels in a relatively good reception area within the broadcast service area of the channel, reception on channel 35 will continue.

Thereafter, the vehicle returns to the broadcasting service area of channel 6 again, and when it is determined in step 117 that the TV tuner 9 is in a better reception state,
The reception channel of the first TV tuner 6 is switched to the search channel (6) at that time (step 11).
8). Therefore, the user can continue to receive the desired broadcast without performing any channel switching operation.

Even when there are two or more channels that are broadcasting the same as the 6th channel, the same broadcasting as that of the first TV tuner 6 is being carried out in the same manner, and the reception condition is better. When the channel is found, the receiving channel of the first TV tuner 6 is switched to the search channel at that time, so that the vehicle runs across the service areas of two channels broadcasting the same broadcast. However, since the set automatically tracks a new channel that is broadcasting the same broadcast, the user can continuously watch the desired broadcast without switching the receiving channel.

In the above-described embodiment, the test signal line of 17H is compared with the first video signal and the second video signal, but the test signal line of 280H or the like is used, or the test signal line of 17H is compared. You may make it compare in both test signal lines of 280H. Further, the comparison is performed between 130H and 131H other than the test signal line, but this may be replaced with two lines other than the other VITS signal lines. Also, 17H (or 280
H) or the like so that only one test signal line is used to compare / determine whether the broadcast related to the first video signal and the broadcast related to the second video signal are the same, or 17H (or 280H) Etc. one test signal line and the other VIT
Compare with 2 lines with specific 1 line other than S signal
You may make it determine.

Further, in the above embodiment, the diversity is performed only on the first TV tuner 6 side, but as shown in FIG. 5, the diversity circuit 21 is provided to the antennas 1 to 4 via the distributors 1a to 4a. The diversity circuit 21 is provided to select an antenna that makes the reception condition of the second TV tuner 9 the best, based on the video signal taken out from the second TV tuner 9, and the first TV Diversity may be performed separately or independently from the tuner 6 side.

[0037]

As described above, according to the present invention, two TV tuners for receiving a desired broadcast on the one hand and a channel search on the other hand, and a test signal line for a video signal received by the two TV tuners are included. Collating means for comparing specific portions to determine whether or not they are the same broadcast, receiving state comparing means for comparing receiving states of two TV tuners, one of the two TV tuners receives a desired broadcast and the other channel A search is performed, the matching means determines that the broadcast is the same,
Further, a control means for switching the desired broadcast reception channel to the search side channel when the reception state comparison means determines that the TV tuner on the search side has a better reception state,
By providing a desired broadcast in one of the two TV tuners and performing a channel search in the other TV tuner, the specific portion including the test signal line is compared with the video signal received by the two TV tuners for the same broadcast. If the TV tuner on the search side has a better reception condition, the reception side of the TV tuner on the search side is switched to the desired broadcast reception channel. Since it is configured to, when the audible channel of the desired broadcast changes due to the movement of the vehicle,
Since the reception channel is automatically switched by tracking this, the user can continuously watch the desired broadcast without performing the channel switching operation.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an in-vehicle TV receiver according to an embodiment of the present invention.

FIG. 2 is a time chart showing a relationship between a video signal and a window pulse.

FIG. 3 is a circuit diagram showing a specific configuration of a video comparison circuit.

FIG. 4 is a flowchart showing the operation of the controller of FIG.

FIG. 5 is a partially omitted configuration diagram showing a modified example of the present invention.

[Explanation of symbols]

 6 First Tuner 9 Second Tuner 11 Collating Unit 17 Reception State Comparison Circuit 19 Control Unit

Claims (1)

[Claims] 1. Two TV tuners that receive a desired broadcast on the one hand and perform a channel search on the other hand, and a video signal received by the two TV tuners is compared by comparing a specific portion including a test signal line with each other. A collating means for collating whether or not it is a broadcast, a receiving state comparing means for comparing the receiving states of two TV tuners, a desired broadcast is received by one of the two TV tuners, and a channel search is performed by the other, and the collating means Control means for switching the desired broadcast reception channel to the search side channel when the reception state comparison means determines that the TV tuner on the search side has a better reception state. Car TV receiver.