JPH10257406A - On-vehicle television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always enable the dispaly of television pictures or the reproduction of television sounds in a satisfactory state by operating video diversity at the time of image display detection and operating audio diversity during the display of no image. SOLUTION: When both a stop detection 13 and a TV detection circuit 10 are turned on, terminals (a) and (c) and terminals (d) and (f) of changeover switch 7 are connected by an antenna control part 12, and an antenna switch system due to a video diversity means is provided. Then, when a reception level is low, an antenna showing the peak video signal level is selected by an antenna changeover switch 5, images are displayed on the television monitor of other seat, and only sounds are reproduced at a driver's seat. When the TV detection circuit 10 is turned off, terminals (b) and (c) and terminals (e) and (f) of changeover switch 7 are respectively connected by the antenna control part 12, an antenna switching system due to an audio diversity means is provided, an antenna in the satisfactory reception state is selected and only sounds are outputted on the monitor of driver's seat.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vehicle television receiver, and more particularly to diversity reception.

[0002]

2. Description of the Related Art In recent years, in-vehicle televisions have become widespread and widely used. For receiving on-board TV, multiple antennas are installed as far as possible on the roof of the vehicle, etc. A diversity scheme for selecting a good antenna is employed.

[0003]

However, in the diversity control of the vehicle-mounted television, the antenna selection is usually performed based on the state of the video signal. Therefore, for example, when the video is not displayed (for example, when only the audio is reproduced) while the vehicle is running or the like. However, it is not always the case that the antenna that can receive the audio signal satisfactorily is selected, and the audio reproduction state may be deteriorated by selecting the antenna having the poor reception state or performing the useless switching of the antenna. there were.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a vehicle-mounted television receiver provided with a diversity receiving circuit in which a vehicle is provided with a plurality of antennas, an antenna having a good reception state is selected and received. In the device, video diversity means for selecting an antenna having a good reception state based on video signals from the plurality of antennas, and selection of an antenna having a good reception state based on audio signals from the plurality of antennas Audio diversity means for performing, and detecting means for detecting whether or not a television image is being displayed, and when the detection means detects that the television image is being displayed, activates the video diversity and detects that the television image is not being displayed. When
And selecting means for operating the voice diversity means.

Further, the detecting means detects whether or not a television image is being displayed based on a running state of the vehicle. Further, the detection means detects that a television image is being displayed when a television monitor installed for a rear seat of the vehicle is operating. Further, the detecting means detects a display state of the rear seat television monitor based on a voltage of a communication line grounded by a circuit of the rear seat television monitor when the rear seat television monitor is connected. It is characterized by.

The voice diversity means selects a predetermined number of antennas from a plurality of antennas and selects an antenna having a good reception state from the selected antennas.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An on-vehicle television receiver according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of the present invention. Reference numerals 1, 2, 3, and 4 denote diversity antennas of the on-vehicle television receiver, which are provided as far away as possible from the body (roof) of the vehicle to which the on-vehicle television receiver is attached (in this example, 4). Reference numeral 5 denotes an antenna changeover switch for selecting one antenna from the four antennas and connecting to the television tuner (receiving circuit) 6 according to an instruction signal from an antenna control unit 9 described later.
The switching state is controlled, and is configured by a switching circuit or the like including a relay, a transistor, and the like.

Reference numeral 6 denotes a television tuner (reception circuit) which comprises a circuit for performing high-frequency amplification, tuning, frequency conversion, double tone, etc., and receives a television broadcast wave to output a video signal and an audio signal. The TV tuner 6 outputs a video intensity signal (AGC voltage for automatic gain control of an amplifier circuit) obtained by performing envelope detection, rectification, low-pass filtering, and the like on the video and received audio signals. Voltage) and an audio signal strength signal (S
It is configured to output a meter voltage (the higher the intensity, the higher the voltage).

Reference numeral 7 denotes a changeover switch for switching the diversity system, that is, an antenna selection control based on a video signal (hereinafter, referred to as a video diversity system) and an antenna selection control based on an audio signal (hereinafter, referred to as an audio diversity system). This is a changeover switch for switching, and is composed of two systems of switching circuits composed of switching transistors and the like. The changeover switch 7 connects the terminals a and c, d and f in the video diversity system, and connects the terminals b and c and e and f in the audio diversity system according to a control signal from the antenna control unit 12. Is done.

Reference numeral 8 denotes a reception level discriminating circuit, which is composed of a comparator and the like, and is provided with a preset reference voltage (S meter voltage or AGC voltage in a state where good reception is possible: input by a control signal from the antenna control unit 12). (Switched in accordance with the comparison target voltage) and the S meter voltage or the AGC voltage, and outputs the result to the antenna control unit 12. 1
Reference numeral 1 denotes a vertical blanking period detection circuit for detecting a vertical blanking period of the video signal output, which is configured by a circuit for synchronizing and separating the video signal, and supplies a signal indicating that a vertical blanking period is present to the antenna control unit 12. Output. Reference numeral 9 denotes a level detection circuit for detecting the levels of the input video signal and the S-meter voltage, which comprises a detection and filtering circuit, an A / D converter, and the like, and outputs the detection result to the antenna control unit 12.

Reference numeral 10 denotes a TV for detecting the state of the rear seat television.
A detection circuit detects whether a TV monitor for a seat other than the driver's seat (such as a rear seat) is installed or whether the TV monitor is operating. A stop detection circuit 13 detects a running / stopped state of the vehicle, and detects, for example, whether a parking brake is applied by detecting a voltage applied to a parking lamp. 1
Reference numeral 2 denotes an antenna control unit for controlling the overall operation of the diversity operation, which is constituted by a microcomputer (microcomputer), and includes a reception level determination circuit 8, a level detection circuit 9,
The input signals from the vertical flyback period detection circuit 11, the TV detection circuit 10, and the stop detection circuit 13 are processed to process the antenna 1,
It outputs a selection instruction signal for selection of 2, 3, 4 or switching of the diversity system.

Next, the operation will be described. FIG. 2 is a flowchart showing the processing of the microcomputer 12, and this processing is started by turning on the power of the in-vehicle television receiver. In step S1, it is determined whether or not the vehicle is stopped based on a signal from the stop detection circuit 13. If the vehicle is stopped, the process proceeds to step S2, and if the vehicle is running, the process proceeds to step S3. In step S2, the diversity receiving system is changed to the antenna switching system by the video diversity unit, and the process proceeds to step S4. In the video diversity system, the terminals a and c and the terminals d and f of the changeover switch 7 are connected to each other so that a video signal is input to each circuit for diversity operation. In step S4, the reception level of the video signal is determined by comparing the preset video signal reference voltage with the AGC (Automatic Gain Control) voltage of the TV tuner 6, and the AGC is compared with the reference voltage.
If the voltage is high (reception signal level is low), the process proceeds to step S5. If the voltage is lower than the reference voltage (reception signal level is high), the process returns to step S1.

In step S5, the antennas 1, 2, 3,
4 are sequentially switched, the respective video signal levels in the case of reception by the antennas 1, 2, 3, and 4 are compared, and the antenna showing the highest video signal level is selected, and the process proceeds to step S6.
Then, in step S6, the selected antenna is connected to the television tuner 6, and the process proceeds to step S7. The switching timing of the antennas 1, 2, 3, and 4 is performed during the vertical flyback period detected by the vertical flyback period detection circuit 11. Step S
In step 7, the image output to the driver's seat monitor is permitted (TV image is displayed), and the process returns to step S1.

In step S3, a determination is made as to whether a television monitor is installed in a seat other than the driver's seat and whether or not the television monitor is operating. If it is not installed, the process proceeds to step S9. In step S8, the diversity receiving system is changed to the antenna switching system by the video diversity unit, and the process proceeds to step S10. In the video diversity system, terminals a and c of the changeover switch 7
d and f are connected to each other so that the video signal is input to each circuit for the diversity operation. Step S10
Then, the reception level of the video signal is determined by comparing the preset video signal reference voltage with the AGC (Automatic Gain Control) voltage of the TV tuner 6, and when the AGC voltage is higher than the reference voltage (reception If the signal level is low, the process proceeds to step S11. If the signal level is lower than the reference voltage (the received signal level is high), the process returns to step S1.

In step S11, antennas 1, 2,.
3 and 4 are sequentially switched, the respective video signal levels when received by the antennas 1, 2, 3 and 4 are compared, the antenna showing the highest video signal level is selected, and the process proceeds to step S12. Then, in step S12, the selected antenna is connected to the television tuner 6, and the process proceeds to step S13. still,
The switching timing of the antennas 1, 2, 3, and 4 is performed during the vertical flyback period detected by the vertical flyback period detection circuit 11. In step S13, the video output to the driver's seat monitor is stopped (only audio is output, and an image is displayed on the other seat television monitor), and the process returns to step S1.

In step S9, the diversity receiving system is changed to an antenna switching system by voice diversity means.
Move to step S15. In the audio diversity system, the terminals b and c and the terminals e and f of the changeover switch 7 are connected to each other so that an audio signal is input to each circuit for diversity operation. In step S16, the reception level of the audio signal is determined by comparing the preset reference voltage (the S-meter voltage in a state where good reception can be performed) with the S-meter voltage output from the television tuner 6. If the S-meter voltage is lower than the reference voltage (reception signal level is low), the process proceeds to step S16. If the S-meter voltage is higher than the reference voltage (reception signal level is high), the process returns to step S1. Step S
At 16, the antennas 1 and 2 are sequentially switched,
2 to compare the level of each audio signal when received
The antenna showing the highest audio signal level is selected, and the routine goes to Step S17. Then, in step S17, the selected antenna is connected to the television tuner 6, and the process proceeds to step S18. In step S18, the video output to the driver's seat monitor is stopped (only audio is output), and the process returns to step S1.

As described above, in this embodiment, if the vehicle equipped with the television receiver is stopped, the television broadcast is received by the diversity system mainly composed of the video signal of the video diversity system, and the vehicle is running. If there is a TV monitor other than the driver's seat, it detects whether there is a TV monitor other than the driver's seat. . If a television monitor is installed in addition to the driver's seat, the television broadcast is received by the diversity system mainly based on the video signal by the video diversity system, and the image is not displayed on the driver's seat TV monitor and the other seats are not displayed. The image is projected on the television monitor for use.

For this reason, the video diversity system is applied during the display of the television image, and the audio diversity system is applied during the non-display of the television image. Therefore, the diversity operation of the appropriate system is always performed, and the reception by the appropriate antenna is performed. realizable. Further, it is possible to prevent the occurrence of switching noise and the like due to useless antenna switching operation. Further, in the audio diversity system, the number of antennas to be switched is reduced, so that the comparison processing time can be shortened, and the number of times of switching can be reduced, thereby preventing deterioration of the sound output due to antenna switching. As for the audio signal, a sufficient effect can be obtained by the diversity operation with a smaller number of antennas than the video signal.

Next, an example of the TV detection circuit 10 will be described with reference to FIG.
This will be described with reference to FIG. FIG. 3 is a diagram showing a configuration of the TV detection circuit 10. From the device side where the antenna control unit (microcomputer) 12 is provided (the antenna control unit 12 is usually provided on the TV tuner 6 side, and each TV monitor is connected by a signal line 31: hereinafter referred to as a main unit), A line 31 connected to a TV monitor TVM2 other than the TV monitor 2 is provided. The line 31 is integrated with the video signal line. By connecting a connector for connecting these signal lines to the TV monitor TVM2 to a connector of the TV monitor TVM2, the line 31 is connected.
Is connected to the ground (ground) of the television monitor TVM2. The ground of the television monitor TVM2 is connected to the negative terminal of the battery together with the ground of the main unit. The line 31 is connected to the power supply via the resistor R1, and is connected to the base of the transistor TR1 whose emitter is grounded. The collector of the transistor TR1 is connected to the power supply via the resistor R2 and to the input terminal of the antenna control unit 12.

Next, the operation will be described. When a television monitor other than that for the driver's seat is not connected, the transistor TR1 is turned on, the collector of the transistor TR1 is substantially grounded, and a low potential signal is input to the input terminal of the antenna control unit 12. When a television monitor other than the driver's seat is connected, the base of the transistor TR1 is at the ground potential via the line 31, and the transistor TR1 is turned off. Accordingly, the collector of the transistor TR1 is set to a high potential state by the power supply connected via the resistor R2, and a high potential signal is input to the input terminal of the antenna control unit 12. As described above, according to the present embodiment, the voltage level of the input signal to the antenna control unit 12 changes depending on the presence or absence of a television monitor other than the driver's seat. Can be identified.

As a method of detecting the state of the television monitor for the other seat (other than the driver's seat), in addition to the above embodiment, the state of the television monitor for the other seat (presence / absence, operation or non-operation) may be determined by communication using a microcomputer. There is a method of detecting whether the operation is in progress or a method of setting by a user using a manual switch.

[0022]

As described in detail above, in the present invention, since the diversity operation is performed in a manner according to the display state of the television image, the display of the television screen or the reproduction of the television sound in a good state is always performed. It can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an in-vehicle television receiver according to an embodiment of the present invention.

FIG. 2 is a flowchart showing processing of an antenna control unit 12;

FIG. 3 is a configuration diagram showing an example configuration of a TV detection circuit 10;

[Explanation of symbols]

 1, 2, 3, 4 ... antenna 5 ... antenna switch 6 ... TV tuner 7 ... switch 8 ········ Reception level determination circuit 10 ····· TV detection circuit 12 ······· Antenna control unit

Claims (5)

[Claims] 1. An on-vehicle television receiving apparatus having a diversity receiving circuit for providing a plurality of antennas in a vehicle, selecting an antenna having a good receiving state, and receiving the selected signals, based on video signals from the plurality of antennas. Video diversity means for selecting an antenna having a good reception state, audio diversity means for selecting an antenna having a good reception state based on audio signals from the plurality of antennas, and whether or not a television image is being displayed. Detecting means for detecting, when the TV image display is detected by the detecting means,
An in-vehicle television receiving apparatus, comprising: selecting means for operating the video diversity and operating the audio diversity means when it is detected that the television image is not being displayed. 2. The in-vehicle television receiving apparatus according to claim 1, wherein said detecting means detects whether or not a television image is being displayed based on a running state of the vehicle. 3. The on-vehicle vehicle according to claim 1, wherein the detection unit detects that a television image is being displayed when a television monitor installed for a rear seat of the vehicle is operating. Television receiver. 4. The rear-view television monitor, when the rear-view television monitor is connected, detects a display state of the rear-view television monitor by a voltage of a communication line grounded by a circuit of the rear-view television monitor. The on-vehicle television receiving device according to claim 3, wherein the receiving is performed. 5. The on-vehicle vehicle according to claim 1, wherein the voice diversity unit selects a predetermined number of antennas from a plurality of antennas and selects an antenna having a good reception state from the selected antennas. Television receiver.