JPH1032764A - Tv receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a TV receiver with which no adverse influence is exerted upon external equipment even after switching the TV received to an external input. SOLUTION: When a key operating part 16 performs the operation of source switching to TV broadcasting, a controller 17 switches a video switching circuit 18 to the TV video signal output side of a demodulation circuit 9, performs the ON control of a power source ON/OFF circuit 8 and lets a local oscillation circuit 5 execute oscillating operation. According to the channel switching operation, the controller 17 controls a PLL circuit 7, varies the oscillation frequency of the local oscillation circuit 5 and switches a reception channel. A TV video is displayed on a liquid crystal dot matrix display 15. When the key operating part 16 performs the operation of source switching to an on-vehicle navigation system 20, the controller 17 switches the video switching circuit 18 to the external video input side, performs the OFF control of the power source ON/OFF circuit 8 and stops the oscillating operation of the local oscillation circuit 5. The image of navigation picture is displayed on the display 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a TV receiver,
In particular, the present invention relates to a TV receiver capable of switching and displaying a video of a TV broadcast and a video based on a video signal input from an external device such as a navigation device.

[0002]

2. Description of the Related Art There is an in-vehicle TV receiver capable of receiving TV broadcast video and audio in a vehicle compartment. The operation of the in-vehicle TV receiver will be described. First, a broadcast signal of a desired channel is selected by a front end from received signals from an in-vehicle antenna, and is converted into a video intermediate frequency signal. The video intermediate frequency signal is input to a demodulation circuit, where a composite video signal and an audio signal are demodulated. After the audio signal is amplified by the amplifier,
Sound is reproduced by the speaker. On the other hand, the composite video signal is input to a video signal processing circuit, where it is subjected to Y / C separation, horizontal / vertical synchronization detection, R / G / B color signal demodulation, and double-speed non-interlace conversion of the horizontal / vertical synchronization signal and color signal. Processing is performed. Double speed non-interlaced color signal, horizontal /
The vertical synchronizing signal is input to a liquid crystal dot matrix display, and double-speed non-interlaced display of a TV image is performed.

[0003] In recent years, on-vehicle navigation devices, which mark the current position on a map so that the vehicle can travel correctly toward a destination, have been rapidly spreading. This in-vehicle navigation device detects a current position by satellite navigation using a GPS receiver, reads map data around the current position from a CD-ROM in which map data is recorded, and uses the read map data to generate a map image. Is drawn, and the own vehicle mark is superimposed and displayed on the screen of the display device. When both the in-vehicle TV receiver and the in-vehicle navigation device described above are mounted on a vehicle, if the both display devices are separately mounted, the dashboard becomes narrow, which is inconvenient, and the cost increases.
For this reason, an in-vehicle TV receiver is provided with an external video input terminal and an external audio input terminal, and a source switching key for switching between TV and external input is provided. It is displayed on the matrix display and the sound of the received TV broadcast is output from the speaker. When the mode is switched to the external input, an image based on a video signal input from an external device (for example, an in-vehicle navigation device) is displayed on a liquid crystal dot matrix display, and a sound based on an audio signal input from the external device is output from a speaker. Output from.

[0004]

However, in the conventional on-vehicle TV receiver, the oscillation operation of the front-end local oscillation circuit continues even after switching from the state of watching TV broadcasting to the navigation screen. The radio wave radiated from the local oscillation circuit enters a GPS receiving system comprising a GPS antenna, a GPS receiver, and a cable connecting the GPS antenna and the GPS receiver as an interference wave,
In some cases, the current position cannot be detected by satellite navigation due to interference with a signal received from the S satellite. The present invention has been made in view of the above-described problems of the related art, and has as its object to provide a TV receiver that does not adversely affect external devices even when switching to an external input.

[0005]

According to a first aspect of the present invention, there is provided a TV receiver which mixes a received signal of a TV broadcast with a local oscillation signal and converts the signal into an intermediate frequency signal. A TV receiver comprising: a TV image based on a formed video signal and a video image based on an externally input video signal from an external device, and switching means for displaying the video image on a display means. Oscillation operation stop control means for stopping the oscillation operation of the local oscillation circuit of the conversion means while displaying the video based on the external input video signal on the display means in conjunction with the switching. As a result, when switching from the state of watching TV broadcasting to the image screen of the external device,
Since the oscillating operation of the local oscillation circuit of the converting means is stopped, no interfering wave is emitted, and the malfunction of the external device can be prevented from occurring.

According to a third aspect of the present invention, in a TV receiver,
Conversion means for mixing a received signal of a TV broadcast with a local oscillation signal to convert the signal into an intermediate frequency signal; A TV receiver provided with a switching unit for displaying the image based on the external input video signal on the display unit in conjunction with the switching between the TV image and the image based on the external input video signal. , The oscillation frequency of the local oscillation circuit of the conversion means,
Oscillation frequency change control means for changing the frequency to a frequency that does not interfere with external devices is provided. Thereby, when switching from the state of watching TV broadcasting to the video screen of the external device, the oscillation frequency of the local oscillation circuit of the conversion means can be changed to a frequency that does not interfere with the external device. Malfunction can be prevented from occurring.

[0007] The TV receiver according to the second and fourth aspects of the present invention is characterized in that the external device is a navigation device that detects a current position by a GPS receiver. Thus, when the navigation device is connected as an external device, after switching from the state of watching TV broadcasting to the navigation screen, the GPS reception system is not interfered by the interference wave, so that the current position can be continuously detected correctly. .

In the TV receiver according to the first and third aspects of the present invention, the switching means performs a switching operation according to a user's source switching operation, or detects the presence or absence of an externally input video signal, and there is no external input. When switching to TV video, when there is an external input, switch to video based on the external input video signal, or when connected to an external device via a control line and input a switching control signal from the external device to external input Switch to video based on external input video signal,
Switching to TV video when the control signal for switching to external input is turned off, or any configuration may be used.

[0009]

FIG. 1 shows an in-vehicle AV according to a first embodiment of the present invention.
FIG. 1 is a block diagram illustrating a configuration of a system. 1 is T for car
V receiver 2 is a vehicle-mounted TV antenna, 3 is a front end, and selects a reception signal of a desired channel from a reception signal of a TV broadcast by the vehicle-mounted TV antenna, converts the frequency, and outputs the converted signal. 4 is an RF amplifier circuit for amplifying the received signal, 5
Is a local oscillation circuit (VCO) for generating a frequency-variable local oscillation signal by voltage control, and 6 is a mixing circuit for mixing the RF-amplified reception signal and the local oscillation signal to convert the mixed signal into a video intermediate frequency signal. Reference numeral 7 denotes a PLL circuit that controls the local oscillation circuit 5 to vary the oscillation frequency. The PLL circuit 7 divides the local oscillation signal by a fixed division ratio, and a programmable divider that divides the output of the prescaler by a variable division ratio. And a phase comparator for comparing the frequency and phase of the output of the programmable divider with the reference signal, and an LPF for extracting a low-frequency component of the output of the phase comparator and outputting a control voltage. A controller described later sets a frequency division ratio corresponding to a broadcast frequency of a desired TV channel to a programmable divider in accordance with a user's channel switching operation, thereby varying the oscillation frequency of the local oscillation circuit 5 and thereby selecting a desired channel. be able to.

Reference numeral 8 denotes a power on / off circuit for turning on / off the power supplied to the local oscillation circuit 5. The power on / off circuit 8 controls the controller while switching to the external input in conjunction with the source switching between the TV broadcast and the external input. To turn off the power supplied to the local oscillation circuit 5 and stop the oscillation operation. When switching to the TV broadcast, the controller performs ON control, supplies power to the local oscillation circuit 5, and restarts the oscillation operation. A demodulation circuit 9 receives a video intermediate frequency signal from the front end 3 and demodulates it to form a TV video signal (here, a composite video signal) and a TV audio signal. Reference numeral 10 denotes an audio switching circuit which selectively selects and outputs a TV audio signal and an external input audio signal input to an A-IN terminal (external audio input terminal) according to switching control of a controller. Reference numeral 11 denotes a low-frequency amplifier circuit that amplifies the audio signal output from the audio switching circuit 10, and 12 denotes a speaker that is driven by the amplified audio signal and reproduces sound.

Reference numeral 13 denotes a video switching circuit which selectively converts a TV video signal and an external input video signal (here, a composite video signal) input to a V-IN terminal (external video input terminal) in accordance with switching control of a controller. Select and output. Reference numeral 14 denotes a video signal processing circuit, which performs Y / C separation,
Perform horizontal / vertical synchronization detection, demodulate R, G, B color signals,
Further, a non-interlace conversion process is performed to output non-interlaced horizontal / vertical synchronization signals and color signals.
Reference numeral 15 denotes a liquid crystal dot matrix display that inputs a non-interlaced horizontal / vertical synchronization signal and color signal and displays a TV image or an image based on an externally input image signal.

Reference numeral 16 denotes a key operation unit for performing a TV channel selection operation, a source switching operation between TV broadcasting and external input, and 17 denotes a microcomputer-structured controller. The PLL circuit 7 operates in accordance with the TV channel selection operation at the key operation unit.
When a frequency division ratio corresponding to a desired channel is set in the programmable divider of the above, channel selection control is performed, and when switching to TV broadcasting is performed in accordance with a source switching operation, the audio switching circuit 10 and the video switching circuit 13 transmit a TV audio signal,
Switch to the TV video signal side to output the TV audio of the desired channel and display the TV video. When the input is switched to the external input, the audio switching circuit 10 and the video switching circuit 13 switch the external input audio signal and the external input video signal. To output audio from the external device and display video from the external device. The controller 17 controls the power on / off circuit 8 to be turned off when the source is switched to the external input by the source switching operation, and is controlled to be turned on when the source is switched to the TV broadcast by the source switching operation.

Reference numeral 20 denotes an on-vehicle navigation device as an external device, of which 21 is an on-vehicle GPS antenna,
22 is a GPS caught by the onboard GPS antenna 21
A GPS receiver for detecting the current position by satellite navigation based on a radio wave of a satellite.
A cable for connecting the receiver 22
A GPS receiving system is configured by the PS antenna 21, the GPS receiver 22, and the cable 23. 24 is a CD-ROM recording map data of various scales, 25 is a C-ROM.
CD-ROM for reading map data from D-ROM 24
A reading unit 26 is a key operation unit that activates a navigation device, performs an operation of enlarging / reducing a map, and performs an operation of calling various service information.

Reference numeral 27 denotes a navigation device main body composed of a microcomputer. When the device is operated by the key operation unit 26, the navigation device 27 receives the current position detected by the GPS receiver 22 based on the current position.
By controlling the CD-ROM reading section 25, the CD-ROM 2
4 is read out from the map data of a predetermined scale including the current position, and the video R
A map image of an area including the current position is drawn on the AM, and a vehicle position mark is drawn over the current position on the map image. When the user performs an enlargement / reduction operation, the CD-RO
The map data whose scale level is lower or higher by one step is read out from the M24 and the video R is read using the read map data.
The map image of the area including the current position is drawn on the AM together with the vehicle position mark. The image in the video RAM is rewritten each time the current position changes. The image of the video RAM is periodically read out and converted into a composite video signal, and V-OUT
A terminal (external video output terminal) outputs the video signal to the in-vehicle TV receiver 1 as an external video input. Further, when the user calls the service information of voice guidance by operating the key operation unit 26, the navigation device main body 27 receives a vehicle-mounted TV signal from the A-OUT terminal (external voice output terminal) of a voice signal obtained by voice-synthesizing the guidance information. Output to the device 1 as an external audio input.

Next, the operation of the above embodiment will be described. It is assumed that the vehicle-mounted TV receiver 1 is in a power-on state.
When the user has previously switched the source to the TV broadcast using the key operation unit 16, the controller 17 switches the audio switching circuit 10 and the video switching circuit 13 to the TV audio signal,
The power is switched to the V video signal side, and the power supply on / off circuit 8 is controlled to turn on the power supply to the local oscillation circuit 5 to perform the oscillation operation. Therefore, the in-vehicle TV receiver 1 is in a state capable of receiving a TV broadcast. When the user performs an operation of switching to a desired channel using the key operation unit 16, the controller 17 determines the corresponding frequency division ratio of the PLL circuit 7. It is set in a programmable divider, the oscillation frequency of the local oscillation circuit 5 is adjusted to the broadcast frequency of the desired channel + the video intermediate frequency, and the broadcast signal of the desired channel is selected and converted to a video intermediate frequency signal. A TV audio signal and a TV video signal (composite video signal) are formed from the video intermediate frequency signal by a demodulation circuit 9, and the TV audio signal is sent to a low-frequency amplifier circuit 11 via an audio switching circuit 10, amplified, and then a speaker. 12 to output TV sound. The TV video signal is supplied to the video switching circuit 13.
To the video signal processing circuit 14 to form non-interlaced R, G, B color signals and horizontal / vertical synchronization signals.
The video is displayed.

When the user wants to view the navigation screen from this state, the key operation unit 16 switches the source to an external input, and the key operation unit 26 starts the navigation device 20. When the source switching operation to the external input is performed, the controller 17 switches the audio switching circuit 10 and the video switching circuit 13 to the external input side.
The power supply to the local oscillation circuit 5 is turned off by controlling the power on / off circuit 8 to be turned off, and the oscillation operation is stopped. This allows
The local oscillation circuit 5 prevents the local oscillation signal from radiating to the outside in the form of radio waves. For this reason, the local oscillation signal does not enter the GPS receiving system, interfere with the GPS reception signal, and does not interfere. Therefore, the GPS receiver 2
2 can correctly detect the current position, and the navigation device main body 27 can draw an image in which the vehicle position mark is accurately superimposed on the map. The map image is converted into a video signal (composite video signal) and output to the in-vehicle TV receiver 1. Further, a voice signal for voice guidance is also output to the in-vehicle TV receiver 1.

The video signal output from the on-vehicle navigation device 20 is input to the video signal processing circuit 14 via the video switching circuit 13, and the non-interlaced R, G,
The B color signal and the horizontal / vertical synchronization signal are formed, sent to the liquid crystal dot matrix display 15, and the image of the navigation screen on which the current position is correctly marked on the map is displayed. The audio signal output from the on-vehicle navigation device 20 is input to the low frequency amplifier circuit 11 via the audio switching circuit 10 and amplified,
And a guidance voice is output.

After that, when the user views the TV broadcast, if the user operates the key operation unit 16 to switch the source to the TV broadcast while the navigation device 20 for the vehicle is in operation, the controller 17 causes the audio switching circuit 10 and the video switching circuit 10 to operate. 13 to the TV side, and power on /
The power supply to the local oscillation circuit 5 is turned on by turning on the off circuit 8, and the oscillation operation is restarted. While the source is switched to the external input, the frequency division ratio set in the programmable divider of the PLL circuit 7 is not changed, so that the TV broadcast that was being viewed before switching to the in-vehicle navigation device 20 is viewed again. can do. It is also possible to switch to another channel by a channel switching operation. Thereafter, when the source switching operation to the external input is performed again by the key operation unit 16, the controller 17 switches the audio switching circuit 10 and the video switching circuit 13 to the external input side, and controls the power on / off circuit 8 to off. Then, the power supply to the local oscillation circuit 5 is turned off, and the oscillation operation is stopped. Since the in-vehicle navigation device 20 is in the operating state and the GPS receiving system is not obstructed by the local oscillation signal, the user can again see the image of the navigation screen in which the current position is correctly marked on the map.

According to this embodiment, the controller 17 controls the power supply on / off circuit in conjunction with the source switching control of the audio switching circuit 10 and the video switching circuit 13 in accordance with the source switching operation of the key operation unit 16. 8 is turned on / off, and while displaying an image based on an external input, the oscillation operation of the local oscillation circuit 5 is stopped. Therefore, the radiation of the local oscillation signal enters the GPS receiving system. It does not interfere with the GPS reception signal and does not interfere, so that the current position can be correctly detected. Therefore, the user can see the image of the navigation screen in which the current position is correctly marked on the map.

FIG. 2 shows a vehicle-mounted A according to a second embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a V system, and the same components as those in FIG. 1 are denoted by the same reference numerals. In the first embodiment, the oscillation operation of the local oscillation circuit is stopped while the source is switched to the external input, while in the second embodiment, while the source is switched to the external input, the local oscillation circuit is stopped. The oscillation frequency of the oscillation circuit is changed to a frequency that does not interfere with the GPS receiving system. Therefore, in FIG. 2, the power on / off circuit 8 in FIG. 1 is omitted, and the power supplied to the front end 3 is supplied to the local oscillation circuit 5 as it is.

The controller 17 of the in-vehicle TV receiver 1A
A follows the TV channel selection operation on the key operation section,
The frequency division ratio corresponding to the desired channel is set in the programmable divider of the PLL circuit 7 to perform channel selection control, and when switching to TV broadcasting is performed according to the source switching operation, the audio switching circuit 10 and the video switching circuit 13 are switched to T.
Switching to the V audio signal and TV video signal side to output TV audio of the desired channel and display TV video, and when switching to external input, the audio switching circuit 10 and the video switching circuit 13 switch the external input audio signal, Switching to the external input video signal side to output audio from the external device and display video from the external device. When the controller 17A is switched to the external input by the source switching operation, the controller 17A sets a predetermined frequency division ratio in the programmable divider of the PLL circuit 7, and adjusts the frequency of the local oscillation signal radiated from the local oscillation circuit 5. ,
Change to a value that does not cause interference even if it enters the GPS receiving system. For example, when the frequency of the GPS radio wave is a MHz, the local oscillation frequency F _LO is: F _LO = a / (p + 0.5) MHz, where p is a positive integer. Thereafter, when the TV is returned to the TV broadcast by the source switching operation, the frequency division ratio of the channel watched before switching to the external input is reset to the programmable divider of the PLL circuit 7 and the oscillation of the local oscillation circuit 5 is started. The frequency is returned to the value before the change, and the TV broadcast of the channel watched before switching to the external input can be received. The other components are configured exactly the same as in FIG.

According to the second embodiment, the controller 1
7A is a variable control of the oscillation frequency of the local oscillation circuit 5 via the PLL circuit 7 in conjunction with the source switching control of the audio switching circuit 10 and the video switching circuit 13 in accordance with the source switching operation of the key operation unit 16. And while displaying the image based on the external input, the local oscillation circuit 5
The oscillation frequency is changed to a value that does not cause interference even if it enters the GPS reception system, so that the radiation of the local oscillation signal enters the GPS reception system and interferes with the GPS reception signal, so that it does not interfere. , The current position can be correctly detected. Therefore, the user can see the image of the navigation screen in which the current position is correctly marked on the map. Also, if the user
When the source is returned to the broadcast, the oscillation frequency of the channel that was being viewed before switching to the external input is returned, so the channel that was viewed before switching to the external input without re-selecting the channel is required. TV broadcast can be received.

In each of the above-described embodiments, the in-vehicle TV is used.
In accordance with the source switching operation at the key operation unit of the receiver, the controller controls the source switching of the audio switching circuit and the video switching circuit, and stops the oscillation operation of the local oscillation circuit while switching to the external input. The oscillation frequency of the local oscillation circuit is changed to a value that does not adversely affect the GPS receiving system.
A detection circuit for detecting whether an external input video signal is input to the N terminal is provided (for example, a horizontal / vertical synchronization signal detection circuit can be used), and the controller responds to the presence or absence of the external input video signal. Source switching control for the audio switching circuit and the video switching circuit (switch to the TV broadcast side when there is no external input video signal, switch to the external input side when there is an external input video signal), and switch to the external input. During this time, the oscillation operation of the local oscillation circuit is stopped or the oscillation frequency of the local oscillation circuit is set to GPS.
It may be changed to a value that does not adversely affect the receiving system.

Further, the controller inputs a notification signal indicating whether or not the in-vehicle navigation device is in operation from the in-vehicle navigation device through a communication line, and determines whether or not the in-vehicle navigation device is in operation. Source switching control for the audio switching circuit and the video switching circuit (switching to the TV broadcast side when the in-vehicle navigation device is not in operation, and switching to the external input side when in operation). While switching to the input, the oscillation operation of the local oscillation circuit may be stopped, or the oscillation frequency of the local oscillation circuit may be changed to a value that does not adversely affect the GPS receiving system.
The external device connected to the vehicle-mounted TV receiver may be other types of AV devices other than the vehicle-mounted navigation device. Further, the TV receiver is not limited to a vehicle receiver.

[0025]

According to the TV receiver of the present invention, while the source is switched to the external input, the oscillation operation of the local oscillation circuit is stopped or the frequency is changed to a frequency that does not interfere with the external device. Therefore, when switching from a state of watching TV broadcasting to a video screen of an external device,
It is possible to prevent the external device from malfunctioning.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a vehicle-mounted AV system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a vehicle-mounted AV system according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1, 1A In-vehicle TV receiver 2 In-vehicle TV antenna 3 Front end 5 Local oscillation circuit 6 Mixing circuit 7 PLL circuit 8 Power on / off circuit 9 Demodulation circuit 13 Video switching circuit 14 Video signal processing circuit 15 Liquid crystal dot matrix display 16 , 26 Key operation unit 17, 17A Controller 20 In-vehicle navigation device 21 In-vehicle GPS
Antenna 22 GPS receiver 23 Cable 24 CD-ROM 27 Navigation device main body

Claims (4)

[Claims] 1. A conversion means for mixing a received signal of a TV broadcast with a local oscillation signal to convert it into a video intermediate frequency signal, and a TV video based on a video signal formed from an output of the conversion means and an external input from an external device. In a TV receiver comprising a switching means for switching a video based on a video signal and displaying the video on a display means, the video based on the external input video signal is displayed in conjunction with the switching between the TV video and the video based on the external input video signal. A oscillating operation stop control means for halting the oscillating operation of the local oscillation circuit of the converting means while displaying on the means. 2. The TV receiver according to claim 1, wherein the external device is a navigation device that detects a current position using a GPS receiver. 3. A conversion means for mixing a received signal of a TV broadcast with a local oscillation signal to convert the signal into an intermediate frequency signal, a TV video based on a video signal formed from an output of the conversion means, and an external input video signal from an external device A video signal based on an externally input video signal in response to switching between a TV video and a video based on an externally input video signal. A TV receiver, further comprising: oscillation frequency change control means for changing the oscillation frequency of the local oscillation circuit of the conversion means to a frequency that does not interfere with an external device during the display. 4. The TV receiver according to claim 3, wherein the external device is a navigation device that detects a current position using a GPS receiver.