JPH1132276A - Television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent adverse effects of local oscillation leakage voltage of a television tuner on peripheral equipment, without using a means for turning on/off the power supply to the tuner. SOLUTION: A television receiver is provided with a recording and reproducing device, such as a VCR section 17, etc., and first and second video source selecting switches 15 and 18 which allow signals from other video source to be inputted. When the VCR section 17 does not use the output of a tuner 12 for recording or a CRT 23, which is provided as a displaying means does not use the output of the tuner 12 for display, a microcomputer 13 detects this state and automatically sets the receiving channel of the tuner 12 to a channel with a low local oscillation leakage voltage. On the other hand, when the VCR section 17 uses the output of the tuner 12 for recording or the CRT 23 uses the output for display, the receiving channel of the tuner 12 remains unchanged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television tuner in a receiver, for example, when a video signal is input from an external video device or the like and displayed on the receiver screen. The present invention relates to a television receiver which is prevented from generating.

[0002]

2. Description of the Related Art Generally, a television receiver (hereinafter referred to as T)
V receiver) is a video cassette recorder (hereinafter VCR)
It has a video input terminal so that it can input video signals from external video equipment.

[0003] In such a TV receiver with a video input terminal, the television tuner of the main body of the receiver is usually kept in operation even when an external video signal is projected on a display means such as a cathode ray tube (CRT). You. This is because when an external device such as a VCR is connected to a TV receiver and a recording medium such as a tape is reproduced and viewed, not only the VCR power supply but also the TCR power supply is used.
This is because it is necessary to turn on the power of the V receiver to bring it into an operation state.

In a TV receiver, the leakage voltage (or the level of unnecessary radiation) of a local oscillator in a frequency converter varies depending on the channel being received.
When a channel having a large local oscillation leakage voltage is received, electronic devices and the like around the receiver may be adversely affected as interference waves.

[0005] In a TV receiver to which a VCR is externally connected or a TV receiver with a built-in VCR, the user has previously viewed a channel which is a TV receiver, and then performs input switching to reproduce and view the VCR side. When you do
Although the VCR video is being displayed on the screen, the power of the television tuner remains on, and the tuner remains in a state of receiving the channel that was being viewed immediately before. At this time, if the channel being received by the television tuner is a channel having a large local oscillation leakage voltage (that is, a local oscillation unnecessary radiation level), the VCR playback video currently displayed on the screen of the receiver or the surrounding electronic device. May have a bad effect as a disturbance wave.

In order to prevent this effect, there is a method of turning off the power of the television tuner in the receiver during VCR reproduction. As a result, it is possible to improve screen disturbance caused by the TV tuner.

However, in the method of turning off the power of the TV tuner during VCR reproduction to eliminate the interference by the TV tuner, a circuit for turning on and off the power supply to the TV tuner is required, and the power supply by the on / off operation is required. An abnormal screen is generated due to a change in load, a transient response at the time of turning on or off, or the like. If attention is paid to prevent this, circuit design becomes difficult and complicated, and the circuit cost increases. Further, the method of turning on and off the power of the TV tuner also has a problem in that when the TV tuner is turned on from the power-off state and the TV image is displayed again, the response until the TV image is displayed is poor. Was.

[0008]

As described above, conventionally,
If you leave the TV tuner running while projecting VCR video on the receiver screen, there is a problem that the TV screen will be disturbed and turn off the TV tuner during VCR playback etc. Power on,
Considering the power supply load fluctuation at the time of turning off, the transient response, and the like, there is a problem that the circuit design becomes difficult and the cost becomes disadvantageous.

Therefore, in view of the above problems, the present invention does not use a means for turning on and off the power of the TV tuner, and uses a local oscillation leakage voltage (or local oscillation unnecessary radiation) of the TV tuner to supply the surrounding equipment. It is an object of the present invention to provide a television receiver that can prevent adverse effects.

[0010]

A television receiver according to the present invention switches a tuner capable of receiving a television broadcast signal, a signal received by the tuner, and a signal from another source. Switching means, display means capable of displaying a signal from the switching means,
Key input means capable of generating an instruction signal for switching the switching means; and, in response to the instruction signal, when the switching means is switched to a signal from another source, the receiving channel of the tuner is locally oscillated. Control means for setting a channel having a small leakage voltage.

According to the first aspect of the present invention, in a television receiver provided with a video input switching means capable of inputting a signal from another video source, when an external video signal is displayed on the display means, By automatically setting the receiving channel of the receiver tuner to a channel having a small local oscillation leakage voltage, it is possible to prevent the image of the receiver screen from being disturbed by noise or the like. At the same time, interference with surrounding devices can be prevented. On the other hand, when the output of the tuner is displayed on the display means, the receiving channel of the tuner is left as it is.

According to a second aspect of the present invention, there is provided a television receiver including a tuner capable of receiving a television broadcast signal, and first switching means for switching between a signal received by the tuner and a signal from another source. A recording / reproducing apparatus capable of recording / reproducing a signal from the first switching means, a signal received by the tuner, a signal reproduced by the recording / reproducing apparatus, and a signal from another source. Switching means, display means capable of displaying a signal from the second switching means, and an instruction signal for switching between the first switching means and the second switching means; Key input means capable of generating an instruction signal for switching the operation state of the keyboard, and the tuner based on the plurality of instruction signals from the key input means. A function to determine whether a signal from the tuner is used or not, and when the signal from the tuner is not used for recording in the recording state of the recording / reproducing device or used for display on the display means. If not, control means for setting the reception channel of the tuner to a channel having a small local oscillation leakage voltage is provided.

According to a second aspect of the present invention, there is provided a television receiver including a recording / reproducing device such as a VCR unit and first and second video input switching means for enabling input of a signal from another video source. In, when the output of the tuner is not used for recording by the recording / reproducing device, or when the output of the tuner is not used for display by the display means,
By detecting this and automatically setting the reception channel of the tuner to a channel having a small local oscillation leakage voltage, it is possible to prevent screen interference such as noise from being applied to the image of the receiver screen. At the same time, interference with surrounding devices can be prevented. On the other hand, when the tuner is used for recording of the recording / reproducing device or for displaying on the display means, the receiving channel of the tuner is left as it is.

[0014]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a main part of a television receiver according to one embodiment of the present invention. In the present embodiment, a one-tuner type television receiver with a built-in VCR will be described.

In FIG. 1, a high-frequency television signal is supplied to an antenna 11, and this television signal is supplied to a tuner 12. The tuning control signal S11 according to the receiving channel of the tuner 12 is supplied from the microcomputer 13 to the tuning control terminal of the tuner 12.

The microcomputer 13 is provided with a key input means 20 described later.
, A function of controlling the channel selection of the tuner 12 by an instruction signal from the controller, a function of switching and controlling the video source selection switches 15 and 18 by an instruction signal from the key input means 20, and a recording by the instruction signal from the key input means 20. A function of switching the operation state of the VCR unit 17 as a playback device.

The video intermediate frequency signal from the tuner 12 is detected by a video detector 14 and output as a video detection signal. A video detection output output from the video detector 14 is supplied to one input terminal b of a video source selection switch 15 as first switching means, while a video detection output of a video source selection switch 18 as second switching means is provided. It is supplied to the input terminal e. A video input terminal 1 is connected to the other input terminal a of the video source selection switch 15 as the first switching means.
6 is supplied. Video input terminal 16
Is supplied with a video signal from an external video device such as a laser disk device or another VCR.

The input terminals a and b of the video source selection switch 15 are connected to one input terminal a by a switching control signal S12 from the microcomputer 13 based on a key input by the key input means 20.
Or b, and the video signal from the input terminal a or b is selectively output to the output terminal c.

The video signal from the video source selection switch 15 is supplied to a VCR unit 17 as a recording / reproducing device. The VCR unit 17 does not include a tuner, and can input a video signal detected by video detection and can record and reproduce the video signal. The video signal reproduced by the VCR unit 17 is
It is supplied to an input terminal d of a video source selection switch 18 which is a second switching means.

The video source selection switch 18 has an input terminal f in addition to the input terminals d and e, and a video signal from a video input terminal 19 is supplied to the input terminal f. A video signal from an external video device such as a laser disk or another VCR is supplied to the video input terminal 19.

The input terminals d, e and f of the video source selection switch 18 are switched to one input terminal d, e or f by a switching control signal S13 from the microcomputer 13 based on a key input by the key input means 20, A video signal from an input terminal d, e or f is selectively output to an output terminal g.

The video signal from the video source selection switch 18 is supplied to a video / chroma / deflection processing circuit 21, and the video / chroma-processed RGB signals are supplied to a cathode of a cathode ray tube (CRT) 23 as a display means. . The horizontal and vertical drive signals deflected by the video / chroma / deflection processing circuit 21 are supplied to the deflection output circuit 2.
2 where the horizontal and vertical deflection outputs are obtained and
It is supplied to the deflection yoke 24 of the RT 23.

In the one-tuner type TV receiver thus configured, the television broadcast signal is supplied from the antenna 11 to the tuner 12. The local oscillation frequency of the tuner 12 is determined by the channel selection control signal S
Selected at 11.

When the switching control signal S13 from the microcomputer 13 selects the input terminal e of the video source selection switch 18 based on the key operation of the key input means 20, the television signal selected by the tuner 12 is used for video detection. The video signal is detected by the detector 14, and the video chroma
It is supplied to the deflection processing circuit 21 and displayed on the screen of the CRT 23.

When the switching control signal S13 from the microcomputer 13 selects the VCR unit input terminal d or the external video side input terminal f of the video source selection switch 18 based on the key operation of the key input means 20, the VCR unit 17 operates. The reproduced video signal or a video signal from an external device connected to the input terminal 19 is supplied to the video / chroma / deflection processing circuit 21 through the switch 18 and displayed on the screen of the CRT 23. At this time, the microcomputer 13 performs channel selection control using the channel selection control signal S11 so as to set the television tuner 12 to a channel (for example, one channel) having a small local oscillation leakage voltage (that is, a local oscillation unnecessary radiation level).

When recording by the VCR unit 17, the video source selection switch 15 is switched to the input terminal b, and the output of the tuner 12 is supplied to the VCR unit 17 via the input terminal b and the output terminal c of the switch 15. You. At this time, by setting the video source selection switch 18 to the input terminal d or f, a channel image being recorded or an external input (such as a laser disk) can be displayed on the CRT screen of the TV receiver.

The microcomputer 13 is supplied with a switching control signal S12 instructing the video source selection switch 15 to select the input terminal b from the key input means 20, and instructing the VCR unit 17 to record from the key input means 20. When the switching control signal S14 is supplied, that is, during the VCR recording, even if the external input signal is being displayed on the screen of the CRT 23, the channel selected by the tuner 12 is kept and the output of the tuner 12 is recorded. Try to keep doing it.

The microcomputer 13 controls switching of the channel selected by the tuner 12 based on an instruction signal from the key input means 20, control of switching the inputs of the video source selection switches 15 and 18 of the TV receiver, and control of the VCR unit 1.
In addition to the function of controlling the operation state such as recording, playback, or stop of the tuner 7, the output of the tuner 12
It has a function of determining whether or not it is being used by the R unit 17 or the CRT 23. When the output of the tuner 12 is not used, the receiving channel of the tuner 12 is set to a channel having a small local oscillation leakage voltage. Tuning control as follows. The channel having a small local oscillation leakage voltage needs to be checked in advance for the type of tuner used and stored in a ROM in the microcomputer 13 or a memory (not shown) connected to the microcomputer 13. There is. Thereby, when the microcomputer 13 determines that the output of the tuner 12 is not used in the VCR unit 17 or the CRT 23, the microcomputer 13 stores the channel in the ROM or the memory (that is, the channel having a small local oscillation leakage voltage).
The tuner 12 is controlled so as to select the channel.

Specifically, the time when the output of the television tuner 12 is not used is the following cases (1) to (3).
At this time, the microcomputer 13 controls the tuning of the tuner 12 so that the receiving channel of the television tuner 12 is switched to a channel having a small local oscillation leakage voltage.

(1) When the switch 18 is on the terminal f side and the switch 15 is on the terminal a side. (2) Even if the switch 18 is on the terminal f side and the switch 15 is on the terminal b side, the VCR section (3) When the switch 18 is set to the terminal d side and the video tape is reproduced by the VCR unit 17, and when the output of the TV tuner 12 is used, the following (1) and (2) ). At this time, the receiving channel of the TV tuner 12 is left as it is.

(1) When the switch 18 is set to the terminal e to receive an image on the TV screen. (2) When the switch 15 is set to the terminal b and the VCR unit 17 is recording, as described above, the output of the tuner 12 is , Or used for recording on the VCR unit 17 or displayed on the screen of the CRT 23, the receiving channel of the tuner 12 is kept as it is, and the video tape of the VCR unit 17 is reproduced and the CRT 23 is reproduced. Is displayed on or
When the output of the tuner 12 is not being recorded by the VCR unit 17 and another source is selected by the video source selection switch 18, the reception channel of the tuner 12 is switched to a channel having a small local oscillation leakage voltage. As a result, it is possible to prevent adverse effects on peripheral devices due to the local oscillation leakage voltage of the TV tuner 12 without using a unit for turning on and off the power of the TV tuner 12.

FIG. 2 is an example of a flowchart of channel selection control of the microcomputer 13 in the one-tuner type VCR built-in television receiver as shown in FIG.

When the screen source is changed (step S1), the microcomputer 13 determines whether or not the screen is a TV screen from the TV tuner 12 (step S2). ch) is left as it is (step S3), and if it is not a TV screen in S2, it is determined whether or not VCR recording is being performed (step S4). S
In step 4, the channel of the TV tuner 12 is kept as it is during VCR recording (step S3), and if not, the channel of the TV tuner 12 is fixed to a channel having a small local oscillation leakage voltage (for example, 1ch). Tuning control is performed (step S5).

FIG. 3 is a block diagram showing an example of the configuration of the tuner 12 in FIG. Here, a case of a channel selection system using a PLL frequency synthesizer method will be described. In the tuner 12, a high-frequency signal (RF signal) from the antenna 11 is supplied to one input terminal of a mixer 41 via a tuning circuit 40, and the other input terminal of the mixer 41 is connected to a voltage-controlled oscillator (hereinafter, VCO). The local oscillation signal from 42 is supplied, and an intermediate frequency signal (IF signal) is obtained as an output of the mixer 41. The VCO 42 includes a prescaler (fixed frequency divider) 43, a programmable frequency divider 44, a phase comparator 45, a reference oscillator 46, and a low-pass filter (LP
F) Together with 47, constitutes a PLL (Phase Locked Loop). The local oscillation signal from the VCO 42 is
And is supplied to a prescaler 43, where the local oscillation frequency is divided by a predetermined number, further divided by a programmable divider 44 into 1 / N, and supplied to one input terminal of a phase comparator 45. Is done. The frequency division ratio (N) of the programmable frequency divider 44 can be changed by a tuning control signal from the microcomputer 13. Accordingly, the microcomputer 13 provides the frequency divider 44 with the frequency division ratio data corresponding to the channel designation by the key input means 20. In the phase comparator 45, the frequency from the frequency divider 44 and the reference oscillation frequency from the reference oscillator 46 are compared in phase.
The signal is converted into a direct current at 47 and supplied to the oscillation control terminal of the VCO 42. As a result, the local oscillation frequency of the tuner can be correctly set to the frequency of the channel specified by the key input unit 20.

When the tuner configured as described above is used as the TV tuner 12, the microcomputer 13 determines various setting states (operation states of the switches 15, 18 and the VCR unit 17) by the key input means 20, and determines the tuner 12. If it is determined that the output of the tuner 12 is not used for recording on the VCR unit 17 or used for display on the CRT 23, the programmable frequency divider 44 is controlled so that the reception channel of the tuner 12 is subjected to local oscillation leakage. A channel having a small voltage (that is, a local oscillation unnecessary radiation level) (for example, 1
The frequency division ratio (N) is set so as to switch to (channel). Thus, it is possible to prevent the television tuner 12 from interfering on the screen.

FIG. 4 is a plan view showing an example of the key input means in FIG. Here, a case where a remote control transmitter is used as the key input means 20 will be described. Reference numeral 50 denotes a power button for turning on / off the power of the TV receiver, 51 denotes a video input switching button for switching the video source selection switch 18, 52 denotes a direct television broadcasting channel button, and 53 denotes a video source selection switch 15. A video input switching button for switching the video signal, 54 is an up / down channel button, 5
5 is a volume button, 56 to 60 are VCR units 17 respectively.
, Operation buttons for rewinding, stopping, playing, fast-forwarding, and recording.

FIG. 5 is a block diagram showing a television receiver according to another embodiment of the present invention. In the present embodiment, a television receiver with a built-in VCR provided with two tuners so that other programs can be viewed even during VCR recording will be described.

The embodiment of FIG. 5 is different from the embodiment of FIG. 1 in that a splitter 25, a second tuner 26, and a second video detector 27 are provided to provide a second video. Detector 27
Video detection output from the video source selection switch 15
Is supplied to the input terminal a of the first embodiment. The high-frequency television signal supplied to the antenna 11 is
5 and are supplied to tuners 12 and 26, respectively. Each tuning control terminal of each tuner 12, 26 has
Tuning control signals S11 and S15 corresponding to the receiving channels of the tuners 12 and 26 are supplied from the tuning control microcomputer 13A. The video intermediate frequency signal from the tuner 12 is detected by the video detector 14 and supplied to the input terminal e of the video source selection switch 18 and supplied to the input terminal b of the video source selection switch 15 as a video detection signal. The video intermediate frequency signal from the tuner 26 is detected by the video detector 27 and supplied to the input terminal a of the video source selection switch 15 as a video detection signal. Key input means 20A
Corresponds to the second tuner 2 in the key input means 20 shown in FIG.
6 is provided with an up / down channel button. Other configurations are the same as those in FIG.

Also in the television receiver having such a configuration, since the tuner on the television side is the tuner 12, the video signal from the second tuner 26 and the second video detector 27 is supplied to the external input terminal shown in FIG. 16 can be considered in the same manner as the video signal input to the same.

In the case of the embodiment of FIG. 5, as in the case of the embodiment of FIG. 1, the video and audio signals of the TV tuner 12 are used for recording on the VCR section 16 or for displaying on the CRT 23. If not, the microcomputer 13A controls the tuning of the tuner 12 so that the receiving channel of the TV tuner 12 is switched to a channel having a small local oscillation leakage voltage (for example, one channel). As a result, it is possible to prevent adverse effects on peripheral devices due to the local oscillation leakage voltage of the TV tuner without using a means for turning on and off the power of the TV tuner 12.

When the video / audio signal of the television tuner 12 is used for recording on the VCR unit 16 or for displaying on the CRT 23, the receiving channel is kept as it is.

In the embodiment of FIG. 1, a television receiver provided with a VCR unit 17 as a recording / reproducing device and a video source selection switch 15 as a first switching means has been described. However, the present invention is not limited to a television receiver having a video input terminal, which does not include the VCR unit 17 and the video source selection switch 15, that is, includes only the video source selection switch 18 as the second switching means. Of course, it can also be applied.

[0043]

As described above, according to the present invention, peripheral devices caused by the local oscillation leakage voltage (or local oscillation unnecessary radiation) of the television tuner can be used without using the means for turning on and off the power of the television tuner. Adverse effects can be prevented. Since the tuner power supply is not turned on / off, there is also an effect that the responsiveness of the image display when the TV image is displayed again is fast.

[Brief description of the drawings]

FIG. 1 is an exemplary block diagram showing a television receiver according to an embodiment of the present invention;

FIG. 2 is a view showing an example of a flowchart of channel selection control of a microcomputer in the television receiver with a built-in VCR in FIG. 1;

FIG. 3 is a block diagram showing an example of the configuration of the tuner in FIG.

FIG. 4 is an exemplary plan view showing an example of key input means in FIG. 1;

FIG. 5 is a block diagram showing a television receiver according to another embodiment of the present invention.

[Explanation of symbols]

 12 Tuner 13 Microcomputer (tuning control and switching control) 15 Video source selection switch (first switching means) 18 Video source selection switch (second switching means) 20 Key input means 23 CRT (display) means)

Claims (3)

[Claims] 1. A tuner capable of receiving a television broadcast signal, switching means for switching between a signal received by the tuner and a signal from another source, and display means capable of displaying a signal from the switching means. Key input means capable of generating an instruction signal for switching the switching means; and, when the switching means is switched to a signal from another source in response to the instruction signal, the reception channel of the tuner is locally controlled. Control means for setting a channel having a small oscillation leakage voltage. 2. A tuner capable of receiving a television broadcast signal, first switching means for switching between a signal received by the tuner and a signal from another source, and a signal from the first switching means. A recording / reproducing device capable of recording / reproducing, a signal received by the tuner, a signal reproduced by the recording / reproducing device, and a signal from another source; And an instruction signal for switching the first switching means and the second switching means, and an instruction signal for switching an operation state of the recording / reproducing apparatus. Possible key input means, and determining whether a signal from the tuner is used based on the plurality of instruction signals from the key input means If the signal from the tuner is not used for recording in the recording state of the recording / reproducing device or not used for display on the display means, the reception channel of the tuner is changed. Control means for setting a channel having a low local oscillation leakage voltage. 3. The control means includes: first determination means for determining whether the display means is displaying a signal from the tuner; and the first determination means displays a signal from the tuner. When it is determined that the recording is not performed, a second determination unit that determines whether or not the recording / reproducing device is recording, and when the second determination unit determines that the recording is not performed,
3. The television receiver according to claim 2, further comprising: means for setting a reception channel of the tuner to a channel having a small local oscillation leakage voltage.