JP2002314891A - Television receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a television receiver capable of dissolving the situation of falling into a standby state where a user cannot obtain any information at the time of changing a channel. SOLUTION: When channel switchover is instructed, a control microcomputer 4 commands a double speed conversion circuit 3 to stop video data write to a frame memory. Since the double speed conversion circuit 3 reads video data from the frame memory and outputs video images, it outputs still images by video data write stoppage. Thereafter, the control microcomputer 4 makes a tuner 1 start a tuning operation so as to receive the radio waves of a requested channel, and when tuning is ended, makes the double speed conversion circuit 3 restart the video data write to the frame memory.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver for receiving a television signal.

[0002]

2. Description of the Related Art A tuner provided in a television receiver mixes a signal of a desired channel and a local oscillation signal to generate and output an intermediate frequency signal (58.75 Mz in Japan). I have. The local oscillation signal is output from the oscillation circuit. This oscillator circuit includes, for example, a variable-capacitance diode or the like whose capacity changes according to an applied voltage, and a local oscillator variable in accordance with a signal of a desired channel so that a signal of a constant intermediate frequency is output from the mixing circuit. Generate a signal. Also, a PLL (Phase Locked Loop) is used instead of the variable capacitance diode.
There is also a frequency synthesizer system provided with a circuit.

[0003]

By the way, when a channel is designated, the local oscillation frequency starts to change, and until a desired intermediate frequency signal is obtained, a distorted screen is displayed when the received signal is displayed as an image. Therefore, a process of applying a screen mute is performed.

However, when the above-mentioned screen mute is performed, nothing is displayed on the screen, and the user is in a waiting state in which no information can be obtained. In particular, in television receivers for countries other than Japan, it takes a long time to execute an algorithm for determining a color system and performing Y / C separation, and the screen non-display state is long.

The present invention has been made in view of the above circumstances, and provides a television receiver which can eliminate a situation in which a user enters a wait state in which no information can be obtained when a channel is changed. With the goal.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a television receiver according to the present invention has a memory for storing video data obtained by D / A conversion of a received video signal, and a designated memory. Channel selecting means for selecting a channel; and stopping the writing of video data to the memory when the channel is designated to display the received video still image before the channel change on the screen, and selecting the channel by the channel selecting means. And control means for restarting the writing to the memory when the station is terminated and displaying the received video.

With the above arrangement, since the final video of the original channel when the channel is changed is continuously displayed on the screen, the display is switched to the received video display of the changed channel. It will be done. Therefore, it is possible to eliminate a situation in which the user enters a waiting state where no information can be obtained.

The memory is preferably a frame memory provided in a double-speed conversion circuit for increasing the number of scanning lines. Since this uses an existing memory, cost can be avoided. Further, an on-screen display circuit for displaying characters on the screen may be provided, and the display of the received video still image before the channel change and the character display indicating that the channel selection is in a transition state may be performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to FIG.
A description will be given based on FIG. FIG. 1 is a block diagram showing a configuration of a television receiver according to this embodiment.
FIG. 2 is a flowchart showing the processing contents at the time of channel switching.

The tuner 1 includes an input section, an amplification section, a mixing circuit, a channel selection processing circuit, and the like. The input unit includes a circuit for matching the input impedance between the antenna feed line and the amplification unit, and various trap circuits for eliminating radio waves that cause interference. The amplification unit is a circuit that amplifies a signal that has passed through the input unit. The mixing circuit mixes the signal of the desired channel and the local oscillation signal to generate an intermediate frequency signal, and outputs the intermediate frequency signal. The local oscillation signal is output from the oscillation circuit. This oscillation circuit includes, for example, a variable capacitance diode whose capacitance changes according to an applied voltage, and a local oscillation signal that is varied according to a signal of a desired channel so that a signal of a constant intermediate frequency is output from the mixing circuit. Generate The channel selection processing circuit receives data of an applied voltage (tuning voltage) corresponding to each channel from a memory, converts the data into an analog signal (voltage) by a D / A converter, and supplies the analog signal to a variable capacitance diode. Further, a signal discriminating circuit is provided, and a synchronizing signal and an AFT (auto fine tuning) voltage are input from another circuit to this discriminating circuit, and when a correct tuning point is reached, a tuning complete signal is given to a tuning processing unit. It has become.

A detection circuit (video chroma circuit) 6 detects a video signal of an intermediate frequency and outputs a video signal (for example, NT signal).
SC signal, but not limited to this type of signal). Also, video input from an external device is performed. Then, a luminance signal (Y) and a color signal (C) are obtained from the video signal.
Is performed, and the separated luminance signal (Y) and color signal (C) are supplied to the double-speed conversion circuit 3.

The double speed conversion circuit 3 incorporates a D / A converter for converting a video signal into digital data and an image memory (frame memory) capable of storing video data for one frame of the video signal. , Video data can be held at an arbitrary timing. The double speed conversion circuit 3 generates a synchronization signal,
This is supplied to the control microcomputer 4 and the deflection circuit 5.

An OSD (on-screen display) circuit 8 generates a video signal based on bitmap data of character information specified by the control microcomputer 4 and outputs the video signal to the mixer 6.

The deflection circuit 5 generates horizontal and vertical sawtooth wave voltages in response to a synchronization signal supplied from the double speed conversion circuit 3 and supplies the voltage to a CRT deflection coil (not shown). Here, in the transient state of the channel change, a synchronization signal cannot be obtained from the received video signal, but a horizontal / vertical sawtooth wave voltage is generated by the synchronization signal supplied from the double speed conversion circuit 3, so that the channel change is not performed. CRT still image display can be performed even in a transient state. The OSD circuit 8
Is controlled by the control microcomputer 4, and the control microcomputer 4 controls the OSD circuit 8 based on the synchronizing signal supplied from the double-speed conversion circuit 3, so that the OSD screen can be displayed even in the transition state of the channel change. Become.

The mixer 6 adds the video signal from the OSD circuit 8 to the video signal output from the double speed conversion circuit 3.

The CRT driver 7 includes a circuit for converting a video signal output from the mixer 6 into RGB signals, and drives a CRT electron gun (not shown).

The control microcomputer 4 issues a channel selection command to the tuner 1, a still image output command to the double speed conversion circuit 3, a character display command to the OSD circuit 8, and the like. The still image output command and the character display command will be described based on the flowchart of FIG. For example, when a channel switching instruction is given by a remote control transmitter, the double speed conversion circuit 3 is instructed to stop writing video data to the frame memory. Since the double speed conversion circuit 3 reads out the video data from the frame memory and outputs the video, a still image is output by stopping the writing of the video data. This still image becomes the still image of the received video at the time of the channel switching instruction (step S1). Then, a character display command is issued to the OSD circuit 8 (step S2). The content of the character display is a content indicating that the channel switching is in a transient state, for example, “during channel switching”. afterwards,
The control microcomputer 4 causes the tuner 1 to start the tuning operation so that the radio wave of the requested channel is received (step S3), and determines whether or not the tuning is completed (step S3).
4). As described above, the tuner 1 receives the synchronization signal or the AFT voltage from the other circuit by the signal discriminating circuit, and gives a tuning completion signal when a correct tuning point is reached. Can determine whether or not the channel selection has ended. When it is determined that the channel selection has been completed, the still image display is canceled (step S5). That is, a command is issued to the double speed conversion circuit 3 to restart the writing of the received video data to the frame memory. Further, a character display change command is issued to the OSD circuit 8 (step S6). That is, the display such as "channel switching" is ended, and the channel number is displayed.

[0018]

As described above, according to the present invention, when the channel is changed, the final image of the original channel is switched to the received image display of the changed channel after being continuously displayed on the screen. What is displayed on the screen. Therefore, it is possible to eliminate a situation in which the user enters a waiting state where no information can be obtained. For example, if the OSD performs a display such as “channel switching”, it is possible to clearly recognize that the still image display state is a channel switching transient state. Further, if the configuration uses a frame memory as a memory, it is possible to avoid a high cost.

[Brief description of the drawings]

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

FIG. 2 is a flowchart showing processing contents at the time of channel switching.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tuner 2 Detection circuit 3 Double speed conversion circuit 4 Control microcomputer 5 Deflection circuit 6 Mixer 8 OSD circuit

Claims (3)

[Claims] 1. A memory for storing video data obtained by D / A conversion of a received video signal, a channel selecting means for selecting a specified channel, and the memory for storing video data when a channel is specified. Control means for displaying a still image before reception of a channel change on the screen by stopping writing to the memory, and restarting writing to the memory when the channel selection by the channel selection means is completed to display the reception image. And a television receiver. 2. The television receiver according to claim 1, wherein the memory is a frame memory provided in a double-speed conversion circuit for increasing the number of scanning lines. 3. The television receiver according to claim 1, further comprising an on-screen display circuit for displaying a character on a screen, wherein the on-screen display circuit is used to display the received video still image before the channel change. A television receiving apparatus for displaying characters indicating that the station is in a transient state.