JP3090315U - Channel selection device for television receiver - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To select the tuning point in the next and subsequent tuning operations for the same channel in a tuning device of a television receiver, and to quickly find a tuning point. SOLUTION: A predetermined center frequency of a channel to be tuned is set, and a higher frequency and a lower frequency are set by arbitrary frequencies, and the presence or absence of a horizontal synchronization signal and a vertical synchronization signal at each frequency is checked. The optimum frequency is selected from the result (# 1: first stage). Further, the tuning operation is performed by fine-tuning the frequency slightly higher or lower based on the optimum frequency until the AFT signal voltage approaches a desired value, and the tuning frequency is selected from the result (# 6). : 2nd stage). This set number of times is stored in the memory, and when the frequency selected in the first stage is the same as the last time at the time of the second or later tuning operation,
Select the tuning frequency from the previously stored number of times set.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a channel selection device for a television receiver that automatically searches and selects a desired channel from television waves.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, for example, in this type of channel selection device using a PLL frequency synthesizer system, it is generally known that an AFT (automatic frequency tuning) operation is performed so that a channel offset from a normal frequency can be selected. Have been. In this case, if all the offset amounts of each channel are stored, the data amount increases, and a large-capacity memory is required. Therefore, it is known that only a part of the reference offset amount is stored, and this is added to the reference PLL data to perform automatic frequency tuning, thereby reducing the storage data amount (for example, JP-A-4-332275).

[0003] For example, a television receiver for the United States can receive broadcast signals of the NTSC system of TV (terrestrial wave), STD system, IRC system, and HRC system of cable television (CATV) broadcast signal. There is a channel selection device having a configuration and having a function of automatically searching for a channel having a broadcast signal. In this channel selection device, the program scan operation analyzes the reception frequency of the channel using the AFT signal and the synchronization signal, determines the broadcast system based on the analysis, and simultaneously stores the frequency in the memory, and performs the channel selection operation. It is known that a channel frequency is sometimes calculated to improve operability and speed up channel selection (for example, see Japanese Patent Application Laid-Open No. 5-64094).

In a channel selection method for receiving a broadcast signal of the NTSC system in a television receiver, a center frequency of a channel to be selected is determined based on detection results of horizontal and vertical synchronization signals at appropriate frequencies. The present applicant has proposed a search method and a method of performing tuning operation by fine-tuning the frequency until the AFT signal voltage approaches a desired value, and performing a tuning operation, and selecting a tuning frequency from the result. .

[0005]

[Problems to be solved by the invention]

 However, in the conventional channel selection device as disclosed in the above-mentioned publication, the frequency data of the channel selected and operated is stored, so that the memory capacity is increased. In the method of selecting a channel in the above two steps, when the tuning points selected in the second step are stored, the selection results of all the channels are stored, and the memory capacity increases. Only the result of frequency selection by horizontal and vertical synchronization signals was stored. In this case, the tuning operation by the fine adjustment setting of the AFT signal voltage in the second stage must be performed each time for the same channel as the previous one, which hinders the speeding up of the channel selection operation.

The present invention solves the above-mentioned conventional problem. In the method of selecting a channel in the above two steps, the result of frequency selection by the first and second horizontal and vertical synchronizing signals and the second step By saving the number of times (not the frequency) checked in step 2, it is possible to reduce the number of times of checking in the second stage in the next and subsequent tuning operations for the same channel, and to quickly find a tuning point. It is another object of the present invention to provide a television receiver channel selection device that can speed up the channel selection.

[0007]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a tuner that selects and amplifies a desired channel from television waves and converts it to an intermediate frequency signal, and amplifies and detects the intermediate frequency signal from this tuner, and performs An intermediate frequency processing unit that outputs a deviation from the specified frequency of the frequency signal as an automatic frequency tuning signal (hereinafter, an AFT signal) and outputs a synchronization signal from a video detection signal; Using the channel selection command from the operation unit, the AFT signal and the synchronization signal from the intermediate frequency processing unit, and the data for channel selection stored in the memory, the reception signal of the desired channel to the tuner. And a tuning control unit for supplying tuning data for selecting a channel, the tuning control unit includes a tuning control unit for selecting a channel of a channel to be tuned. Center frequency, a frequency higher by an arbitrary frequency than the center frequency, and a frequency lower by an arbitrary frequency than the center frequency, and the presence or absence of a horizontal synchronization signal and a vertical synchronization signal at each frequency is checked. A first selecting means for selecting an optimum frequency from the result; a fine tuning and setting of the frequency to a slightly higher or lower frequency until the AFT signal voltage approaches a desired value; and a tuning operation is performed. The second selecting means for selecting, the storing means for storing the set number of times in the second selecting means in the memory, and the frequency selected by the first selecting means at the time of the second and subsequent tuning operations are the same as the previous time. And a third selecting means for selecting a tuning frequency from the previously set number of times stored by the storing means. It is intended to reduce the adjustment tuning operation number of times.

In the configuration of the present invention, the tuning control unit sets a predetermined center frequency of a channel to be tuned, and a higher frequency and a lower frequency by an arbitrary frequency higher than the predetermined center frequency. The presence or absence of the synchronization signal and the vertical synchronization signal is checked, and the optimum frequency is selected based on the result (first stage). Further, the tuning operation is performed by fine-tuning the frequency to a slightly higher or lower frequency until the AFT signal voltage approaches a desired value based on the optimum frequency, and a tuning frequency is selected from the result ( 2nd stage). This set number of times is stored in the memory. If the frequency selected in the first step is the same as the previous time in the second or subsequent tuning operation, the tuning frequency is set from the previously stored number of times. select. As a result, the number of times of tuning in the second stage can be reduced, and a tuning point can be quickly found. As a result of the second stage, when the frequency is stored, the data amount increases, but since the set number of tunings is stored, the data amount does not increase.

The present invention also provides a tuner that selects and amplifies a desired channel from television waves and converts it into an intermediate frequency signal, amplifies and detects the intermediate frequency signal from this tuner, and detects the intermediate frequency signal. An intermediate frequency processing unit that outputs a deviation from a specified frequency as an automatic frequency fine adjustment signal (hereinafter, an AFT signal) and outputs a synchronization signal from a video detection signal, an operation unit that issues a channel selection command, To select a desired channel reception signal for the tuner using the tuning command, the AFT signal and the synchronization signal from the intermediate frequency processing unit, and the data for tuning stored in the memory. And a channel selection control unit for supplying channel selection data, wherein the channel selection control unit appropriately selects a channel to be selected. A first selecting means for selecting a center frequency from the detection result of the synchronization signal at the frequency of the first and a tuning operation by fine-tuning the frequency until the AFT signal voltage approaches a desired value, and selecting a tuning frequency from the result. A second selection unit for performing the selection, and a storage unit for storing the tuning result of the second selection unit in a memory. The tuning frequency is selected from the previous tuning result stored by the storage means.

The second selecting means performs a tuning operation by finely adjusting and setting the frequency until the AFT signal voltage approaches a desired value, and selects a tuning frequency from the result. The number of times set by the selection means is stored in the memory.

[0011]

[Embodiment of the invention]

 Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a block configuration of a television receiver to which a channel selection device according to the present invention is applied. Television radio waves (TV or CATV signals) are received by an antenna 1, and these signals are selectively amplified only by a specific channel by a tuner 2 and converted into an intermediate frequency signal. The intermediate frequency signal from the tuner 2 is amplified in the intermediate frequency processing unit 3, and the video signal and the audio signal are detected and demodulated. The video signal is amplified by the video amplification circuit 4 and then displayed on the CRT 5 as an image. The audio signal is amplified by the audio amplification circuit 6 and is output as audio by the speaker 7. The tuner 2 uses, for example, a voltage controlled oscillator (VCO) using a variable capacitance diode.

The intermediate frequency processing unit 3 outputs a deviation of the intermediate frequency signal from a specified frequency as an automatic frequency tuning signal (hereinafter, AFT signal) and outputs a synchronization signal from a video detection signal. The microcomputer 8 constitutes a tuning control unit based on a well-known PLL frequency synthesizer system, and includes a tuning command from the operation unit 9, an AFT signal and a synchronization signal from the intermediate frequency processing unit 3, and a memory 10. Using the stored data for tuning, tuning data for selecting a reception signal of a desired channel is supplied to the tuner 2. The microcomputer 8 has a function of calculating a frequency division ratio of a programmable frequency divider (not shown) according to a designated channel selection channel. By changing the frequency division ratio, the control voltage applied to the VCO in the tuner 2 is controlled. And the local oscillation frequency of the tuner 2 is changed. As a result, the tuner 2 can select a specified channel. As information necessary for calculating the frequency division ratio for the channel selection operation, information from the memory 10 and the AFT signal and the synchronization signal from the intermediate frequency processing unit 3 are used.

The microcomputer 8 sets a center frequency of a channel to be selected, a frequency higher by an arbitrary frequency than the center frequency, and a frequency lower by an arbitrary frequency than the center frequency. A function (first selection means) of checking the presence or absence of the horizontal synchronization signal (Hsync) and the vertical synchronization signal (Vsync) in the above, and selecting the optimum frequency based on the result, and adjusting the frequency until the AFT signal voltage approaches a desired value. A function to fine-tune and set the tuning frequency slightly higher and lower and perform the tuning operation, select the tuning frequency from the result (second selection means), and save the number of times set in the second selection method in the memory 10 Function (storing means) and saves when the frequency selected by the first selecting means during the second and subsequent tuning operations is the same as the previous time. (Third selection means) for selecting a tuning frequency from the previously set number of times stored by the means.

Next, the tuning operation by the microcomputer 8 will be described with reference to the flowchart of FIG. As shown in FIG. 4, the scanning operation in the first selecting means includes a predetermined center frequency (β) of a channel to be selected, a frequency (γ) higher by an arbitrary frequency than the center frequency, and a center. A frequency (α) lower than the frequency by an arbitrary frequency is set, the presence or absence of a horizontal synchronization signal (Hsync) and a vertical synchronization signal (Vsync) at each frequency is checked, and an optimum frequency is selected from the result (# 1). : 1st stage). The selected frequency is stored in the memory 10 (# 2). FIG. 3 shows the # 1 subroutine (# 11 to # 17).

Further, the microcomputer 8 checks whether or not the current tuning is the same frequency as the previous one (# 3). If it is not the same (NO in # 3), it is shown in FIG. 5 as the second selecting means. As described above, the tuning operation (fine tuning) is performed by fine-tuning the frequency slightly higher or lower until the AFT signal voltage approaches a desired value (the best point is 2.5 V when the maximum voltage is 5 V). (# 5), a tuning frequency is selected from the result (# 6: second stage), and the number of times set in this second stage is stored in the memory 10 (# 7: storage means).

In the above, if the current tuning is the same frequency as the previous one (YES in # 3), a tuning frequency is selected as the third selecting means from the previously set number of times stored in the memory 10 (# 4). ). Thus, when the selected frequency is the same as the previous frequency, the number of fine adjustment tuning operations in the second and subsequent tuning operations can be reduced.

As described above, in the channel selection device of the present embodiment, a predetermined center frequency of a channel to be tuned, and a frequency higher and lower by an arbitrary frequency than that are set. The presence or absence of the horizontal synchronization signal and the vertical synchronization signal in the above is checked, and the optimum frequency is selected based on the result (first stage). Based on this optimum frequency, the frequency is slightly increased until the AFT signal voltage approaches a desired value. The tuning operation is performed by fine-tuning the lower and upper ones, and the tuning frequency is selected from the result (second stage). The number of times set is stored in the memory 10 and the frequency is selected during the second and subsequent tuning operations. If the frequency selected in the first step is the same as the previous one, the tuning frequency is selected from the stored number of previous settings. The number of trainings can be reduced, and tuning points can be found quickly. Furthermore, when the frequency is stored as a result of the second step, the amount of data increases, but since the set number of tunings is stored, the amount of data to be stored can be reduced. In addition, since the number of times of tuning in the second stage can be reduced, the number of times of communication with the memory 10 can be reduced, and the channel selection can be stabilized.

[0018]

[Effect of the invention]

 As described above, according to the present invention, the number of fine adjustments set in the previous tuning is stored, and when the second and subsequent tunings have the same frequency as the previous tuning, the previous tuning stored in the memory is stored. Since the tuning frequency is selected from the set number of tunings, the number of tunings can be reduced, tuning points can be found quickly, tuning speed can be increased, and the set number of tunings can be saved instead of the frequency. , The amount of data is reduced. Furthermore, the number of times of communication with the memory can be reduced, which leads to stable tuning.

[Brief description of the drawings]

FIG. 1 is a block diagram of a television receiver to which a channel selection device according to an embodiment of the present invention is applied.

FIG. 2 is a view showing a flowchart of a channel selection operation of the apparatus.

FIG. 3 is a diagram showing the subroutine.

FIG. 4 is a view showing a scan area for selecting an optimal frequency in a first stage in the channel selection operation.

FIG. 5 is a diagram showing a fine adjustment tuning procedure in a second stage in the channel selection operation.

[Explanation of symbols]

 2 Tuner 3 Intermediate frequency processing unit 8 Microcomputer (tuning control unit) 9 Operation unit 10 Memory

Claims (3)

[Utility model registration claims] 1. A tuner for selecting and amplifying a desired channel from a television wave and converting it to an intermediate frequency signal, and amplifying and detecting the intermediate frequency signal from the tuner to obtain an intermediate frequency signal from a specified frequency. An intermediate frequency processing unit that outputs the shift as an automatic frequency tuning signal (hereinafter, an AFT signal) and outputs a synchronization signal from a video detection signal, an operation unit that provides a channel selection command, a channel selection command from the operation unit, Using the AFT signal and the synchronization signal from the intermediate frequency processing unit and the data for tuning stored in the memory, supply tuning data for selecting a reception signal of a desired channel to the tuner. A channel selection device for a television receiver, the channel selection device comprising: a predetermined center frequency of a channel to be selected; -Set a frequency higher by an arbitrary frequency than the frequency and a frequency lower by an arbitrary frequency than the center frequency, check the presence or absence of a horizontal synchronization signal and a vertical synchronization signal at each frequency, and select an optimum frequency from the result. A first selecting means for performing a tuning operation by fine-tuning the frequency to a slightly higher or lower frequency until the AFT signal voltage approaches a desired value, and selecting a tuning frequency from the result.
Selecting means, storing means for storing the set number of times in the second selecting means in a memory, and when the frequency selected by the first selecting means at the time of the second or subsequent tuning operation is the same as the previous time, A third selecting means for selecting a tuning frequency from a previously set number stored by the storing means, wherein the number of fine adjustment tuning operations is reduced in the above case; . 2. A tuner for selecting and amplifying a desired channel from television waves and converting the same to an intermediate frequency signal, amplifying and detecting the intermediate frequency signal from the tuner, and detecting the intermediate frequency signal from a specified frequency. An intermediate frequency processing unit that outputs the shift as an automatic frequency fine adjustment signal (hereinafter, an AFT signal) and outputs a synchronization signal from a video detection signal, an operation unit that gives a channel selection command, and a channel selection command from this operation unit Using the AFT signal and the synchronization signal from the intermediate frequency processing unit and the data for channel selection stored in the memory, the channel selection data for selecting the reception signal of the desired channel to the tuner. And a tuning control unit for supplying a tuning signal. The tuning control unit, for a channel to be tuned, at the appropriate frequency. First selecting means for selecting a center frequency from a signal detection result; and second selecting means for performing a tuning operation by fine-tuning and setting the frequency until the AFT signal voltage approaches a desired value, and selecting a tuning frequency from the result. And a storage unit for storing the channel selection result in the second selection unit in a memory. If the selected channel is the same as the previous channel during the second or subsequent channel selection operation, the channel is stored by the storage unit. A tuning device for a television receiver, wherein the tuning frequency is selected from the previous tuning result. 3. The second selecting means performs a tuning operation by fine-tuning and setting the frequency until the AFT signal voltage approaches a desired value, and selects a tuning frequency from the result. 3. The apparatus according to claim 2, wherein the number of times set by the selection means is stored in a memory.