JP3551249B2 - TV tuners and video equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a television tuner used for a television receiver, a video tape recorder, and the like, and to a video device such as a television receiver and a video tape recorder.
[0002]
[Prior art]
The frequencies of the television radio waves are assigned to each country or region by CCIR (International Radio Committee) in order to prevent interference. For example, the Japanese channel receiving frequency list in FIG. 7 and the American channel receiving frequency list in FIG. As shown in the table, the frequency for each channel number varies greatly from country to country.
Manufacturers of video equipment such as television receivers, video tape recorders, and the like arbitrarily set each of the shipping destinations based on a list of channel receiving frequencies of shipping destinations as shown in FIGS. A channel plan as shown in FIG. 6 is created and stored in a ROM (Read Only Memory) of a microcomputer built in a video device to be manufactured.
[0003]
With this channel plan, the user can easily perform channel setting operations in the channel preset mode of the video device.
For example, if the channel number to be received is set to 02 in the channel preset mode, the station of 48.25 MHz is selected from the channel plan (FIG. 6) stored in the ROM of the microcomputer, and the broadcast station is selected. If the frequency is known, it is possible to receive by selecting a channel number.
[0004]
In the above-described channel plan, the channel number is [02] = 48.25 MHz. However, in the video equipment, even if the received frequency deviates from 48.25 MHz due to some influence, the tuning operation of the fine adjustment is performed. It is possible to receive.
In video equipment, if the broadcast frequency is shifted, or if a newly opened broadcasting station is broadcasting at a frequency shifted from the above-mentioned channel plan, each channel can be received. The maximum deviation amount of the number from the center frequency is set, and reception is possible within the set range. This range is called a “coverage range” and is generally assigned to the plus / minus side with respect to the center frequency of each channel number.
[0005]
For example, when the shipping destination is Europe, the coverage range is set to ± 4.6 MHz with respect to the center frequency (48.25 MHz for channel number [02]). Therefore, with channel number [02], reception is possible in the range of 43.65 MHz to 52.85 MHz.
[0006]
For example, when a broadcast frequency of 49.00 MHz is received with channel number [02], there is a difference of 750 kHz between 49.00 MHz and 48.25 MHz of channel number [02] stored in the ROM of the microcomputer. Each time channel number [02] is selected, a channel selection time corresponding to the difference of 750 kHz is required, and noise is generated on the screen of the video device until the channel selection is completed.
In order to avoid such a problem, the frequency 49.00 MHz selected and received once is stored, and thereafter, when the same channel number is selected, 49.00 MHz is used instead of 48.25 MHz. What is necessary is just to perform a tuning reception operation.
[0007]
By the way, many recent video devices use a PLL (Phase Locked Loop) synthesizer for the television tuner. In the TV tuner, a PLL synthesizer is incorporated in a local oscillation circuit as shown in FIG. 2. In this local oscillation circuit, a reference oscillator 20 such as a crystal oscillator for outputting a reference clock and a reference oscillator 20 are output. For example, the phase of the fixed frequency divider 21 that divides the clock by 1024 and outputs a reference frequency signal having the reference frequency fr is compared with the phase of the reference frequency signal and the output signal of the variable frequency divider 26 described later. A phase comparison circuit 22 that outputs a corresponding signal.
[0008]
The local oscillation circuit further includes a low-pass filter 23 for smoothing a signal corresponding to the phase difference, a VCO 24 (Voltage Controlled Oscillator) for outputting a frequency signal having a frequency fosc corresponding to the signal voltage output from the low-pass filter 23, and a VCO 24. A frequency divider 26 for dividing the frequency signal output by the frequency divider 8 by 8, a variable frequency divider 26 for further dividing the output signal of the frequency divider 25 by N (N is a natural number), and a microcomputer of video equipment And a shift register 27 that stores the frequency control signal (binary number of N) received by the bus interface 28 and provides the variable frequency divider 26 with the frequency control signal and the band identification signal. .
[0009]
In the above-described local oscillation circuit, when the phase of the frequency signal of the frequency fosc output from the VCO 24 is locked, the reference frequency fr and the frequency division ratio of the frequency dividers 25 and 26 inserted in the PLL and the frequency division ratio 8 × N are obtained. Therefore, fosc = fr × 8 × N, and outputs a local oscillation signal of frequency fosc. The television tuner mixes the local oscillation signal and the tuned and amplified television wave, and outputs an intermediate frequency signal having a frequency corresponding to the difference therebetween.
Therefore, this television tuner can change the reception frequency in fr × 8 frequency units, and the reception frequency corresponding to each channel number is also converted into a numerical value related to N and stored.
[0010]
For example, if the oscillation frequency of the reference oscillator 20 is 4.433 MHz, the frequency division ratio of the fixed frequency divider 21 is fr = 4.433 MHz / 1024, and the frequency unit is fr × 8 = 4.433 MHz × 8. /1024=34.6376 kHz.
[0011]
Therefore, in the case of the broadcast frequency (reception frequency) of 49.00 MHz of the above-mentioned channel number [02], a multiple of 34.6376 kHz is 49.00 MHz / 34.6376 kHz = 1414.5. The unit (step) may be stored, and an 11-bit capacity is required to store the unit.
[0012]
Since the frequency of the current television radio wave does not exceed the 1000MHz, 1000MHz / 34.6376kHz = 28868.3 ··· ≒ 28868 ( Step) <32768 ^{= 2 15} next, if there is storage capacity 15 bits per channel number Therefore, it is possible to store the data in the memory of the microcomputer in a format of 15 bits per channel number (selection data) as shown in FIG. Of course, the above-described channel plan is also stored in the ROM of the microcomputer in a format of 15 bits per channel number.
[0013]
FIG. 9 is a flowchart showing the above-described conventional channel setting operation of a video device incorporating such a microcomputer. When the channel number is set in the channel preset mode (S40), the microcomputer reads the channel reference step number corresponding to the set channel number from the channel plan stored in the ROM (S42).
Next, the microcomputer executes a tuning operation centering on the read channel reference step number automatically or manually by the user (S44). When the tuning is completed (S46), the microcomputer calculates the number of channel steps at that time. Reading is performed (S48).
[0014]
The microcomputer identifies UHF, VHFH, and VHFL bands (frequency bands) from the read channel step numbers, and creates band data for band switching (S50).
Next, the microcomputer stores the set channel number, the read channel step number, and the created band data in the memory (S52).
The microcomputer executes the above operation every time a channel number is set (S40), and the channel preset mode is canceled. When the channel setting is completed (S54), the microcomputer returns.
[0015]
[Problems to be solved by the invention]
As described above, in the conventional video equipment and television tuner, the reception frequency corresponding to the channel number is stored as 15-bit data. However, recently, the number of channels has increased, and the memory required for that has been increased. There is a problem that the capacity has increased to a level that cannot be ignored.
[0016]
As a technique relating to the above-described PLL synthesizer, Japanese Patent Laid-Open No. 61-269411 discloses a "PLL control method" in which, in a wireless communication device, the oscillation frequency of a PLL oscillation circuit controlled by a CPU can be arbitrarily set according to the purpose of use. No. 5,009,045.
[0017]
The present invention has been made in view of the above circumstances, and it is an object of the first and second inventions to provide a television tuner capable of reducing a memory capacity for channel setting.
A third aspect of the present invention aims to provide a video device provided with the television tuner according to the first or second aspect.
[0018]
[Means for Solving the Problems]
A television tuner according to a first invention tunes to a television wave for each channel number by changing a tuning frequency around a frequency for each channel number of a channel plan, and receives the tuned television wave. A first storage means for converting the frequency for each channel number of the channel plan into a channel reference step number in frequency units obtained by dividing a reference oscillation frequency by a predetermined frequency division ratio, and storing the first storage means; When operated, the tuning frequency is changed in units of the frequency by changing the number of channel steps around the channel reference step number of the channel number stored in the first storage means, so that the TV radio wave is transmitted. From the number of channel steps tuned and tuned to the television signal, Means for subtracting the number of channels reference steps of the channel number 1 of the storage means for storing a second storage means for storing together with the channel number the subtraction result of said means, when the channel number is selected operation Means for adding, to the channel reference step number of the channel number stored in the first storage means, a subtraction result stored together with the channel number in the second storage means , based on the addition result of the means. It is characterized by being tuned to a television wave and receiving the tuned television wave.
[0019]
In this television tuner, the first storage means converts the frequency for each channel number of the channel plan into a channel reference step number in frequency units obtained by dividing the reference oscillation frequency by a predetermined frequency division ratio, and stores and converts the frequency. Means for changing the number of channel steps around the channel reference step number of the channel number stored in the first storage means when the channel number is selected and operated by the tuning unit in the frequency unit. Is changed to tune to the television radio wave, and the channel reference step number of the channel number stored in the first storage means is subtracted from the number of channel steps tuned to the television radio wave, and the second storage means The result of the subtraction is stored together with the channel number. The adding means includes, when a channel number is selected and operated, a subtraction result stored in the second storage means together with the channel number in the channel reference step number of the channel number stored in the first storage means. The addition is performed, the television signal is tuned to the television signal based on the addition result, and the tuned television signal is received. As a result, it is not necessary to store the frequency of each channel number in the channel plan and the reception frequency of the channel number tuned to the television wave, and a TV tuner that can reduce the memory capacity for channel setting is realized. Can be done.
[0020]
The television tuner according to the second invention further includes means for identifying a frequency band of the television wave based on the result of the addition and creating band data for band switching, and further comprising a band based on the band data created by the means. Is switched to tune to the television wave, and the tuned television wave is received.
[0021]
In this television tuner, the frequency band of the television wave is identified based on the addition result of the adding means, band data for band switching is created, and the band is switched based on the created band data to tune to the television wave. Since a tuned television wave is received, there is no need to store band data for switching the frequency band for each channel number, and a TV tuner that can reduce the memory capacity for channel setting can be realized. I can do it.
[0022]
According to a third aspect of the present invention, there is provided a video apparatus including the television tuner according to the first or second aspect.
[0023]
In this video device, since the television tuner described in claim 1 or 2 is provided, the memory capacity for channel setting can be reduced.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described with reference to the drawings showing the embodiments.
FIG. 1 is a block diagram showing a main configuration of an embodiment of a television tuner and a video device according to the present invention. This video equipment is a television receiver (so-called televideo) incorporating a video tape recorder (VTR). A television wave received by an antenna 8 is selectively amplified by a tuner 7 and converted into an intermediate frequency signal. And supplied to the TV processing circuit 6.
[0025]
The tuner 7 tunes to the television wave, amplifies and outputs the tuned television wave, and a local oscillator that outputs a local oscillation signal higher than the tuning frequency of the high frequency amplifier 11 by the frequency of the intermediate frequency signal. An oscillation circuit 12 and a mixing circuit 13 that mixes a television wave output from the high-frequency amplification circuit 11 and a local oscillation signal output from the local oscillation circuit 12 and outputs an intermediate frequency signal having a frequency of the difference between them. I have.
[0026]
The TV processing circuit 6 amplifies the intermediate frequency signal and separates the signal into a television signal and an audio intermediate frequency signal. After the audio intermediate frequency signal is amplified, the audio signal is detected and amplified, and output from a speaker (not shown).
After amplifying the television signal, the TV processing circuit 6 separates the television signal into a carrier chrominance signal C and a luminance signal Y, and reproduces the color difference signals RY, GY, BY. The reproduced color difference signals R-Y, G-Y, and B-Y are added to the amplified luminance signal Y, respectively, and become color signals R, G, and B, and input to the CRT 2 (CRT). In the CRT 2, the color signals R, G, B are electron beams corresponding to the respective intensities.
[0027]
The TV processing circuit 6 separates the vertical synchronization signal V and the horizontal synchronization signal H from the luminance signal Y, and supplies the vertical synchronization signal V to the vertical drive circuit 5 and the horizontal synchronization signal H to the horizontal drive circuit 4, respectively.
The vertical drive circuit 5 generates a sawtooth voltage synchronized with the applied vertical synchronization signal V, and drives the vertical deflection coil of the CRT 2 accordingly.
[0028]
The horizontal drive circuit 4 outputs a horizontal drive signal synchronized with the supplied horizontal synchronization signal H, drives the horizontal deflection coil of the CRT 2, and provides the same to the high voltage circuit 3.
The high voltage circuit 3 boosts and rectifies the B power supply voltage by a switching operation based on the applied horizontal drive signal H and a built-in flyback transformer, and outputs the voltage as a high voltage. The output high voltage is applied to the anode of CRT2.
[0029]
On the other hand, the TV processing circuit 6 supplies the amplified television signal to a VTR processing circuit 15 of a built-in video tape recorder (VTR) in preparation for recording.
When recording, the VTR processing circuit 15 separates a given television signal into a carrier chrominance signal C and a luminance signal Y, FM-modulates the luminance signal Y, and frequency-converts the carrier chrominance signal C. The mixture is given to the built-in VTR cylinder head 17 (head cylinder).
[0030]
When reproducing, the VTR processing circuit 15 separates the reproduced signal read by the cylinder head 17 into a carrier chrominance signal C and a luminance signal Y, FM-demodulates the luminance signal Y, and frequency-converts the carrier chrominance signal C. The two are mixed and supplied to the TV processing circuit 6 as a television signal.
The high-frequency amplifier circuit 11, the local oscillation circuit 12, the TV processing circuit 6, the VTR processing circuit 15, and the cylinder head 17 are connected to the microcomputer 10 by a bus 19, and the operation of the microcomputer 10 is controlled.
[0031]
The microcomputer 10 includes a reference channel memory 10a, which is a ROM storing a channel number of a channel plan serving as a reference for channel selection and a numerical value related to the reception frequency, and a reception frequency tuned to a television wave by a channel setting operation. And a channel memory 10b for storing numerical values associated with the channel numbers in correspondence with the channel numbers.
The microcomputer 10 is connected with an operation unit 9 for a user to operate the television receiver.
[0032]
FIG. 2 is a block diagram illustrating a main configuration of the local oscillation circuit 12.
The local oscillation circuit 12 includes a reference oscillator 20 such as a crystal oscillator that outputs a reference clock, and a fixed output that divides the clock output from the reference oscillator 20 by, for example, 1024 and outputs a reference frequency signal having a reference frequency fr. A frequency divider 21 is provided with a phase comparison circuit 22 that compares the phases of a reference frequency signal and an output signal of a variable frequency divider 26 described later and outputs a signal corresponding to the phase difference.
[0033]
The local oscillation circuit 12 further includes a low-pass filter 23 that smoothes a signal corresponding to the phase difference, a VCO 24 (Voltage Controlled Oscillator) that outputs a frequency signal having a frequency fosc corresponding to the signal voltage output from the low-pass filter 23, and a VCO 24. A frequency divider 26 for dividing the frequency signal output by the frequency divider 8 by 8, a variable frequency divider 26 for further dividing the output signal of the frequency divider 25 by N (N is a natural number), and a microcomputer of video equipment And a shift register 27 that stores the frequency control signal (binary number of N) received by the bus interface 28 and provides the variable frequency divider 26 with the frequency control signal and the band identification signal. .
[0034]
In the local oscillation circuit 12, when the phase of the frequency signal of the frequency fosc output by the VCO 24 is locked, fosc = fosc = from the reference frequency fr and the frequency division ratio 8 × N of the frequency dividers 25 and 26 inserted in the PLL. fr × 8 × N, and outputs a local oscillation signal of frequency fosc.
The high-frequency amplifier circuit 11 uses an electronic tuning circuit that changes the tuning frequency by an electric signal using a variable capacitance diode.
Therefore, the tuner 7 can change the receiving frequency in fr × 8 frequency units, and also converts the receiving frequency corresponding to each channel number into a numerical value related to the N and stores it in the channel memory 10b.
[0035]
For example, if the oscillation frequency of the reference oscillator 20 is 4.433 MHz, the frequency division ratio of the fixed frequency divider 21 is fr = 4.433 MHz / 1024, and the frequency unit is fr × 8 = 4.433 MHz × 8. /1024=34.6376 kHz, and the reception frequency stored in the reference channel memory 10a and the channel memory 10b is converted into a numerical value (step number) related to a multiple or a multiple of 34.6376 kHz.
[0036]
Hereinafter, the operation of the video device having such a configuration will be described with reference to the flowcharts of FIGS.
When the channel number is set in the channel preset mode (S2 in FIG. 3), the microcomputer 10 reads the channel reference step number corresponding to the set channel number from the channel plan stored in the reference channel memory 10a (S4). ).
Next, the microcomputer 10 performs a tuning operation centering on the read channel reference step number automatically or manually by the user (S6), and when tuning is completed (S8), the number of channel steps at that time is performed. Is read (S10).
[0037]
The microcomputer 10 subtracts the read (S4) channel reference step number from the read (S10) channel step number, and obtains a storage step number to be stored in the channel memory 10b (S12).
The microcomputer 10 causes the channel memory 10b to store the set (S2) channel number, the obtained (S12) absolute value of the number of storage steps and the obtained (S12) sign of the number of storage steps (S14).
The microcomputer 10 executes the above operation every time the channel number is set (S2), the channel preset mode is released, and when the channel setting is completed (S16), the process returns.
[0038]
In the above channel setting operation, for example, if the coverage range for the center frequency for each channel number is within ± 4.5 MHz, 4.5 MHz / 34.6376 kHz = 129,9. The storage capacity required for one channel number of the memory 10b is 9 bits including the 1-bit sign, and the storage format of the channel memory 10b is as shown in FIG.
[0039]
If the cover range is within ± 4.4 MHz, then 4.4 MHz / 34.6376 kHz２７127 (steps), and the storage capacity required for each channel number of the channel memory 10b includes 1-bit sign. Becomes 8 bits.
Therefore, the storage capacity is only about half the storage capacity per channel number of 15 bits conventionally required, and the reception frequency for each channel number can be stored with a small capacity without reducing the reception accuracy. I can do it.
[0040]
When the channel number is selected by the user (S20 in FIG. 5), the microcomputer 10 reads the channel reference step number corresponding to the set channel number from the channel plan stored in the reference channel memory 10a (S22).
Next, the microcomputer 10 reads the absolute value of the storage step number and the sign of the storage step number corresponding to the set (S20) channel number (S24) stored in the channel memory 10b (S14 in FIG. 3) (S24).
[0041]
Next, the microcomputer 10 calculates the number of channel steps by adding the read (S24) storage step number to the read (S22) channel reference step number (S26).
Next, the microcomputer 10 identifies UHF, VHFH, and VHFL bands (frequency bands) from the determined (S26) number of channel steps, and creates band data for band switching (S28).
[0042]
Next, the microcomputer 10 adds the number of steps corresponding to the frequency of the intermediate frequency signal to the determined (S26) channel step number, and generates a local oscillation signal corresponding to the frequency of the local oscillation signal to be oscillated by the local oscillation circuit 12. The number of steps is determined (S30).
Next, the microcomputer 10 gives the obtained (S26) channel step number and the created (S28) band data to the high-frequency amplifier circuit 11 via the bus 19, and determines the (S30) local oscillation step number and created (S30). S28) The band data is provided to the local oscillation circuit 12 via the bus 19 (S32), and the process returns.
[0043]
In the above channel selection operation, band data is created from the determined (S26) number of channel steps (S28), so that the storage capacity of band data, which conventionally required 4 bits for each channel number, becomes unnecessary. The reception frequency for each channel number can be stored in a smaller capacity.
[0044]
【The invention's effect】
According to the television tuner according to the first invention, it is possible to realize a television tuner capable of reducing a memory capacity for channel setting.
[0045]
According to the television tuner according to the second invention, it is not necessary to store data for switching the frequency band for each channel number, and it is possible to realize a television tuner capable of reducing the memory capacity for channel setting. .
[0046]
According to the video device of the third aspect, the memory capacity for channel setting can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a main configuration of a television tuner and a video device according to an embodiment of the present invention.
FIG. 2 is a block diagram illustrating a main configuration of a local oscillation circuit.
FIG. 3 is a flowchart illustrating an operation of the video device according to the present invention.
FIG. 4 is an explanatory diagram showing a storage format of a channel memory.
FIG. 5 is a flowchart showing an operation of the video device according to the present invention.
FIG. 6 is an explanatory diagram showing an example of a channel plan.
FIG. 7 is an explanatory diagram showing a list of reception frequencies for Japan channels.
FIG. 8 is an explanatory diagram showing a list of U.S. channel reception frequencies.
FIG. 9 is a flowchart showing the operation of a conventional video device.
FIG. 10 is an explanatory diagram showing a conventional format for storing the number of steps corresponding to a reception frequency for each channel number.
[Explanation of symbols]
Reference Signs List 7 Tuner 8 Antenna 10 Microcomputer 10a Reference channel memory 10b Channel memory 11 High-frequency amplifier circuit 12 Local oscillation circuit 13 Mixing circuit 19 Bus 22 Phase comparison circuit 24 VCO
26 Variable frequency divider 27 Shift register

Claims (3)

By changing the tuning frequency around the frequency of each channel number of the channel plan, a TV tuner that tunes to the television wave of each channel number and receives the tuned television wave,
A first storage unit for converting a frequency for each channel number of the channel plan into a channel reference step number in frequency units obtained by dividing a reference oscillation frequency by a predetermined frequency division ratio, and storing the channel number; The tuning frequency is changed in units of the frequency by changing the number of channel steps around the channel reference step number of the channel number stored in the first storage means to tune to a television wave. Means for subtracting the number of channel reference steps of the channel number stored in the first storage means from the number of channel steps tuned to the television wave, and a second means for storing the result of the subtraction together with the channel number . when a storage unit, the channel number is selection operation, said first memory means stores Channel reference step number of the channel number, the television said second storage means and means for adding the subtraction result to be stored together with the channel number, tuned to a television radio wave based on the addition result of the unit, tuned A TV tuner characterized by receiving radio waves. The addition result identifying the frequency band of the television radio wave based on the further comprising means for creating a band data for the band switched tunes to television radio wave is switched to the band based on the band data to which the means is created A TV tuner designed to receive tuned television signals. A video device comprising the television tuner according to claim 1.

Images