JP2940743B2 - Tuning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency synthesizer type tuning apparatus.

[0002]

2. Description of the Related Art VCRs (Video Cassette Recorders) and T
In a frequency synthesizer type tuning device and a voltage synthesizer type tuning device used for a V receiver, a station (must be able to receive a broadcasting station) and a stationless station in order to improve the tuning speed during up / down tuning. The information of (cannot receive a broadcast station) is written as a locality determination bit in advance in correspondence with each channel of the memory. In this way, at the time of channel selection up / down, a channel whose local bit is OFF (no station) is skipped, and only a channel whose local bit is ON (station) can be selected.

[0003] The writing of the local bit as the data for discriminating the presence or absence of the local station is performed by an all-channel auto search performed at the time of presetting. It was done.

That is, when the auto search button is pressed,
The automatic search starts (S1), but N = 1 is set as the channel number (S2). Then, channel selection data of one channel is output, which is set in the programmable frequency divider (S3). When the tuning data is output, a WAIT process of about 150 msec is performed (S4). 150ms waiting by this WAIT processing
ec is the time required for the tuner circuit to stabilize after setting the channel selection data. If it is determined that 150 msec has elapsed (S5), then a determination is made as to whether a station is present or not (S6). The determination in step 6 includes a signal indicating whether or not the horizontal synchronization signal exists within a predetermined period, and an AFT signal.
-Determine the presence or absence of a broadcasting station based on the S-shaped curve signal.
If it is determined in step 6 that there is no station, the station bit is turned off.
Is written in a memory (EEPROM (electrically rewritable non-volatile memory)) (S8), and if it is determined in step 6 that there is a station, an AFT operation is performed (S7).
Even if the broadcast frequency is deviated from the regular value by the AFT operation, a fine tuning operation is performed so as to tune to the deviated frequency. Then, in step 8, the local bit is turned on and written into the memory together with the deviation amount (fine adjustment amount) from the normal value obtained by the fine tuning operation.

Next, in step 9, N = N + 1, and in step 10, it is determined whether or not the search for all channels has been completed. If not completed, steps 3 to 9 are repeated, and it is determined that the search has been completed. Then, the all channel search operation ends (S11).

[0006]

SUMMARY OF THE INVENTION EEPRO
In M, when writing continuously, after writing to each address,
A write prohibition period of about 20 msec occurs. In the above embodiment, an interval of 20 msec is required between the writing of the local bit and the writing of the fine adjustment amount.

The accumulation of the write prohibition period undesirably increases the time required for the search operation.

Accordingly, the present invention seeks to overcome such disadvantages.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a tuning apparatus in which an auto-preset is performed by automatically searching all channels. After setting tuning data to the tuner, the tuner operates. In a configuration in which a channel determination bit is set in advance during a predetermined period until the channel becomes stable, so as to indicate that the channel is in a non-station state.

In the frequency synthesizer tuning device, after the tuning data is set in the programmable frequency divider, the selected channel is set in advance for a predetermined period until the PLL circuit including the programmable frequency divider becomes stable. The configuration is characterized in that a locality determination bit is set so as to indicate that the mobile station is non-stationary.

[0011]

According to the above arrangement, the WAIT period until the tuner is stabilized is used as the time for writing the stationless information.

[0012]

FIG. 1 is a block diagram of a portion related to a channel selection circuit of a VCR. Reference numeral 1 denotes an electronic tuning type tuner, which internally includes a local oscillation circuit 2 including a voltage controlled oscillator.

Reference numeral 3 denotes a PLL together with the local oscillation circuit 2.
(Phase Locked Loop) is a PLL-IC constituting a circuit. The PLL-IC 3 includes a prescaler 4, a programmable counter 5 as a programmable frequency divider (N is a variable value with N frequency divider), a phase comparator 6, a charge pump 7, a reference oscillator 8, a frequency divider 9, a band switch. It comprises a drive circuit 10.

The local oscillation frequency output from the local oscillator 2 is divided by a prescaler 4 and then applied to a programmable counter 5. The programmable counter 5 divides the output of the prescaler 4 by N and applies the output as one input of the phase comparator 6.

Here, the value of N is determined by channel data (frequency-divided data) as channel selection data from within the microprocessing unit 11.

The output of the reference oscillator 8 is frequency-divided by a frequency divider 9, and the output is applied as the other input of the phase comparator 6. The output of the phase comparator 6 is applied to a charge pump 7. The charge pump 7 has a function of applying a control voltage corresponding to the output of the phase comparator 6 to the local oscillator 2, and thereby the channel is selected.

The band data as channel selection data is output from the microprocessing unit 11 and added to the band switch driving circuit 10. The band switch driving circuit 10 receives the data and drives the band switch 12 to receive the band data. Is set to one of VHF low band (VL), VHF high band (VH), and UHF band (U).

Reference numeral 13 denotes an up / down key, and reference numeral 14 denotes a remote control transmitter.
It has ten keys 15 <0> to <9> and a <100th> key.

Reference numeral 15 denotes a remote control receiving circuit, and all of these output signals are applied to the microprocessing unit 11. Reference numeral 16 denotes a display device driven by an output signal from the microprocessing unit 11, and a fluorescent display tube is used as a display element. Further, by performing on-screen display on a screen, a television receiver can be used as a display device.

The microprocessing unit 11 further receives an AFT-S curve signal (SC) generated based on an IF signal obtained from an IF (intermediate frequency) circuit and a horizontal synchronizing signal from a synchronizing separation circuit per unit time. A signal (SD) obtained when a predetermined number of signals are detected is input to the microprocessing unit 11 based on these signals.
Is determined.

A ROM (Read Only Memory) is provided inside the microprocessing unit 11, and a series of programs for performing a channel selection operation are stored in the ROM.

Reference numeral 17 denotes a memory provided outside the MPU 11 (EEPROM (rewritable nonvolatile memory))
The contents as shown in FIG. 2 are set in the memory.

In FIG. 2, an actual channel is data for specifying a broadcasting station to be actually selected, and the microprocessing unit 11 calculates a predetermined frequency division ratio based on the channel number represented by the data. And set the programmable counter.

Next, an all-channel search according to the present invention will be described with reference to the flowchart of FIG.

When the auto search button is pressed, the automatic search starts (S1), but first, N = 1 is set as the channel number (S2). Then, channel selection data of one channel is output, which is set in the programmable frequency divider 5 (S3). When the channel selection data is output, a WAIT process of about 150 msec is performed (S
4). 150msec waiting by this WAIT processing
Is the time required for the PLL circuit and / or tuner circuit to stabilize after setting the channel selection data.

In this embodiment, a write operation is performed on the memory (EEPROM (electrically rewritable non-volatile memory) 17) so that the local bit is turned off during the WAIT process. (S5).

That is, while the WAIT process is being performed, the station bit is unconditionally set to OF regardless of whether the station is actually stationed or not.
It is done to F.

If it is determined that 150 msec has elapsed (S6), then it is determined whether the station is actually occupied or not (S7). The determination in step 7 includes a signal indicating whether or not the horizontal synchronization signal exists within a predetermined period, and an AFT signal.
-Determine the presence or absence of a broadcasting station based on the S-shaped curve signal.

If it is determined in step 7 that there is no station, the process proceeds to step 10 because the station bit has already been written to the memory 17 as OFF in step 5.

On the other hand, if it is determined in step 7 that the station is owned,
An AFT operation is performed (S8). Even if the broadcast frequency is deviated from the regular value by the AFT operation, a fine tuning operation is performed so as to tune to the deviated frequency. Then, in step 9, the deviation amount (fine adjustment amount) obtained by the fine tuning operation
At the same time, the local bit is set to ON and written to the memory.

Then, in step 10, N = N + 1 is set, and in step 11, it is determined whether or not the all channel search has been completed.
0 is repeated, and when it is determined that the search has been completed, the all-channel search operation is completed (S12).

As described above, according to the present invention, in general, when all channels are searched, a channel selection operation is performed on the tuner in consideration of the fact that the number of non-station channels is overwhelmingly greater than that of station channels. After that, during the time to wait for the tuner circuit to stabilize, the write operation was performed on the memory in advance with the channel set to stationless. Can save the writing processing time. For example, the number of search channels is 72 (normal channel: 62, CATV channel: 1).
0), if there are 10 local channels, there are 62 non-station channels, and 20 msec × 62 channels = 1240 m
sec.

[0033]

According to the present invention, there is an effect that the speed of the auto preset operation in the tuning device can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a channel selection device embodying the present invention.

FIG. 2 is a diagram showing a memory map for explaining a channel selection device of the present invention.

FIG. 3 is a diagram showing a flowchart for explaining the operation of the tuning apparatus of the present invention.

FIG. 4 is a diagram showing a flowchart for explaining the operation of a conventional channel selection device.

[Explanation of symbols]

 Reference Signs List 1 Tuner 2 Local oscillator 4 Prescaler 5 Programmable counter 6 Phase comparator 7 Charge pump 8 Reference oscillator 9 Divider 10 Band drive circuit 11 Microprocessing unit 12 Band switch 13 Up / down switch 16 Display 17 Memory

Claims (2)

(57) [Claims] 1. A tuning apparatus in which an auto-preset is performed by automatically searching all channels, wherein after setting tuning data to a tuner, a predetermined period until the tuner is stabilized. A channel selection device for setting a occupancy determination bit in advance to indicate that the channel is in a non-station state. 2. A frequency synthesizer tuner in which auto-preset is performed by automatically searching all channels, wherein after setting tuning data to a programmable divider, the programmable divider is set to A tuning apparatus, wherein a station determination bit is set in advance to indicate that the selected channel is untuned during a predetermined period until a PLL circuit including the circuit stabilizes.