JPS62225082A - Channel selection equipment - Google Patents

Abstract

PURPOSE:To prevent the intermission of station retrieval at other channels by giving a frequency starting station retrieval from the vicinity of each channel and presetting it to a desired channel for a short time. CONSTITUTION:A channel selection equipment l converts an input broadcast signal into an IF signal via a tuner 3 and gives it to a video IFA 4. A microcomputer MPU 8 is provided with a memory 9 storing code signal data generating a tuning voltage corresponding to each broadcast frequency detected by the station retrieval, the code signal data in the memory 9 is outputted sequentially to a tuning voltage generating circuit 5 by depressing an operation key 11 of search-up or search-down and the user selects the desired broadcast channel. In the automatic station retreival, a tuning voltage increasing (or decreasing) sequentially is applied to the tuner 3, the local oscillation frequency is changed little by little and the station retrieval of the key 11 from the operation point of time is applied.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention provides a method for starting the search from near each broadcast frequency when searching for stations by gradually changing the tuning voltage range. Regarding the channel selection device.

(Prior Art) In recent years, the majority of radio reception weapons such as television receivers have adopted an electronic FI'I tuner system in which the receiver section uses a parallax diode or the like as a variable capacitance element. It became so. According to this electronic tuning tuner, since the receiving channel is determined by the value of the tuning voltage, it is easy to convert the tuning voltage into digital data, and the connectivity of the digital circuit forming the tuning part is easily established. Become. In other words, channel selection devices using electronic tuners are broadly classified into analog type and digital type, but the rear right type is the digital type that can be easily connected. This digital type includes a voltage synthesis method and a frequency synthesis method.The voltage synthesis method (No If method is a method in which the tuning voltage is stored (preset) as a digital code signal C, and the frequency synthesis method is a method in which the tuning voltage is stored (preset) as a digital code signal C. There is a method in which J: stores the local oscillation frequency, that is, the tuning voltage, in the data specifying the division ratio of one frequency.

This type of digital channel selection device also uses a microphone []
It also has good connectivity with computers. Therefore, while searching for stations using the Micro Combi 2-E, the automatic search operation in which the channel 11 is set to the channel that is actually being broadcast is conventionally performed as follows. It will be held in

First, set the mode selector switch to preset mode,
When a key for searching up or down is pressed, the microcomputer, for example, generates a tuning voltage based on this keying signal. This tuning voltage 4
．． The oscillation frequency of the electronic tuning tuner is changed by gradually raising or lowering the oscillation frequency corresponding to ij:-ing fa';'r. When the electronic tuning tuner tunes to the frequency of a certain channel, the microcomputer determines that it is a broadcast signal and automatically stops the one-step operation. The tuning voltage at the time of stopping is stored in the memory as the digital code signal or the frequency division ratio code signal. By repeating such operations, the tuning voltage for a given voltage channel becomes constant.
By setting the mode 1, 7J conversion switch to the image receiving mode, each preset data can be read out and normal channel selection operations can be performed.

(Problems that the invention is trying to solve) In the above conventional channel selection device, for example,
When searching the low band in the channel, that is, the VL band, change the tuning voltage from the minimum voltage of the band. while detecting broadcast signals. With this method, it takes time to reach the 11th-p channel, and if there is a broadcast on a lower frequency than the 1st channel, 1. During t-1-reach (automatic station search), the broadcast signal may stop the leave, and the first channel that should be the first to be broadcasted may not be broadcast, or unnecessary broadcasting may occur. Preset data for broadcast signals is stored in the memory, resulting in undesired broadcasts being received when performing a channel selection operation.

Also, when trying to search for example the 50th channel of the U HF channel band, the 12th channel is received,
The disadvantage was that it took a very long time to search from there.

SUMMARY OF THE INVENTION Therefore, the present invention aims to eliminate the above-mentioned drawbacks and to provide a channel selection device that can prevent a search from stopping in a different channel other than a predetermined broadcast channel and can shorten the search time. .

[Structure of the Invention] (Means for Solving the Problems) The channel selection device of the present invention has a channel selection mode in which J: retuning is performed on Brisera 1-data, and a Brisera 1-data for each broadcast frequency ( oscillation frequency variable means for changing the oscillation frequency of the local oscillation circuit according to the applied voltage; and a tuning voltage generator for applying a gradually changing tuning voltage to the oscillation frequency variable means. means for detecting the presence or absence of a horizontal synchronizing signal when the tuning voltage is applied; and if the horizontal synchronizing signal is detected, station searching is stopped and the tuning voltage or frequency is switched to the specified tuning voltage or frequency; Means for storing data and means for predetermining a starting voltage for applying said tuning voltage are provided.

(Function) When set to the search mode by the mode switching means, the starting voltage for searching is gradually changed from the vicinity of the value corresponding to the actual broadcast frequency, and in this case, the horizontal synchronization signal at J3 When a horizontal synchronizing signal is detected, the tuning voltage data or frequency division ratio data in that case is stored in the storage means, and the tuning mode is set to the tuning mode. The channel will be selected.

(Example) Hereinafter, the present invention will be specifically explained with reference to the drawings. FIG. 1 shows a tuning voltage generation circuit according to the present invention in a block diagram, FIG. 2 shows a block diagram of the configuration of an embodiment of the tuning device of the present invention, and FIG. A calibration curve for tuning voltage is shown.

As shown in FIG. 2, the channel selection device 1 of one embodiment has an antenna 2.
The broadcast signal input from the tuner 3 is mixed with a local oscillation signal and converted to an intermediate frequency, and the video intermediate frequency amplification circuit 1
input. In this case, the tuning voltage for setting the broadcast signal to a predetermined intermediate frequency is determined by converting the output pulse of the tuning voltage generation circuit 5 using pulse width modulation (PWM) 1 type into the voltage 1 (width) by the amplifier circuit 6. Thereafter, it is converted into direct current through a low-pass filter 7 and generated.

PWM data for generating output pulses of the tuning voltage generation circuit 5 is provided by a microcomputer (Ml).
U) J: is made in 8. This MPU 81.1
RO (not shown) written with predetermined program data
It also has a memory 9 which generates a tuning voltage and stores code signal data corresponding to each broadcast frequency detected by the search station. By pressing the search up or search down operation key 11, the code signal data stored in the memory 9 is sequentially output to the tuning voltage generation circuit 5, and the Korg selects the desired broadcast channel. It's a monkey.

Also, for the automatic station searching for 1-mode signal data corresponding to each of the above broadcast frequencies, set the 7-mode changeover switch 12 to the preset mode side and press the UP or SEARCH DOWN key. This is done by inputting a keying signal to the MPU 5 side.
Through this automatic station search, the tuning voltage generating circuit 5,
A tuning voltage that gradually increases (or decreases) is input to the tuner 3 via the amplifier circuit 6 and the LPF 7,
By applying this tuning voltage to the varactor diode forming the local oscillation circuit in the dicorner 3,
This allows the local oscillation frequency to be changed little by little.

Since this local oscillation frequency is changed little by little, a signal having a frequency that differs from this frequency by the intermediate frequency is amplified by the video intermediate frequency amplification circuit 4. Furthermore, after the video is detected by the video detection circuit 13 and amplified by the video amplification circuit 14, it is displayed on the cathode ray tube 15, and the signal that has passed through the video detection circuit 13 is input to the horizontal synchronization signal detection circuit 16. The presence or absence of a horizontal synchronization signal is detected.

The output of this horizontal communication detecting circuit 16 is input to the MPU 8, and when there is a horizontal communication g, the MPU 8 determines that the broadcast signal is correct and stops the search operation. This code 45 generates the tuning voltage when the operation stops.
The number data is stored in the memory 9. By repeating this reach operation for each broadcast channel, code signal data corresponding to the tuning voltages of a predetermined number of channels is stored in the memory 9.

Therefore, when the mode changeover switch 12 is set to the reception (tuning) mode and normal tuning operation is performed, 16 code signal data corresponding to the number of channels selected are sent to the screen.
, and a corresponding buying electric current is applied to the readout data. With this tuning voltage, broadcast No. 13 of the corresponding channel will be received, but since the characteristics of the varactor diode change due to ambient temperature and aging, the output of the video intermediate frequency amplification circuit 4 Automatic fine adjustment (A
FT) A correction voltage is applied to the varactor diode through the circuit 17 to ensure that the local oscillation frequency differs by exactly 1 [1.FT] by the video intermediate frequency. ``I'm doing it.

The ΔFT circuit 17 is configured such that the correction voltage If is inputted to the MPU 8 via an A/D conversion circuit (not shown). For example, after an appropriate amount of time has elapsed after setting to image reception mode and performing a channel selection operation, MPtJ8 takes in this correction voltage digital data and outputs code signal data including this correction voltage valve to tuning voltage generation circuit 5. At the same time, the data previously stored in the memory 9 is replaced with code signal data including this correction voltage valve. This replacement is performed so that the correction signal data input from the ΔFT circuit 17 to the MPU 8 becomes 0. In this way, the broadcasting code information data in the grid 9 can be adapted to changes over time. In addition, the tuner 3 is used for the low band of the first to third Bouyanelles and the first to first
By switching between the two channels of high band and U II F band with the band selector switch 18, it is possible to receive J.
J, sea urchin.

By the way, one embodiment of the channel selection device 1 of the present invention is a system that allows you to search each broadcast channel in a short time and without interrupting the search for other undesired channels.
In order to do this, the code (, F-8 data) for each broadcast channel is preset, and 16 white moving stations are performed near each broadcast channel.For this reason, as shown in Figure 3, the tuning voltage VT The tuning voltage for an arbitrary V channel (in this example, the first channel) is determined by taking into account variations in varactor diodes, etc., with respect to the calibration curve CT of the receiving frequency (CH), which is 3.1 (V). In other words, from the voltage slightly outside B and C (for example, the outside on the lower side) to the 7
(R pressure) to serve.

FIG. 1 shows a schematic configuration of the tuning voltage generating circuit 5 for performing the size search shown in FIG. 3 for each broadcasting channel.

For example, code data corresponding to the starting voltage for setting 4 nodes for each broadcast channel, that is, the voltage indicated by the sign in FIG. Depending on the operation performed, the MPU 8 causes the latch circuit 21 to latch the data from the memory 9 as PWM data. On the other hand, in the clock generation circuit 22, its clock pulses are counted by a binary counter 23, and the counted output is inputted to a digital comparator 24, where the output data of the latch circuit 21 is compared. If the comparison by the comparator 24 results in a match, the flip-flop 25 is hit;
On the other hand, if the binary counter 23 overflows, the flip-flop 25 is reset by its output. By repeating this operation 1, the flip-flop 2
5 outputs a PWM pulse. This PWM pulse voltage is amplified by an amplifier circuit 6, and then passed through a low-pass filter (or integrating circuit) 7 to generate a tuning voltage shown in D in FIG. This tuning voltage is applied to a varactor diode in the tuner 3, and the reception frequency corresponding to this tuning voltage (for example, the first y-th
~17 channels) signals are received.

If the actual -V1/replication curve for the varactor diode used in this buyuna 3 is as shown by the solid line in FIG.
Since no horizontal synchronizing signal is detected, the MPU 8 slightly changes the data sent to the latch circuit 21 to slightly increase the tuning voltage. By repeating this operation, the tuning voltage is changed little by little to increase the tuning voltage. A) An interrupt is generated to MPU8 and the MP
U8 interrupts a program that changes PWM data little by little, and executes a routine to store the data in memory 9 as code signal data.

Therefore, when presetting the next broadcasting channel (for example, the 2nd channel 11 or the 3rd channel if there is no broadcasting on this channel) in the same way, the reference numeral D' in FIG. This will start with the tuning voltage. Note that △=, B′.

C' represents the same meaning as without the ''.

In this way, the preset is completed by setting the presettable number of broadcast channels, and when the reception mode is set, MPUEH is selected. In response to the channel operation, corresponding data is read from the memory 9, and the read data is latched into the latch circuit 21. According to this latched data, a tuning voltage corresponding to the Tlfn channel (gA, A-, etc. in FIG. 3) is applied to the rosette diode of the tuner 3, and the tuning voltage (marked gA, A-, etc. in FIG. 3) is applied to the rosette diode of the tuner 3. The broadcast signal of the channel will be received.

According to the tuning device 1 that operates in this way, the starting voltage for searching is set near each channel/channel, so it takes a short time to set the actual tuning voltage. It can be completed in a short amount of time, and it is also possible to prevent the station search from being interrupted midway by receiving another broadcast channel and broadcasting to that other channel, or from being interrupted midway.

In the above embodiment, the starting voltage when searching for a station is set to SJI+.
The code number data for i5' is stored in the memory 9, etc., but the range of variation in the characteristics of the varactor diodes to be used is investigated in advance to determine the curve passing through the curves shown in Figure 3, D', etc. It is also possible to program J: to output the code signal D data corresponding to D, D', etc. when inputting J:.

Furthermore, in the above embodiment, when obtaining the code signal data for each broadcast channel, the frequency is changed gradually from the lower frequency to higher, but it is also possible to change the frequency from the higher frequency to lower gradually. is obvious.

By the way, although the above embodiment is a voltage synthesizer type tuning device 1, the present invention can be similarly applied to a frequency synthesizer type.

A specific example of the tuning voltage generating circuit 31 in this case is shown in FIG.

MPtJ8- reads frequency division ratio data corresponding to the reach start voltage (Nori, D', etc. in FIG. 3) from the mesh 9', and latches it into the latch circuit 21'.

This latch circuit 21- outputs the data to a programmable frequency divider 32, passes through a prescaler 33, and then outputs the data to a tuner 3.
A frequency obtained by dividing the local oscillation frequency F[ of '(for example, FL
/K). The output pulse of the programmable frequency divider 32 is input to the frequency/phase comparison ff13/I, and the phase is compared with the clock pulse passed through the frequency divider 36 of the reference frequency generation circuit 35.

The error signals of these two clock pulses are applied through a low-pass filter 7' to a control terminal TC of a voltage controlled oscillator (Co) such as a varactor diode forming a local oscillation circuit of the tuner 3'. By forming such a feedback loop, the oscillation frequency of the local oscillator circuit, that is, the frequency F[] corresponds to the value specified by the division ratio data applied from the latch circuit 21' to the programmable frequency divider 32. Set to search frequency.

Therefore, the MPU 8' checks whether there is a horizontal synchronizing signal at the output of the horizontal synchronizing signal detection circuit 16' in the case of the frequency division ratio data (for example, whether the level of this detection circuit 16' has become H" or not. ).If it is not detected, make the surrounding ratio data by MPU8'μ a little smaller than the above digital value and make the local oscillation frequency FL a little higher.In this case, 6 horizontal open period signals are detected. Repeat this operation, and if a horizontal synchronization signal is detected, store the frequency division ratio data in memory 9.
’.

In this way, it is possible to perform brillette in a short period of time in substantially the same manner as in the above-mentioned embodiment.

[Effect of the invention 1 As described above, according to the present invention, since the frequency at which station searching is started is performed from near each tunnel,
You can switch to the desired channel in a short time,
It also prevents the search from being interrupted by another channel.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a tuning voltage generating circuit forming an embodiment of the channel selection device of the present invention, and FIG. 2 is a block diagram showing the configuration of an embodiment of the channel selection device of the present invention.
FIG. 3 is a characteristic diagram showing the relationship between tuning voltage and image receiving frequency for explaining the operation of one embodiment, and FIG.
FIG. 7 is a block diagram showing another embodiment of a tuning voltage generation circuit that forms a single-station device. 1... Tuner selection device 3... Tuner 5... Tuning voltage generation circuit 7... Low pass filter 8... Microcomputer (MPU) 9... Memory 21... Latsua circuit 22... Clock generation circuit 23...Binary counter 24...Comparator 25...Flip opening Fig. 2, l Fig. 4

Claims (1)

[Scope of Claims] An oscillation frequency variable means formed using an element that forms a local oscillation circuit and whose local oscillation frequency changes depending on an applied tuning voltage; means for switching to a search mode for performing station search to obtain data; voltage variable output means for changing the tuning voltage little by little and outputting it to the oscillation frequency variable means; and an intermediate signal received when the tuning voltage is applied. capture the frequency,
horizontal synchronization signal detection means for detecting the presence or absence of a horizontal synchronization signal; and when the horizontal synchronization signal is detected, stopping the station search;
a storage means for storing tuning data corresponding to the tuning frequency or tuning voltage in that case; and in the case of the search mode, a search station determined in advance to a frequency near each broadcast frequency to be searched; What is claimed is: 1. A channel selection device comprising: a start frequency setting means; and in a search mode, a channel search is performed from the search start frequency.