JPS611113A - Channel selecting device - Google Patents

Abstract

PURPOSE:To write a data of a required channel into a memory by taking correlation between channels having an input electric field strength at automatic search preset and applying gain control of a tuner in response to the strength of the input electric field. CONSTITUTION:A gain control section 44 is controlled by a 2-bit signal from a CPU27 and an RF.AGC to the tuner 3 is changed over into four stages. The CPU27 stores a channel selection data to a memory 28, the data is read so as to execute channel selection and the correlation between channels having the input electric field is taken at automatic search preset and the gain control of the tuner 3 is applied in response to the strength of the input electric field. Thus, a channel having a strong electric field is written in the memory 28 with priority and a channel having a weak electric field is written in the memory 28 under the control of the RF gain.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a channel selection device for a television receiver.

Conventional Structure and Problems Conventionally, there are various methods for storing the necessary channel selection information in the memory in a tuning device having a channel selection information memory. There is. This presetting method automatically sweeps the receivable channels from the smallest channel to the largest channel, and stores only the stations from which broadcast waves are being emitted in the memory. However, with this method, broadcasts with very high electric field strength and broadcasts with very weak electric field strength are stored in the memory regardless.

FIG. 1 shows a conventional channel selection system for a television receiver. (1) is a VI (F antenna), (2) is a UHF antenna, (3) is an electronic tuner with a beam actance element as a tuning element, (4) is a video intermediate frequency amplification unit, (
5) is a video detection section, (6) is a video amplification section, (7) is a video output section, (8) is a CRT, (9) is an audio intermediate frequency amplification section, (10) is an audio detection section, (11) is the audio amplification section, (1
2) is a speaker, (13) is a 1/n fixed frequency divider (where n is an integer), (14) is a crystal oscillator, and (15) is a P
The LL circuit is composed of a phase comparator, a variable frequency divider, and a reference frequency generation frequency divider.

(16) is a low-pass filter, and (17) is an S-curve generating section, which generates a signal obtained by passing the output of the tuning circuit of 58.75M) Iz through the low-pass filter, that is, an S-curve. (18
) are three DCs with different outputs from the S curve generator (17).
A voltage comparator unit compares levels A, B, and C and outputs the comparison output; (19) is a synchronization separation circuit that separates a horizontal synchronization signal and a vertical synchronization signal from the video detection output; (20) is a vertical oscillation and Vertical deflection output circuit, (21) is horizontal oscillation circuit and horizontal AFC circuit, (22) is horizontal output and flyback 1 to lance, (23) is gate to amplifier 1, (24)
is an integrating circuit, (25) is a waveform square part, (26) is a hand switching circuit that supplies band switching voltage to the tuner (3), (27) is a microcomputer that performs channel selection control,
(28) is a memory unit that stores channel selection information.

(29) is a key matrix section to which a channel selection switch, a preset switch, and an O1 search start switch are connected. (30) is a channel display section that displays the selected channel number. When the key 1-rix section (29) is operated to set the preset mode 1- and the O1-search start switch is operated, the microcomputer (27) performs the O1-search operation based on the flowchart 1- in FIG. I do.

Here, in order to sweep a channel with broadcast waves and automatically store the channel data in the memory section (28), it is necessary to detect the presence or absence of broadcast waves. Therefore, as a signal presence/absence detection means, the horizontal synchronization signal from the synchronization separation circuit (] 9) and the horizontal oscillation output from the horizontal oscillation and horizontal AFC1 circuit (21) are combined by an ant gate (23).
It is waveform-shaped by a waveform shaping section (25) via an integrating circuit (24) and inputted to a microcomputer (27). When the horizontal synchronization signal and the horizontal oscillation output are in phase, the microcomputer (27) determines that the signal is "present."

In addition, the output of the S curve generator (]7) is converted to three-value DC/\
DC level 8, which corresponds to the center of the S-curve, is compared with a DCC level above about 2 volts above the S-curve center and a DC level C about 2 volts below the S-curve center. However, it is assumed that the amplitude of the S curve is 12 volts from 0 to 1.

In other words, when the S-curve output is between A and B, the local oscillation frequency of the tuner (3) is lower than the normal reception frequency, and when the S-curve output is between A and C, the mitalocomputer (27) The PLL circuit (15) determines that the frequency is higher than the normal frequency and makes it as close to Δ as possible.
The frequency division ratio is changed to achieve the optimum reception state. This data is then stored in the memory section (28). Furthermore, the channel number being received at this time is output to the channel display section (30). Also, microcomputers (
27) outputs an output for switching the V T-I F low band, biband, and U HF band, and sequentially sends channel reception data to the PLL circuit (15), which uses the S curve information and signal presence detection signal described above. Channels to be recorded are selected and sequentially stored in the memory section (28). Next, when this storage mode is finished, the key matrix section (29) is switched to the normal reception mode.
When the channel selection switch is operated, the information stored in the memory section (28) is read out and the channel is selected as described above.

FIG. 2 shows a flowchart of automatic channel writing in conventional auto search. First, the key matrix section (
When the mote switch 29) is switched from the normal reception mode to the storage mode and the auto search start button is pressed, the auto search will start. This start is step (3)
This is the auto search start shown in 1). Next, the microcomputer (27) sets the position number P to 1117.
1 [Step (32): l. A position is a button for selecting a channel. Usually, there are 12 buttons for channel selection, and the switches are sequentially numbered, and these are called position numbers. It is assumed that this position number and the 7-trace number in the memory section (28) correspond to one increment. Next, the channel number N is set to Lt I II [step (33)]. That is, in step (33), data for receiving one channel is sent to the PLL circuit (15), and the data for receiving one channel is sent to the PLL circuit (15).
6), band switching data specifying VHF low hand is sent. Next, in the channel display section (30)
Display OI I+ [step (34)], P L
Send channel data N to the T-circuit (15) [step (35)] and wait until the loop of the PLL circuit (15) is locked [step (36)]. Next, the presence or absence of the signal is detected as described above (step (37)), and if there is no signal, the channel number data is incremented (step (3g)). At this time, if the channel number is only up to 62 channels, then check whether the number exceeds 62 channels [step (39)]
] If it is less than LL62 channel, step (34)
Return to , display the channel, and repeat the same process.

If it is determined in step (37) that there is a signal, step (40) is executed following step (37) to write channel number data N to memory address P of the memory section (28). Then, the position number is incremented (step (4+-)). After step (41), check whether the number of channels exceeds 62 in the same way as step (39) [step (42)] If the number of channels is less than 62, then proceed to step (38).
Execute (39). If it is determined in step (39) that the number of channels exceeds 62, then step (43) is executed. That is, channel number - 6
If it becomes larger than 2 channels, there is no need to perform an O1-search, so in step (43), the position number P is set to LL ], H and the data at the memory address P is sent to the PLL circuit (15). The channel display section (30) is set to N and the process ends [step (44)].

In addition, since the position number is the MAX position, ie, 12 position here, in step (42), if it is determined that the position number exceeds position -12, step (
43).

Such conventional channel selection devices have the following problems.

In other words, in areas where strong electric field broadcasts and weak electric field broadcasts coexist, there is a limited number of positions (here 12
position), it is possible to end by writing a weak electric field to most positions. For example, in the broadcast area from Sanarai 1 where VI-IF broadcasts are converted to UHF and transmitted, the strong electric field is 50 channels [hereinafter, channels are abbreviated as channels], 52 channels, 58 channels, 60 channels,
62ch, weak electric field], 3ch.

19ch, 24ch, 26ch, 28ch, 36ch,
Assuming that radio waves of 38ch and 40ch are mixed, the conventional channel selection device selects 13ch, 13ch and 40ch in the first position.
19ch in 2nd position, 24ch in 3rd position
, 26ch in the 4th position, 28c in the 5th position
h, 36ch in the 6th position, 3 in the 7th position
Data is written in the memory section (28) so that the weak electric field broadcast of 40ch can be received at the 8th position.
50ch in the 9th position, 52c in the 10th position
h, the strong electric field of 54ch is written to the 11th position and the strong electric field of 56ch is written to the 12th position, but the required strong electric field broadcasting of 58ch, 60ch, and 62ch is not written and ends. In other words, in such areas, i! By catching the broadcast radio waves of the il electric field and transmitting the weak electric field channels to most positions, 12 positions were occupied only by the weak electric field channels without catching the necessary strong electric field broadcasts. It's something to put away.

OBJECTS OF THE INVENTION An object of the present invention is to provide a channel selection device that can set a necessary station even if it is an O-I search preset.

Structure of the Invention The channel selection 1 of the present invention is configured to store channel selection data in a memory, read out the stored data, and execute channel selection. It is configured to take the correlation between the two and control the gain of the tuner according to the strength of the input electric field, so that channels with strong electric field strength can be written to memory preferentially, and the RF gain can be controlled even for channels with weak electric field strength. It is characterized by making it possible to write to memory.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 73 and 4. It should be noted that in FIG. 3, the same reference numerals are used to denote the same functions as those in FIG. 1, and the explanation thereof will be omitted.

In FIG. 3, (44) is a gain control section, and (45) is a C level detection section. Reference numeral (46) denotes an AGC voltage generation section, which is also necessary in the conventional example shown in FIG. 1, but is omitted in FIG.

Now, the gain control section (44) is controlled by a 2-bit signal from the microcomputer (27), and is configured to be able to switch the RF-AGC voltage to the tuner (3) in four stages. ing.

Here, the switching data RA of RF-AGC voltage is RA
= φ, the gain of tuner (3) is minimum and RA
=3, it is assumed to be the maximum. In addition, the output signal of the AGC level detection section (45) is converted into a 4-pin digital signal, which is processed by the microcomputer (27
).

Next, the auto search preset operation will be explained based on the flowchart shown in FIG.

When the key matrix section (29) is set to the normal channel selection mode and the memory mode changeover switch and the auto search start button is pressed, the auto search star 1-flow is activated (step (47)). First, position P
to II I II (Step (48)), and channel number N to It I II (Step (49))
. Next, RF-AGc voltage 0) switching data RA=φ
Set it to [step (50 months, i.e. tuner (
3) Set the gain to the minimum. Next, the channel display area (
Display channel display data N in step (51)), the first channel display data is 1117
It is 7. Then, it sends channel number data N to the PLL circuit (15) [step (52)] and waits for the PLL loop to lock [step (53)]. Next, it is determined whether there is a signal (step (54)), and if there is no signal, the channel number data N is incremented (step (55)). When step (55) is executed, it is then determined whether the channel number data exceeds the maximum value of existing channel numbers [up to 62ch in Japan] [step (56)) L, 62c.
If h has not been exceeded, the process returns to step (52) and the above-described operation is repeated. Also, in step (56) 62c
If it is determined that the channel number N exceeds h, the channel number N is set to "1" [step (57)], and the RF
, - Increment the AGC voltage data [step (58)). The result of step (58) is tr 37
Check whether it is 1 or not (step (59)) and set ``3''
In the following cases, the process returns to step (52) and the above-described operation is repeated.

If it is determined in step (54) that there is a signal, step (60) is executed. This step (6
0), the channel number data N and the IA data obtained by digitally converting the intermediate frequency AGC output voltage are stored in the memory address I of the memory (28). Step (
60), the position number is incremented [
Step (61)), check whether the result does not exceed the MΔX position (here 12 positions) [
Step (62)), and if it has not been exceeded, return to step (55) and perform the above-mentioned operation. Further, if the MAX position is exceeded, step (63) is executed. Step (63) 1' calculates strong magnetic field channels based on RF-AGC voltage switching data RA and IA data, rearranges them in order of strong magnetic field channels from the beginning of the position, and stores them in the memory section (28). let That is, channels whose input electric field strength is above a certain level (50 dB in this case) are first rearranged from the first position in descending order of channel number, then channels whose input electric field strength is 40 dB to 49 dB, and then channels lower than that are rearranged. After completing step (63), position P is then
II, send the channel data at memory address P=1 to the PLL circuit (15), set the channel display to N, and send the RF-AGC control data to position LL I.
Set the optimum value for the channel stored in 11 and turn the tuner (
3) to the RF-AGC input. Note that although this embodiment is explained using a 2-bit RF AGC control output for convenience, it is not limited to this number of bits.

As described in the detailed description of the invention, the tuning device of the present invention is configured to perform auto-search briefing 1 to sometimes correlate each channel of the input electric field strength and perform tuner gain control according to the strength of the human electric field strength. Therefore, it is possible to prevent writing of only weak electric field channels for all 12 positions as in the conventional case. Channel data of necessary channels with strong electric field strengths can be written into memory, eliminating the need to manually search for and write strong electric field channels one by one.

Also, depending on the radio wave condition, R+? - Since the AGC value is controlled, it is possible to select channels under optimal reception conditions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional television receiver equipped with a channel selection data storage type tuning device, FIG. FIG. 4 is a configuration diagram of an embodiment of a television receiver equipped with a channel selection device, and FIG. 4 is an auto search preset low chart diagram of FIG. 3. (1) (2)...VI-IF, UHF antenna, (3
)...Tuner, (4)...Eiwei intermediate frequency amplification section, (
5)...Video detection section, (J5)...PLL circuit.
(17)・S curve generation unit, (18)・Voltage comparison unit,
(19)...Synchronization separation circuit, (21)...Horizontal oscillation circuit and horizontal AFC circuit, (23)...Antoge-1-,
(24)... Integrating circuit, (25)... Waveform shaping section,
(26)...band switching circuit, (27)...microcomputer, (28)...memory section. (29)
...to the key matrix section (44)...gain control section, (
45)...AGC level detection section, (46)...AGC
Voltage generation section Figure 1

Claims (1)

[Claims] 1. Channel selection data is stored in memory and the stored data is read out again to execute channel selection. At the start of auto search preset, the correlation between each channel of the input electric field strength is calculated and the input electric field A tuning device configured to perform tuner gain control according to the strength of the intensity.