JPS5929970B2 - electronic tuning receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic tuning receiver that can be applied to, for example, a television receiver, and in particular is capable of detecting a channel number without using an expensive and complicated counter. The system automatically programs the broadcasting station channel based on the detection of the broadcasting station.

Hereinafter, an embodiment in which the present invention is applied to a color television receiver will be described with reference to FIG. 1. 1 is an antenna;
Reference numeral 2 indicates a tuner, and the tuner 2 includes a high frequency amplifier 3, a mixer 4, and a local oscillator 5.

In this example, the UHF band is received, and the local oscillator 5 is configured as a variable frequency oscillator using a variable capacitance diode as a tuning element, so that so-called electronic tuning is performed. Further, 6 is a video intermediate frequency amplifier, 7 is a video detector, 8 is a brightness signal amplifier,
9 is a color signal amplifier, 10 is a color signal demodulation circuit, 11 is a burst separation circuit, 12 is a color subcarrier generation circuit, 13 is a matrix circuit to which a luminance signal and a color signal are applied, 14 is a video amplifier, and 15 is a color cathode ray tube. , 16 is an audio intermediate frequency amplifier, 17 is an audio demodulation circuit, 18 is an audio amplifier, 19
is a speaker. These configurations are similar to general color television receivers. Further, 21 indicates a sweep circuit that generates a sawtooth sweep control voltage for controlling the oscillation frequency of the local oscillator 5, and the sweep start and sweep stop of the sweep circuit 21 is controlled by the output of an AND gate 22.

-), if the output of the AND gate 22 is ``O'', the control voltage to the local oscillator 5 gradually increases, and if the output is ``1'', the control voltage remains at a constant level. A voltage corresponding to the deviation from the tuning point is applied to the local oscillator 5 by an AFC circuit 20 to maintain the tuning state. The output of the local oscillator 5 is then supplied to a detection section 23 that detects the channel number. As shown in FIG. 2, the detection section 23 includes a delay line 101 using an ultrasonic medium, a matrix circuit 102, detection diodes 103 and 104, and a differential amplifier 105.

The delay line 101 includes an input side converter 106 and an output side converter 1.
07 is provided, and its delay time τ is determined by (τ=l/v) from the sound velocity in the ultrasonic medium and its length l, and the accuracy of the delay time is extremely good and there is almost no frequency characteristic. The oscillation output SA of the local oscillator 5 is supplied from a terminal 100 to the input side converter 106 of this delay line 101. and delay line 10
1 output side converter 107 with a time delay of τ and mutually 1
Output signals SB and -SB having a phase difference of 8' are obtained.
The levels of these signals S3 and -SB are attenuated due to loss in the delay line 101. This delay line 101
The output signals SB and -SB are supplied to a pair of connection points a and b of the matrix circuit 102 in which resistors having the same resistance value R are bridge-connected. Also, one of the other pair of connection points of the matrix circuit 102, point c, is grounded, and the other point d is connected to the input terminal 100 from which the oscillation output SA of the local oscillator 5 is obtained. Here, the value R of each resistor constituting the matrix circuit 102 is made equal to the output impedance of the converter, so that impedance matching is achieved by making the impedance between points a and b equal to R. ing. Furthermore, the oscillation output SA supplied from point d appears at the point a and point b, respectively, at a level of 1/2 due to resistive voltage division. On the other hand, the signals S8 and -SB applied to points 2a and b have opposite phases, so they do not occur at points c and d. Here, the oscillation output SA of the local oscillator 5 is A
If it is expressed as Sln(i)t, the signal SB passed through the delay line 101 becomes a'Sinω(t-τ), so
The composite signals Sc and Sc' generated at points a and b are expressed as Sc=MSlnωt−f−Slnω(t−τ)
・・・・・・(1) SC′=MSlnωt−Msinω
(t-τ) ...(2}.

If these signals are expressed as vectors, they will be as shown in FIG. 3. In FIG. 3, 0A represents the vector of signal SA, AC represents the vector of signal SB, and AC/ represents the signal -
The vector of SB is shown. Vector 0A is vector AC and AC! The vectors AC and Ad rotate in the same direction around A with a constant phase difference of 180, and the phase difference is ωτ.
Therefore, the above-mentioned composite signals Sc and Sc' become vectors 0c and 0c', which are subjected to amplitude modulation and phase modulation by vectors AC and Ad. The amplitude characteristic B and amplitude of this composite signal are expressed by equations (1) and (2).

However, it is m-A7a. Here, due to the loss of the delay line 101, if m<1, then equation (3) and (4) are B=
a(1+MCOsωτ) a+a′COsωτ ・・・・・・(
5) Bi=a(1-MCOSωτ)' =a-ACOSωτ...
・It becomes (6).

Therefore, the composite signals Sc and Sc' are connected to the diodes 103, respectively.
By detecting with and 104, equations (5) and (6) are obtained.
A detection output proportional to the amplitude characteristic expressed by the equation can be obtained. Then, if each detection output is supplied to the differential amplifier 105 and calculated, the voltage E obtained at the output terminal 108 of the differential amplifier 105 is E-(2a′COSωτ)K
......(7). However, K is the product of the detection efficiency and the gain of the differential amplifier 105. The output voltage of the differential amplifier 105 expressed by this equation (7) is O
Consider the following points.

That is, (2a'COSωτ)K-0...
... To set (8), COS2πfτ=0
It is sufficient to find the conditions that satisfy (9).

This is π 2πfτ−nπ+i (n=0, 1, 2...)...
It's none other than...

UO) formula, Fm=(+x)+(n-0,1,2...
)......AD.

Here, if a sawtooth wave-like sweep control cage pressure is generated as shown in Fig. 4A and the local oscillation frequency is increased, the output cage pressure E is as shown by equations (7) and (self). It changes periodically. This is shown in FIG. 4B. As is clear from the above explanation, the period of this output cage pressure E is (1/τ).

In the channel plan of TV broadcasting, 6 [MHz
] Since broadcast waves are allocated at intervals, the delay time τ
If it is set to (1/6) [μSec], changes in the oscillation frequency of the local oscillator 5 can be detected every 6 [MHz]. In other words, if the output voltage E is supplied to the waveform shaping circuit 24 (FIG. 1) and pulses are generated at a rate of one per cycle as shown in FIG. It corresponds to the number. The output of this waveform shaping circuit 24 is counted by a channel number counter 25.

Channel number 1 The channel number detected by the detection unit 23 by the counter 25 is a 4-bit binary code (BC
D code). Since the channel number is a two-digit number, the first and second digits are each converted into a 4-bit code. This code is comparison time 1st route 26,
The signal is supplied to a display decoder 27 and a discrimination circuit 29. The display decoder 27 drives a display device 28 in which, for example, light emitting diodes are arranged in the shape of a sun character and display numbers. Further, the determination circuit 29 determines the maximum value of the channel number plus 1 (for example, 62+1). Further, 30 indicates a nonvolatile memory device composed of, for example, a MAOS element, and the read R and write W operations of this memory device 30 are controlled by the output of an AND gate 31. That is, if the output of the AND gate 31 is "1", it is in the write state, and if it is "0", it is in the read state. The storage device 30 is configured to be addressed by an address counter 32. Also,
33 is, for example, a city that actually has a broadcasting station in Japan.
This shows a group of 12 tuning switches with numbers assigned to them, and when you press any one of the tuning switches, you will receive the corresponding binary code and the fact that the tuning switch was pressed. A control signal K is generated from the encoder 34 and supplied to the address counter 32. The address counter 32 operates to designate the address of the storage device 30 by the output code of the encoder 34 in the individual channel selection mode, and to increment the address by the output of the AND gate 31 in the program mode. The output pulse from the signal detection section 35 is supplied to the AND gate 31 . The signal detection section 35 detects the presence or absence of a synchronization signal in the video intermediate frequency signal to detect the presence or absence of a broadcast wave.If the other input input of the AND gate 31 is "1", the broadcast wave is One pulse is generated every c, which increments the address counter 32.

Further, numeral 36 indicates a program switch that is pressed in the program mode, and when the program switch 36 is pressed, a set pulse is generated to the flip-flop 38 via the differentiation circuit 37.

The output Q of the flip-flop 38 becomes "1" in the program mode and becomes "0" during individual channel selection, and the output of the discrimination circuit 29 is supplied as a set input. Further, the sweep circuit 21, channel number counter 25 and address counter 32 are reset by a pulse generated by pressing the program switch 36. The reset of the sweep circuit 21 is that the sweep control voltage is set to an initial value. Further, the output Q of the flip-flop 38 is supplied to the AND gate 31, and also supplied to the AND gate 22 after being phase-inverted. The comparison output S of the comparison circuit 26 is supplied to the AND gate 22 . At the same time, the output Q becomes "1", so that the following operation is performed. In other words, the address counter 32 is made to perform an increment operation based on the output of the AND gate 31, and the comparator circuit 2
6 is simply a passing circuit, which passes the output of the channel number counter 25 and supplies it to the storage device 30, the display lamp 39 lights up to indicate the program mode, and the video intensifier 14 and audio amplifier The device 18 is shut off to prevent unsightly screen and audio conditions during the program mode. To explain the operation of the above embodiment of the present invention, the program mode will be described.

First, by pressing the program switch 36, the flip-flop 38 is set and its output Q becomes "1". Therefore, the video and audio no longer come out, and the display lamp 39
lights up. Also, the output Q is inverted and the AND gate 2
2, the output of the AND gate 22 is always "0", a sweep control voltage is generated from the sweep circuit 21, and the sweep is started. Then, the detection section 23 and the waveform shaping circuit 2
4 and the channel number formed by the channel number counter 25 are provided to the storage device 30 through the comparison circuit 26. The memory device 30 enters the write state only when the output of the AND gate 31 is "1". Since the output of the AND gate 31 becomes "1" only when there is a broadcast wave, the channel number (binary code indicating a two-digit number) at that time is written into the storage device 30. This write operation is performed between the lowest channel and the highest channel. Then, the number obtained by adding 1 to the highest channel number is detected by the discrimination circuit 29, and the flip-flop 38 is reset based on the output, and the output Q is set to 1.
The value becomes 0', and the program mode ends. In this way, the storage device 30 dynamically stores only channel numbers in the UHF band where broadcast waves are present. Next, regarding the individual channel selection mode, when any one of the channel selection switches 33 is pressed, a corresponding code is generated from the encoder 34 and applied to the address counter 32.

Since the output Q of the flip-flop 38 is 00', the address counter 32 does not operate as a counter.
The code from the encoder 34 is output as is, and the corresponding address in the storage device 30 is specified. At this time, since the output of the AND gate 31 is 0'', the memory device 30
is in a read state, and the channel number of the designated address is supplied to the comparison circuit 26 and compared with the output of the channel number counter 25. When the two do not match, the output S of the comparator circuit 26 is 60'', and therefore the output of the AND gate 22 is also 601, and the sweep circuit 21 generates a sweep control voltage.As a result, the channel number also changes. The signals change sequentially, and when the two match, the output S becomes 61'', the output of the AND gate 22 becomes 6r'', the sweep stops, and the broadcasting station corresponding to the pressed channel selection switch can be received. Maintaining the state tuned to this reception channel is done by AFC.
This is done by applying the AFC voltage obtained from the circuit 20 to the local oscillator 5 as a control voltage. Also, receive. The communication channel number is displayed on the display device 28. Even when another channel selection switch is pressed, the desired broadcast station can be received from among those programmed in the same manner as described above. According to the present invention, it is possible to automatically store in advance the channel numbers on which the radio waves are present in the storage device 30, so that channel number programming can be done using numerical keys or the program board as in the past. This is easier than using .

Furthermore, since the delay line 101 as shown in FIG. 2 is used to detect the channel number in relation to the local oscillator 5, the detection section 23 can be constructed easily and inexpensively. Another embodiment is shown in which parts corresponding to those in FIG. 1 are denoted by the same reference numerals.

In this example, each of the tuning switches in the tuning switch group 33 can be automatically programmed to correspond to an arbitrary channel number. That is,
Switch the mode switch to program mode, press the channel select switch in that state, start sweeping in one direction after a certain period of time, stop the sweep for a certain period of time at the channel with the next broadcast station, and memorize this channel. When you want to do so, you stop pressing the channel selection switch and write the channel number mentioned above to the address corresponding to the channel selection switch you operated. In Figure 5, 41
1 shows a mode switch configured as a lock-type push button switch, and the output "1" generated by pressing the mode switch 41 is supplied to an AND gate 42, a comparison circuit 26, and a modulation circuit 43 (to be described later). is treated as a mere passing circuit, and a red band-shaped display is displayed on the screen of the color cathode ray tube 15 by the modulation circuit 43 to indicate that programming is in progress.

Next, when a desired channel selection switch from the channel selection switch group 33 is pressed, an address signal corresponding to the channel selection switch pressed by the encoder 34 and a control signal KCl'' indicating that the channel selection switch has been pressed are transmitted. Since the control signal K is supplied to the AND gate 42, its output becomes "r". The output of this AND gate 42 is supplied to the AND gate 31, and is also inverted and supplied to the AND gate 22. Therefore, the output of the AND gate 22 becomes TOl and is swept by the sweep circuit 21. Then, the output of the signal detection unit 35 is "1" on a channel with broadcast waves.
Therefore, only in this case, the output of the AND gate 31 is 0.
It becomes 1゛. When the output of the AND gate 31 becomes 11'', the storage device 30, which has been in the read state until then,
enters a writing state, and a code corresponding to the channel number passed through the comparison circuit 26 is written by the channel number counter 25. This written address corresponds to the channel selection switch being pressed. here,
Look at the channel number or screen on the display device 28, and if it is not the channel you want to program, keep pressing the channel selection switch. Then, after a certain period of time, the sweep starts again, and then stops for a certain period of time on the channel with the next broadcast wave. And if it's the channel you want, you can just let go of the channel selection switch. In this way, the control signal KI) becomes 0, and the sweep is stopped. Similarly, channel numbers can be written into the memory circuit 30 in correspondence with individual channel selection switches. When the mode switch 41 is turned off at the end of the program, the system enters the individual channel selection mode. The operation of the individual tuning mode is the same as in the previous embodiment, so the explanation will be omitted, but the channel received when the tuning switch is pressed is the channel programmed to correspond to this tuning switch. It becomes. The above-mentioned modulation circuit 43 has the configuration shown in FIG.

In FIG. 6, reference numeral 111 indicates a transistor that is turned on when the mode switch 41 is turned on.
The second emitter is grounded. The collector of the transistor 112 is connected to the power supply terminal +Vcc, and is also connected to the green and blue signal transmission paths via diodes 113G and 113B. A series circuit of a capacitor 114 and a resistor 115 is inserted between the base of the transistor 112 and the ground, and a predetermined DC voltage is applied to one end of the capacitor 114 via resistors 116, 117, and 118. A sawtooth wave with a vertical period as shown in the figure is supplied from a terminal 119 to the other end. In this way, in the program mode, the transistor 112 is turned on only during a period in which the voltage across the capacitor 114 exceeds a certain value, and at this time, the green and blue signal transmission paths are grounded, and the color cathode ray tube 15 receives the red signal. Only the signal is supplied, so that a red band appears at the top or bottom of the screen of the color cathode ray tube 15 to indicate that it is currently in the program mode.

Of course, a display lamp may be turned on as in the above-described embodiment, or display means such as modulating an audio signal may be used.

Another embodiment of the present invention shown in FIG.
Another advantage is that it is possible to easily program a plurality of channel selection switches (No. 3) to correspond to arbitrary broadcast channels.

Generally, when performing such programming, the first
As a step, an arbitrary broadcast channel is selected, and as a next step, this broadcast channel is memorized by pressing an arbitrary channel selection switch, but according to the above-mentioned embodiment, it is possible to select an arbitrary broadcast channel in two steps. It can be programmed all at once. Note that in the above description, the present invention is applied to a color television receiver that receives the UHF band, but it can also be applied to a case that receives the HF band, and furthermore, it can be applied to a receiver such as an FM receiver. can.

[Brief explanation of drawings]

Figure 1 is a system diagram of an embodiment of the present invention, Figure 2 is a partial connection diagram thereof, Figures 3 and 4 are vector diagrams and waveform diagrams used to explain Figure 2, and Figure 5 is a bookmark diagram. A system diagram of another embodiment of the invention, FIG. 6 is a partial connection diagram thereof. 5 is a local oscillator, 21 is a sweep circuit, 23 is a detection section, 25
is a channel number counter, 26 is a comparison circuit, 30 is a storage device, 33 is a group of channel selection switches, 34 is an encoder, 3
6 is a program switch, 41 is a mode switch, 10
1 is a delay line.

Claims (1)

[Claims] 1. A local oscillator whose local oscillation frequency is varied by a control signal, a sweep circuit that generates the control signal, a delay line, and the output of this delay line are vector-combined to control changes in the local oscillation frequency to a predetermined frequency. A detection unit that detects at intervals, a channel number counter that counts the output of this detection unit, a storage device that stores the output of this channel number counter, multiple tuning switches, and support for operation of this tuning switch. an encoder that generates an address signal for the storage device, and a comparison circuit that compares the readout output of the storage device with the output of the channel number counter; is written in the storage device, and in the individual tuning mode, the channel number of the storage device corresponding to the address of the tuning switch is read out.
An electronically tuned receiver in which sweeping is stopped upon a coincidence output from the comparison circuit.