JPS60194679A - Television receiver - Google Patents

Abstract

PURPOSE:To prevent the absence of both an image and a sound from continuing for a relatively long time after channel switching and power-on operation by resetting screen blanking a specific time after the input of a channel selection signal regardless of a complete tuning state and performing proper processing. CONSTITUTION:When channel selecting operation is performed, sound muting and screen blanking are started a slightly later. Then, AFT (automatic frequency adjusting) operation is started and when a complete tuning state is not obtained within 500ms, the screen blanking is reset 500ms after the start of the sound muting and screen blanking as shown in a figure B. The sound muting is reset at the time Te when the complete tuning state is obtained as shown by an alternate long and short dash line in the figure B. If the complete tuning state is not obtained even after a series of operations for WAFT (wide-range leading-in operation), the sound muting is reset at the point Tf of the completion of the series of operations.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel television receiver, and more particularly, to a television receiver in which both sides are blocked until the local oscillator frequency is adjusted by an automatic frequency adjustment (AFT) circuit after a tuning operation. TV Jijin Uke ranked and muted the audio! The purpose is to prevent viewers from erroneously determining that there is a malfunction when it takes a relatively long time to adjust the local oscillation frequency.

BACKGROUND TECHNOLOGY AND PROBLEMS In television receivers, after tuning operation, the AFT circuit corrects the local oscillation frequency to bring the intermediate frequency to a normal value, that is, until an effective television broadcast signal is input. This produces intermittent noise, which is harsh on the ears and makes the screen look unsightly. Therefore, after the channel selection operation, the AFT circuit finishes pulling in the effective television broadcast signal and until the state is completely tuned, the audio is muted and the screen is blanked, causing discomfort to the user. There are some things that we have taken into consideration to ensure that this is not the case.

Some television receivers of this type use a channel selection controller using a microcomputer to control CA.
There are some devices that have an extremely wide pull-in range that allows them to pull in even offset signals from TV and the like. Figure 1 shows the action of pulling in a wide range (
For convenience, this will be referred to as "rWAFT operation" below. ) is a flowchart for explaining WA
FT operation will be explained. When a channel selection command signal is input by turning on the power switch, channel selection operation, etc., the local oscillation frequency is changed to tune to a frequency that is, for example, 0.2 MHz lower than the center frequency fO of the selected channel, and the AFT circuit outputs the AFT signal. It is determined whether the voltage is obtained or not, and if the determination result "rYES" is obtained, the AF
The local oscillation frequency is finely adjusted by AFT operation by the T circuit. If the judgment result is “NO”,
The local oscillation frequency is adjusted to a frequency that is, for example, IMHz higher than the center frequency fO of the selected channel, and if the AFT voltage is still not obtained, the frequency is tuned to a frequency that is 1.4 MHz lower than fo.

If the AFT voltage is still not obtained even after doing this, the series of operations described above is repeated three more times until the AFT voltage is obtained. If the AFT voltage is still not obtained after repeating this series of operations four times, the local oscillation frequency is set to a value that tunes to a frequency 0.2 MHz lower than the center frequency f of the selected channel. change and maintain that state (that is, try to achieve a perfect tuning state).

In a television receiver with performance that allows acquisition over a wide range by the series of operations for WAFT shown in FIG. 1, video blanking and There is no problem because audio muting is canceled immediately after the channel selection operation, but when pulling in offset broadcast waves, it takes a relatively long time, for example, 2 to 3 seconds, and during that time video blanking and audio muting are performed. Since this continues, there is a risk that viewers may mistakenly believe that a malfunction has occurred in the television receiver. This problem also occurs when receiving an image in a region or location with a weak electric field, or when adjusting the direction of the rod antenna to achieve the optimum image receiving state. Then, image reception in the weak electric field region or mouth/
There is also the problem that it becomes difficult or impossible to adjust the image reception condition by adjusting the antenna.

OBJECT OF THE INVENTION The present invention has been made to solve the above-mentioned problems.
The purpose is to prevent a user from misunderstanding that a failure has occurred in a television receiver.

SUMMARY OF THE INVENTION A television receiver of the present invention that achieves the above object is provided with at least an automatic frequency adjustment means, a single screen blanking means, and an audio muting means, and when a channel selection signal is input, the television receiver performs screen blanking and audio muting. A television receiver that adjusts the local oscillation frequency in a tuned state, and cancels screen blanking after a certain period of time has elapsed after inputting a tuning signal, regardless of whether it is in a completely tuned state. Furthermore, if a complete tuning state is achieved before the end of a series of local oscillation frequency adjustment operations, at the time of realization; The present invention is characterized in that the audio muting is canceled at the end of the series of local oscillation frequency adjustment operations.

Embodiments Below, the television receiver of the present invention will be explained in detail according to embodiments shown in the accompanying drawings.

2 to 4 are for explaining an example of implementation of the television receiver of the present invention, and FIG. 2 is a block diagram showing the circuit configuration of the television receiver. In the figure, l is a tuner, 2 is a video intermediate frequency amplification circuit, 3 is a video detection circuit, 4 is a video amplification circuit, and 5 is a cathode ray tube, which receives the output of the video amplification circuit 4 and displays video on the screen.

6 is an audio intermediate frequency amplification circuit, 7 is an FM demodulation circuit for audio demodulation, 8 is an audio amplification circuit, and 9 is a speaker for reproducing the audio signal output from the audio amplification circuit.

10 is a microcomputer, 11 is its CPU, 12
is the ROM, 13 is the RAM, 14 is the system bus, and 15 is the timer.

20 is a light receiver that receives an infrared control signal from a remote controller (not shown) and converts it into an electrical signal; 21 is a remote control receiving circuit that decodes the control signal output from the light receiver 20; The decoded control signal is transmitted to the system bus 14 via the interface 31. 22 is a key device having multiple selection keys and the like. When a channel selection key or the like is operated, a signal corresponding to the content of the operation is obtained, and this signal is transmitted to the system bus 14 via the interface 32.

Reference numeral 23 denotes a channel selection voltage generation circuit which, when a channel selection operation is performed on the key device 22 or the remote controller and a channel selection signal is input to the system bus 14 through the interface 32 or 31, specifies the channel via the interface 33. When the channel receives a signal, it generates a tuning voltage corresponding to that channel. This tuning voltage is applied to tuner l, and tuner l
When receiving the tuning voltage, the local oscillation frequency of a local oscillation circuit (not shown) built in the tuner l becomes a value corresponding to the tuning voltage, and the tuning is then performed.

24 is an AFT circuit which extracts the carrier wave component of the video intermediate frequency signal from the signal from the video intermediate frequency amplification circuit 2, performs FM detection on this, and generates an AFT voltage. This AFT voltage is supplied to the tuning voltage generation circuit 23 to finely adjust the tuning voltage. Further, the output signal from this AFT circuit 24 is supplied to the system bus 14 via an interface 34. Then: AF in microcomputer 10
T is used to determine whether a television broadcast signal is received.

25 is a blanking circuit, and when it receives a blanking start command through the system bus 14 or interface 35, its output signal, that is, the blanking signal BS, becomes "1".
When the blanking end command is received, the blanking signal BS becomes "0". This blanking signal B
S is supplied to the video amplification circuit 4, and blanking signal BS
When the period is "1", the video is blanked.

26 is a muting circuit, and when it receives a muting start command from the system bus 14 through the interface 36, its output, the muting signal MS, becomes rL.
J, and when the muting end command is received, the muting signal MS becomes rQJ. This muting signal MS is supplied to the audio amplification circuit 8 (or the video intermediate frequency amplification circuit 6 as shown by the two-dot chain line), The audio is muted when the muting signal MS is in the rll period.

FIG. 3 is a flowchart showing a programmer for channel selection. The operation for channel selection will be explained according to this diagram.

(B) “Has a channel selection been input?” First, it is determined whether a channel selection has been input, and rYEsJ
If the judgment result is obtained, proceed to step (b) of the method. If the judgment result is rNOJ, rYE
This determination is repeated for those that yield a determination result of sJ.

Channel selection input is performed not only when an operation for tuning (up or down a channel, operation to directly specify a channel) is performed, but also when the power switch is turned on. /AIR switch, A
If there is an NT/AUX switching function, this is when the switching is performed.

(b) rMs=1. Bs=t, timer reset" If a channel selection operation etc. is performed and a determination result of rYESJ is obtained in step (a) as a result, the muting signal MS is set to rlJ, and the blanking signal BS is set to "l". Then, the timer 15 is reset to start time measurement. When the output signals MS and BS are set to rlJ in this way, audio muting and screen blanking are started, and the timer 15 starts measuring time.

(C) "Tuning selection operation" Next, the tuning voltage generation circuit 23 generates a tuning voltage corresponding to the selected channel. Then, the tuning voltage is applied to the tuner 1.

(d) rWAFT operation When the channel selection operation in step "c" is completed, the WAFT operation as shown in FIG. 1 is started. As a result, when the state is close to the tuning state, the AFT circuit 2
The AFT voltage is generated from 4, and then the AFT is brought into a perfectly tuned state by finely adjusting the tuning voltage.
Action will be taken. It should be noted that even if a series of local oscillation frequency adjustment operations are performed to complete the tuning operation and obtain a perfect tuned state, a perfect tuned state may not always be achieved.

(E) rJUST TUNE? The signal sent from the J AFT circuit 2.4 to the interface 34 is monitored, and it is determined whether the frequency of the signal output from the video intermediate frequency amplification circuit 2 is within a predetermined frequency range corresponding to the AFT pull-in range. Ru.

(f) rMs=OJ When the determination result of rYEsJ is obtained by the determination in step (e), a hemuting release command is issued to the muting circuit 26 via the interface 36. Then, the muting signal MS changes from "1" to "0".
” and the sound is output from the speaker 9.

()) rBs=0'' Next, a blanking release command is issued to the blanking circuit 25 via the interface 35.

Then, the output signal BS of the blanking circuit 25 becomes "l".
The value changes from 0 to 0, and the image is displayed.

(H) Is rBs=o and MS=O? Next, it is determined whether the output signal BS of the blanking circuit 25 is 0 and the output signal MS of the muting circuit 26 is 0. When this judgment result is "rYEs",
The program for tuning ends.

(S) rWAFT operation completed? ” Step (E) rJAsT TUNE? If the result of the determination J is "NO", it is determined whether a series of local oscillation frequency adjustment operations for WAFT substantially similar to those shown in FIG. 1 have been completed. Note that the completion of a series of dynamic local oscillation frequency adjustment operations does not mean that a complete tuning state has been reached, but rather that a predetermined step has been completed. Of course, there is a good possibility that even after completing this series of operations, the tuning state may not be completely reached. By the way, has this rWA FT operation ended? '' may be made by measuring time with a timer (a timer different from the timer 15) and determining whether a certain predetermined time has elapsed, which is sufficient for the series of operations to be completed.

If a determination result of rYEsJ is obtained by the determination in this step (su), rMs in the step (to)
=o" is performed. That is, even if the tuning state is not complete, blanking is canceled when a series of operations for WWAFT is completed.

(J) "Read timer" If the determination result of step (S) is "NO", the measurement time of the timer 15 is read.

(Le) "Step > 500 m s J step 15
A determination is made as to whether or not the measured time is greater than 500 m5. The 500m5 period was selected as a time during which viewers would not feel anxious due to the lack of images or sound, but the time may vary depending on national characteristics, and other times may be used. Needless to say, it's a good thing.

If the judgment result rNOJ is obtained in this judgment, that is, if 500m5 has not yet elapsed after the channel selection operation, etc., the process returns to step (d), the WAFT operation is performed, and then step (home) is reached. ) is determined.

Also, if the determination result of rYEsJ is obtained in this step (ru), that is, after 1 channel selection operation is performed, 50
When 0m5 elapses, step (g) (7) rBs=OJ
In other words, when 500m5 has passed, blanking is canceled even if the tuning state is not completely reached.

By the way, if rBs=o in step (h) and MS
=O? If the determination result of "J" is "NO", the "WAFT operation" of step (d) is performed. Therefore, even if blanking has been canceled, if muting has not been canceled, step (d) r
"WAFT operation" is performed. And step (ho)
rJUST TUNE? If the judgment result of "rYES" is obtained by the judgment of J, or is the rWAFT in step (S) completed? ”, r
When a determination result of YESJ is obtained, the operation of step (to) rMS=OJ is performed, and muting is canceled.

According to such a television receiver, the pull-in operation is performed as shown in FIGS. 4(A) and 4(B). First of all,
When a complete tuning state is achieved within 500 m5, screen blanking and audio muting, which were started almost at the same time, are canceled at the time Tc when a complete tuning state is reached, as shown in FIG. 5(A). Specifically, when a channel selection operation is performed (that time is Ta
shall be. ) Audio muting and screen blanking will start after a slight delay. Thereafter, the AFT operation is started, and when a complete tuning state is achieved within 500 m5, audio muting and screen blanking are canceled at the time of realization (TC).

However, if a complete tuning state is not achieved within 500 m sυ, as shown in (B) in the same figure, 5 minutes after the start of audio muting and screen blanking.
Screen blanking is canceled when 00m5 has elapsed.

Therefore, for example, in a television receiver using a rod antenna, the orientation of the rod antenna can be changed to obtain an optimal image reception IE while viewing the screen. Thereafter, when a perfect tuning state is achieved, the audio muting is canceled at the time point Te when the perfect tuning state is achieved, as shown by the two-point chain in FIG. 2(B).

By the way, even if the series of operations for WAFT is completed (
At that time Tf) If a perfect tuning state is not achieved, the audio muting is also canceled at the time Tf when the series of operations is completed. This prevents the viewer from misunderstanding that a failure has occurred in the audio circuit system, and even if, for example, a good image reception condition cannot be obtained because the image is received in an area with a weak electric field. You can see images and hear sounds in the image receiving state.

In implementing the present invention, the receiver must be able to perform screen blanking and audio muting independently of each other; If so, the audio muting may be of a type that applies muting at the AF output circuit stage or a type that applies muting at the audio intermediate frequency amplification circuit stage.

Alternatively, it may be of a type in which the audio control output signal (usually a PWM signal) and the muting signal are applied through separate terminals, or the audio control output signal and the muting signal are applied through the same terminal to control the volume. It may also be of a type in which muting is applied by setting the volume of the signal to O. The former type has the advantage that the timing and speed of audio muting is completely unaffected by the time constant of the integrating circuit that integrates the PWM signal to create the volume control voltage, while the latter type saves the number of terminals. It has the advantage of being able to

Further, regarding the video circuit system, the Y/C circuit and the deflection circuit may be constructed in separate ICs, or may be constructed in one IC.

Effects of the Invention As described above, the television receiver of the present invention includes at least automatic frequency adjustment means, screen blanking means, and audio muting means, and when one channel selection signal is input, screen blanking and audio muting are performed. This is a TV receiver that adjusts the local oscillation frequency while the tuning is in progress, and the screen blanks after a certain period of time has elapsed after the input of the tuning signal, regardless of whether the tuning is complete or not. If the complete tuning state is achieved before the completion of the series of local oscillation frequency adjustment operations, then the complete tuning state is not achieved even after the above series of local oscillation frequency adjustment operations are completed. The present invention is characterized in that audio muting is canceled at the end of a series of local oscillation frequency adjustment operations.

Therefore, when a broadcast signal is not received for a certain period of time or more, video blanking is forcibly canceled, so that settings for obtaining optimum image reception conditions can be made without any trouble, for example, by adjusting the direction of the rod antenna. or,
It is possible to prevent the TV receiver from being misunderstood as having a malfunction. After that, audio blanking is canceled when complete engagement is achieved.
If the pull-in cannot be performed until the end of a predetermined series of operations to obtain a complete muting state, audio blanking is canceled at the end of the series of local oscillation frequency adjustment operations. Therefore, there is no risk of the audio circuit system breaking down.

[Brief explanation of drawings]

FIG. 1 is a flowchart for explaining the WAFT operation, FIGS. 2 to 4 are for explaining an example of implementation of the television receiver of the present invention, and FIG. 2 is a circuit block of the television receiver. 3 are flowcharts for explaining the operation, and FIG. 4 is a time chart for explaining the operation. Explanation of symbols 24: automatic frequency adjustment means. 25...Screen blanking means, 26--φ audio muting means Fig. 1 Fig. 3 Ne r'b Book (B) TaTb ld Te If Procedural amendment (voluntary) August 7, 1982 Patent Application No. 49946, name of the invention Television receiver 3, relationship with the case of the person making the amendment Patent IJJ 8 people Address Tokyo Parts 6-7-35 Name (2+
8) Sony Corporation, Agent Address: 3-1-10-401-5, Irifune, Chuo-ku, Tokyo
The detailed description of the invention column, drawing 6, and contents of the amendment in the specification to be amended will be deleted. (2) On page 10 of the specification, line 5 from the bottom, "J" in "What can be obtained" is corrected to "until obtained." (3) On page 13 of the specification, line 5 from the bottom, rJ ASTJ is corrected to rJUsTJ. (4) On the bottom line of page 13 of the specification, "a series of moving parts" is corrected to "a series of local parts." (5) In the first line of page 14 of the specification, insert ``action'' between ``adjustment'' and ``action.'' (6) Delete "W" on the 7th line from the bottom of page 14 of the specification. (7) 5th line from the bottom of page 14 of the specification, “Blanking J
is corrected to "muting". (8) Specification FF, page 118, line 9, “Implementation, J” and “
Insert "J" between "to" and "to". (9) On page 18, line 11 of the specification tube, correct "necessary" to "necessary." (10) Page 18 of the specification, line 7 from the bottom, “Type” and “
Insert ``no'' between ``も''. (l l) Insert "no" between "type" and "mono" in the fifth line from the bottom of page 18 of the specification. (12) In the third line from the bottom of page 20 of the specification, "blanking" is corrected to "muting." (13) In the second line from the bottom of page 20 of the specification, "muting" is corrected to "tuning." (14) On page 21, line 2 of the specification, ``Blanking J is corrected to ``muting''. (15) In the third line of page 21 of the specification, insert ``and misunderstanding'' between ``failure'' and ``to be caused.'' (16) Replace Figure 2 of the drawing with Figure 2 of the attached corrected drawing. 7. List of attached documents (1) Corrected drawing (Figure 2) 1 copy

Claims (1)

[Claims] The system is equipped with automatic frequency adjustment means, screen blanking means, and audio muting means, and when a tuning signal is input, the local oscillation frequency is adjusted while screen blanking and audio muting are being performed. A television receiver that cancels screen blanking after a certain period of time has elapsed after inputting a channel selection signal, regardless of whether it is in a completely tuned state, and then before completing a series of local oscillation frequency adjustment operations. If a perfect tuning state is achieved in the above-mentioned series of local oscillation frequency adjustment operations, the audio mute is turned off at the time when the complete tuning state is achieved. A television receiver characterized in that the setting is canceled.