JP3047316U - Video tape recorder - Google Patents

Abstract

(57) [Summary] (With correction) [Problem] To provide a video tape recorder with a time correction function that can suppress an increase in the number of circuit components, increase productivity and reduce cost. SOLUTION: In this video tape recorder, time adjustment in a main body is performed using a broadcast time signal.
At that time, when the control signal detecting circuit 4 in the main body is not performing an operation for detecting a control signal, a time signal is input to the control signal detecting circuit 4 to detect the time signal. I have to. A control signal detecting circuit 4 includes a control head 1 for detecting a control signal, an amplifier 2 for amplifying a signal detected by the control head 1, and a comparator 3 for converting an output of the amplifier 2 into a pulse signal.
And an audio circuit 6 for inputting a broadcast time signal
Are provided.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to an improvement of a video tape recorder that adjusts the time in a main unit using a broadcast time signal.

[0002]

[Prior art]

 In conventional video tape recorders, etc., multi-functionality has been advanced, and a function for displaying the time of the clock and a time limit for automatically performing various operations such as recording of a reserved program based on the time of the built-in clock. One having a control function is known. Clock adjustment to match the time of the clock built into these types of devices to the correct time can be done manually by the user himself or with a highly accurate time signal that is broadcast from the broadcasting station every specific hour. This is done by automatic correction by detecting the signal.

[0003] As a system or a clock for automatically correcting the time by detecting a broadcast time signal signal, those disclosed in Japanese Utility Model Publication No. 59-42716 and Japanese Patent Publication No. 7-27038 are known. . In each of these cases, the inherent properties of the time signal are used, and the audio signal is generated based on the time signal signal format, such as the frequency of the forecast sound and the hour sound, or the time interval between the occurrence of the forecast sound and the hour sound. The system is configured to accurately separate only the time signal from, and detect the hourly sound to perform automatic time correction.

As shown in FIG. 10, a 440 Hz sinusoidal sound signal lasts 0.1 seconds, and a silent signal of 0.9 seconds is repeated three times, and then an 880 Hz sound signal is generated as shown in FIG. It lasts for 3 seconds. Note that the signal of 880 Hz for the last three seconds gradually decreases in two seconds after the sound volume at a constant level for one second.

[0005]

[Problems to be solved by the invention]

 However, in the conventional automatic correction method, it is necessary to provide a time signal detection circuit for separating and detecting a time signal signal from an audio signal, separately from a circuit for a device main body. For example, a circuit as shown in FIG. 11 may be used as a circuit when the above-mentioned time signal is used in a video tape recorder.

The time signal detection circuit 30 receives an audio signal, cuts off a sound having a higher frequency than the above-mentioned time signal by a low-pass filter 31, and shapes a sound signal including the time signal by a comparator 32. Output as pulse signal and input to microcomputer.

However, in such a time signal sound detection circuit 30 dedicated to the time signal sound, since each component, for example, the comparator 32 and the like is used only for detecting the time signal sound, it is compared with a circuit without an automatic time correction function. However, the number of components in the circuit will increase significantly, and productivity will decrease, and the price will increase.

An object of the present invention is to provide a video tape recorder with a time correction function capable of suppressing an increase in the number of circuit components, increasing productivity and reducing costs. It is another object of the present invention to provide a video tape recorder that stabilizes the time signal when a microcomputer determines a time signal and does not destabilize control of the microcomputer.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, in the video tape recorder according to the first aspect, in a video tape recorder that adjusts the time in the main unit by using a broadcast time signal, a control signal detecting circuit in the main unit is used. When the operation for detecting the control signal is not performed, the time signal is input to the control signal detecting circuit to detect the time signal.

According to a second aspect of the present invention, there is provided a video tape recorder comprising a control head for detecting a control signal, an amplifier for amplifying a signal detected by the control head, and a comparator for converting an output of the amplifier to a pulse signal. In a video tape recorder having a control signal detection circuit and an audio circuit for inputting a broadcast time signal, a control circuit for turning on the audio circuit when the control signal detection circuit is not operating; A switch is provided between the comparator and the comparator to input a signal from the audio circuit to the comparator at the same time as the audio circuit is turned on.

According to a third aspect of the present invention, in the video tape recorder according to the second aspect, a low-pass filter is provided between the audio circuit and the comparator so as to cut off a frequency higher than the frequency of the time signal signal. ing.

According to a fourth aspect of the present invention, in the video tape recorder according to the third aspect, the audio circuit is a tuner for audio, and an emitter follower circuit is connected to an output section of the tuner. A low-pass filter is connected to the circuit, and a switch is connected to the low-pass filter. The other end of this switch is input to the minus side of the comparator.

[0013] In addition, in the invention according to claim 5, in the video tape recorder according to claim 3 or 4, the low-pass filter includes two resistors connected in series and another resistor respectively connected to each resistor. A two-stage low-pass filter consisting of two capacitors whose ends are grounded is connected to a resistor on the ground side of each capacitor.

According to a sixth aspect of the present invention, there is provided a video tape recorder for adjusting a time in a main body using a broadcast time signal signal, an audio circuit for inputting a time signal signal, and a time signal signal. A microcomputer that turns on the audio circuit a predetermined time before a signal is generated, a comparator that shapes the signal output from the audio circuit into a pulse signal and inputs the pulse signal to the microcomputer, and a circuit that connects the audio circuit and the comparator. A two-stage low-pass filter composed of two resistors connected in series and two capacitors connected to the respective resistors and having the other end grounded. A resistor is connected to the ground side of each capacitor.

[0015] The video tape recorder of the present invention adjusts the time in the main body by using a broadcast time signal. At that time, a part of the control signal detection circuit that detects the control signal recorded on the video tape is also used to detect the time signal. This is achieved by using the control signal detection circuit during playback of the video tape recorder, while detecting the time signal when the circuit is not operating.

In detecting such a broadcast time signal, a low-pass filter is provided to cut high-frequency components of the audio signal, for example. Then, a resistor is connected to the ground side of the capacitor that constitutes the low-pass filter, and high-frequency components are sufficiently cut.

[0017]

[Embodiment of the invention]

 Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 9. Note that the first embodiment will be described first with reference to FIGS.

The video tape recorder of this embodiment has a function of receiving a television broadcast and a recording function for recording, reproducing, pausing, and the like, as in the related art, and causes the respective functions to be performed. The circuit for is provided. Here, descriptions of those general functions and circuits will be omitted, and the circuits and functions of the time adjustment part will be mainly described.

Generally, as shown in FIG. 2, recording channels CH1 and CH2 of two recording heads (not shown) are alternately formed on a recorded video tape VT. When an image is recorded on the video tape VT, a control signal CS of 30 Hz indicating the recording position of the image is recorded at the head of each channel CH1.

In the circuit for time adjustment of the present invention, a control head 1 for detecting the control signal CS during reproduction, an amplifier 2 for amplifying the signal detected by the control head 1, and an amplifier 2 for amplifying the signal detected by the control head 1. A part of a control signal detecting circuit 4 including a comparator 3 for pulsing the output signal is used for time adjustment.

The control signal CS pulsed by the comparator 3 is input to a microcomputer 5 serving as a control circuit, and is used for control during video reproduction. Other signals are also input to the microcomputer 5, and various circuits in the video tape recorder are controlled by the microcomputer 5.

The microcomputer 5 also controls a tuner 6 which is a part of an audio circuit in the video tape recorder. An emitter follower circuit 7 for removing noise and reducing impedance is connected to an audio output section of the tuner 6, and a low-pass filter 8 for cutting high-frequency components is connected to the emitter follower circuit 7. A switch 9 controlled by the microcomputer 5 is provided between the low-pass filter 8 and the comparator 3. The detected control signal is input to the plus side of the comparator 3, and the detected time signal is input to the minus side as described later.

The microcomputer 5 turns on the tuner 6 and turns on the switch 9 a predetermined time, for example, 10 minutes before the time signal generation time calculated by the time function in the video tape recorder. ing. This control of the microcomputer 5 is automatically performed when the video tape recorder is turned off. In other words, even if the time setting function is operating internally, the video tape recorder is apparently completely turned off, and the user of the video tape recorder starts to operate the time setting function by the microcomputer 5. You are not aware of that.

As described above, the microcomputer 5 turns on the tuner 6 and the switch 9 for time adjustment only when the control signal detection circuit 4 is not operating. Specifically, for example, as described above, the case where the video tape recorder is turned off or the case where the video tape recorder is not in the playback mode is a target. In this embodiment, the video tape recorder is used. The time setting function is activated when is turned off.

Next, an operation of detecting the time sound signal by the above-described circuit will be described.

When the video tape recorder is off, the control head 1 and the like are not operating, and a predetermined reference voltage is input to the plus side of the comparator 3. The microcomputer 5 turns on the built-in tuner 6 and the switch 9 ten minutes before the time when the time signal is generated by the built-in clock. If the television (not shown) connected to the video tape recorder is not controlled by the tuner 6 of the video tape recorder, it is possible to enter the time setting function even if the television is on. . However, when the television is set to be controlled by the tuner 6, when the television is operated, the video tape recorder is in the ON state, so that the time setting function cannot be entered.

When the tuner 6 is turned on, an audio signal from a television station that generates a time signal is continuously output from the tuner 6 to the emitter follower circuit 7. The emitter follower circuit 7 removes noise in the audio signal, lowers the impedance, and transmits the signal to the low-pass filter 8. The low-pass filter 8 passes low frequency components such as 440 Hz and 880 Hz of the time signal in the audio signal, and cuts high frequency components.

A low frequency such as a time signal that has passed through the low-pass filter 8 enters the negative side of the comparator 3 and is output as a pulse signal that is compared with a predetermined voltage on the positive side and inverted. The output pulse signal enters the microcomputer 5, and the microcomputer 5 detects whether or not the signal is a time signal. In the case of a time signal, a signal of 880 Hz comes in after a signal of 440 Hz continues for 0.1 second every second. Therefore, the microcomputer 5 detects the state, determines that a time signal sound is received when a signal of 880 Hz enters, and corrects the time of the clock in the video tape recorder based on the time signal signal.

On the other hand, when the video tape recorder is in the reproduction state, the microcomputer 5 does not turn on the tuner 6 and the switch 9 even 10 minutes before the time of the generation of the time signal. At this time, the control signal CS of 30 Hz detected by the control head 1 is amplified by the amplifier 2 and input to the plus side of the comparator 3. At this time, since a predetermined voltage is input to the negative side of the comparator 3, the comparator 3 compares the predetermined voltage with the voltage and the control signal CS of 30 Hz is pulsed with the same phase and output.

When the video tape recorder was turned off and the microcomputer 5 turned on the tuner 6 and the switch 9 in a state 10 minutes before the time when the time signal sound was generated, The video tape recorder may be turned on before the time of occurrence. In such a case, the microcomputer 5 detects that the video tape recorder has been turned on, and turns off the switch 9. Further, in this embodiment, the time for detecting the time signal signal is 10 minutes before and after the time signal sound generation time calculated by the built-in clock, but it is 20 minutes before and after, 29 minutes before and after 59 minutes. It may be seconds.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the circuit configuration shown in FIG. 1 is further embodied. The components having the same functions as those of the first embodiment are described with the same reference numerals.

A direct current of 5.5 V is applied to an audio output section of the tuner 6 controlled by the microcomputer 5. Then, since the output of the time signal from the tuner 6 becomes 500 mV in effective value (1.3 V peak-to-peak), the output from the tuner 6 turned on by the microcomputer 5 as shown in FIG. Is a value that oscillates around 5.5V.

This signal is output after being reduced in impedance by the emitter follower circuit 7. In the emitter follower circuit 7, a resistor R1 of 47 KΩ is connected to the base of the transistor Tr1, one end of a 0.0022 μF capacitor C1 is connected between the two, and the other end is grounded. A voltage of 10 V is applied between the collector and the emitter of the transistor Tr1, and the emitter is grounded via a 10KΩ resistor R2.

The signal that has passed through the emitter follower circuit 7 is reduced by 0.6 to 0.7 V by the V _{BE of} the transistor Tr 1, and a certain amount of noise-like high-frequency components are removed, and the signal shown in FIG. Become. This signal is input to the low-pass filter 8.

The low-pass filter 8 has a two-stage low-pass filter configuration. That is, a first low-pass filter configuration of a resistor R3 of 10 KΩ, a capacitor C2 of 0.01 μF, and a resistor R5 of 820Ω, a resistor R4 of 10 KΩ, a capacitor C3 of 0.01 μF, and a second low-pass filter of the resistor R5 described above. And a structure. As shown by the solid line in FIG. 5, this low-pass filter 8 cuts frequency components on both sides when 650 Hz is set to “0”, and cuts particularly high-frequency frequencies. That is, at 5 KHz, the passing amount is 1/10 (−20 dB) at 650 Hz. Here, the reason why 650 Hz is set as the maximum pass frequency is that the time signal sound signal is 440 Hz and 880 Hz, so that it is in between.

When the capacitors C2 and C3 are directly grounded without using the resistor R5 in the low-pass filter 8, the cut amount in the high frequency band is reduced as shown by a dotted line in FIG. If a large amount of high-frequency component remains, the signal is pulsed and enters the microcomputer 5, which undesirably makes the operation of the microcomputer 5 unstable.

The signal whose high frequency has been cut by the low-pass filter 8 is input to a switch 9 including a transistor Tr 2. When the time adjustment function is performed, a LOW signal is input from the microcomputer 5 to the base of the transistor Tr2. When the transistor Tr2 is turned off, a signal from the low-pass filter 8 is input to the comparator 3. I have. When the time adjustment function is not performed, a HIGH signal is input to the transistor Tr2, the transistor Tr2 is turned on, and the signal from the low-pass filter 8 is not detected. That is, a signal from the tuner 6 is not inputted to the control signal detecting circuit 4 except when the time adjusting function is operated.

The signal from the low-pass filter 8 is input to the negative side of the comparator 3 via the capacitor C4 of 0.0068 μF when the transistor Tr2 is turned off (= when the switch 9 is turned on). The DC component of about 4.8 V is removed by the capacitor C4, and once becomes a signal centered on 0 V shown in FIG. 4C.

The comparator 3 includes an operational amplifier OP1 and a plurality of resistors, and outputs a voltage of 5V. The signal shown in FIG. 4 (c) rides on the divided voltage of 2.5V divided by the two 4.7KΩ resistors R6 and R7 in the control signal detecting circuit 4, and the signal shown in FIG. And input to the minus side of the operational amplifier OP1. This signal is output from the operational amplifier OP1 as a pulse signal as shown in FIG. 6B, although it has some hysteresis. Note that a resistor R8 of 56 KΩ is inserted between the resistor R6 and the minus side of the operational amplifier OP1.

A microcomputer 5 is connected to the control head 1, and when the video tape recorder is in a reproducing state, the control head 1 is operated and a status signal RECCTL for detecting the control signal CS is transmitted. It is supposed to be. The control head 1 and the amplifier 2 for amplifying the signal are the same as those in the related art, and a detailed description thereof will be omitted. Further, the signal SLOW-L to that effect is input to the comparator 3 at the time of slow reproduction in the triple mode (1/3 speed) from the microcomputer 5. Then, the duty ratio at that time is changed.

FIG. 7 shows the waveform of the audio output of the tuner 6 when the time adjustment function is working, and the microcomputer input signal which is shaped and input to the microcomputer 5. As shown in FIG. 7, during the audio output of the tuner 6, the high frequency is cut and the low output level audio is cut. In this embodiment, the minimum output level of the tuner 6 is 250 mVRMS (= effective value), and the frequency at which no pulse output occurs when the input signal is 600 mVRMS is 4 KHz. Note that the output of the tuner 6 is 500 mVRMS on average except for the time signal.

When the resistor R5 in the low-pass filter 8 is removed and short-circuited, when the input is 600 mRMS, the frequency at which pulse output does not occur is 5.8 KHz, and the cut ratio in the high frequency band decreases. Similarly, when the input is 1 VRMS, the pulse output becomes zero at 8 KHz.

Next, a third embodiment will be described with reference to FIG.

In the third embodiment, the time signal is taken not from the tuner 6 but from the luminance / color / audio section 11 which is also a part of the audio circuit. The taken-in signal is input to the low-pass filter 8 via the capacitor C6. Here, the reason why the emitter follower circuit 7 shown in the first and second embodiments does not exist is that the output section of the luminance / color / audio section 11 has already been reduced in impedance.

As in the second embodiment, the low-pass filter 8 has a two-stage configuration, and two capacitors are grounded via a resistor R11. This resistor R11 serves to further cut high frequency components as in the second embodiment. The audio signal that has passed through the low-pass filter 8 passes through the switch 9 and is introduced into the comparator 3 having the capacitor C4 described in the second embodiment. The switch 9 has a configuration similar to that of the second embodiment, and is controlled by the microcomputer 5. Then, when a LOW signal is input to the switch 9, a signal from the low-pass filter 8 is output to the comparator 3.

In the third embodiment, since the audio output is taken out, the audio output is generated a predetermined time before the time when the time signal ON signal is generated, for example, 10 minutes before. This means that, for example, when both the video tape recorder and the television are turned off and the time setting function starts to operate, the sound of the television is suddenly output. For this reason, in the third embodiment, the mute circuit 12 for disabling the audio output is arranged in front of the output amplifier (not shown) so that the microcomputer 5 can operate the mute function at the same time as the time setting function operates. I have to.

The above-described embodiments are examples of preferred embodiments of the present invention, but are not limited thereto, and various modifications may be made without departing from the gist of the present invention. It is feasible. For example, the time adjustment function may be operated not when the video tape recorder is off but when the playback function of the video tape recorder is not operating.

The configuration in which the resistor R5 or the resistor R11 is connected to the capacitor of the low-pass filter 8 to further cut the high-frequency component is the same as in the above-described first to third embodiments. The control signal detection circuit 4 may not be used for detecting a time signal, but may be applied to a circuit having an independent time signal signal detection circuit 20 as shown in FIG. That is, a resistor R21 may be provided in the low-pass filter 8 portion after the input of the audio signal and connected to both capacitors to further cut the high frequency component.

Further, the low-pass filter 8 may have a single-stage configuration instead of a two-stage configuration, or may have three or more stages. Further, although various controls are performed by the microcomputer 5, other control circuits may be employed, or the functions may be performed by two or more control circuits. The provision of the resistors R5, R11 and R21 in the low-pass filter 8 may be provided in a device other than the time signal signal detection by the video tape recorder, for example, a device such as a television, a radio or a clock.

[0050]

[Effect of the invention]

 As described above, in the video tape recorder according to the first aspect, since the control signal detection circuit is also used for detecting the time signal, the number of parts can be reduced, the productivity is increased, and the cost is reduced. Can be achieved.

In the invention according to the second aspect, since the comparator of the control signal detection circuit is also used for detecting the time signal, the number of parts can be reduced, the productivity can be increased, and the cost can be reduced. be able to.

Further, in the invention according to the third aspect, since high-frequency components in the audio signal are cut by the low-pass filter, the operation of the microcomputer can be stabilized even when the signal processing is performed by the microcomputer thereafter. it can.

Further, according to the invention of claim 4, since the time signal is extracted from the tuner, a mute circuit required for extracting from the luminance / color / audio section is not required and control is simplified. Is done. When the time adjustment function is not working on the plus side of the comparator, a conventional control signal is input, so that a conventional signal can be obtained when the control signal is detected.

In addition, according to the present invention, since the resistor is connected to the ground side of the capacitor of the low-pass filter, the cut amount in the high frequency region can be increased, and the time signal signal can be extracted. Stabilizes. Furthermore, when a microcomputer is connected to determine the time signal, the operation of the microcomputer is not destabilized.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration for detecting a signal for time adjustment in a video tape recorder according to a first embodiment of the present invention;

FIG. 2 is a diagram for explaining control signals recorded on a video tape recorder.

FIG. 3 is a circuit diagram showing a configuration for detecting a signal for time adjustment in a video tape recorder according to a second embodiment of the present invention;

FIG. 4 is a diagram showing signals generated in the circuit shown in the second embodiment of the present invention.

FIG. 5 is a diagram for explaining a filter function of a low-pass filter in the circuit shown in the second embodiment of the present invention.

FIG. 6 is a diagram showing a signal input to a comparator and an output signal from the comparator in the circuit according to the second embodiment of the present invention, wherein (A) shows a signal input to the comparator, and (B) Indicates a signal output from the comparator.

FIGS. 7A and 7B are diagrams showing a tuner audio output of the circuit shown in the second embodiment of the present invention and a microcomputer input signal input to the microcomputer, and FIG. 7B is a partially enlarged view of FIG.

FIG. 8 is a circuit diagram showing a configuration for detecting a time adjustment signal in the video tape recorder according to the third embodiment of the present invention.

FIG. 9 is a circuit diagram showing another example of a low-pass filter for cutting a high frequency frequency employed in the present invention.

FIG. 10 is a diagram for explaining a waveform of a time signal signal.

FIG. 11 is a circuit block diagram for explaining an example in which detection of a time signal is performed using a dedicated circuit in a video tape recorder.

[Explanation of symbols]

 Reference Signs List 1 control head 2 amplifier 3 comparator 4 control signal detection circuit 5 microcomputer (control circuit) 6 tuner (part of audio circuit) 7 emitter follower circuit 8 low-pass filter 9 switch

Claims (6)

[Utility model registration claims] 1. A video tape recorder for adjusting the time in a main unit using a broadcast time signal signal when a control signal detecting circuit in the main unit does not perform an operation for detecting a control signal. A video tape recorder, wherein the time signal is input to the control signal detection circuit to detect the time signal. 2. A control signal detecting circuit comprising a control head for detecting a control signal, an amplifier for amplifying a signal detected by the control head, and a comparator for converting an output of the amplifier into a pulse signal, and a time signal to be broadcast. A video tape recorder having an audio circuit for inputting a signal, a control circuit for turning on the audio circuit when the control signal detection circuit is not operating, and the audio circuit interposed between the audio circuit and the comparator. A switch for inputting a signal from the audio circuit side to the comparator at the same time as turning on the video tape recorder. 3. The video tape recorder according to claim 2, wherein a low-pass filter is provided between said audio circuit and said comparator to cut off a frequency higher than the frequency of said time signal. 4. The audio circuit is an audio tuner, an emitter follower circuit is connected to an output of the tuner, a low-pass filter is connected to the emitter follower circuit, and the switch is connected to the low-pass filter. 4. The video tape recorder according to claim 3, wherein the other end of the switch is input to the minus side of the comparator. 5. The low-pass filter is a two-stage low-pass filter consisting of two resistors connected in series and two capacitors connected to the respective resistors and having the other end grounded. 5. The video tape recorder according to claim 3, wherein a resistor is connected. 6. A video tape recorder for adjusting the time inside a main unit using a broadcast time signal signal, wherein an audio circuit for inputting the time signal signal is provided at a predetermined time before the time signal signal is generated. A microcomputer that turns on the audio circuit, a comparator that shapes a signal output from the audio circuit into a pulse signal and inputs the pulse signal to the microcomputer, and a low-pass filter that is inserted between the audio circuit and the comparator. This low-pass filter is a two-stage low-pass filter including two resistors connected in series and two capacitors connected to the respective resistors and having the other end grounded,
A video tape recorder wherein a resistor is connected to the ground side of each capacitor.