KR0136922Y1 - Fault-detection apparatus for video cassette recorder - Google Patents

Abstract

The present invention relates to an apparatus for detecting an audio defect in a video cassette recorder, which enables a video cassette recorder to detect and display an abnormality of an audio system. A first comparing unit 81 for outputting a first comparing signal; A second comparing unit 82 which detects an envelope of the audio signal read out by the audio head and outputs a second comparison signal by comparing it with a predetermined reference value; A third comparison unit 83 for outputting a third comparison signal by comparing an audio carrier frequency for modulation and demodulation during recording and reproduction of the audio signal with a predetermined reference clock; A fourth comparing unit 84 which detects an envelope of the audio signal modulated by the audio carrier frequency and outputs a fourth comparison signal by comparing with the predetermined reference value; A determination unit (85) for outputting digital information of a predetermined format based on the first, second, third, fourth comparison signals from the first, second, third, and fourth comparison units (81,82,83,84); An audio signal applied to the audio head, an audio signal reproduced from the audio head, the head switching signal, and a display control signal for notifying whether the audio carrier frequency is abnormal according to the digital information from the determination unit 85; A microcomputer 90; A display unit 100 for displaying an audio signal applied to the audio head, an audio signal reproduced from the audio head, the head switching signal, and an abnormality of the audio carrier frequency based on a display control signal from the microcomputer 90; It includes.

Description

Audio fault detection device in video cassette recorder

1 is a block diagram of an audio fault detection apparatus according to the present invention.

2 is a diagram showing a communication data format with a microcomputer.

* Explanation of symbols for main parts of the drawings

10: audio head 20,60: first and second signal amplifier

30: playback signal processor 40: audio carrier oscillator

50: recording signal processing unit 70: servo unit

81: head switching signal comparison unit 82,84: first, second A / D conversion unit

83: audio carrier comparison unit 85: determination unit

90: micom 100: OSD unit

The present invention relates to an apparatus for detecting an audio defect in a video cassette recorder. In particular, a video cassette recorder (in this invention, hi-fi video) determines an input / output signal of an audio signal processing system and detects whether an audio signal is reproduced or recorded. The present invention relates to an apparatus for detecting an audio defect in a video cassette recorder, which can be displayed.

In general, a high fidelity video cassette recorder (VHS) adds an audio head to the head drum, and uses an rotating audio head to FM modulate the audio signal and record it in the depths of the video tape. A video cassette recorder capable of recording on the surface layer of a video tape and reproducing and recording high quality audio signals in both stereo channels.

In the above-described hi-fi video cassette recorder, there is a need for a method of determining whether an audio signal is properly recorded and reproduced due to a failure of an audio signal processing system and recognizing it to a user.

Accordingly, an object of the present invention is to provide an apparatus for detecting an audio defect in a hi-fi video cassette recorder, which is capable of detecting and displaying an abnormality during playback and recording of an audio signal in a hi-fi video cassette recorder.

An apparatus for detecting an audio defect in a hi-fi video cassette recorder according to the present invention is an apparatus for checking an input / output operation state of an audio signal in a video cassette recorder, and compares a head switching signal for switching an audio head with a predetermined reference clock. A first comparator for outputting a first comparison signal, and a second comparator for detecting an envelope of the audio signal read out by the audio head and outputting a second comparison signal by comparing it with a predetermined reference value; A third comparison unit for outputting a third comparison signal by comparing an audio carrier frequency for modulation and demodulation during recording and reproduction of the audio signal with a predetermined reference clock; A fourth comparing unit which detects an envelope of the audio signal modulated by the audio carrier frequency and outputs a fourth comparison signal by comparing it with a predetermined reference value; A determination unit for transmitting digital information of a predetermined format based on the first, second, third and fourth comparison signals from the first, second, third and fourth comparison units; A microcomputer for outputting an audio signal applied to the audio head, an audio signal reproduced from the audio head, the head switching signal, and a display control signal for notifying whether the audio carrier frequency is abnormal according to the digital information from the determination unit; And a display unit for displaying whether an audio signal applied to the audio head, an audio signal reproduced from the audio head, the head switching signal, and the audio carrier frequency are abnormal based on the display control signal from the microcomputer.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of an apparatus for detecting an audio defect in a video cassette recorder according to the present invention. The signal processor 50, the servo unit 70, the first, second, third, and fourth comparison units 81, 82, 83, and 84, the determination unit 85, the microcomputer 90, and the OSD unit 100 are included. do.

In the figure, the audio head 10 reads the audio signal recorded in the deep portion of the video tape magnetic layer and applies it to the first signal amplifier 20 while the two audio heads are switched to each other based on the rotation of the head drum. The audio signal from the second signal amplifier 60 is recorded in the deep portion of the video tape magnetic layer.

In addition, the first signal amplifier 20 amplifies an audio signal applied from the audio head 10 and applies it to the reproduction signal processor 30, and the reproduction signal processor 30 is a channel from the audio carrier oscillator 40. The audio signal from the first signal amplifier 20 is demodulated and stereo-separated based on the carrier frequency to output the separated audio signals of the two channels (R, L).

In addition, the audio carrier generator 40 oscillates the left (L) channel carrier frequency of 1.30 MHz and the right (R) channel carrier frequency of 1.70 MHz because the audio signal is a stereo two channel.

On the other hand, the recording signal processing unit 50 FM-modulates, synthesizes and outputs the audio signals R and L applied using both channel carrier frequencies from the audio carrier oscillation unit 40.

The second signal amplifying unit 60 amplifies the audio signal from the recording signal processing unit 50 into an easy-to-record signal and applies it to the audio head 10.

In addition, the servo unit 70 selectively rotates and runs the head drum and the video tape based on the drive control signal from the microcomputer 90, and outputs a head switching signal resulting from the rotation of the head drum.

On the other hand, the first comparison unit 81 compares the head switching signal 30Hz from the servo unit 70 with the reference oscillation signal, determines whether the head switching signal is within a predetermined range, and outputs the first comparison signal.

The second comparator 82 detects an envelope of the audio signal read out from the first signal amplifier 20 and compares it with a predetermined reference signal to compare a second comparison signal indicating whether an audio signal of a normal level is read. Output

In addition, the third comparison unit 83 outputs a third comparison signal by comparing with a predetermined reference oscillation frequency to determine whether both channel carrier frequencies (1.3 MHz and 1.7 MHz) from the audio carrier oscillation unit 40 are accurately oscillated. do.

On the other hand, the fourth comparator 84 detects an envelope, compares it with a predetermined reference signal, and outputs a fourth comparison signal in order to determine whether the modulated audio signal from the recording signal processor 50 has a normal level.

The determination unit 85 indicates the abnormality of the audio system based on the first, second, third and fourth comparison signals from the first, second, third and fourth comparison units 81, 82, 83, and 84. The data is formatted as data information DATA as shown in FIG. 2 of the predetermined bit (8 bits) and transmitted to the microcomputer 90 in synchronization with the clock signal CLK.

On the other hand, the microcomputer 90 controls the overall operation of the video cassette recorder, selectively outputs a drive control signal for controlling the servo unit 70, and records it based on the data information DATA from the determination unit 85. And a display control signal for recognizing the abnormality of the audio system at the time of reproduction to the OSD unit 100.

The on-screen display (OSD) unit 100 reproduces the head switching signal, the audio signal applied to the audio head 10 at the time of recording, and the audio head at the time of reproduction, based on the display control signal from the microcomputer 90. A predetermined text signal for displaying an abnormality of an audio signal, an oscillation of an audio carrier frequency, etc. is synthesized and output to an applied video signal or a blue-back signal.

Next, an operation process of the audio failure detecting apparatus in the video cassette recorder including the above-described configuration unit will be described in detail.

First, during recording, the microcomputer 90 applies a drive control signal to the servo unit 70, and the servo unit 70 records the applied video and audio signals on the video tape while rotating and running the head drum and the video tape. .

At this time, the audio carrier frequency (R, L) is respectively oscillated by the audio carrier oscillator 40, the audio signal (R, L) applied from the recording signal processor 50 is FM-modulated and synthesized by the second signal amplifier 60 ) Is applied.

Then, the second signal amplifier 60 amplifies the audio signal to be applied to the audio head 10 to record the audio signal.

On the other hand, the FM signal modulated and synthesized by the recording signal processor 50 is applied to the fourth comparator 84 to compare the envelope detection and a predetermined reference signal to compare the fourth comparison to determine whether the audio signal to be recorded has a normal level. The signal is applied to the determination unit 85.

In addition, the third comparison signal for determining whether the two channel carrier frequencies oscillated by the audio carrier oscillator 40 are applied to the third comparator 83 to determine whether the two channel carrier frequencies are oscillated normally by reference clocks, respectively. Is applied to 85.

In addition, the servo unit 70 determines whether the head switching signal (30 Hz), which is generated due to the rotation of the head drum and reproduces while switching the video head and the audio head 10 (not shown), has the correct frequency. For comparison, the first comparison effect is compared to the predetermined reference clock is applied to the determination unit 85.

Then, the determination unit 85 converts the data having a predetermined format as shown in FIG. 2 into 8 bits, i.e., abnormality of the modulated audio signal (7th bit), and abnormality of R channel carrier frequency (6th bit). And the L channel carrier frequency abnormality (5th bit), head switching signal abnormality (4th bit), power supply abnormality (2nd bit), and the like, and the microcomputer 100 synchronizes with the predetermined clock CLK. Is applied.

At this time, abnormality (third bit) of the reproduced audio signal is ignored since it is recording.

On the other hand, the machicomm 90 received the data of the above-described format applies a display control signal to the OSD unit 100 to inform the presence of abnormality, the OSD unit 100 corresponds to the applied image signal or blue back signal By synthesizing and outputting the text signal, the user can check whether there is an abnormality in the audio system.

On the other hand, during reproduction, an audio signal is read out from the video tape through the audio head 10 while rotating and running the head drum and the video tape under the control of the servo unit 70 similarly to the above-described recording.

At this time, the audio signal read out from the audio head 10 is applied to the first signal amplifier 20, amplified, and then applied to the reproduction signal processor 30 to be FM demodulated and stereo separated.

In addition, the audio signal amplified from the first signal amplifier 20 is applied to the second comparator 82 so as to determine whether the reproduced signal is reproduced at a normal level. Is applied to the determination unit 85.

Then, the judging section 85 causes the abnormality of both channel carrier frequencies (the 6th and 5th bits), the abnormality of the head switching signal (the 4th bit), and the abnormality of the reproduced audio signal (the third Bit) and an 8-bit data format indicating whether or not there is a power supply abnormality (second bit) is applied to the microcomputer 90.

At this time, the seventh bit is ignored because it is a reproduction mode.

Then, the microcomputer 90 applies a display control signal to the OSD unit 100 to recognize whether there is an abnormality in both channel carrier frequencies, an abnormality in the head switching signal, an abnormality in the reproduced audio signal, and an abnormal power supply. The OSD unit 100 synthesizes the corresponding text signal into an image signal or a blue back signal and outputs the text signal, so that the user can recognize an abnormality of the audio system using a monitor (not shown).

As described above, according to the present invention, by determining whether the audio system is abnormal during recording and playback, the user can easily grasp the defective state of the audio system during production or repair.

Claims (1)

An apparatus for checking an input / output operation state of an audio signal in a video cassette recorder, comprising: a first comparison unit (81) for outputting a first comparison signal by comparing a head switching signal for switching an audio head with a predetermined reference clock; A second comparing unit 82 which detects an envelope of the audio signal read out by the audio head and outputs a second comparison signal by comparing it with a predetermined reference value; A third comparison unit 83 for outputting a third comparison signal by comparing an audio carrier frequency for modulation and demodulation during recording and reproduction of the audio signal with a predetermined reference clock; A fourth comparing unit 84 which detects an envelope of the audio signal modulated by the audio carrier frequency and outputs a fourth comparison signal by comparing with the predetermined reference value; A determination unit (85) for outputting digital information of a predetermined format based on the first, second, third, fourth comparison signals from the first, second, third, fourth comparison units (81,82,83,84); Outputting an audio signal applied to the audio head, an audio signal reproduced from the audio head, the head switching signal, and a display control signal for notifying whether the audio carrier frequency is abnormal according to the digital information from the determination unit 85; A microcomputer 90; A display unit 100 for displaying an audio signal applied to the audio head, an audio signal reproduced from the audio head, the head switching signal, and an abnormality of the audio carrier frequency based on a display control signal from the microcomputer 90; Apparatus for detecting audio failure in a video cassette recorder comprising a.