KR940008580Y1 - Circuit for checking recording of video cassette recorder - Google Patents

Abstract

No content.

Description

Recording check circuit of video cassette recorder

1 is a conventional two-head video cassette recorder block diagram.

2 is a block diagram of a conventional four-head video cassette recorder.

3 is a block diagram of a video cassette recorder recording confirmation circuit according to the present invention.

4 is a state diagram of a head drum made in the recording confirmation circuit of the video cassette recorder according to the present invention.

* Explanation of symbols for main parts of the drawings

10: recording signal processing circuit 20: reproduction signal processing circuit

30: first transfer circuit 40: second transfer circuit

50: switching circuit 51: first switching signal output unit

52: second switching signal output unit T1, T2: rotary transformer

H1 to H4: Head

The present invention relates to a video cassette recorder (hereinafter referred to as a VCR). In particular, the recording of a VCR such that a video signal input to the VCR is recorded on a video tape and the recorded video signal is reproduced and displayed on a monitor. It relates to a confirmation circuit.

Currently used VCRs operate in a recording mode in which a predetermined video signal is recorded on a video tape under user control, and in a playback mode in which a video signal recorded on a video tape is reproduced and displayed on a monitor or the like. However, such a conventional VCR has been inconvenient because there is no way to check whether or not a predetermined video signal is correctly recorded on a video tape in the recording mode. This will be described with reference to a conventional VCR block diagram. FIG. 1 is a block diagram of a conventional two head VCR, and FIG. 2 is a block diagram of a four head VCR. First, in the case of a two-head VCR, when a user wants to record a predetermined video signal on a video tape, the user can turn off the switch SW11 and turn on the switches SW13 and SW14 by using an operation button or the like of the VCR. It is in a state. Therefore, the input image signal is processed by the recording signal processing circuit 10 and processed by the luminance signal and the color signal, and is then recorded on the video tape by being applied to the video heads H1 and H2 through the rotary transformer T1. At this time, the user has no way of confirming whether the video signal is correctly recorded on the video tape. However, to check this, after operating the VCR for a predetermined time in the fast rewind mode Rewind, the switch SWl1 is turned on, and the switches SW13 and SW14 are turned off to the heads H1 and H2. It should be confirmed that the video signal detected by?) Is amplified by the amplifiers Amp11 and Amp12, and then processed by the reproduction signal processing circuit 20 and displayed on a monitor or the like.

At this time, the switch SW12 causes the video signal of the head in contact with the video tape to be applied to the reproduction signal processing circuit 20 by the PC pulse of the head drum on which the heads H1 and H2 are mounted. 2 is a block diagram of a conventional four-head VCR. At this time, as in the two-head VCR of FIG. 1, it is impossible to simultaneously confirm whether or not the video signal is correctly recorded on the magnetic tape. That is, the conventional four-head VCR records video signals on a video tape using the general standard heads H1 and H2, or is located close to the standard heads H1 and H2, and is located near the top of the VCR. The recording heads H3 and H4 used for low speed reproduction or high speed reproduction other than the reproduction speed are used to determine whether to record. At this time, when the video signal is to be recorded using the standard heads H1 and H2, the switch SW21 is connected to the terminal a. Then, the switch SW24 is turned off, and the switches SW22 and SW23 are turned on so that video signals are sequentially applied to the heads H1 and H2 through a rotary transformer T1 to the video tape. The video signal is recorded.

In this recording mode, the switch SW24 is turned off to form a passage between the switch SW21 and the rotary transformer Tl. At this time, when the user wants to record the video signal using the heads H3 and H4, the switch SW21 is switched to the terminal b, the switch SW27 is turned off, and the switch ( By turning SW25) and SW26 on, the heads H3 and H4 write to the image scene hol video tape sequentially. However, in the conventional four-head VCR, any configuration capable of confirming that the video signal is accurately recorded in the process of recording the video signal using the head H1, H2, or the head H3, H4 is found. Can't see However, the video signal of the recording signal processing circuit 10 was applied to the reproduction signal processing circuit 20 like the two-head VCR, and only the monitor could confirm whether the video signal was input.

For reference, the operation of the play mode of the four-head VCR may be performed using only the heads H1 and H2 during the normal speed playback. A clear image can be obtained. therefore. The switch SW25 (SW26) may be turned on to block a passage through which the video signals detected from the heads H3 and H4 are applied to the reproduction signal processing circuit 20. At this time, the switches SW22 and SW23 are turned off, the switches SW28 are sequentially switched to terminals a and b by the GP pulse of the head drum, and the switch SW30 is connected to the terminals a. By switching, the video signal detected by the heads H1 and H2 is amplified by the amplifiers Amp21 and Amp22 and sequentially applied to the reproduction signal processing circuit 20.

However, when the VCR is operated in the low speed playback or the high speed playback mode, only the heads H1 and H2 cannot accurately detect the video signal of the magnetic tape. In this mode, the heads H3 and H4 are used simultaneously in addition to the heads H1 and H2. That is, the switches SW25 and SW26 are turned off, and the switch SW29 is also switched according to the PG pulse of the head drum, so that the image signals detected by the heads H3 and H4 are amplifiers Amp23 and Amp24. Is amplified and applied to the switch SW30. At this time, the switch SW30 is an envelope not showing the envelope waveform of the video signal detected by the heads H1 and H2 and the envelope waveform of the video signal detected by the heads H3 and H4. By comparing the waveform comparator, the envelope waveform is switched to the larger side, so that only a relatively small video signal is applied to the reproduction signal processing circuit 20 to maintain a clearer image than the two-head system.

However, as described above, in the conventional two-head and four-head VCR, the method of confirming that the video signal is accurately recorded on the video tape in the recording mode is the method of confirming the VCR in the playback mode after the recording of the predetermined video. There was no.

Therefore, when a user records and plays a predetermined picture after recording the VCR in the recording mode, video signals are not recorded on the video tape due to a user's mistake of VCR operation.

The present invention is to solve this problem, the object of the present invention is to use the conventional four-head method, so that the video signal is recorded on the video tape and played back at the same time, the user can confirm whether the VCR is correctly performing the recording mode The present invention provides a recording confirmation circuit of a VCR.

A feature of the present invention for achieving the above object comprises: a recording signal processing circuit for processing luminance and color signals so that an input video signal can be recorded on a video tape; The video signal processed by the recording signal processing circuit is selectively recorded on the video tape by the first and second heads mounted on the head drum, or the video signal recorded on the video tape is detected and output as a detection video signal. A first transfer circuit; A second transfer circuit which always detects the video signal recorded on the video tape with the third and fourth heads mounted on the head drum and outputs the detected video signal as a detected video signal; And a switching circuit connected between the first and second transfer circuits and the reproduction signal processing circuit, the switching circuit for selectively applying to the processing circuit.

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

3 is a block diagram of a recording confirmation circuit of a VCR according to the present invention, which includes a recording signal processing circuit 10, a reproduction signal processing circuit 20, first and second transmission circuits 30, 40 and a switching circuit. It consists of 50. In more detail, the recording signal processing circuit 10 processes the luminance signal and the color signal so as to record an input video signal on a video tape, and has the same configuration as that of a conventional VCR. The playback signal processing circuit 20 is also configured to process the video signal detected by the video head to be displayed on the receiving tube or the like as in the conventional VCR. The first transfer circuit 30 is to record the video signal of the recording signal processing circuit 10 to the video tape using the heads H1 and H2, or to detect the video signal recorded on the video tape. The configuration is the same as a conventional VCR. That is, the first transfer circuit 30 of the present application connects the amplifier Amp1 and the rotary transformer Tl formed in the head drum to the write signal processing circuit 10 in series. At this time, by connecting the grounded switch SW1 between the amplifier Amp1 and the rotary transformer T1, the output of the amplifier Amp1 is applied to the transformer Tl according to the switching of the switch SW1. The rotary transformer Tl is mounted in the head drum of the VCR, and the secondary windings are connected to the first and second heads H1 and H2, respectively. In this case, switches SW2 and SW3 are connected to the rotary transformer Tl, and when the switch SW1 is in an off state, the switches SW2 and SW3 are in an on state and the head Hl is turned on. (H2) is configured to sequentially record the video of the input signal of the recording signal processing circuit 10. The switches SW2 and SW3 of the rotary transformer Tl are turned off when the switch SW1 is in an on state so that the detected video signals of the video tapes detected by the heads H1 and H2 are detected. It is configured to apply to the switching circuit (50).

The second transfer circuit 40 detects an image signal recorded on the video tape by the first and second heads H1 and H2 and applies the same to the switching circuit 50. Like the circuit 30, it is mounted in the head drum. That is, the second transfer circuit 40 is a rotary transformer T2, and the third and fourth heads H3 and H4 are configured. In this case, as shown in FIG. 4, the third and fourth heads H3 and H4 are positioned in close proximity to the first head Hl and the third head H3, and the first head Hl. The fourth head (H4) is positioned in close proximity to the second head (H2) mounted on the head drum at an angle of 180 °. In this case, the third and fourth heads H3 and H4 are configured to lie behind the first and second heads H1 and H2 in the traveling direction of the head drum indicated by the arrow.

At this time, the rotary transformer (T2) is configured so that the tab portion is grounded so that the third and fourth heads (H3), (H4) always detect the video signal of the video tape. At this time, the rotary transformers Tl and T2 are separated from each other by a nonmagnetic material so that the video signals of the heads Hl, H2 and the heads H3 and H4 are not affected by each other.

In addition, the switching circuit 50 is configured to selectively apply the detected image signal of the video tape detected by the first and second transfer circuits 30 and 40 to the reproduction signal processing circuit 20 selectively. The rotary transformers Tl and T2 are connected to the switches SW4 and SW5 through amplifiers Amp2 to Amp4, respectively. At this time. The switches SW4 and SW5 are controlled to be switched by the first switching signal output unit 51, and the first switching signal output unit 51 detects the rotation state of the head drum by PG pulses. The switches SW4 and SW5 are controlled to apply the detected video signals of the heads H1 to H4 for detecting the video signals recorded on the video tape among the heads H1 to H4 to the switch SW6. . The switch SW6 is configured to be selectively switched to the switches SW4 and SW5 according to the control of the second switching signal output unit 52. The second switching signal output unit 52 is an envelope of a detected video signal of a video tape detected by the heads H1 and H2 and a detected video signal of a video tape detected by the heads H3 and H4. By comparing waveforms. The switch SW6 is controlled so that the composite video signal having the larger envelope waveform is applied to the reproduction signal processing circuit 20. In this case, the switch SW7 which is not described may selectively watch the video signal of the reproduction signal processing circuit 20 floating on the video signal applied to the recording signal processing circuit 10 according to a user's selection using a monitor or the like. To be.

The recording confirmation circuit of the VCR according to the present invention configured as described above operates in the recording mode by turning off the switch SW1. That is, the image signal applied to the signal processing circuit 10 is processed to a luminance and color signal so as to be recorded on the video tape, amplified by the amplifier Amp1, and then applied to the rotary transformer Tl. At this time. The first and second heads Hl and H2 connected to the secondary winding of the rotary transformer Tl alternately contact the video tape as the head drum rotates. Therefore, the video signals transmitted through the rotary transformer Tl are alternately recorded on the video tape by the first and second heads H1 and H2. In this case, the third and fourth heads are close to the first and second heads H1 and H2 as shown in FIG. 4, so that the first and second heads H1 and H2 are The recorded video signal is detected and applied to the rotary transformer T2. That is, the video signals recorded on the video tape by the first and second heads H1 and H2 are immediately detected by the third and fourth heads and applied to the rotary transformer T2. At this time. The switches SW4 and SW5 are connected to the video tape by the first switching signal output unit 51 according to the rotation of the head drum, that is, the first and third heads H1 and H3 are in contact with the video tape. When the terminal (a) is switched, and when the second and fourth head (H2), (H4) in contact with the video tape is switched to the terminal (h).

Accordingly, the detected image signal detected by the rotary transformer T2 is applied to the switch SW6, but since the switches SW2 and SW3 of the rotary transformer Tl are on, the switch SW4 is used. No video signal is applied. At this time. The second switching signal output unit 52 compares the envelope waveforms of the video signals applied from the switches SW4 and SW5 to switch the switch SW6 to the larger side. At this time. Since the switch SW4 does not output any video signal, the video signal of the rotary transformer T2 is applied to the reproduction signal processing circuit 20. therefore. If the switch SW7 is turned off, the user can check whether the video signal is correctly recorded on the video tape through the monitor. At this time, since the transformers Tl and T2 are configured together in the head drum, the signals recorded by the first and second heads H1 and H2, and the third and fourth heads H3 and ( H4) For example, the signals detected may interfere with each other and change into noise. In order to prevent such a state, the present invention is to insulate the non-magnetic material between the rotary transformer (Tl), (T2) to prevent this interference by both signals.

Next, a description will be given of performing operations similar to those of the conventional four heads in the slow playback mode or the like of the present invention. First, the user turns on the switch SWl to block the passage between the recording signal processing circuit 10 and the first transfer circuit 30, and turns off the switches SW2 and SW3 to turn off the switch SWl. The first and second heads H1 and H2 detect the video signal of the video tape and operate the VCR in a reproducing mode which is applied to the switching circuit 50. The third and fourth heads H3 and H4 detect the video signal of the video tape in the same manner as in the recording mode so that the rotary transformer T2 applies the detected video signal to the switching circuit 50. . At this time, the switches SW4 and SW5 allow the video signal of the heads H1 to H4 in contact with the video tape to be applied to the switch SW6 by the first switching signal output unit 51 as described above. At this time, in the low speed playback mode, the high speed playback mode, and the still picture mode of the VCR, a noise phenomenon occurs because the running directions of the heads H1 and H2 do not match the tracks of the video tape. However, in the present application, as in the conventional four-head VCR, the second switching signal output unit 52 compares the image signal envelope waveforms of the switches SW4 and SW5 so that the switch SW6 is switched larger. Therefore, since the video signal having a large envelope waveform, that is, the damage is applied to the reproduction signal processing circuit 20, a relatively clear image can be maintained even in a low speed reproduction mode or the like.

As such, the present application detects and reproduces the video signals recorded on the video tapes by the first and second heads by the third and fourth heads in the recording mode, thereby confirming whether the video signals are correctly recorded on the video tape. In the mode, the envelope waveforms of the video signals detected by the first and second heads are compared to improve the image quality by reproducing the cone video signals.

Claims (3)

A recording signal processing circuit 10 for processing luminance and color signals so that an input video signal can be recorded on a video tape; The video signal processed by the recording signal processing circuit 110 is recorded on the video tape by the first and second heads H1 and H2 selectively mounted on the head drum according to the switching, or the image recorded on the video tape. A first shear circuit 30 which detects a signal and outputs it as a detected video signal; and a video signal recorded on a video tape is always detected by the third and fourth heads H3 and H4 mounted on the head drum. A second transmission circuit 40 outputting the detected video signal; The first and second transfer circuits 30 and 40 are connected between the play signal processing circuit 20 and the detected video signals of the first and second transfer circuits 30 and 40 are converted into the play signal. A recording confirmation circuit of a VCR having a switching circuit (50) which is selectively applied to a processing circuit (20). The method of claim 1, wherein the switching circuit; A first switching signal output unit (51) for outputting another switching signal to the PG pulse of the head drum; A detection image signal of the first, second heads H1 and H2 is selectively output according to a switching signal of the first switching signal output unit 51 connected to the first transfer circuit 30. A first switch SW4; When connected to the second transfer circuit 40, the detection image signal of the third, fourth head (H3), (H4) is selectively output according to the switching signal of the first switching signal output unit 51 A second switch (SW5) and: a second switching signal output unit (52) for outputting a switching signal by comparing envelope waveforms of the detected image signals of the first and second switching (SW4) and (SW5); And a third switch SW6 for selectively outputting detection image signals of the first and second switches SW4 and SW5 according to the switching signal of the second switching signal output unit 52. VCR recording confirmation circuit. The recording confirmation circuit of claim 1, wherein the first transfer circuit (30) and the second transfer circuit (40) are separated from each other by a nonmagnetic material.