JPH03169181A - Video tape recorder - Google Patents

Abstract

PURPOSE:To limit reproducing by the third person by requiring the input of a personal identification code at the time of reproducing. CONSTITUTION:A comparator circuit 3 compares the output of a control signal decoder 7 with the personal identification code from a memory 2 and when the compared result shows coincidence by conveying a magnetic tape to a personal identification code write position, a mute signal is outputted from the comparator circuit 3 to a mute circuit 9. On the other hand, the reproducing signals of pictures and sounds are applied from a picture and sound reproducing circuit 10 to the mute circuit 9 and the mute circuit 9 mutes video and sound signals to be outputted to a display device 11 with the input of the mute signal. Therefore, the picture and sound are not outputted at the display device 11. When the code same as the personal identification code stored in the memory 2 is inputted to the comparator circuit 3 by operating a personal identification code input device 1, the comparator circuit 3 stops outputting the mute signal. Thus, the third person who does not know the personal identification code can not execute reproducing.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a video table recorder, and particularly to a video table recorder that records a password and protects playback by coding a control signal adopted in the VHS system. Regarding the video table recorder.

(Prior art) Conventionally, ■S type video table recorder (hereinafter referred to as VT
(also referred to as R), a control signal for synchronization with the control track of the magnetic tape is recorded. Furthermore, by changing the duty ratio of this control signal, pinary codes can be recorded. For example, on the control track, a cue code indicating a joint between magnetically recorded video and audio, an address code indicating a distance from a predetermined reference position, a time code, etc. are recorded.

FIG. 2 is a waveform diagram showing control signals in a VHS system VTR, where FIG. 2 (a> shows logic "On" and FIG. 2 (b) shows logic "1".

The logic “0” control signal has a duty ratio of 60±
5%, and the duty ratio of the logic 11 1 I1 control signal is 27±2.5%. These ゛r
By sequentially recording the control signals O N , 11 1 I+, the format of the cue code shown in FIG. 3 can be formed, for example. The cue code is 1 bit “O” indicating the reference position, 61±3 bits “1”
By recording this cue code, the magnetic tape can be easily transported to the recording start position without repeating complicated operations such as fast forwarding, rewinding, and playing. can do.

FIG. 4 is an explanatory diagram showing the format of user data and time code based on control signals.

The header consists of 1 bit “O” indicating a predetermined reference position, 9 bits “1” and 1 bit “O”. Following this header, user data consists of 16 bits. User data is made up of 4 digits BCD (pinary code decimal), and each digit is 4 digits.
It is made up of bits. Furthermore, the time code consists of 31 to 33 bits. By recording this time code, it is possible to display the running time of the tape, and it is also possible to play back the video after a certain period of time from the current position.

By the way, in conventional video tape recorders, for example, videos recorded using the V-S system can be played back unlimitedly if a model of the S-S system is used. That is, during recording, recording on a magnetic tape can be made impossible by breaking the write-preventing pawl provided on the tape cassette, whereas there are no restrictions during playback. Therefore, videos that need to be kept confidential from third parties must be recorded on tape cassettes exclusively for the user. Furthermore, if a video that is inappropriate to be shown to children or the like at home is recorded, extreme care must be taken in storing the tape cassette.

(Problems to be Solved by the Invention) As described above, in the conventional video table recorder described above, even video recorded by a third party can be easily played back, so the recorded video cannot be kept confidential. There was a problem in that it was extremely difficult to put it on.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide a video table recorder capable of restricting playback by a third party by requiring input of a password during playback.

[Structure of the Invention] (Means for Solving the Problems) A video table recorder according to the present invention includes an input device for inputting a password code, a memory for storing the password code, and a control signal that is controlled by the password code. a recording means for modulating the control signal and recording it on a control track of a magnetic tape; a reproducing means for reproducing and demodulating the control signal of the magnetic tape and outputting the code; and storing the code from the reproducing means in the memory. a comparison circuit that outputs a match signal when the comparison results match, and a comparison circuit that outputs a match signal;
and a prohibition means for prohibiting derivation of the reproduced signal.

(Function) In the present invention, the password code input through the input device is stored in the memory and magnetically recorded on the control track of the magnetic tape by the recording means. At the time of reproduction, the reproduction means reproduces and demodulates the control signal and outputs the password code to the comparator circuit. When the magnetic tape is conveyed to the PIN code recording position, the output of the playback means matches the PIN code stored in the memory, so the matching output activates the mute circuit or stops the playback. As a result, the display device is not supplied with a reproduced video signal or the like. When the same code as the password code recorded on the magnetic tape is input through the input device, the mute circuit becomes inactive, or the playback mode is set again and the playback video signal etc. is provided to the display device. In this way, reproduction by a third party who does not know the password is made impossible.

(Embodiment) Hereinafter, an embodiment of the present invention will be explained in detail based on the drawings. FIG. 1 is a block diagram showing an embodiment of a video tape recorder according to the present invention. This is an example of a case where the signal rewriting function is not provided.

The password code input device 1 is equipped with operation keys (not shown), and the password code can be input by user operation. The password code from the password code input device 1 is output to the memory 2 and the comparison circuit 3.

Note that the password code is composed of, for example, a four-digit number. The password code stored in the memory 2 is given to the control signal encoder 4.

The control signal encoder 4 creates a control signal to be recorded on a control track of a magnetic tape (not shown), and the password code from the memory 2 is written into the user data section (see FIG. 4). The PIN code recording switch 5 is controlled to be turned on or off by being supplied with a switching signal based on a user's operation, and a control signal from the control signal encoder 4 is supplied to the control head 6 to magnetically record on the control track of the magnetic tape.

During reproduction, the control head 6 reproduces the control signal and supplies it to the control signal decoder 7. The control signal decoder 7 decodes the control signal, reads out the password written in the user data section, and outputs it to the comparison circuit 3. The comparator circuit 3 also has a personal identification code stored in the memory 2, and the comparator circuit 3
When the password code included in the reproduction control signal from the control signal decoder 7 matches the password code in the memory 2, a mute signal is output to the mute circuit 9. Further, the comparator circuit 3 is configured to stop supplying the mute signal to the mute circuit 9 if the same code as this code is input from the code input device 1 during playback.

The mute circuit 9 is supplied with video and audio signals from the video and audio reproduction circuit 10, and when a mute signal is input from the comparison circuit 3, mutes these video and audio signals. When the mute signal is not input, the mute circuit 9 outputs the video and audio signals as they are to the display device 11. The display device 11 displays the video and outputs the audio based on the signal from the mute circuit 9.

The video and audio reproduction circuit 10 supplies video and audio signals reproduced by a head (not shown) to the mute circuit 9.

Next, the operation of the video table recorder configured as described above will be explained.

If reproduction by a third party is to be made impossible, the user uses the password code input device 1 to input an arbitrary password during recording. This password code is stored in the memory 2 and converted by the control signal encoder 4 into a 4-digit BCD code in which each digit has a 4-bit structure, for example. Note that if the password code is already stored in the memory 2, there is no need to input a new password code.

Next, the user turns on the switch 5 immediately before recording to which playback protection is to be applied. As a result, a control signal containing the password is given to the control head 6 and is stored in the control track of the magnetic tape.

During reproduction, the control signal reproduced by the control head 6 is supplied to the control signal decoder 7 and decoded. The comparison circuit 3 compares the output of the control signal decoder 7 and the PIN code from the memory 2, and when the magnetic tape is conveyed to the PIN code writing position and the comparison results match, the comparison circuit 3 outputs a mute signal. The signal is output to mute circuit 9.

On the other hand, the video and audio reproduction signals are supplied from the video and audio reproduction circuit 10 to the mute circuit 9, and the mute circuit 9 mutes the video and audio signals output to the display device 11 in response to the input of the mute signal. As a result, no video or audio is output on the display device 11.

Here, the user operates the password code input device 1 to input the same code as the password stored in the memory 2 into the comparator circuit 3 . Then, the comparator circuit 3 stops outputting the mute signal. As a result, the mute circuit 9 stops the mute operation, and the display device 11 receives video and audio signals and outputs reproduced images and audio.

Of course, the supply of the mute signal can also be stopped by rewriting the password stored in the memory 2. In this case, the password can only be rewritten after entering the same password as the stored password, and in the end, a person who does not know the password that was stored in memory 2 at the time of recording will be able to rewrite the password. Reproduction by three parties is not possible.

Furthermore, by using a non-volatile memory element such as an EEPROM as the memory 2, the contents of the PIN code in the memory 2 will not change even if the power is turned off.
Reproduction by a third party can be prevented.

As described above, in this embodiment, the PIN code is recorded on the control track, and during playback, the reproduced video and audio signals of the part where the PIN code is recorded are muted,
This mute is canceled and the reproduced video and audio can be obtained only when the password code is input by the user's operation.

Therefore, reproduction by a third party who does not know the password is impossible. For example, when the embodiment device is adopted in a general household, videos that are inappropriate for children can be made unplayable by an extremely simple operation of inputting a password. Note that it may be configured so that the playback mode is not switched to the stop mode when a portion where the password code is recorded is detected.

[Effects of the Invention] As explained above, the present invention has the effect that reproduction by a third party who does not know the password code is impossible.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the video table recorder according to the present invention, Fig. 2 is a waveform diagram showing control signals in a VTR of the S type, and Fig. 3 is an explanation showing the format of the cue code. FIG. 4 is an explanatory diagram showing the format of user data and time code. 1... [1! I code input device, 2... memory, 3
... Comparison circuit, 4... Control signal encoder 6... Control head, 7... Control signal decoder, 9... Mute circuit.

Claims (1)

[Scope of Claims] An input device for inputting a PIN code, a memory for storing the PIN code, and a recording means for modulating a control signal according to the PIN code and recording it on a control track of a magnetic tape. a reproduction means for reproducing and demodulating the control signal of the magnetic tape and outputting the PIN code, and comparing the PIN code from the reproduction means with the PIN code stored in the memory, and when the comparison results match; A video tape recorder comprising: a comparison circuit that outputs a coincidence signal; and a prohibition means that prohibits derivation of the reproduced signal based on the coincidence signal.