JPH04205761A - Drop-out position indicating device for video tape - Google Patents

Abstract

PURPOSE:To promote the position detecting accuracy by operating a marker device according to calculation of a calculating device. CONSTITUTION:A video head signal 17 from a video tape recorder 4 is detected by a drop-out detector 14 connected to the recorder 4, and when the signal is lowered below a prescribed output, a drop-out detected signal is generated, and the moment that a video head 3 reaches P point a number (n) is set by a head position counter 15, whereas this number is decreased as the head 3 proceeds to Q point to make the counter zero at the Q point, so that signals 0, 1,..., (n) are generated in turn according to a position of the head by inputting a head changeover signal 18, and these signals are inputted to a calculating device 16 to perform its calculation processing of them. By this processing, the marker device is operated via a marker operating device 19, and the video tape 1 is directly marked around a drop-out position. By this method, the drop- out position can rapidly and accurately be marked up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a videotape dropout position display device, and more particularly, the present invention relates to a videotape dropout position display device, and more particularly, it detects a videotape dropout position, directly marks the area around the dropout position, and detects the dropout position of a videotape. The present invention relates to a videotape dropout position display device for displaying dropout positions.

[Conventional technology]

If there is dust attached to the magnetic layer of the video tape or there is minute damage, recording and playback will not be possible due to the defect.
When the videotape signal is viewed on a television, it appears as white dots or line noise on the screen, significantly degrading the picture quality. This is called dropout, and as one of the ways to improve the quality of video tapes, it is important to obtain as little dropout as possible, and it is necessary to perform this evaluation.

This dropout evaluation method involves recording a high-frequency signal in which a synchronization signal is added to a video signal of a constant amplitude during the videotape production process, and detecting cases where the peak value and signal width of the reproduced signal exceed the allowable values. , and calculate the number using Shihasoku's VTR Dropout Counter VHOI.
Count with a drop-out counter device such as BZ,
Conventionally, a method of determining whether a videotape is good or bad based on this count number has been commonly used. However, with this conventional method, although it is possible to judge the quality of the videotape by comparing the size and number of dropouts,
, it is not possible to analyze the causative agent.

Therefore, in recent years, as a method to easily and quickly detect dropouts and analyze the cause, magnetic markers are recorded on the audio track located directly above or below the dropout defect location on video tape. A method has been proposed. (Special Publication No. 58-2625) [Problem to be Solved by the Invention] However, with this method of recording magnetic markers on the audio track, the recording on the audio track only indicates the approximate position of the dropout. In particular, in recent video tape recorders, the shortest recording wavelength is less than 1 μm, and the size of defects that cause dropouts is several tens of meters larger than conventional video tape recorders.
Since the size is from μm to several μm, accurate dropout position detection cannot be performed. Furthermore, in order to improve the S/N ratio of audio signals, many recent video tape recorders use a system that records audio signals using a rotating head attached to a cylinder. There is a problem that magnetic marking cannot be performed by the head.

[Means to solve the problem]

This invention was made as a result of various studies in view of the current situation, and includes a function of moving in the width direction of the video tape and a marker device for marking the video tape in the video tape running path of the video tape recorder. A dropout detector for detecting a dropout by reproducing a video signal recorded on a videotape, and a head position counter for detecting a video head position at the time of detecting a dropout are connected to a computing device and installed, respectively. By connecting a computing device to a marker device and activating the marker device by the computing device to directly mark the area around the dropout position on the videotape,
The dropout position on the videotape can be detected with high accuracy, and the cause can be easily analyzed.

[Embodiment] Hereinafter, an embodiment of the videotape dropout position display device of the present invention will be described based on the drawings.

FIG. 1 is an explanatory diagram of a videotape scanning system. In the figure, 1 is a videotape, which runs in the direction of arrow A. Reference numeral 2 denotes a video track, which is recorded on the videotape I in an inclined state at an inclination angle θ. A video head 3 scans the video track 2 in the direction of arrow B.

As shown in the device configuration diagram of FIG. 2, the video head 3 includes:
Usually, a rotating cylinder 5 disposed inside the tape recorder 4
There are two on the top. And videotape 1 is
L passes over this rotary cylinder 5 via guide rollers 6 and 7, and is then run in the direction of arrow A via guide rollers 8 and 9, sandwiched between Kyupskun 10 and pinch roller 11, and guided by guide roller 12. While the videotape 1 is running, the marker device 1 installed on the running path of the videotape 1
Pass 3.

L is the length of the video track 2. Now, divide the video track 2 from the starting end P to the ending end Q into n equal parts, and from point Q to P.
0, 1, 2 towards the point. ......i,...
・・・・・・・・・Assuming that equally divided points are set like n-1, n, and a dropout is detected at the i-th point from point Q, the distance X from point i to point Q is calculated by the following formula. (% formula % Here, if the running speed of the videotape 1 in the direction of arrow A is Assuming that the time required to reach point j of the device 13 is t2, this time t2 is
When the distance from point Q to the marker device 13 is defined as X2, the following equation is obtained.

Therefore, point i on the video track 2 is
The time t required to reach the top is .

Further, the position y in the width direction of the videotape 1 from the end point Q of point i is determined by the following equation (5).

y −−L sinθ (5) Here, in equations (4) and (5), θ, V, and Xz are constants determined by the video tape recorder, and L and n are arbitrary. It is a constant. Therefore, if the dropout position i is determined from equations (4) and (5), j of the marker device 13 is determined.
The delay time to the point and the position y of the marker position 13 in the width direction of the video tape 1 are uniquely determined.

In FIG. 2, an arithmetic unit 16 connected to the video tape recorder 4 via a dropout detector 14 and a head position counter 15 calculates the following equations (4) and (
5) is an arithmetic unit that performs the arithmetic processing, and a dropout detector 14 connected to the video tape recorder 4 detects the video head signal 17 taken out from the video tape recorder 4.
is detected and generates a dropout detection signal when the output falls below a predetermined level.
In the head position counter 15 connected to the head position counter 15, the number "n" is set at the moment the video head 3 reaches point P, and as the video head 3 moves toward point Q, it is sequentially subtracted and
When the head switching signal 18 is input, the counter becomes "0" at the point, and then the signal 0 corresponding to the head position is sequentially changed to L by inputting the head switching signal 18.
,1,2,・・・・・・・・・1.・・・・・・・・・
n is generated and manually inputted to the arithmetic unit 16 connected to the F lossop-out detector 14 and the head position counter 15.
The calculation process 5) is performed.

Then, by this calculation process, the marker device 13 is activated via the marker activation device 19 connected to the calculation device 16, and the marker device 13 is moved to the position y at a time delayed by the amount of time. Marks are placed directly around the dropout location on the videotape 1.

FIG. 3 shows the operating mechanism of the marker device 13 which is actuated by the output from the arithmetic device 16 via the marker actuating device 19. As a mechanism capable of moving in two vertical directions, it is provided with a y-direction movement mechanism 20 and a two-direction movement mechanism 21 each using an independent electromagnetic coil, and a cylindrical marker 22 is attached. Then, a current is applied from the marker actuating device 19, and the marker is moved to a predetermined position by the y-direction moving mechanism 20, and furthermore, the two-direction moving mechanism 21 is momentarily actuated, and the marker 2 is moved to a predetermined position by the y-direction moving mechanism 20.
2 is pressed onto the videotape 1, and a mark 24 is made around the dropout position 23 on the videotape 1, as shown in FIG. Note that the marker device 13
The y-direction moving mechanism 20 and the Z-direction moving mechanism 21 have been described using electromagnetic coils, but are not limited to using electromagnetic coils.If equivalent functions can be obtained, electric stages, Other methods such as driving by an actuator using a piezo element may also be used.

[Effect]

The videotape dropout position display device of the present invention is constructed as described above, and when displaying the dropout position of the videotape 1, a video signal is recorded on the videotape 1 in advance, rewound, Perform playback.

Next, at the moment when the video head 3 reaches point P, which is the starting point of the video track 2, a video head switching signal 18 is output from the video tape recorder 4, inputted to the head position counter 15, and a video head switching signal 18 is input. At the same time, the number "n" is set. Then, as the video head 3 scans and moves with the rotation of the rotary cylinder 5, a position signal subtracted corresponding to the position is output to the arithmetic unit 16.

When the video head 3 scans a dropout existing on the video track 2, the output of the video head signal 17 momentarily drops, and at the same time, the input of this signal activates the dropout detector 14. A dropout detection pulse signal corresponding to the output reduction level of the video head signal 17 and its time is output to the arithmetic unit 16.

In the arithmetic unit 16, the instantaneous head position signal corresponding to the video head position from the head position counter 15 and the dropout detection pulse signal from the dropout detector 14 are inputted and arithmetic processing is performed, and the above equation is calculated. (
The delay time t and marker device y expressed in 4) and (5) are calculated, and this output is input to one marker actuating device.

This activates the marker device 13, and as shown in FIG. 4, a mark 24 is marked around the dropout position 23 when the dropout position 23 passes through the marker device 13.

After the mark 24 is marked around the dropout position 23, the mark 24 is visually inspected, and its center is examined with a microscope or with an X-ray microanalyzer (XMA) or the like. By using this analysis method, the cause of dropout can be quickly analyzed.

[Effects of the Invention] As explained above, the videotape dropout display device of the present invention includes a marker device that marks any position on the videotape during the videotape running path of the videotape recorder. A dropout detector for detecting dropouts by reproducing video signals recorded on a videotape, and a head position counter for detecting the video head position at the time of detecting a dropout are connected to an arithmetic unit. At the same time, a computing device is connected to the marker device, and the computing device calculates the dropout detection signal on the videotape and the video head position signal at that time. Once the position is on the marker device, the marker device is actuated to directly mark the area around the dropout, allowing for a quick and accurate display of the dropout on the videotape. Furthermore, it is possible to easily analyze the cause of dropout.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a videotape scanning system, Fig. 2 is a device configuration diagram of a dropout position display device of the present invention, Fig. 3 is an explanatory diagram of the mechanism of a marker device, and Fig. 4 is a diagram of a dropout position display device of the present invention. 1 is a plan view of a videotape marked by a position indicating device; FIG. 1...Video tape, 2...Video track, 3...
- Video head, 4... Tape recorder, 5... Rotating cylinder, 6. -7.8, 9.12... Guide roller, 10... Capstan, 11... Pinch roller, 13... Marker device, 14... Dropout detector, 15... Head position Counter, 16... Arithmetic device, 17... Video head signal, 18... Head switching signal, 19... Marker actuating device, 20.
...Y-direction actuation mechanism, 21...Z-direction actuation mechanism, 22
... Marker, 23 ... Dropout position, 24
...Mark, L...Length of video track, θ...
Inclination angle of video truck, patent applicant Hitachi Maxell, Ltd.

Claims (1)

[Claims] 1. A marker device that marks any position on the videotape is provided in the videotape running path of the videotape recorder, and the video signal recorded on the videotape is played back and dropped out. A dropout detector that detects a dropout and a head position counter that detects the video head position when detecting a dropout are connected to a computing device and deployed, respectively.The computing device is connected to a marker device and the computing device A dropout position display device for a videotape, characterized in that the dropout position is displayed by activating a marker device by calculating a mark on the videotape. 2. If the head position counter divides the video track diagonally inclined with respect to the video tape from the end point to the start point into n equal parts, and the dropout detection point is defined as i, then this i
2. The dropout position display device for a videotape according to claim 1, wherein the videotape dropout position display device is a head position counter that outputs a count number i from 1 to an end point as a video head position. 3. The computing device determines the length of the video track as L, the inclination angle of the video track with respect to the longitudinal direction of the video tape as θ, the distance from the end of the video track to the marker device at the time of dropout detection as x_2, and the running speed of the video tape as V, when the dropout detection point of the video track obtained by dividing the video track from the end point to the start point into n equal parts is i,
The following formula t=L・cosθ/(n・V)・i+x_2/Vy
= L・sinθ/n・i, move the marker device to the position y in the videotape width direction from the time of dropout detection to the delay time, and activate the marker device after the delay time t. 2. The videotape dropout position indicating device according to claim 1, wherein the videotape dropout position indicating device is an arithmetic device for outputting a signal for marking a mark on the videotape. 4. The marker device uses the input signal from the arithmetic device to
2. The dropout position display device for a videotape according to claim 1, which is a marker device having a function of moving in the width direction of the videotape and a function of making a mark on the videotape.