JPS6327779B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dropout counter for a disk-shaped information recording medium, which detects positions on a substantially straight line in the radial direction of the medium and calculates dropout pulses present at each position by one. To provide a dropout counter capable of checking dropouts with high accuracy by counting individual dropout groups and counting the number of tracks included therein.

The applicant previously proposed a disk-shaped information recording medium (hereinafter referred to as a disk) as shown in Figure 1, in which main information signals such as video signals and audio signals are recorded in a spiral shape as changes in geometric shapes. . When manufacturing or inspecting such disks, manufacturers detect whether or not dropouts have occurred in the disks to determine the quality of the disks. Conventionally, there is a method of visual inspection using a microscope, etc., but it is impossible to accurately check the number of dropouts that exist on the entire disk, and the disadvantage is that there is no objectivity in determining the quality of the disk. It was hot.

On the other hand, another method is to count the number of dropouts that occur when playing a disc. For example, as shown in Figure 1,
Dropout 2 over 5 tracks on disk 1
If there are dropouts 2b over 2 tracks a and 2b, it is only necessary to obtain a pulse signal as shown in Fig. 2 and count it to detect that there are 7 dropouts. Although the number of dropouts can be accurately inspected, the number of dropout clusters (visually detected as 2) cannot be accurately detected, and there is a drawback that accurate quality control cannot be performed.

The present invention eliminates the above drawbacks, and the third
An example will be described below with reference to the drawings.

FIG. 3 shows a block system diagram of an embodiment of a dropout counter according to the present invention. In the figure, a dropout pulse a as shown in FIG. 4A, which has entered the input terminal 3, is supplied to the flip-flop 4, and the flip-flop 4 is placed in the set state as shown in FIG. 4B. The counter 5 counts the clock signal from the terminal 6 by setting the flip-flop 4, and when a predetermined number of counts (from the time when the first pulse of pulse a is generated to a time just before the disk rotates once) is completed, a count end signal is sent. Output. As a result, the monostable multivibrator (hereinafter referred to as monomulti) 7 is triggered, and a rotational position pulse d of a predetermined width as shown in FIG. 4D is taken out and supplied to the flip-flop 8 and monomulti 9. A pulse c as shown in FIG. 4C is taken out from the monomulti 9 and supplied to the flip-flop 4, which resets the pulse c as shown in FIG. be done.

When the dropout pulse a' comes in again during the H level period of the output pulse d of the monomulti 7, the flip-flop 4 is set, the counter 5 starts counting, and the fall of the output pulse d of the monomulti 7 causes the flip-flop to drop out. 8 is set and the fourth
A signal e as shown in FIG. E is taken out. The state of the flip-flop 8 is determined by the signal d and the signal b.If the signal b is at the H level when the signal d falls, it is in the set state, and if the signal b is at the L level when the signal d falls, it is in the reset state.

If the dropout disappears when the disk rotates three times after the first dropout, flip-flop 4 remains reset by signal c of monomulti 9, and flip-flop 8 remains reset by signal d.
It is reset by the fall of the signal b and the L level of the signal b. When the flip-flop 8 falls, a dropout end pulse f as shown in FIG. 4F is taken out from the monomulti 11. For example, for a disk with dropouts 2a and 2b at two locations, such as the one shown in FIG. 1, two dropout end pulses f are taken out, and the inspector confirms that there are dropout groups at two locations. obtain.

In this way, a position pulse d is created by the occurrence of a dropout, and a dropout pulse a is added thereto.
If it exists, it is regarded as a series of dropout groups located approximately on a straight line in the radial direction of the disk, and this is counted. This allows the number of dropout groups to be tested more easily and accurately than by visual inspection using a microscope.

The counter 10 counts the number of continuous drop-out tracks, and a concrete block diagram thereof is shown in FIG. In the same figure, the signal c from the monomulti 9 is supplied to the hexadecimal counter 12,
When the dropout continues for 15 tracks, a signal is taken out and the flip-flop 13 is set, while the decimal counter 14 is set. When dropout continues for 150 tracks, counter 1
A signal is taken from flip-flop 4 and sent to flip-flop 15.
is set. The gate circuit 16 satisfies the condition that 1≦N<15, where N is the number of continuous tracks of dropout.
When 15≦N<150 (i.e., there is an output from flip-flop 13 but no output from flip-flop 15), output terminal 1 is applied.
6b, when 150≦N (that is, the output of flip-flop 13 is present, and the output of flip-flop 15 is
output terminals 16c) are configured such that signals are taken out from the output terminals 16c, respectively.

For example, if the dropout continues for 20 tracks, a signal is taken from the counter 12 and the flip-flop 13 is set. At this time, no signal is taken out from the counter 14, and the flip-flop 15 remains in the reset state. When the dropout is completed, the fourth
A dropout end pulse f as shown in FIG. F is taken out and supplied to the gate circuit 16 as a trigger. This trigger causes the gate circuit 16 to take in the states of the flip-flops 13 and 15, and a signal is taken out from the output terminal 16b. This allows the inspector to determine that the dropout is 15
It can be confirmed that the number of tracks continued for more than 150 tracks. The dropout end pulse f is delayed by a predetermined time in the delay circuit 18, and is supplied to the counter 12 and flip-flop 13 to reset them.

In this way, since signals are taken out from the output terminals 16a to 16c in accordance with the number of continuous tracks of dropouts, it is possible to easily know the size of the dropout group in the radial direction.

FIG. 6 shows a block diagram of another embodiment of the counter of the present invention. In the figure, 19 ₁ to 19 ₃ are first to third group detection circuits each having the configuration shown in FIG. 3, and the three output terminals of each circuit correspond to the output terminals 16a to 16c shown in FIG. . Reference numeral 20 denotes a gate circuit that determines the operational priority of the group detection circuits 19 ₁ to 19 ₃ .

Among the dropout pulses a shown in FIG. 4A that have entered the input terminal 3', the first dropout pulse is selected by the gate circuit 20 and supplied to the first group detection circuit ₁₉₁ , where it is in,
The number of continuous tracks of dropout is counted in the same manner as explained in FIGS. 3 to 5, and signals corresponding to the number of tracks are taken out from the respective output terminals 19 _1a to 19 _1c .

Here, while the first group detection circuit 19 ₁ is operating,
In other words, on a concentric circle with a series of dropouts in the disk radial direction from the first dropout,
If there is a dropout other than this series of dropouts (dropout 2c in Figure 1),
The gate circuit 20 is activated by the output of the detection circuit ₁₉₁ and the dropout pulse a, and its output is supplied to the second group detection circuit ₁₉₂ , which counts the number of continuous tracks of dropout and calculates the number of continuous tracks. The corresponding signals are sent to their respective output terminals 19.
Extracted from _2a to 19 _2c . At this time, the gate circuit 20 outputs the output signal b of the flip-flop 4 of the first group detection circuit ₁₉₁ and the output signal d of the monomulti 7.
Using the pulse g (Fig. 4G) obtained by
If a dropout pulse is received while pulse g is at the H level, it is determined that the dropout is different from the dropout being counted. Similarly,
If there is yet another dropout on the concentric circle, the third group detection circuit ₁₉₃ is activated.

The outputs of the detection circuits 19 ₁ to 19 ₃ are ORed by a gate circuit 21 comprising an OR circuit, and supplied to a weighting circuit 22 comprising, for example, a microcomputer. Here, calculations are performed according to the number of continuous tracks of the dropout, for example,
A judgment is made such that 15 tracks or less are acceptable, and 150 or more tracks are unacceptable.

Note that the application of the weighting circuit is not limited to that shown in FIG.
Of course, it may be used by connecting to a to 16c.

As described above, the dropout counter of the disc-shaped information recording medium according to the present invention is configured to detect the dropout by the dropout pulse reproduced from the disc-shaped information recording medium on which the information signal is spirally recorded. A position detection circuit that generates a rotational position pulse for a predetermined time at a position approximately one rotation after the position where the pulse exists, and a position detection circuit that generates a predetermined level state when a dropout is detected within the time that the rotational position pulse is generated due to the rotation. and a circuit that obtains a pulse that returns from the predetermined level state to the original level when dropout is not detected within the time, obtains a dropout end pulse when the pulse returns to the original level, and counts the dropout end pulse. Because of this, it is possible to check the number of dropouts more accurately than the conventional method in which the number of dropouts is measured visually, it is possible to judge the quality of the disk objectively, and it is also possible to count the number of tracks included in the dropout group. Since an additional circuit is provided, the size of the dropout in the disk radial direction can be easily determined, which is convenient in terms of quality control.Furthermore, the provision of stages according to the size of the dropout makes it possible to automatically judge whether the disk is good or bad. In addition, since a plurality of dropout group counting circuits are provided in parallel to the input to sequentially detect dropout groups existing at a plurality of different positions in the rotational direction of the disk, the dropout group on the disk can be easily detected. It has features such as being able to accurately determine the location of the object and performing more accurate quality control.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a disc-shaped information recording medium with dropouts, FIG. 2 is a dropout pulse waveform diagram output by reproducing the medium shown in FIG. 1, and FIG.
4A to 4G are block system diagrams and signal waveform diagrams for explaining the operation of an embodiment of the dropout counter according to the present invention, respectively, and FIG. 5 is a concrete block diagram of the counter 10 shown in FIG. 3. System diagram: FIG. 6 is a block system diagram of another embodiment of the counter of the present invention. 1...Disk, 2a-2c...Dropout, 3...Dropout pulse input terminal, 4,
8, 13, 15...flip flop, 5, 10
... Counter, 7, 9, 11 ... Monostable multivibrator, 12 ... Hexadecimal counter, 14 ... 10
Advance counter, 16, 20, 21... gate circuit,
18...Delay circuit, _191-193 ...Group detection circuit, ₂₂ ...Weighting circuit.

Claims (1)

[Scope of Claims] 1. A dropout pulse reproduced from a disk-shaped information recording medium on which an information signal is spirally recorded causes a predetermined position at a position approximately one rotation after the position where the dropout pulse exists. a position detection circuit that generates a rotational position pulse for a certain amount of time; and a position detection circuit that is at a predetermined level when a dropout is detected within the time period in which the rotational position pulse is generated due to the rotation, and at the predetermined level when the dropout is not detected within the time period. A disk characterized in that it is provided with a dropout group counting circuit that obtains a pulse that returns from a level state to the original level, obtains a dropout end pulse when the pulse returns to the original level, and counts the dropout end pulse. Dropout counter for information recording media. 2. A rotational position pulse is generated for a predetermined period of time at a position approximately one rotation after the position where the dropout pulse exists by a dropout pulse reproduced from a disk-shaped information recording medium on which an information signal is recorded in a spiral shape. a position detection circuit that generates a position pulse; and when a dropout is detected within the time period during which the rotational position pulse is generated by the rotation, the dropout is at a predetermined level state, and when the dropout is not detected within the time period, the dropout state is returned from the predetermined level state to the original level. a dropout group counting circuit that obtains a pulse returning to the original level, obtains a dropout end pulse when the pulse returns to its original level, and counts the dropout end pulse; and a dropout group included in the dropout group detected by the dropout group counting circuit. 1. A dropout counter for a disc-shaped information recording medium, comprising a track number counting circuit for counting the number of information signal tracks. 3. A rotational position pulse is generated for a predetermined period of time at a position approximately one rotation after the position where the dropout pulse exists, using a dropout pulse reproduced from a disk-shaped information recording medium on which an information signal is recorded in a spiral manner. a position detection circuit that generates a position pulse; and when a dropout is detected within the time period during which the rotational position pulse is generated by the rotation, the dropout is at a predetermined level state, and when the dropout is not detected within the time period, the dropout state is returned from the predetermined level state to the original level. a dropout group counting circuit that obtains a pulse returning to the original level, obtains a dropout end pulse when the pulse returns to its original level, and counts the dropout end pulse; and a dropout group included in the dropout group detected by the dropout group counting circuit. A disk characterized in that it is provided with a track number counting circuit that counts the number of information signal tracks, and a circuit that is provided with a plurality of stages depending on the size of the number of tracks and determines the quality of the medium according to the stage. Dropout counter for information recording media. 4 A rotational position pulse is generated for a predetermined period of time at a position approximately one rotation after the position where the dropout pulse exists by a dropout pulse reproduced from a disk-shaped information recording medium on which an information signal is recorded in a spiral shape. a position detection circuit that generates a position pulse; and if a dropout is detected within the time period in which the rotational position pulse is generated by the rotation, the dropout is at a predetermined level state, and if dropout is not detected within the time period, the dropout state is returned to the original level from the predetermined level state. A dropout collective counting circuit that obtains a pulse that returns to the original level, obtains a dropout end pulse when the pulse returns to its original level, and counts the dropout end pulse, is connected to the input of the dropout pulse in multiple stages in parallel. 1. A dropout counter for a disc-shaped information recording medium, characterized in that the dropout counter is provided in a disc-shaped information recording medium and sequentially detects dropout groups existing at a plurality of different positions in the rotational direction of the medium.