JPH087560Y2 - Period fluctuation width detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a laser display and a laser disc inspection apparatus.

[Outline of device]

In order to detect the periodic fluctuation width of the rotation of the laser disc player due to warpage or deflection of the disc, a method of directly detecting the rotation speed of the motor and comparing it with a reference value to obtain an error can be considered.

However, CLV (Constant
In order to keep the linear velocity constant like the linear velocity method, there are some that change the rotation speed by the inner and outer circumferences of the disk plate. With this method, in order to detect the rotational speed error, a function of detecting the pickup (head) position and changing the reference value is required, which requires a complicated and expensive device. Therefore, paying attention to the fact that the horizontal sync signal contained in the video signal recorded on the disc is reproduced at a constant cycle regardless of the player system, the cycle error of this signal is measured, and the error is integrated. By the
We devised a device that automatically measures the width of periodic fluctuations.

[Conventional technology]

 FIG. 2 shows a block diagram of a conventional device.

1 is a laser disc player, 2 is a disc, 3 is a pickup (head) for extracting the signal stored in the disc, 4 is a conversion circuit for reproducing the signal into a video signal, 5 is a motor for rotating the disc and its control A circuit, 6 is a correction circuit such as a time base collector (TBC) for correcting a temporal change of a reproduced video signal, 17 is an oscilloscope, and 18 is an example of a measured waveform.

In this method, the output of the correction circuit built in the video disc player 1 is used as a reference and is connected to the trigger input (TRIG) of the oscilloscope 17, and the period fluctuation width of the horizontal synchronizing signal included in the video output of the video conversion circuit 4 is changed. Is measured.

That is, using the afterimage of the oscilloscope 17, the measured waveform
The maximum fluctuation of rotation is obtained by visually observing the period fluctuation width T _E shown in Fig. 18.

[Problems to be solved by the device]

In the above-mentioned conventional device, since the output of the correction circuit of the video disk player is used as a reference, it is affected by the characteristics of the correction circuit, and it is necessary to visually check the oscilloscope screen for a long time. There were many variations depending on the measurer, and reliable data could not be obtained.
An object of the present invention is to solve these drawbacks by automatically measuring the period variation width of the horizontal synchronizing signal and obtaining highly accurate data.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a sync separation circuit for extracting a horizontal sync signal from a video signal before time base correction, a cycle counter for counting the cycle of the extracted horizontal sync signal, and a cycle counter output signal. Error detection circuit that detects an error with respect to the horizontal sync signal reference value and sends an error signal, a limiter circuit that sends a correction error signal that limits the maximum value of the error signal to a predetermined amount, and a cycle different from the horizontal sync signal. A non-measurement period detection circuit that detects the non-horizontal synchronization signal period that is the period of the signal that has been accumulated, and the correction error signal is accumulated except during the non-horizontal synchronization signal period, and the accumulation of the correction error signal is prohibited during the non-horizontal synchronization signal period And a PP value detection circuit for obtaining the maximum period fluctuation width of the accumulated value output from the accumulator circuit.

[Action]

According to the present invention, the cycle of the horizontal synchronizing signal is measured by the cycle counter by the above means, and the cycle error is calculated with high accuracy by comparing it with the reference value (constant) and accumulated. The difference between the maximum value and the minimum value, that is, the PP value is obtained, and the periodic fluctuation width with respect to the reference value is obtained. As a result, it becomes possible to automatically measure the period variation width with respect to the reference value of the horizontal synchronizing signal, which significantly reduces the burden on the measurer and enables highly accurate data to be obtained.

〔Example〕

An embodiment of this invention will be described below with reference to FIG. 1
Is a laser disc player, 2 is a disc, 3 is a pickup (head) for extracting the signal recorded on the disc, 4 is a conversion circuit for reproducing the signal into a video signal, 5 is a motor for rotating the disc and its control circuit Reference numeral 6 is a correction circuit such as a time base collector (TBC) for correcting the temporal change of the reproduced video signal, 7 is a period fluctuation width measuring device, and 8 is a sync separation for separating a composite sync signal from the video signal. A circuit, 9 is a cycle counter that measures the cycle of the horizontal sync signal included in the composite sync signal, 10 is an error detection circuit that compares the output of the cycle counter with a reference value and calculates a cycle error, 1
1 is a limiter circuit to reduce the influence on the large period change caused by the loss and increase of the horizontal sync signal due to dropout, 12 is an accumulator circuit that accumulates the period error, and 13 is a composite sync signal. A non-measurement period detection circuit that detects this period and prohibits accumulation in order to prevent erroneous operation due to the measurement of a periodic signal, which is different from the horizontal synchronization signal such as the included equivalent pulse, 14 is the PP value of the accumulation result That is, the PP value detection circuit for obtaining the maximum value of the period variation width, and 15 are microcomputers for inputting the maximum value of the output of the PP value detection circuit and for displaying or printing on a printer or the like.

 Hereinafter, this operation will be described.

A video signal, which is output from the video conversion circuit 4 of the laser disc player 1 and which has a periodic fluctuation due to the uneven rotation of the disc, is input to the periodic fluctuation width measuring device 7.

In the cycle fluctuation width measuring device 7, the composite sync signal contained in this video signal is extracted by the sync separation circuit 8 and sent to the cycle counter 9 and the non-measurement period detection circuit 13.

The cycle counter 9 continuously measures the cycle between each pulse of the composite synchronizing signal. The error detection circuit 10 compares the measured value with a reference value (constant) to obtain an error and sends it to the limiter circuit 11.

The limiter circuit 11 focuses on the fact that the cyclic error of the composite synchronizing signal due to the uneven rotation is small, and limits the maximum value of the error in order to reduce the effect of a large cyclic change due to dropout or the like.

By accumulating this error ε'in the accumulator circuit 12,
Calculate the periodic fluctuation. On the other hand, the composite sync signal includes a pulse having a period different from that of the horizontal sync signal, such as an equivalent pulse. In order to prevent malfunction due to this, the non-measurement period detection circuit 13 causes the equivalent pulse generation period. Is detected, and the accumulator of the accumulator circuit 12 is stopped during this period.

In the PP value detection circuit 14, the PP value of the accumulation circuit 12, that is,
The maximum value of the periodic fluctuation width is obtained and sent to the microcomputer 15, and the measurement result is displayed and printed.

[Effect of device]

According to the present invention, the horizontal sync signal extracted from the signal reproduced from the disc is accumulated with the error with respect to the horizontal sync signal reference value, and the maximum period fluctuation value is obtained from the accumulated value. It is possible to automatically measure the period fluctuation width with respect to the signal reference value, greatly reducing the burden on the measurer and obtaining highly accurate data.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional device. 1: Laser disc player, 2: Disc plate, 3: Pickup, 4: Video conversion circuit, 5: Motor and control circuit, 6: Correction circuit, 7: Period fluctuation width measuring device, 8: Sync separation circuit, 9: Period Counter, 10: Error detection circuit, 11: Limiter circuit, 12: Accumulation circuit, 13: Non-measurement period detection circuit, 14: PP value detection circuit, 15: Microcomputer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyuki Onzo 2480 Santo, Hiratsuka City, Kanagawa Mitsubishi Plastics Corporation Hiratsuka Factory (56) Reference JP 62-33363 (JP, A) JP Sho 59-116962 (JP, A) JP 59-20859 (JP, A) JP 55-131772 (JP, A) JP 2-22561 (JP, A) Actual development Sho 59-18504 (JP, U) Actual Kaihei 2-38884 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A cycle separation width detecting device for detecting a cycle fluctuation width of disk rotation based on a video signal reproduced from a disk; a sync separation circuit for extracting a horizontal sync signal from the video signal before time axis correction; A cycle counter that counts the cycle of the extracted horizontal synchronization signal, an error detection circuit that detects an error of the output signal of the cycle counter with respect to the reference value of the cycle of the horizontal synchronization signal, and outputs an error signal, and the error signal A limiter circuit that sends a correction error signal that limits the maximum value to a predetermined amount, and a non-measurement period detection circuit that detects a non-horizontal synchronization signal period in which a signal having a period different from the period of the horizontal synchronization signal exists. An accumulator circuit that accumulates the correction error signal except during the non-horizontal synchronization signal period, and prohibits accumulation of the correction error signal during the non-horizontal synchronization signal period; A cycle fluctuation width detection device comprising: a PP value detection circuit that calculates the PP value of the accumulated value output from the accumulation circuit and outputs the PP value as the maximum cycle fluctuation width.