DE3409557A1 - SYSTEM FOR DETECTING AND DISPLAYING IMPURITIES FOR A SYSTEM FOR READING INFORMATION - Google Patents

Description

System for the detection and display of
Impurities for a readout system
of information

description

The invention relates to a system for the detection and display of contamination for a system for Reading out information, and in particular a system with which contaminants such as those for example occur on a recording medium and a cause of drop-outs is determined and the presence of impurities are displayed to the operator of the system for reading out information.

In systems for reading out information, as in-2Q For example, playback systems for video information and / or sound information, causes the presence of impurities on the recording medium a transducer or on a readout head a temporary absence of the high-frequency playback signal, a so-called "drop-out", which leads to a relatively high level of noise in the reproduced picture or the played sounds. Therefore, these systems need to read out recorded information contain a system that compensates for such drop-outs -QQ can ren.

The usual systems for compensating for drop-outs determine the mean value between the data immediately before the occurrence of a drop-out and the data immediately after the drop-out and use this mean value for compensation. In other cases

will be the data immediately before the drop-out or the data before a specified period of time the drop-out occur, used for the compensation.

With these systems to compensate for drop-outs 5

however, the following problem occurs: There are Contaminants on a larger area of the recording track then the recording medium For example, it is difficult to get the drop-outs over a

to compensate for a correspondingly long period of time. In the all-10

In general, the occurrence of drop-outs over such a long period of time has caused the quality to decrease the reproduced picture and / or sound information has noticeably deteriorated. Furthermore has in some

Cases this long drop-out time to a function 15

malfunction of the servo system that led to the setting the readout position of the transducer is used. So it would be useful to develop a system that recognizes the existence of detects and indicates contamination,

so that the operator of the system removes the contaminants

on the recording medium, the transducer or on other components can remove.

It is therefore an aim of the present invention to

a system for the detection and display of contaminants

To create conditions for a system for reading out information, with the help of which the operator the system for reading information can remove the impurities, so that a better Playback of the recorded picture and / or sound information

mations results. In addition, the aforementioned malfunction of the servo system is prevented.

This is according to the invention by the in the characterizing

Part of claim 1 specified features achieved.
35

Appropriate embodiments are in the subclaims

Pi-

chen compiled.

The advantages achieved with the invention are based on darc on that the inventive system for detection and displaying information to a contamination detector for determining an abnormal condition the readout signal and for generating a contamination detection signal and a holding device "For storing the contamination detection signal having; if there is any contamination, a corresponding display is made according to the output signal the holding device.

5 The invention is explained below on the basis of exemplary embodiments with reference to the accompanying schematic Drawings explained in more detail. Show it

Figure 1 is a block diagram of a first embodiment of a detection and display system of impurities according to the present invention,

Fig. 2 is a block diagram of a second embodiment in which the device for
an integrator is provided to generate the contamination detection signal,

Figure 3 is a block diagram of a third embodiment of a system for detection
and display of impurities after the
Invention, in which the envelope of the reproduced high-frequency signal is determined,

Fig. 4 is a block diagram of a fourth embodiment

./ir-

Form in which the level of the reproduced high-frequency signal is determined will,

Fig. 5 is a block diagram of a fifth embodiment

rungsformrn, in which the envelope of a focus error signal generated by the pickup is generated, is determined,

Fig. 6 is a block diagram of a sixth embodiment in which the level of the focus error signal and comparing a tracking error signal to produce the contamination detection signal to create,

Fig. 7 is a block diagram of a seventh embodiment in which an error in the reproduced Information in the form of encoded data is determined, and

FIG. 8 is a block diagram of an eighth embodiment in which the system of FIG an integrator for the integration of the

Frequency of the error signal is provided. 25th

Reference is now made to FIG. 1 which shows a first embodiment of a system for detecting and display of contaminants according to the present invention

Invention represents.
30th

As can be seen from FIG. 1, this system has a pickup 1 for picking up a high frequency Signal component representing information recorded on a recording disk; it 35

can for example be a sound or a

Act video disc; this pickup 1 supplies an output signal which at the same time contains a focus error signal component, which is the distance between the convergence point of the reading laser beam and the surface of the recording disk and has a tracking error signal component that is the deviation of the light spot of the read out laser beam from the center of the recording track. The one from the transducer

! Q 1 generated RF signal component is a drop-out detector 2 supplied. The drop-out detector 2 has the following structure, for example: A positive pulse and a negative pulse are generated in synchronization with the zero cross points of the high frequency signal; min-

2g at least one of these impulses is used for triggering a multi-trigger, monostable multivibrator (hereinafter referred to as r-mmvbr = retriggerable monostable multivibrator) with a predetermined time constant, for example 207ns

2Q used. This time constant corresponds to the r-mmvbr iir essentially the maximum period of the RF signal. If the RF signal is absent for a period longer than the specified period, this leads State to a reversal of the state of the output signal of the r-mmvbr. Therefore, at the Q output of the r-mir.vbr a drop-out detection signal can be generated, which consists, for example, of a negative impulse. The drop-out detection signal thus generated is then fed to a counter 3. The counter 3 has

₃ q, for example, a binary counter that counts the drop-out signal, a pulse generator for generating a sequence of pulses with a constant interval that are fed to the reset terminal of the binary counter, and several iriitein-

",. other connected, logical links on, which respond to the output signal of the binary counter

speak and generate a high level output signal when the count of the binary counter is a has reached the specified value. The counter 3 together with the drop-out detector 2 forms the contamination detector, which, as the contamination detection signal, has the aforementioned high-level output signal from the counter 3 delivers when a drop-out to more than a specified time within the specified period of time Number of times has occurred.

The contamination detection signal will then be on a timer circuit 4 is applied, which acts as a holding means. The timer circuit 4 can, for example after the creation of the pollution-proof-5

Position signal generate an output signal with a high level for a predetermined period of time T _2. The output of the timer switch 4 is then sent to a
Display device 5 applied, which consists for example of a light-emitting diode.

Referring now to the block diagram of FIG. 2, a second embodiment of the present invention Invention will be explained. This second embodiment has substantially the same structure as that

first embodiment of FIG. 1 with the exception of the Structure of the device for generating the contamination detection signal according to the frequency the occurrence of drop-outs within the specified period of time. This system contains in detail

the pick-up 1, the drop-out detector 2, the timer circuit 4 and the display device 5. In this case However, embodiment, the drop-out detection signal generated by the drop-out detector 2 is sent to one Integrator 6 created. In this integrator 6, the drop-out detection signal is integrated to a To generate output signal whose level is proportional

to the frequency of the frequency of occurrence of the drop-out within the specified time period.
The output of the integrator 6 is in a

Comparator 7 compared with a reference signal. The 5th

Drop-out detector 2, integrator 6 and comparator 7 as a whole form the contamination detector, which generates a high level signal as the contamination detection signal when the number of times the occurrence of the drop-out signals during -

of the predetermined unit time is greater than a predetermined number. By supplying this contamination detection signal the timing circuit 4 becomes the occurrence of contaminants on the recording medium for example, displayed in the same way as in the system of FIG.

Figures 3 and 4 show further embodiments the contamination detection and display system of the present invention. With both of them Embodiments according to Figures 3 and 4, the system has essentially the same structure as the system of Fig. 1 with the exception that the detection of contaminants by detecting a

The amplitude of the RF signal changes, the 25th

is recorded by the transducer 1. In detail, in the embodiment of FIG. 3, that of the Sensor 1 received RF signal to an envelope detector δ supplied, for example by an AM-

Detector circuit is formed. An output signal 30

this envelope detector 8 is then used in a comparator 9 compared with a reference signal. When a drop-out occurs, i.e. when the level of the output signal of the envelope detector 8 or the detector for the beginning or the end of the information momentarily

becomes smaller than a reference voltage, the grain

parator 9 an output pulse signal whose pulse width or pulse duration corresponds to the period in which the level of the output signal from the envelope detector

8 falls. This output pulse signal of the comparator 5

9 is in turn passed to a pulse width detector 10, which during the presence of the The pulse signals supplied to the comparator 9 counts a clock signal and generates an output signal with a high level, if he determines from the count value that the pulse width is greater than a predetermined value. The envelope detector 8, the comparator 9 and the pulse duration detector 10 together form the contamination detector, that is, the high level output of the pulse width detector 10 of the timer circuit 4 as the contamination detection signal when the level drop of the enveloping signal due to the The absence of the RF signal has extended over a period of time which is longer than a predetermined period of time

is. Subsequently, the determination of the contamination is carried out

supply by means of the display device in the same way as in the embodiment of FIG.

In the embodiment of FIG. 4, the RF signal 25th

led from the transducer 1 to a level detector 11,

for example by a half-wave rectifier circuit for receiving the RF signal and a Integrator circuit formed for the integration of the output signal of the half-wave rectifier circuit 30th

will. The level detector 11 thus generates an output signal whose level is proportional to the level of the RF signal is; this output signal of the level detector 11 is applied to a comparator 12 in which the Output signal of the level detector 11 with a pre-

given reference voltage signal is compared. The Pe-

Thus, the detector 11 and the comparator 12 constitute the contamination detector which generates a high level output signal from the comparator 12 and supplies this signal as the contamination detection signal to the timer circuit 4 while the output signal drops to the level of the RF signal. Then the determination of the contamination of the recording medium is shown again in the same way as in the embodiment IQ according to FIG. 1 on the display device.

FIGS. 5 and 6 show further embodiments of the system for the detection and display of contamination according to the present invention having substantially the same structure as the embodiment have according to Figure 1 with the difference that the detection of contamination by exploiting a Error signal occurs, which is generated by the pickup 1.

According to Figure 5, a focus error signal that is generated by the pickup 1, an envelope detector 13 supplied. The enveloping detector 13 is constructed so that it is the enveloping of a low frequency Component of the focus error signal can determine. The envelope detector 13 forms together with the Comparator 14 and the pulse width detector 15, the contamination detector of the timer circuit 4, a high level output signal of the pulse width detector 10 as a contamination detection signal supplies when the level drop of the low, enveloping signal of the low-frequency component of the focus error signal is determined for more than a predetermined period of time. Then this determination of

_r , impurities on the recording medium as in the previous embodiments by means of the display

- 10 -

direction 5 shown.

In the embodiment of Figure 6, a focus error signal and a tracking error signal generated by the pickup in a comparator 16 with each other compared. The comparator 16 thus generates a noise signal in pulse form when the level difference between the focus error signal and the tracking error signal occurs abruptly due to contamination the recording medium has changed. This pulse-like output signal of the comparator 16 is on a Counter circuit 17 having, for example, the same structure as the counter circuit 3 in the above embodiment Has; this counter circuit supplies the timer circuit 4 with an output signal of high level to when the pulse-like output signals from the comparator are within a predetermined period of time are generated at more than a predetermined number of times. Then the detection of impurities in the same way as in the above embodiments by means of the display device 5 shown.

Figures 7 and 8 show block diagrams of further embodiments of the detection system Display of impurities according to the present invention, which differs from the first embodiment of the invention differ only in that the determination of the impurities by means of an error takes place in the coded data contained in the RF signal; this is the case when recording the information has been carried through PCM (pulse code modulations) systems.

In the system of Figure 7, the encoded data contained in the RF signal is passed to a code error detection circuit 18 supplied. If there is an error in

- 11 -

the coded data is detected by the code error detection circuit 18, signals such as an error detection signal and an interpolation command signal, generated and given to the counter circuit 19. The counter circuit 19 has the same, for example Structure like the counter circuit 3; this counter circuit counts the number of times of occurrence of the error detection signal or the interpolation command signal for a predetermined period of time. When the count has reached a predetermined number, an output signal of high level is generated and is supplied to the timer circuit 4 as a contamination detection signal. Then the Festig position of the impurities by means of the display device 5 in the same way as in the above Embodiments carried out.

In the embodiment according to FIG. 8, the error detection signal or the interpolation detection signal, which are generated by the code error detection circuit 18, is sent to an integrator 20. The integrator 20 in turn generates a voltage signal, the level of which corresponds to the number of times the code error detection signal or the interpolation command signal occurs. The output signal of the integrator 20 is compared in a comparator 21 with a predetermined reference voltage; Thus, the comparator 21 generates an error detection signal when the q ₃ Kodefehlerfeststellungssignal or Interpolationsbefehlssignal during a unit time is generated more than a predetermined number of times. The error detection signal from the comparator 21 is then given to the timer circuit 4. the

Finding the impurities will be the same 3t>

- 12 -

/ II

Way as in the above embodiments by means of the display device shown.

From this explanation it can be seen that the basic idea of the present invention is the determination and display of contamination of the recording medium enables. This allows the stable, reliable and trouble-free operation of a playback system, such as a playback system for video and / or sound information, are maintained, by cleaning the surface medium, reproducing magnetic head or mirrors that form part of the pickup system; the respective

¹ ^ cleaning process is initiated according to the status shown by the display device. It thus becomes possible to obtain high quality picture and / or sound signals from the reproduction system; furthermore, malfunctions of the servo system of the reproduction system can be avoided, thereby maintaining the stable operation in reproduction.

The described embodiments can still various modifications and variations can be made. For example, instead of the timer circuit, which is used in the preferred embodiments, a monostable multivibrator or a flip-flop circuit can be used as a holding device. In addition, instead of a light emitting diode, a fluorescent vacuum tube, a liquid crystal device or an alarm device with a buzzer can be used for the representation or display of contamination. In addition, it is not absolutely necessary to indicate and present the detection of contamination; as an alternative to this you can other methods can also be used, such as a

- 13 -

■ / \ <h.

Interruption or pause in playback, the
Ejecting the recording medium or similar measures.

In the case of a device for reproducing information with an electrostatic pickup, the remaining Lifetime of the needle of this pick-up together with the detection of contaminants on the recording device being represented. The following thought is used: Because the The needle of the transducer system causes a change in the frequency characteristic of the transducer output signal, which in turn leads to an associated change in the amplitudes of the carrier waves for the video and / or Sound information, the remaining life of the needle can be determined from the difference between the amplitudes the carrier will be appreciated.

Claims (13)

GRÜNECKER. KINKELDEY. STOCKMAIR & .PARTNER- PIONEER ELECTEONIC COEPOEATION 4-1, Meguro 1-cliome Meguro-ku Tokyo, Japan PA EUROPEAN PATEN " A. GRÜNECKER, nft .- »*» DR H KINKELDEY qipl-'ng DR W STOCKMAIR. w. img. * e < DR K SCHUMANN dipl <™ -s P H JAKOB. DiPi.-IMG DR G BEZOLD. opl-chem W MEISTER, DIPLING H HILGERS. dipl -ing DR H. MEYER-PLATH. »PL .mg 8000 MUNICH 22 MAXlMlLiANSTRASSf 58 P 18 653-dg System for the detection and display of
Impurities for a readout system
of information Claims [IJ Contamination detection and display system for a system for reading out information, characterized by a contamination detector (2, 3, 5 to 21) for detecting an abnormal state of a readout signal taken from a recording medium and for generating a Contamination Resistant : ■ -. ':.: 3A09557 Position signal, by a holding device (4), which the contamination detection signal for a holds a predetermined period of time and an output signal for this predetermined period of time after a last Receipt of the contamination detection signal generated and by a display device (5) for the Representation of the detection of a contamination according to the output signal of the holding device (4). 2. System for the detection and display of contamination according to claim 1, characterized in that the contamination detector has a drop-out detector (2) for determining the absence of a read-out _15th nen signal and for generating a drop-out detection signal and a device (3, 6) responsive to the drop-out detection signal for generating the contamination detection signal corresponding to the frequency of the drop-out detection signal 2Q has within a predetermined period of time. 3 “System for the detection and display of contamination according to claim 2, characterized in that the responsive to the drop-out detection signal Filing a counter (3) for enumerating the drop-out signal and for generating the contamination detection signal is when the drop-out detection signal becomes more than a predetermined number of Times is generated within a predetermined period of time. 4. System for the detection and display of contamination according to claim 2, characterized in that the one responsive to the drop-out detection signal Establishing an integrator (6) for integration 35 of the drop-out detection signal to a comparator (7) for comparing the integrator output signal (6) with a predetermined reference level and for generating the contamination detection signal, when the output signal of the integrator (6) 5 becomes greater than the reference level. 5. System for the detection and display of contamination according to one of claims 1 to 4, characterized in that that the contamination detector has an amplitude detector responsive to the signal read out (8, 11) for generating an output signal that is a measure of the amplitude of the signal read out represents, and one on the output signal of the amplitude tuddetektors (8, 11) appealing device (9, 15 10, 12) for the generation of the contamination detection signal corresponding to the instantaneous level of the output signal of the amplitude detector (8, 11). 6. System for the detection and display of contamination according to claim 5, characterized in that the amplitude detector is a detector (8) for the determination the beginning or the end of the information to generate an envelope signal for the readout 25 This signal is, and that the device responsive to the output signal of the amplitude detector is a
Comparator (9) for comparing the level of the enveloping signal with a predetermined reference level and to generate a comparator output signal, if 30th the level of the enveloping signal is greater than the reference level, and a pulse duration detector (10) for generating the contamination detection signal when the output of the comparator (9) is generated for more than a predetermined period of time. 7. System for the detection and display of contamination according to claim 5, characterized in that the amplitude detector is a level detector (11) for determining the level of the signal read out, and that the device responsive to the output signal of the amplitude detector (11) is a comparator (12) for comparing the output signal of the level detector (11) with a predetermined reference level and for 2Q the generation of the contamination detection signal is when the output signal of the level detector (11) is greater than the reference level. 8. System for the detection and display of contamination according to claim 1, characterized in that the contamination detector has a level detector (13, 16) for detecting a change in the level an error signal component, which represents an error in the readout position and in the read out signal 2Q nal is included, and to generate this level change representative output signal and one responsive to the output signal of the level detector (13, 16) Means (14, 15, 17) for the generation of the contamination detection signal according to the 2g generation of the output signal of the level detector. 9. System for the detection and display of contamination according to claim 8, characterized in that _Qr . the level detector a detector (13) to start with or the end of the information is an enveloping A signal for a focus signal component contained in the read-out signal is generated, and that the device responding to the output signal of the level detector a comparator (14) for the Ver-35 equal to the enveloping signal with a given one Reference level and for generating a comparator output signal, if the level of the enveloping signal is greater than the reference level, and a pulse duration detector (15) for the generation of the contamination 5 has detection signal when the comparator output signal is generated during a period longer than a predetermined period of time. 10. System for the detection and display of contamination according to claim 8, characterized in that the level detector, a comparator (16) for comparing the level of a focus error signal component and a Level of a tracking error signal component contained in the read out signal are included, and for generation 15 of a comparator output signal is when the difference between the levels of the error signals is greater than a is a predetermined value, and that the device responsive to the output signal of the level detector is on Counter (17) for counting the comparator output signal 20th and for generating the contamination detection signal is when the comparator output signal is more than a predetermined amount within a predetermined period of time Number of times has been generated. 11. System for the detection and display of contamination according to claim 1, characterized in that the contamination detector an error detector (18) for the detection of an error in the encoded Data contained in the read-out signal, 30 and for generating an error detection signal upon detection of this error and a device responsive to the error detection signal (19, 20, 21) for generating the error detection signal in accordance with the frequency of generation of the error detection signal has within a predetermined period of time. 12. System for the detection and display of contamination according to claim 11, characterized in that the device responsive to the error detection signal includes a counter (19) for counting the error detection signal and for the generation of the contamination detection signal when the failure detection signal within a given period of time at more than a given number of times is produced. 13. System for the detection and display of contamination according to claim 11, characterized in that the one responsive to the error detection signal Establishing an integrator (20) for integration 15 of the error detection signal and for the generation an integration signal and a comparator (21) for comparing the integration signal with a Reference signal and for the generation of the error contamination signal when the level of the integra- tion signal is greater than the reference level.