JPS6231428B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a converting means for reproducing a signal from a recording locus (hereinafter referred to as a track) of a signal recorded on a recording medium, and a signal reproducing scanning position of the converting means in the direction of the track. scanning moving means for moving in a substantially vertical direction; control means for controlling the signal reproduction scanning position so that it is on the track; The present invention relates to an information reproducing apparatus having a track detecting means for detecting that the scanning position has arrived.

An example of such a reproducing device is an optical reproducing device, which converges a light beam generated from a light source onto a disc-shaped record carrier (hereinafter referred to as the record carrier), and creates a concentric or spiral pattern on the record carrier. The light beam is controlled so as to be positioned on a track recorded on the record carrier, and a photodetector detects the reflected light of the light beam from the record carrier or the transmitted light that passes through the record carrier, and reads the signal. It is something. Generally, a He--Ne laser or a semiconductor laser is used as a light source, and an audio signal, a video signal, or a video signal and an audio signal are recorded on a record carrier with unevenness or shading. The light beam is focused to about 1 .mu.m for high-density recording, with a signal track width of about 1 .mu.m and a track pitch of about 2 .mu.m. Therefore, the converging lens used to focus the light beam has a large numerical aperture and a short depth of focus. Focus control is performed to constantly irradiate this focused light beam onto the record carrier.
Since focus control is not directly related to the present invention, detailed description will be omitted.

An object of the present invention is to reproduce signals recorded on a record carrier, especially image signals, at a speed different from the recording speed (slow motion reproduction, quick motion reproduction, still reproduction, etc.) in the above-mentioned optical reproduction device. The goal is to provide a device that makes it possible.

Another object of the present invention is to provide a device suitable for searching and reproducing a video signal at a specific address from among a large amount of video signal information recorded by assigning an address signal to a record carrier. be.

Conventionally, this kind of means involves opening up the tracking control system (controlling the focused light beam so that it is positioned on the track on the record carrier), and transmitting positive rectangular pulses and negative rectangular pulses to the tracking element. This was done by closing the tracking control again after adding the

In such conventional methods, the amount of movement of the light beam varies depending on the characteristics of the tracking element, so the amplitude or pulse width of the applied pulse must be adjusted according to the characteristics of the tracking element, making adjustment extremely difficult. In addition to being troublesome, it is extremely difficult to accurately jump over two or more predetermined track positions. Furthermore, if the recording track shape is distorted due to eccentricity or the like, or if the recording track pitch is uneven or irregular, it may not be possible to even jump to an adjacent track reliably. The present invention eliminates the above-mentioned drawbacks, makes it possible to reliably jump to a predetermined track, stabilize playback at a speed different from the recording speed, and reliably jump to a designated track to enable stable high-speed searching. It's about doing.

A detailed explanation will be given below with reference to the drawings. FIG. 1 shows an embodiment of the apparatus of the present invention. A light beam 2 generated from a light source 1 passes through an intermediate lens 3 and a semitransparent mirror 4, is redirected by a total reflection mirror 5, and is focused onto a record carrier 7 by a converging lens 6. The reflected light 8 reflected on the record carrier 7 passes through the converging lens 6 again, has its direction changed by the total reflection mirror 5 and the semi-transparent mirror 4, and is received by the two-split photodetector 9. The output of the photodetector 9 is sent to an amplifier 10.
a and 10b, detected by envelope detection circuits 11a and 11b, and envelope detection circuits 11a and 11a by differential amplifier 12.
1b difference signal is obtained. The compensation circuit 13 is for compensating the phase characteristics of the tracking control system, and the switch _SW1 is for opening and closing the tracking control system. The output of the differential amplifier 12 passes through a compensation circuit 13 and a tracking drive circuit 14 to drive a tracking element 15. The total reflection mirror 5 is attached to a tracking element 15, and tracking is controlled by the tracking element 15 so that the light beam 2 focused on the recording carrier 7 accurately scans the recording track. As the tracking element 15, one having the same structure as a galvanometer, a bimorph piezoelectric element, etc. can be used. The record carrier 7 is a motor drive control circuit 17
It is rotated by an electric motor 16 driven by. The light source 1, intermediate lens 3, semi-transparent mirror 4, tracking element 15, converging lens 6, and two-split photodetector 9 that constitute the optical system are placed on a transfer table 21, and the transfer table 21 is transferred by a support 20. It is attached to the movable part 19 of the linear motor 18 for
By moving the linear motor 18, the scanning position of the light beam 2 on the record carrier 7 can be moved in a direction perpendicular to the track direction. During normal reproduction, the linear motor 18 is driven by the linear motor drive control circuit 24 through the output of the tracking drive circuit 14 through a filter circuit ₂₃ that passes only low frequency components. Further, a speed detector 25 is attached directly or indirectly to the movable part 19 or the support 20 of the linear motor 18, and a voltage corresponding to the moving speed of the movable part 19 is fed back to the linear motor drive control circuit 24. This is aimed at stabilizing the linear motor drive control system. The linear motor 18 drives the transport stage 21 so that the light beam 2 focused on the record carrier 7 is evenly positioned on the track. Tracking element 15 and linear motor 18
This relationship is such that when there is a rapid displacement of the track position due to eccentricity, distortion, vibration, etc. of the track on the record carrier 7, tracking is performed by displacing the scanning point of the light beam 2 by the tracking element 15. The linear motor 18 is driven so that the driving voltage becomes zero on average. In this device, as described above, signals are recorded on the record carrier 7 as spiral or concentric tracks. When a video signal corresponding to one field or one frame per rotation is recorded in a spiral, the scanning point of the light beam 2 is skipped backward by one track every rotation in addition to playback at the normal speed. It can be used to play back still images, to perform high-speed playback at a desired speed by jumping forward a predetermined number of tracks during one rotation, or to perform high-speed playback at a desired speed by jumping forward a predetermined number of tracks during one rotation. It is possible to obtain reverse motion playback at a desired speed by skipping over the cursor. In addition, when signals are recorded concentrically, it is suitable for still image recording and is often used in still image file devices that play the same track over a relatively long period of time. After reproducing information on a certain track, a random access function is required to reproduce information on another designated track in accordance with a request, and the scanning position of the light beam 2 must be quickly jumped to another designated track. As mentioned above, when performing special playback at a speed different from normal recording (still playback, quick motion playback, back motion playback, slow motion playback, etc.) or playback using the random access function, the light beam 2 is scanned. It is necessary to quickly and accurately jump positions from one playback track to another. Hereinafter, shifting the scanning position of the light beam from one track to another will be abbreviated as jumping. The present invention provides a method suitable for performing such jumping. This will be explained below with reference to the drawings.

In Fig. 1, A is a synchronization pulse input for starting jumping when performing jumping, and B
is the output obtained by adding the outputs of the amplifiers 10a and 10b by the sum circuit 26. The jumping stop pulse generating circuit 30 confirms from the output of the summation circuit 26 that the light beam 2 has crossed the track on the record carrier 7 and has come onto the designated track, and outputs a pulse to stop jumping. The jumping command circuit 27 outputs a jumping command based on the jumping synchronization pulse, and outputs a jumping stop command based on the output of the jumping stop pulse generating circuit 30. Since the jumping voltage generation circuit 28 generates a jumping voltage based on the output of the jumping command circuit 27 and drives the linear motor 18 via the switch SW ₃ and the linear motor drive control circuit 24, the transfer stage 21 on which the elements constituting the optical system are placed is It is moved in the radial direction of the record carrier 7, and the scanning point of the light beam 2 on the record carrier 7 is moved in a direction perpendicular to the track direction. switch
SW ₃ is opened and closed by an inverting circuit 29, and its opening and closing operation is completely opposite to that of switches SW ₁ and SW ₂ , which open and close in conjunction with each other. Under normal conditions, switches SW ₁ and SW ₂ are closed, and switch SW ₃ is open. Therefore, the tracking control system operates, the light beam 2 is tracking on the track, and the linear motor 18 adjusts the position of the transfer table 21 so that the tracking element 15 vibrates at a suitable position near the midpoint of zero applied voltage. It is configured to perform stable and accurate tracking servo control. Next, the operation during jumping will be described. When a jumping synchronization pulse is input to A in the normal playback state described above, the jumping command circuit 27 outputs a jumping command, switches SW ₁ and SW ₂ are opened, the tracking control system is in an open state, and switch S ₃
closes. At the same time, the jumping voltage generation circuit 28
generates a jumping voltage and switches _SW3 ,
The linear motor 18 is driven via the linear motor drive control drive 24. Movable part 1 of linear motor 18
9 is moved, the transfer stage 21 is moved, and the scanning point (convergence point) of the light beam 2 on the record carrier 7 is moved in a direction perpendicular to the track direction, leaving the track that was being tracked and sequentially moving to the adjacent track. go across. The jumping stop pulse generating circuit 30 detects the number of tracks that the scanning point of the light beam 2 sequentially crosses, and when it is confirmed that the scanning point of the light beam 2 has come on the designated track, the jumping stop pulse generating circuit 30 generates a jumping stop pulse. This pulse causes the jumping command circuit 27 to output a jumping stop command, stop the jumping voltage generation circuit 28 from generating the jumping voltage, close the switches SW ₁ and SW ₂ again, and close the switch SW _3.
is opened to return to the normal reproduction state, and tracking control is performed so that the scanning point of the light beam 2 accurately scans the designated track. The jumping stop pulse generation circuit 30 will be explained with reference to FIG. The output B of the summation circuit 26 is input to an envelope detection circuit 30, further passes through an amplification waveform shaping circuit 31, and is input to a counting circuit 32. The output of the setting circuit 33 for setting the number of jumping lines and the output of the counting circuit 32 are input to the coincidence circuit 34, and when the outputs of the setting circuit 33 and the counting circuit 32 become equal, the coincidence circuit 34 generates a jumping stop pulse. At the same time, the counting circuit 32 is reset.
When performing special playback such as slow motion playback or still playback, the number of jumps is set to the setting circuit 33 according to the special playback mode, and when performing a random access function in a still image information file, etc. In this case, the number of differences between the currently reproduced track and the designated track may be set using a logic circuit or a microprocessor. The relationship of signals from the sum circuit 26 to the amplification waveform shaping circuit 31 will be explained with reference to FIG. a is the output of the summation circuit 26 when the light beam 2 crosses the track, and b is the output of the envelope detection circuit 3.
0 and c are the outputs of the amplification waveform shaping circuit 31. It is desirable that the amplification waveform shaping circuit 31 has hysteresis characteristics to prevent chattering. In FIG. 2, instead of envelope-detecting the output of the summation circuit 26 by the envelope detection circuit 30, either one of the outputs of the envelope detection circuits 11a and 11b or the sum signal can be used. Note that the counting circuit 32, the setting circuit 33, and the matching circuit 34 can be constructed from counter circuits that can be preset.

An example of the jumping voltage generating circuit 28 will be explained with reference to FIG. 4. The jumping voltage generation circuit 28 surrounded by a dotted line is the pulse voltage generation circuit 3.
5. It is composed of a step voltage generation circuit 36, a reverse pulse voltage generation circuit 37, a sum circuit 38, an inversion circuit 39, and switches SW ₄ and SW _5. The output F of the jumping voltage generation circuit 28 passes through the switch SW ₃ . It is added to the linear motor drive control circuit 24. As shown in FIG. 4, the drive control system of the linear motor 18 is controlled according to the moving speed of a bar magnet 41 that is supported by a coupling body 40 on the movable part 19 of the linear motor 18 or the support body 20 of the transfer table 21 and moves in conjunction with the movable part 19. The output of the speed detector 25 is amplified to an appropriate level by the amplifier circuit 44 from the output of the speed detection element 43 which generates a voltage in the coil 42, and the output is fed back to the linear motor drive control circuit 24.
Therefore, the movable portion 19 of the linear motor 18 is controlled to move at a speed corresponding to the voltage applied to the linear motor drive control circuit 24. When a constant voltage is applied to the linear motor drive control circuit 24, the movable portion 19 of the linear motor 18 moves at a constant speed corresponding to the applied voltage except during startup.

In order to make jumping stable, the tracking control system must be able to pull in the relative speed between the moving speed of the light beam 2 on the record carrier 7 and the moving speed of the track due to eccentricity or track pitch unevenness, etc. when jumping. is necessary.
There is a limit to the relative speed that the tracking control system can pull in, and if the relative speed exceeds the limit, when the tracking control system is closed again, the truck will not be pulled into the predetermined detected track, but will be pulled into another track that has gone too far. Sometimes it happens. Therefore, to ensure stable retraction, when the tracking servo is closed again, it is desirable to apply a brake to bring the relative movement speed between the light beam 2 and the track below the retraction speed of the tracking control system to prevent overshoot. If the moving speed of the light beam on the record carrier 7 differs depending on the number of jumps and the jumping distance, the braking force needs to be changed depending on the moving speed. Therefore, a means for detecting the speed of the light beam 2, etc. is required, and the apparatus becomes very complicated.
Therefore, if the light beam 2 is moved at a substantially constant speed and a substantially constant braking force is applied, an extremely simple device can be obtained. From the above, it is preferable to move the movable portion 19 of the linear motor 18 at approximately constant speed during jumping. As described above, if a constant voltage is applied to the linear motor drive control circuit 24, the linear motor 18 moves at a constant speed corresponding to the voltage, so a step voltage is preferable for the jumping voltage generating circuit. However, since the linear motor drive control system does not have a constant speed at the time of startup, the characteristics can be further improved by superimposing a pulse voltage only for a certain period of time at the time of startup in order to improve the characteristics at the time of startup. As the braking force, a voltage of opposite polarity to the applied voltage may be applied to the linear motor drive control circuit 24 for a certain period of time. Therefore, it is preferable that the jumping voltage generation circuit 28 include a pulse voltage generation circuit, a step voltage generation circuit, and a reverse polarity pulse generation circuit. In FIG. 4, when the jumping synchronization pulse A is input to the jumping command circuit 27, the jumping command circuit 27
triggers the pulse voltage generation circuit 35 and step voltage generation circuit 36. Pulse voltage generation circuit 3
5. The output of the step voltage generation circuit 36 is the sum circuit 3
8 and is added to the linear motor drive control circuit 24 as the output F of the jumping voltage generation circuit 28 via the switch SW ₄ or the inverting circuit 39 and the switch SW ₅ . The pulse voltage generating circuit 35 operates only for a short period of time, and the input E that generates the pulse _voltage is for determining the direction of jumping.
SW ₅ is operated to make the output of switch SW ₄ or SW ₅ the output F of the jumping voltage generation circuit 28.
When the output F of the jumping voltage generation circuit 28 is applied to the linear motor drive control circuit 24, the movable part 19 of the linear motor 18, and therefore the transfer table 21, starts to move, and since the tracking control system is in the open state, the transfer is stopped. As the table 21 moves, the light beam 2 deviates from the track being tracked and sequentially crosses adjacent tracks until it reaches the designated track, and a jumping stop pulse input D is applied to the jumping command circuit 27, and the step voltage generating circuit 36 is stopped, and the reverse pulse generation circuit 37 is triggered to generate a reverse pulse for braking. The width of the reverse pulse for braking is set by the jumping command circuit 27 for a certain period after the jumping stop pulse input D is applied to the jumping command circuit 27, and the reverse pulse is generated by the command output of the jumping command circuit 27. and the switch in Figure 1.
SW ₃ is opened, switches SW ₁ and SW ₂ are closed again, and the tracking control system is operated again to perform tracking to the designated track.

The above operation will be explained using waveform diagrams. FIG. 5 shows a case where the setting circuit 33 is set to jump five lines, where a shows the output of the jumping command circuit 27, and b shows the jumping voltage generation circuit 28.
c is the output of the summation circuit 26 when the light beam 2 on the record carrier 7 crosses the track, d is the output of the envelope detection circuit 30 which envelope-detected the output of the summation circuit 26, and e is the amplified waveform. The output f of the shaping circuit 31 is the waveform of the output D of the coincidence circuit 34 that generates the jumping stop pulse. It is preferable to generate the reverse pulse between the moment when the light beam 2 on the record carrier 7 enters the designated track and the moment when it reaches the center of the track. It is also possible to stop the jumping by causing it to occur between the moment when the jump occurs and the moment when the vehicle exits the truck. It is also possible to generate a jumping stop pulse at the moment the vehicle leaves a track one track before the desired track, and generate a reverse pulse to pull the vehicle into the desired track. In FIG. 4, the pulse voltage generating circuit 35 is for compensating the characteristics at the time of rising, and can be omitted. It is obvious that circuits other than those shown in FIG. 4 can also be used as the jumping voltage generating circuit. As the jumping synchronization pulse input A, a vertical synchronization signal of an image signal or a frequency-divided version thereof can be used.

In the present invention shown in FIG. 1, a method has been described in which a linear motor is used as a means for moving the transfer table 21, but a general electric motor and a rack and pinion or the electric motor are connected to a ball screw, and the transfer table 21 is transferred by the ball screw. If you use other transfer means such as
It goes without saying that the present invention is not limited to the embodiments. Note that as the light source 1, any light source such as a semiconductor laser or a He--Ne laser can be used.

As described above, in the present invention, during jumping, the transfer stage on which the optical system is mounted is moved to move the scanning point of the light beam 2 on the record carrier in a direction substantially perpendicular to the track, so that jumping is performed. There is no limit to the number of jumps caused by the following causes when the scanning point of the light beam 2 on the record carrier 7 is moved by varying the deflection angle of the light beam 2 by the tracking element 15, and the jumping can be stably performed over a wide range. It can be done reliably. When moving the light beam 2 using the tracking element 15, (1) If the tracking element 15 is moved significantly, the light beam 2 will protrude from the aperture of the converging lens 6.

(2) When jumping exceeds the tracking signal detection range (also called tracking control range, approximately 300 to 500 μm) determined by the field of view and aberrations of the converging lens 6, the specified track is detected and jumping is stopped; Even if the tracking control system is closed again, tracking control becomes impossible and stable jumping is impossible.

In this respect, the present invention does not have the above-mentioned drawback of performing jumping without changing the relative positions of the light beam 2 and the converging lens 6 because the transfer stage is moved, and jumping can be performed over a wide range.

According to the present invention, the light beam is scanned in a direction substantially perpendicular to the track, and when it is detected that the light beam has reached the desired track, the tracking control system causes the light beam to be pulled into the desired track to perform jumping. , stable jumping can be performed regardless of eccentricity, etc. Note that the present invention is not limited to the above-mentioned embodiments,
It goes without saying that various modifications can be made.

The present invention has been explained above using an optical reproducing device as an example, but it is also applicable to a magnetic reproducing device that uses a magnetic material as a recording medium, a capacitive reproducing device that uses a recording medium that records a signal by changing the capacitance due to unevenness, etc. Needless to say, it can also be used.

According to the present invention, it is possible to stably obtain special reproduction images such as still images, slow motion images, quick motion images, and back motion images that are reproduced at a time different from the time recorded on a record carrier. I can do it. The present invention is also suitable for use in a search device that records still images concentrically and is intended to instantaneously search and reproduce a desired still image.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a block diagram showing the specific configuration of the jumping stop pulse generation circuit shown in FIG. 1, and FIG. 3 is a waveform diagram explaining the operation when the light beam crosses the track.
FIG. 4 is a block diagram showing one embodiment of the jumping voltage generating circuit, and FIG. 5 is an explanatory diagram of the same operation. DESCRIPTION OF SYMBOLS 1... Light source, 5... Total reflection mirror, 7... Record carrier, 9... 2-split photodetector, 11a, 11b...
Envelope detection circuit, 12...Differential amplifier, 1
3...Compensation circuit, 14...Tracking drive circuit, 15...Tracking element, 18...Linear motor, 21...Transfer table, 23...Filter circuit, 24...Linear motor drive control circuit, 25...
... Speed detector, 26 ... Sum circuit, 27 ... Jumping command circuit, 28 ... Jumping voltage generation circuit, 29 ... Inversion circuit, 30 ... Jumping stop pulse generation circuit.

Claims (1)

[Claims] 1. A conversion means for reproducing an information signal from a signal track on a recording medium, a tracking control means for controlling tracking so that the signal reproduction scanning position of the conversion means is on the track, and operation and malfunction of the tracking control means. a switching means for controlling the operation; a scanning movement means for moving the signal reproduction scanning position of the conversion means in a direction substantially perpendicular to the track direction; a pulse voltage, a step voltage, and a brake for driving the scanning movement means; track detecting means for detecting that the signal reproducing scanning position of the converting means moved by the scanning moving means is at or near a desired track, and track jumping start. a track jumping command means for generating a track jumping start signal, and the track jumping start signal generated by the track jumping command means operates the switching means and disables the tracking control means. At the same time, the signal generating means is operated to generate a pulse voltage and a step voltage to drive the scanning moving means, moving the converting means at a substantially constant speed, and detecting the track in relation to the output of the track detecting means. The jump command means is operated to stop the generation of the pulse voltage and step voltage of the signal generation means, generate a reverse polarity pulse voltage for braking, and operate the switching means to again put the tracking control means into the operating state. An information reproducing device characterized by: