JPS6243253B2 - - 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; moving the scanning position and detecting when it crosses the track;
The present invention relates to a playback device having track detection means for detecting that the scanning position is on a desired track.

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 or a video signal and an audio signal are recorded on a record carrier with unevenness or shading. The width of the signal track is approximately 1μ
m, the track pitch is about 2 .mu.m, and the light beam is focused to about 1 .mu.m for high-density recording. 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.

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 this case, it is extremely difficult to scan by jumping over two or more tracks, and if there is eccentricity or uneven track pitch, it may become unstable to reliably jump to an adjacent track. 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 enable stable high-speed searching by reliably jumping to a designated track. It's about doing.

A detailed explanation will be given below with reference to the drawings. FIG. 1 shows one embodiment of the device 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 11 by differential amplifier 12.
1b difference signal is obtained. The compensation circuit 13 is for compensating the phase of the tracking control system, and the output of the differential amplifier 12 is connected to the compensation circuit 13 and the drive circuit 1.
4, the tracking element 15 is driven. The total reflection mirror 5 is attached to a tracking element 15, and the recording carrier 7 is
The upwardly focused light beam 2 is scanned in a direction perpendicular to the track direction. The record carrier 7 is rotated by an electric motor 16, and the record carrier 7 and the electric motor 16
is constructed so that it can be moved in a direction perpendicular to the track direction on the record carrier 7 by a transport motor 17. The transfer motor 17 is driven by a drive circuit 19 using the output of the compensation circuit 13 via a filter circuit 18 . The transport motor 17 is driven in such a way that the light beam 2 focused on the record carrier 7 is located evenly on the track. The relationship between the tracking element 15 and the transport motor 17 is such that the tracking element 15 scans the light beam 2 to track sudden displacements such as eccentricity of the track on the record carrier 7, and the driving voltage of the tracking element 15 increases. The transfer motor 15 is driven so that the average value becomes zero. In this device, as described above, signals are recorded on the record carrier 7 as spiral or concentric tracks. Therefore, if a video signal equivalent to one field or one frame is recorded in one rotation, the scanning beam can be skipped one track backwards in one rotation as shown in Figure 2a. For image playback, if you jump forward one track during one rotation as shown in Figure 2b, you will get double speed playback, and if you jump two tracks backward during one rotation as shown in Figure 2c, you will get reverse motion playback. becomes.
When the signals are recorded concentrically as shown in Figure 2d, it is suitable for still image recording and is often used in still image file devices that play back the same track over a relatively long period of time. However, in this case, after reproducing the information on one track (for example 1), the scanning beam must be transferred to another track (for example 4) according to the request.
Hereinafter, jumping the scanning beam from one track to another will be abbreviated as jumping.

In FIG. 1, symbol A is a synchronizing pulse input for starting jumping when performing jumping, and symbol A is an output obtained by adding together the outputs of amplifiers 10a and 10b by a summation circuit 20. The jumping stop pulse generating circuit 21 confirms from the output of the summation circuit 20 that the light beam 2 crosses the track on the record carrier 7 and is on the designated track, and outputs a pulse to stop jumping. A jumping command circuit 22 outputs a jumping command based on the jumping synchronization pulse, and a jumping voltage generating circuit 2 outputs a jumping stop command based on the output of the jumping stop pulse generating circuit 21.
3 generates a jumping voltage based on the output of the jumping command circuit 22, and drives the tracking element 15 via the drive circuit 14. Furthermore, the process of jumping will be explained in detail. While the tracking control is in progress, the scanning beam 2 is scanning on a certain track. When a jumping synchronization pulse is input to A in this state, the jumping command circuit 22 outputs a jumping command, and the jumping voltage generating circuit 23 generates a jumping voltage. The jumping voltage is applied to the tracking element 1 via the drive circuit 14.
5, the light beam 2 is moved in a direction perpendicular to the track direction on the record carrier 7 by a total reflection mirror 5 attached to a tracking element 15, and is moved in a direction away from the track being tracked. However, after leaving the track, it sequentially crosses adjacent tracks. The jumping stop pulse generation circuit 21 generates a jumping stop pulse after confirming that the light beam crosses the track and reaches the specified track. Based on this pulse, the jumping command circuit 22 outputs a jumping stop command, and then Accordingly, the jumping voltage generating circuit 23 stops generating the jumping voltage, and the light beam 2 scans the designated track. The jumping stop pulse generation circuit 21 will be explained with reference to FIG. The output A of the summation circuit 20 is inputted to an envelope detection circuit 31, further passed through a comparison circuit 32 and a waveform shaping circuit 33, and then inputted to a counting circuit 34. The output of the setting circuit 35 for setting the number of jumping lines and the output of the counting circuit 34 are input to the matching circuit 36, and when the outputs of the setting circuit 35 and the counting circuit 34 become equal, the matching circuit 36 is inputted.
generates a jumping stop pulse and resets the counting circuit 34. The relationship between the signals from the sum circuit 20 to the waveform shaping circuit 33 will be explained with reference to FIG. a is the output of the summation circuit 20 when the light beam 2 crosses the track, b is the output of the envelope detection circuit 31, c is the output of the comparison circuit 32, and d is the output of the waveform shaping circuit 33. It is desirable that the comparator circuit 32 has hysteresis characteristics to prevent chattering. Further, the waveform shaping circuit 33 is for preventing malfunction, and the output of the comparison circuit 32 can be directly input to the counting circuit 34. Further, instead of envelope-detecting the output of the sum circuit 20 by the envelope detection circuit 31, 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 34, setting circuit 35, and coincidence circuit 36 can be constructed from presettable counter circuits.

An example of the jumping voltage generation circuit 23 will be explained with reference to FIG. 5. The jumping voltage generating circuit 23 is composed of a ramp voltage generating circuit 51, a reverse pulse generating circuit 52, a sum circuit 53, an inverting circuit 54, and switches 55 and 56. When the jumping synchronization pulse is input to the jumping command circuit 22, the jumping command circuit 22 triggers the ramp voltage generation circuit 51. As the lamp voltage increases, the light beam deviates from the track being tracked, crosses adjacent tracks one after another, and reaches the designated track. When the light beam reaches the designated track, a jumping stop pulse input is applied to the jumping command circuit 22, and the lamp voltage generating circuit 51 is activated. is stopped, and the reverse pulse generation circuit 52 is triggered to generate a reverse pulse for braking. The input power is used to determine the direction of jumping, and it operates the switch 55 or switch 56, and the output power of the switch 55 or switch 56 is transferred to the drive circuit 14.
is applied to perform jumping. The above operation will be explained using waveform diagrams. FIG. 6 shows a case where the setting circuit 35 is set to jump two beams, where a is the output of the summation circuit 20, b is the jumping synchronization pulse, and c is when the light beam 2 on the record carrier 7 crosses the track. At the same time, d is the output of the matching circuit 36 that generates a jumping stop pulse, e is the output of the jumping command circuit 22, and f is the waveform of the output of the jumping voltage generating circuit. The temporal relationship between waveforms a and c is such that a signal (waveform c) that crosses the track is generated between the moment when the light beam 2 on the record carrier 7 enters the track and the moment when it reaches the center of the track, and vice versa. Although it is preferable to generate a pulse to stop jumping, it is also possible to generate a pulse between the moment the vehicle reaches the center of the track and the moment it exits the track to stop jumping by generating a reverse pulse. Reverse pulse generation circuit 5 in FIG.
The second reverse pulse is for stabilizing the pull-in of the tracking control system when jumping is stopped.
If the moving speed of the light beam at the time of the jumping stop command becomes faster, the light beam will not be drawn into the desired track at the jumping stop command position, but will be drawn into another track. Therefore, the brake is applied by a reverse pulse to reduce the moving speed to ensure that the light beam is not pulled into the desired track at the jumping stop command position. The pulse width or amplitude can be changed depending on the number of jumps. Also, as the jumping voltage, Fig. 5,
Voltage waveforms other than those described in FIG. 6 may also be used. The vertical synchronization signal of the image signal or its frequency-divided signal can be used as the jumping synchronization pulse input a.

As described above, according to the present invention, since a voltage that gradually increases like a lamp voltage is used as a jumping voltage to drive the tracking element, the voltage can be adjusted regardless of variations in characteristics of the tracking element, changes over time, uneven track pitch of the disk, etc. As the light beam rises, the light beam is moved in a direction perpendicular to the track, thereby making it possible to jump across adjacent tracks in sequence, thereby ensuring that the light beam reaches the designated track. Then, it detects that the track has reached the desired track and causes the tracking control system to pull the track into the desired track to perform jumping, so it is reliable regardless of track pitch irregularities, variations in tracking element characteristics, disk eccentricity, etc. Moreover, jumping can be performed quickly. It goes without saying that the present invention is not limited to the above-described embodiments, and can be modified in various ways.

Although the present invention has been explained above using an optical playback device as an example, it can also be applied to a magnetic playback device that uses a magnetic material as a recording medium, a capacitive playback device that uses a recording medium that records signals by changing the capacitance, etc. It goes without saying that it is possible.

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 in concentric circles and whose purpose is 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 an explanatory diagram when reproducing at a speed different from that during recording, FIG. 3 is a block diagram showing a specific configuration of the jumping stop pulse generation circuit 21 shown in FIG. 1, and FIG. FIG. 5 is a block diagram showing one embodiment of the jumping voltage generating circuit, and FIG. 6 is a waveform diagram explaining each part of FIG. 5. DESCRIPTION OF SYMBOLS 1... Light source, 5... Reflection mirror, 7... Record carrier, 9... 2-split photodetector, 11a, 11b...
Envelope detection circuit, 12...Differential amplifier, 1
3... Compensation circuit, 14, 19... Drive circuit, 15
... Tracking element, 17 ... Transfer motor, 1
8... Filter, 20... Sum circuit, 21... Jumping stop pulse generation circuit, 22... Jumping command circuit, 23... Jumping voltage generation circuit.

Claims (1)

[Claims] 1. A record carrier having a track for recording an information signal, a converting means for reproducing a signal from the track of this record carrier, and a tracking control so that the signal reproduction scanning position of the converting means scans on the track. scanning moving means for moving the signal reproducing scanning position of the converting means in a direction substantially perpendicular to the track; a gradual increase signal and a braking pulse signal for driving and controlling the scanning moving means; a driving voltage generating means for generating a driving voltage, a track detecting means for counting the tracks crossed by the converting means moved by the scanning moving means and detecting when a desired recording track has been reached, and a command for instructing the start of jumping. means for operating the driving voltage generating means in response to a command signal from the commanding means to generate a gradual increase signal, driving the scanning moving means, and controlling the driving voltage generating means in relation to the output of the track detecting means. A regeneration device characterized in that it generates the brake pulse signal.