JPS6353630B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disc-shaped information recording carrier reproducing apparatus such as a video disc player, and more particularly to a so-called locked track release system.

Here, locked track means that when reproducing information from a disc-shaped information recording carrier, the information detecting means continues to reproduce the same information recording track on the disc-shaped information recording carrier multiple times even though there is no special command.

Conventionally, disc-shaped information recording carrier playback devices such as video disc players (hereinafter simply referred to as players)
Regarding the locked track release system, see 1.
The frame number recorded for each frame is finally detected, 1 is added to that value and stored in a register, and compared with the frame number detected in the next frame, if it is not the same in the case of normal playback. , and in the case of reverse playback, the difference is “2”
At other times, it was detected that a locked track was occurring and the locked track release means was operated.

However, in such a system, the expected effect cannot be obtained on a disk-shaped information recording carrier (hereinafter referred to as a disk) on which a motion picture film is converted into a television signal and recorded thereon for the following reasons.

In other words, while a movie film has 24 frames per second, the NTSC television system, for example, has 30 frames per second, so the so-called 2-
It is recorded using a known technique called 3 conversion. According to this 2-3 conversion method, as shown in Figure 1, one frame of a movie film is recorded in two fields of a television image, and the next frame is recorded in the next three fields. This operation is repeated over and over again, and in the end, 1 frame of 3 fields is recorded 12 times, and 1 frame of 2 fields is recorded 12 times per second, which is exactly the same as that of a television signal.
It handles 30 frames, so there is no time lag or missing frames.

In FIG. 1, the symbol A(C/B) indicates the frame number, C the field number, and B the number of fields in one frame.

However, on discs recorded by converting motion picture film into video signals as described above, the frame number may not increase regularly by 1 for each revolution, so the conventional locked track detection system described above cannot detect locked tracks. False detection may occur.

Conversely, if frame numbers are assigned in increments of 1 every round, when searching for a desired screen and reproducing a still image, a screen spanning two frames may be reproduced as a still image. The drawback was that a good still screen could not be obtained.

In addition, especially with regard to locked tracks in grooved discs, there are cases where the track returns naturally after being locked several times. At this time, if the stylus is forcibly driven in the radial direction of the disk by the release device, it may cause more scratches on the disk surface, so it is better to wait for the stylus to return for a while, but in conventional systems, the locked track release device always was being driven.

Additionally, if a dropout occurs in the area where the frame number is recorded on the disk, the frame number cannot be detected, and even if the correct track is being traced, if the frame number becomes unreadable even once, the locked track release means will be activated. There were also some flaws.

In order to solve such problems, a counter counts the number of times a locked track is detected, and when a locked track is detected two or more times in a row, a release means is activated, and a locked track is detected once. After that, next disk 1
An invention has been devised in which the value of a counter is reset to zero when a locked track is not detected during rotation (for example, in Japanese Patent Application Laid-Open No. 1983-1999).
12537). However, this method has the disadvantage that if a locked track causes the pick-up to go back two or more tracks, the locked track cannot be detected because the locked track does not occur consecutively.

The present invention has been made in view of the above, and an object of the present invention is to provide a disk-shaped information recording carrier reproducing device that eliminates the above-mentioned drawbacks.

The present invention will be explained below using examples.

FIG. 2 is a block diagram of one embodiment of the present invention.

A frame number read out from the disk every round or every half round is inputted from an input terminal 1 as serial or parallel data, and is compared with the value of a register 6 by a frame number comparison circuit 2. A signal having a frequency synchronized with one rotation of the disk is inputted from the terminal 7, and provides the comparison circuit 2 with timing for comparison. Further, the clock generating circuit 8 counts the signal applied to the terminal 7 and supplies it to the gate 5 and the counter 3 as a clock signal of a stepped down frequency.

The register 6 is connected so that the frame number from the input terminal 1 is rewritten only when the gate 5 is activated by the output from the clock generating circuit 8.

The comparator circuit 2 determines whether the contents of the register 6 match the frame number newly input from the input terminal 1 in accordance with the signal input from the terminal 7, and generates an output only when they match.

The counter 3 accumulates the output of the comparison circuit 2, and is cleared when a signal is applied from the clock generation circuit 8. Further, when the integrated value exceeds a predetermined value, the counter 3 sends an output to a drive signal generating circuit 4 which outputs a signal for driving a locked track release device (not shown).

Note that the counter 3 and clock generation circuit 8 are as follows:
The predetermined value and the clock generation cycle can be varied by signals from a control device 9 such as a microcomputer.

Furthermore, if the player equipped with the system of the present invention has a desired screen still mode (still mode), etc. in addition to the normal playback mode, the control device 9
In order to prevent the system according to the present invention from operating while this mode is in operation, an output prohibition signal is generated in the drive signal generator 4, and after the operation is completed, a clock signal is generated in the clock generator circuit 8 in order to prevent the counter 3 from operating. It also has the function of outputting a signal to reset the count value.

The operation of this embodiment configured as above will be explained. The gate 5 is activated by a clock signal output from the clock generating circuit 8 at predetermined time intervals, and the contents of the register 6 are rewritten. Further, the comparator circuit 2 receives a pulse from the input terminal 7 that is generated every rotation of the disk, and the register 6
and the frame number that is input from input terminal 1 and is reproduced every round or half round of the disc. At this time, the comparator circuit 2 generates a coincidence output when the gate 5 is activated, but at the same time a clear signal is input to the counter 3, so the counter 3 does not count the coincidence output.

Assume now that a clock signal is output once every three revolutions of the disk (once every three pulses are input from terminal 7). If a locked track does not occur on a disk on which information has been recorded using the normal method, the value of counter 3 will always be zero, and the value of counter 3 will always be 0.
If the disc has information recorded using the -3 conversion method, it is "0" or "1". However, if a locked track occurs and does not return naturally by the time the next clock signal is input, the counter 3 is cleared by the next clock signal, the contents of register 6 are rewritten, and then the locked track is released. Since the contents of the register 6 and the 3 frame numbers input from the input terminal 1 match, the value of the counter 3 is incremented every revolution of the disk. Therefore, the value of the counter 3 will be 1 or more in the case of a normal type disk, and 1 or 2 or more in the case of a 2-3 conversion type disk. When the value of the counter 3 exceeds a predetermined value (for example, 2) set by a command from the control device 9, the drive signal generation circuit 4 outputs a drive signal to the locked track release device.
Escape from the locked truck.

For example, if the predetermined value according to the command from the control device 9 is set to "2", the disk rotation will be 2 revolutions at the shortest (if a locked track occurs at the same time as the clock signal is input), and 4 revolutions at the longest. (If a locked track occurs in the cycle following the cycle in which the clock signal was input), the locked track release device is activated.

Furthermore, by changing the predetermined value of the counter 3 or the clock generation cycle of the clock generation circuit 8 under the control of the control device 9, the waiting period for natural recovery can be increased or decreased, or the time period until the locked track release device is operated can be changed. It is also possible to change the width between the shortest and longest lengths. Therefore, it is possible to deal with variations in the characteristics of the players or to take measures according to the characteristics of the disc (for example, switching a predetermined value of the counter between the normal method and the 2-3 conversion method).

As another embodiment, as shown in FIG. 3, a latch 5' is provided in place of the gate 5, and the value of the latch 5' is held in the register 6 using a clock signal obtained through a delay circuit 10 that delays the signal for a predetermined time. You may let them. By doing this, when a clock is generated from the clock generation circuit 8, one input can be inputted to the comparator 2 with a predetermined time delay, and when the clock generated one cycle earlier in the comparator 2, the register 6 can be compared with the address just extracted.

Furthermore, when the frame number is recorded as parallel data, the clock generation circuit 8 does not necessarily need to generate a clock signal synchronized with one revolution of the disk, and the contents of the register 6 can be rewritten and rewritten every predetermined time. All that is required is to clear the contents of counter 3.

As described above, according to the present invention, since the counter for counting the number of locked track detections is reset by a clock signal generated at a predetermined period, even when a 2-3 converted disk is used, drop-outs etc. Even if the frame number cannot be read temporarily due to an adverse effect, the locked track release device will not malfunction, and even in the case of a locked track where pick-up is returned for two or more tracks, this will be detected and released. can do.

According to the present invention, locked track can be released regardless of whether the disk is grooved or non-grooved, and whether information is detected optically, capacitively, or magnetically. Furthermore, it goes without saying that the present invention can also be applied to so-called reverse playback in which playback continues while jumping back.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between information recording tracks, frame numbers, and field numbers on a disk, FIG. 2 is a block diagram of one embodiment of the present invention, and FIG. 3 is a diagram of another embodiment of the present invention. It is a block diagram. 2... Comparison circuit, 3... Counter, 4... Drive signal generation circuit, 5... Gate, 6... Register,
8...Clock generation circuit, 5'...Latch, 10
...Delay circuit.

Claims (1)

[Scope of Claims] 1. When the occurrence of a locked track is detected from the address information extracted by an address extracting means which reproduces information from a disc-shaped information recording carrier containing address information in each round and extracts the address information, the locked track is detected. A disk-shaped information recording carrier reproducing device having locked track release means for releasing a locked track, a clock generating means for generating a clock at predetermined time intervals, a register for rewriting and holding the address information in response to the clock, and a register for rewriting and holding the address information in accordance with the clock, Locked track detection means for detecting a locked track by comparing the output with the output of the address extraction means; a counting means for counting the locked track detection signal reset in response to the clock and detected by the locked track detection means; and the counting means. and a drive signal generating means for detecting the output of the locked track and generating a drive signal upon detecting that the detected value is equal to or higher than a predetermined value, and the locked track release means is driven by the drive signal. Disc-shaped information recording carrier reproducing device. 2. The disc-shaped information recording carrier reproducing apparatus according to claim 1, wherein the locked track detecting means detects a locked track depending on the coincidence between the output of the register and the output of the address extracting means.