JPH0772972B2 - Information playback device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information reproducing apparatus for reproducing various kinds of information disks or information disks in which plural kinds of information having different linear densities are recorded in different areas.

2. Description of the Related Art As optical disc players, players that reproduce two types of CDV discs and compact discs have been commercialized. In such a player, it is necessary to detect which disc is loaded in order to change the internal operation mode according to each disc. Further, when reproducing a CDV disc, it is necessary to discriminate the inner EFM area and the outer video area because the reproduction signal processing methods are different. Conventionally, the code written in the innermost peripheral area is read to determine which disc. In addition, the area of the CDV disk is mechanically detected by providing a switch that is turned on when the head position reaches the beginning of the video area. For example, TV technology April 86 pp
25-33, Radio Technology Separate Volume MOVEMENT VOL.11 pp29-32, Videocom February 1988, pp42-47.

Problems to be Solved by the Invention In the above example, when the video area of a CDV disc is automatically played, it is impossible to determine whether it is a CDV disc or a compact disc unless the code of the innermost circumferential area is read. However, there was a problem that it took time to reproduce.
Further, since the video area is mechanically detected by the switch, there are problems that the accuracy is low and a contact failure is likely to occur.

Means for Solving the Problems The present invention reads a reproduction signal from an information disc, and a head movable in a radial direction of the information disc, a motor for rotating the information disc, and a rotation speed of the motor.
A frequency generator that outputs an FG signal, and a cycle determination means that detects the cycle of each of the reproduction signal and the FG signal and obtains and outputs the ratio of these cycles, and based on the output of the cycle determination means It is characterized in that the type or presence of the information disc is determined.

Further, the present invention, a plurality of types of information of different linear densities, an information disk recorded in different areas, a read signal from the information disk, and a head movable in the radial direction of the information disk, A motor that rotates the information disk, a frequency generator that outputs an FG signal according to the number of rotations of the motor, a cycle of each of the reproduction signal and the FG signal is detected, and a ratio of these cycles is obtained and output. A cycle discriminating means, and discriminating which of the areas the head is reproducing based on the output of the cycle discriminating means.

Effect The present invention, with the above-mentioned configuration, is a disc having a video area even if the rotation speed is not normal,
You can determine if it is not. Further, even when the video area and the audio area are mixed in one disc, it is possible to determine which area. As a result, it is not necessary to read the code in the innermost area, and when the CDV disc is loaded, it is possible to shorten the time until the video region is reproduced by determining that the CDV disc is the CDV disc. Further, since it is not necessary to use a mechanical switch, it is possible to improve the accuracy and the contact failure.

Embodiment Hereinafter, an information reproducing apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a main part of an optical disc player for both compact discs and CDV discs to which the present invention is applied. Disk 1
Is attached to the rotary shaft of the spindle motor 2 and rotated. An FG signal is output from the frequency generator 3 attached to the spindle motor 2 according to the rotation speed. The head 4 optically reads information from the disc 1 and outputs a reproduction signal. If the playback signal is in the video domain,
In the case of the audio signal, the video signal demodulated by FM is EFM demodulated, converted into the audio signal and output. The CDV disc has an audio area on the inner circumference and a video area on the outer circumference. here,
On the disc, the inner audio area is approximately 1.8 μm
Written at a recording wavelength of 6.6 μm and a recording wavelength of about 1.2 μm in the outer video area. Therefore, it can be said that there is an average difference of about 2.5 times in the linear recording density between the inner audio area and the outer video area. Reference numeral 5 is a cycle discriminating means for outputting a discrimination result from the cycle of the input FG signal and the reproduction signal. For example, the ratio of each cycle may be calculated. FIG. 2 is an operation explanatory diagram showing how many pulses the reproduced signal is input per one rotation according to the position of the head 4. As you can see from this figure,
It can be seen that the number of pulses of the reproduction signal input per unit rotation angle differs between the inner audio region and the outer video region due to the difference in linear density. Therefore, the region can be discriminated based on whether the discrimination result of the period discriminating means is larger or smaller than a certain appropriate value. That is, with the above-described configuration, a correct determination result can be obtained even when the disc is not rotated properly. In order to specifically calculate the ratio, a counter may be used to input the reproduction signal to the clock terminal of the counter and the rising pulse of the FG signal to the reset terminal to latch the counter value immediately before the reset. Here, an example in which the area is discriminated in one disc has been described, but the present invention can be applied to disc type discrimination. Position of the video area of the CDV disc,
That is, by moving the head somewhere within a radius of 37.5 mm to 58.5 mm from the rotation axis of the motor and observing the above-mentioned discrimination result, it is possible to detect a CDV disc in the video area, a compact disc in the audio area, and further If the value is 0, it can be identified that there is no disc.
In particular, if this determination is made in the lead-in area of the video area that is located at a radius of 37.5 mm to 39 mm from the rotation axis of the motor, when the CDV disc is detected, the video area can be quickly played back at that position. You can Also, in the case of an optical disc player that plays three types of discs: laser discs, CDV discs and compass discs, the radius of the lead-in area of the laser disc is 53.5 mm.
If this judgment is made from the position of 5 to the position of the lead-out area of compact discs and CDV discs up to 58.5 mm, the disc presence / absence and the switching of the processing method of the reproduction signal are discriminated once for all discs. be able to. The cycle determining means has an appropriate number of reproduction signals,
After the frequency division, the cycle may be compared with the cycle of the FG signal, or may be modified without departing from the spirit. Also, the information written on the information disk is not limited to this example,
It does not matter if there is a difference in the number of pulses of the reproduction signal per unit rotation angle. In some cases, the reproduction signal does not have to be the signal itself read from the disc, and may be, for example, an extracted synchronization signal or another frequency-multiplexed signal.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to easily discriminate between two types of discs that are difficult to discriminate by their shapes. For example, whether it is a CDV disc or a compact disc can be stably determined without the trouble of reading the innermost code and even when the rotation is not normal. Further, even when a plurality of types of information are recorded on one disc such as a CDV disc, each area can be discriminated stably and accurately without using mechanical means. .

[Brief description of drawings]

FIG. 1 shows a compact disc, CDV, to which the present invention is applied.
FIG. 2 is a block diagram of a main part of an optical disc player which also serves as a disc, and FIG. 2 is an operation explanatory diagram showing the number of pulses of a reproduction signal per one rotation. 1 ... Disk, 2 ... Spindle motor, 3 ... Frequency generator, 4 ... Head, 5 ... Cycle discrimination means.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A 63-55772 (JP, A) JP-A 60-195770 (JP, A) JP-A 59-185069 (JP, A) JP-A 59- 96562 (JP, A) JP 62-243167 (JP, A) JP 57-55563 (JP, A) Actually opened 61-156061 (JP, U)

Claims (6)

[Claims] 1. A read signal is read from an information disk, and
A head that is movable in the radial direction of the information disk, a motor that rotates the information disk, a frequency generator that outputs an FG signal according to the rotation speed of the motor, the reproduction signal and FG
A cycle discriminating means for detecting each cycle of the signal and obtaining and outputting a ratio of these cycles, and discriminating the type or presence or absence of the information disc based on the output of the cycle discriminating means. Information playback device. 2. A radius of 37.5 mm from the motor rotating shaft to the head.
The information reproducing apparatus according to claim 1, wherein the information reproducing apparatus is located between 58.5 mm and determines the type or presence of the information disk based on the output of the cycle determining means. 3. A read signal is read from the information disk,
A head that is movable in the radial direction of the information disk, a motor that rotates the information disk, a frequency generator that outputs an FG signal according to the rotation speed of the motor, the reproduction signal and FG
A cycle discriminating means for detecting each cycle of the signal and calculating and outputting a ratio of these cycles, and positioning the head between the motor rotating shaft and a radius of 53.3 mm to 58.5 mm, and the cycle discriminating means. Based on the output of the disc, the type or presence of the information disc is discriminated, compact disc, CD
Playback device for both discs and laser discs. 4. A read signal is read from the information disc, and
A head that is movable in the radial direction of the information disk, a motor that rotates the information disk, a frequency generator that outputs an FG signal according to the rotation speed of the motor, the reproduction signal and FG
A cycle discriminating means for detecting each cycle of the signal and obtaining and outputting a ratio of these cycles, and positioning the head by a motor rotating shaft within a radius of 37.5 mm to 39.6 mm; Based on the output of, the compact disc characterized by determining the type or presence of the information disc,
CDV disc combined playback device. 5. An information disk in which a plurality of types of information having different linear densities are recorded in different areas, a read signal from the information disk, and a head movable in the radial direction of the information disk, A motor that rotates the information disk, a frequency generator that outputs an FG signal according to the number of rotations of the motor, a cycle that detects the cycle of each of the reproduction signal and the FG signal, and calculates and outputs the ratio of these cycles. An information reproducing apparatus comprising: a discriminating means, and discriminating which of the areas the head is reproducing based on the output of the cycle discriminating means. 6. The information disc includes EFM-modulated audio or digital data in the inner peripheral area and FM in the outer peripheral area.
The information reproducing apparatus according to claim 5, wherein a modulated video signal is recorded.