JPH0743885B2 - Disk playback device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a disc reproducing apparatus, and particularly to disc reproducing suitable for reproducing information from a disc on which time information is recorded together with main information such as a digital audio disc. Regarding the device.

[Conventional technology]

As an example in which the main information and the time information are recorded on the spiral track of the disc, a digital audio signal can be optically read as the main information, as disclosed in JP-A-60-43270. There is a compact disc (CD) recorded as. Regarding the recording format of a CD, as described in the above publication, it is made continuous by forming a predetermined small frame unit, and each small frame has a period of about 136 μsec. It is composed of a frame synchronization information part, a sub-code information part, and a data part containing music information of main information. The subcode information portion is composed of 98 small frames, and includes time address information in units of large frames with a period of about 13.3 ms.

As described above, when the signal is reproduced from the disc on which the digital signal information is recorded by an optical means or the like, the reading position on the disc by the information reading means is apt to be moved by an external force or the like, and is accidentally moved. In this case, reproduction information may be omitted or duplicated. Therefore, in the above publication, when the information reading means is inadvertently moved by an external force or the like, the position of the information reading means and the rotation speed of the disk are controlled to move the information reading means to the original reproduction position. It was.

[Problems to be solved by the invention]

In the above-mentioned conventional technique, when the information reading means is inadvertently moved by an external force or the like, the position of the information reading means is controlled to a regular reading position on the disc, so that reproduction information is not lost or duplicated. There is a problem that an abnormal reproduction state such as noise or temporary interruption of reproduction occurs in the reproduction information from the time when the information reading means is inadvertently moved until it returns to the regular position.

An object of the present invention is to solve the above-mentioned problems, that is, to suppress abnormal reproduction state such as noise or temporary interruption of reproduction during the period from when the information reading means is inadvertently moved to when it returns to the regular position, and vibration resistance is provided. It is an object of the present invention to provide a disc reproducing apparatus which improves the performance and operates stably without being adversely affected by scratches on the disc.

[Means for solving problems]

The above object can be achieved as follows. That is, first, the data reproduced from the disc is written in the memory.
If a track jump occurs, it is discriminated, the pickup is moved to the position before the track jump, and the data is reproduced from the disc. When the reproduced data from this disc reaches the location where the track jump occurs, the data discontinuity on the memory is eliminated by setting the write address of the memory to the value next to the write address at the location where the track jump occurs. Data is read from the memory at a constant cycle of the sampling frequency.

[Action]

Since the memory for storing the reproduction data from the disc stores the reproduction data for a fixed time, the read data from the memory reads the stored data during the time for moving the position of the pickup after the occurrence of the track jump. As a result, the data to be digital-analog converted can be continuously reproduced without being discontinuous.

〔Example〕

 An embodiment of the present invention will be described below with reference to FIG.

The configuration shown in FIG. 1 takes a compact disc player as an example. Reference numeral 1 is a compact disc, 2 is a motor for rotating the disc, 3 is a pickup for optically reading out a signal on the disc, 4 is a signal for amplifying a signal from a pinkup, and a reproduction signal from the disc and a tracking error signal A preamplifier circuit 5 to obtain a servo circuit for servo-controlling the pickup 3 and the motor 2 by a track, a focus error signal from the preamplifier, and a speed detection signal of the motor 2 obtained from the digital signal processing circuit 6,
After 6 incorporating a reproduction signal from the disk, EFM demodulation in accordance with the recording format, error detection and correction, performs error correction processing, 2 data of the data the sampling frequency 44.1KH _z number of quantization bits 16-bit channel (LR Channels) alternately, and a digital signal processing circuit consisting of a timing circuit for obtaining the speed detection signal of the motor 2 from the frequency fluctuation of the synchronizing signal reproduced from the disk 1 and for performing these operations, 7 is a digital signal An oscillator 8 for generating a reference clock of the signal processing circuit 6 is recorded on the disk 1 and the time information separated by the digital signal processing circuit 6 is input, and the presence or absence of a track jump is detected and controlled from the continuity thereof. A track jump detection circuit that supplies a signal, and 9 receives a signal from the track jump detection circuit 8 and a memory 16 and a counter 17 Control to control the counter value of the write address counter 10 by comparing the time information with the contents of the memory 16 and the counter 17, and to make the servo circuit 5 jump to return the position of the pickup 3 to the original position. A control circuit for supplying a control signal, 10 is a write address counter, which is a digital signal processing circuit 6
The clock operates in synchronization with the data output from the. A read address counter 11 counts with a clock synchronized with the data output from the digital signal processing circuit 6. Reference numeral 12 denotes a switch for switching the outputs of the counters 10 and 11, which is controlled by the digital signal processing circuit 6 to select the output of the counter 10 when writing to the memory 13 and the output of the counter 11 when reading out, and this switching is performed by the output data of the digital signal processing circuit 6. The switching control is performed in synchronization with. 13 is a memory, 14 is a DA converter for converting the output data of the memory 13 into digital data, and 15 is a DA converter.
A sample and hold circuit that samples and holds the output of 14 to obtain a 2-channel audio signal, 16 is a memory that stores the time information immediately before when a track skip signal is detected, 17 is a counter, and memory 16 and At the same time, the time information immediately before the time when the track skip signal is detected is set, and the time information is counted in synchronization with the clock obtained from the digital signal processing circuit 6 and used as a reference signal to be compared with the time information. Reference numerals 18 and 19 denote gates, and 20 denotes a memory. When a track skip signal is detected, the control circuit 9 sends a signal to the gate 19 to store the address of the write address counter 10 in the memory 20. When the contents of the memory 16 and the time information of the data reproduced when the pickup moves to the position before the track jumps, the control circuit 9 causes the gate
A signal is sent to 18 to set the contents of the memory 20 in the write address counter 10. Reference numeral 21 is a clock signal, and 22 is an error detection signal of the time information signal, which outputs a signal when it is detected that the time information has an error.

The operation of FIG. 1 will be described below.

The signal detected by the pickup 3 from the track of the disk 1 is amplified by the preamplifier 4 and added to the digital signal processing circuit 6. The digital signal processing circuit 6 separates the time information and transmits the time information to the track skip detection circuit 8 through the signal line 8S. In addition, the digital signal processing circuit 6
Is adapted to output to the memory 13 alternately binary coded 16-bit audio data is in two channels based on the clock oscillated by the sampling frequency 44.1KH _z by oscillator 7, therewith controls the clock 21 synchronized Circuit 9, write address counter 10 and read address counter 11
Supply to.

Here, the operations of the track skip detection circuit 8 and the control circuit 9 will be described with reference to the timing chart of FIG. FIG. 2 is a timing chart when a track jump occurs.

The time information from the digital signal processing circuit 6 consists of minutes, seconds, and frames as shown in FIG.
75 seconds. When the pickup 3 traces the track of the disc 1 accurately, the minutes, seconds, and frames change continuously continuously, but when a track jump occurs, it becomes discontinuous. Here, the time information indicated by X in FIG. 2 is determined to be erroneous by the error detection signal 22, and is naturally discontinuous. The track jump detection circuit judges this discontinuity, generates a track jump signal 8T as shown in FIG. 2, and inputs this to the control circuit 9. The control circuit 9 uses the track jump signal 8T to set the data immediately before the track jump signal 8T is obtained in the memory 16 and the counter 17. In Figure 2, (minutes, seconds, frames) = (1,11,1)
Is. At the same time, the control circuit 9 also sends a signal to the gate 19 to store the address when the track skip signal 8T is obtained in the memory 20. In FIG. 2, 8 is the address. After that, the counter 17 counts in synchronization with the clock 21 as shown in FIG. Then, the time information 8S at that time is compared with the contents of the counter 17 every clock.
However, it is not necessary to make a comparison when the time information 8S is detected as an error, so the comparison may be omitted. If there is no error detection in the time information 8S and the content of the counter 17 and the time information 8S are different, it can be known that a track skip has occurred. In FIG. 2, the time information 8S is (1,15,5) whereas the counter 17 is (1,11,4), which are different. Although only one piece of time information is compared here, it is also possible to determine whether or not the time information 8S is continuous by comparing the pieces of time information with the reciprocal time information. Since the contents of the time information 8S and the contents of the counter 17 are different and it is found that the track jump has occurred, the control circuit 9 gives the servo circuit 5 a signal for generating a jump pulse for returning the trace position of the pickup 3. . At this time, the counter
By comparing the contents of 17 and the time information 8S, it is possible to determine whether the pickup 3 flew toward the front or back compared to the original position, and accordingly, the shamp direction is the original time. Either the pulse 9B after the comparison with the information or the pulse 9F before the comparison with the original time information in the shamp direction is output. By this operation, the position of the pickup 3 traces the track before the occurrence of the track jump, and the time information changes as shown in FIG. 8S. As a result, when the contents of the memory 16 and the time information 8S match, that is, when the position of the pickup 3 reaches the position before the occurrence of the track jump, the control circuit 9 outputs the address gate pulse 9G and the address is stored in the memory 20. The address that has been set is set in the write address counter 10. As can be seen from FIG. 2, the data on the memory 13 can be made continuous by controlling the write address in this way.

Next, the timing chart shown in FIG. 3 will be described. Third
The timing chart in the figure shows time information due to scratches on the disc
8S shows a case where a part of 8S becomes discontinuous or a part of error is detected, and therefore, the data input to the memory 13 is normal. Also in this case, since the time information 8S becomes discontinuous at the place shown in FIG. 3 as shown in FIG. 2, the track jump detection circuit 8 outputs the track jump signal 8T.
Is output as shown in FIG. Thereafter, information is stored in the memory 16, the counter 17, and the memory 20, respectively, as in the case of FIG. 2, and the counter 17 counts in synchronization with the clock 21. Then, the time information 8S and the contents of the counter 17 are compared, but unlike the case of FIG. 2, the time information 8S and the contents of the counter 17 match in FIG. 3 ((1,11,4 in FIG. 3 Place)). In this case, the jump pulse 9B or 9F does not occur,
That is, it is determined that the time information is continuous and no track jump has occurred. As a result, the write address of the memory 13 is not changed.

As described above, in the configuration of FIG. 1, it is possible to distinguish between a track jump and a simple scratch, and the influence of the scratch can be reduced.

Next, consider the operation of the memory 13. The output data from the digital signal processing circuit 6 is binary encoded 16-bit data, and two channels are alternately output. This output data is written according to the value of the write address counter 10. As described above, even when a track skip occurs and a discontinuous signal is stored in the memory 13, the value of the write address counter 10 is stored in the memory 13 when the pickup returns to the original position and reproduces the correct signal. The data is set to a value that makes it continuous, and eventually the discontinuous signal is erased and stored in the memory 13. Therefore, continuous signals are stored in the memory 13.

The read address counter 11 delays the reading from the value of the write address counter 10 by a certain difference.
This difference corresponds to the permissible value of the write address counter 10 during the stop period. Therefore, this difference amount is determined in consideration of the time for returning the pickup 3 to the original position, and this difference amount can also be increased by increasing the capacity of the memory 3.

In this way, the contents stored in the memory 3 can be continuous data, and these data can be sequentially read out to the DA converter.
By adding to 14, continuous sound can be reproduced even when a track shamp occurs.

Another embodiment of the present invention is shown in FIG. The circuit of FIG. 4 is obtained by removing the error detection signal of the time information signal from the circuit of FIG. Since the operation of FIG. 4 is almost the same as the operation of FIG. 1, only different parts will be described. In Fig. 4, the time information is displayed for a while after the track skip signal 8T is output.
The contents of 8S and counter 17 are compared. Then, by checking the degree of coincidence of the two contents, it is checked whether the discontinuity is caused by a track jump or discontinuity due to a mere scratch on the main body. The reliability of the system determines how many samples to examine and how well they match. Fourth
In the case of the embodiment shown in the figure, it is possible to eliminate erroneous determination of the influence of the track jump and the scratch due to the missed detection of the time information.

The above embodiment is explained using the Q channel of the subcode which is one of the recording formats of the compact disc. The Q channel is completed in 98 frames, and since this is 1/75 second, finer control cannot be performed. However, the present invention is not limited to this format. For example, as shown in FIG. 5 (a), a device for reproducing an address of M _n in each frame D _n , or as shown in FIG. 5 (b), First, in a device that gives a large address M _n every few frames and then reproduces a signal D _{nk in} which an address N _k is provided again,
Track control is possible up to a finer time.

Although not particularly described in the present invention, the time information and the main data are configured to be completely synchronized. For example, in order to realize this, the time information generation circuit and the main data generation circuit are synchronized with the oscillator. To get it to move.

〔The invention's effect〕

According to the present invention, a reproduction data is written using a memory,
In addition, since the discontinuity of information is monitored for a relatively long time when a track jump occurs, it is possible to distinguish between discontinuities due to track jumps and discontinuities due to scratches, etc. By detecting the track skip without changing and changing the write address of the memory,
Even if a track jump occurs, there is an effect that it can be continuously reproduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
FIG. 4 is a timing chart showing the operation of the track jump detection circuit 8 and the control circuit 9, FIG. 3 is another timing chart showing the operation of the track jump detection circuit 8 and the control circuit 9, and FIG. Is a block diagram showing another embodiment of the present invention, and FIG. 5 is a signal format diagram to which the present invention can be applied. 8: Track skip detection circuit, 9: control circuit, 10:
Write address counter, 11 …… Read address counter, 13 …… Memory, 17 …… Counter.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshifumi Shibuya 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside the Home Appliances Research Laboratory, Hitachi, Ltd. (72) Inventor Masafumi Nakamura 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa (56) References JP-A-59-54012 (JP, A) JP-A-60-145568 (JP, A)

Claims (2)

[Claims] 1. A disc having a track on which digitized information data and a time code based on a recording start end of the information data are recorded, and the track is arranged spirally or concentrically. In a disc reproducing device for reproducing information data, rotating means for rotating the disc, and reproducing by taking in a signal from the disc, detecting and correcting an error of the reproduced signal, separating the information data and the time code, Information reading means for outputting these data and error detection signal; storage means for storing the information data obtained by the information reading means in a predetermined address order determined by a time code obtained by the information reading means; The value of the time code obtained by the reading means is discontinuous in time When there is a discontinuity detecting means for detecting that the discontinuity is detected by the discontinuity detecting means, a time code storing means for storing the time code before the occurrence of the discontinuity and the information reading means are provided. The obtained time code error detection signal indicates that an error has been detected. With respect to the time code, the time code counting means for counting the elapsed time thereafter and supplementing the time code, and the value of the time code counting means And the time code obtained by the information reading means are compared, and the value of the time code counting means and the time code are determined on the condition that the error detection signal does not detect an error with respect to the time code. When they are different, it is determined that a track jump has occurred, the track jump is detected, and a detection unit that outputs a signal indicating the track jump occurrence is used. The information reading means is moved to the reading position on the disc before the occurrence of the track jump by the output of the track jump detecting means, and the time code output from the information reading means is stored in the time code storage means. Until the time code before the occurrence of the track jump coincides with the write control means for controlling the write address to the storage means so as not to advance, and the information data is read from the storage means at a constant time interval according to a predetermined address order. A disk reproducing apparatus comprising a read control means. 2. A disc reproducing apparatus according to claim 1, wherein the write control means outputs the discontinuity detection output of the discontinuity detection means when the discontinuity reproduction is performed. When there is an output indicating the occurrence of a track jump from the address storage means for storing the write address to the storage means and the track jump detection means, the information reading means is moved to the reading position on the disk before the track jump occurs, Setting means for setting the value of the address storage means as a write address when the time code output from the information reading means coincides with the time code stored in the time code storage means before the occurrence of the track jump; A disc reproducing apparatus comprising: