JPH07122002A - CD controller - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To provide a CD control device having a simple structure to improve vibration resistance and reliability. [Structure] A second pickup 2 for reading data which precedes the first pickup 1 forming a read output signal by a predetermined time is provided to store data substantially corresponding to a first and second time difference. The output signal of the second pickup is stored in the memory circuit 8, the read signal from the first pickup and the corresponding data stored in the memory circuit 8 are compared, and the memory circuit 8 outputs the mismatch signal.
The data stored in the first pickup is output again, and during this period, the track control is performed so that the data corresponding to the data output from the memory circuit 8 is output from the first pickup. To output the data from.

Description

Detailed Description of the Invention

[0001]

This invention relates to a CD (compact,
The present invention relates to a disc) control device, and more particularly to a technique effectively used for a portable or vehicle-mounted CD player.

[0002]

2. Description of the Related Art Sound skipping due to vibrations and the like in a CD player is the greatest problem when the optical disk is used for portable and vehicle installation. For this reason, development of materials for the vibration system of the pickup and adoption of a floating structure that floats the pickup from the chassis have been devised.
Regarding compactness and weight reduction and float technology for maintaining the relative position of the optical disc and the optical pickup, "Compact Disc Reader" published by Ohmu Co., Ltd., Heitaro Nakajima, page 21.
8 to page 229.

Since there is a limit to the above structural measures, the optical disk is rotated at a speed twice that of the normal speed, the data is pre-read at the speed twice, and stored in the semiconductor memory to read the data. It has been proposed that even if the optical pickup loses track of the audio track due to vibration or the like, the data is stored in the memory so that the sound is not interrupted. Regarding such a reading method, there is "Denpa Shimbun" issued April 23, 1992.

[0004]

However, since the optical disc is rotated at a high speed, the power consumption becomes large. In particular, since the portable CD player is battery driven, the increase in power consumption cannot be ignored. Further, there is a problem that the control circuit becomes complicated in order to detect the sound skip.

An object of the present invention is to provide a CD control device having a simple structure and improved vibration resistance and reliability. The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0006]

The outline of a typical one of the inventions disclosed in the present application will be briefly described as follows. That is, the first pickup forming the read output signal is provided with the second pickup for reading the data preceding by the predetermined time, and the first pickup is provided.
And an output signal of the second pickup is stored in a memory circuit that stores data substantially corresponding to the second time difference, and the read signal from the first pickup and the corresponding data stored in the memory circuit are stored. By comparison, the data stored in the memory circuit is output by the non-coincidence signal, and the track control is performed so that the data corresponding to the data output from the memory circuit is output from the first pickup by using this interval. After that, the data is again output from the first pickup.

[0007]

According to the above-mentioned means, it is possible to detect the deviation of tracking due to vibration or the like with a simple structure and to perform the relay by outputting the data stored in the memory circuit during that time. Track control can be performed so that data corresponding to the data output from the circuit is output from the first pickup.

[0008]

1 is a block diagram showing an embodiment of a CD player system according to the present invention. The CD player system of this embodiment is directed to a vehicle-mounted or portable CD player system.

In this embodiment, one optical disc (C
An optical pickup (hereinafter, simply referred to as a pickup) 1 and a pickup 2 are provided for D). These pickups 1 and 2 are designed to read data from the optical disk CD at the same time. However, the pickup 2 and the pickup 1 and 2 are arranged so that the pickup 1 can always prefetch data for about 2 to 3 seconds.
The relative positional relationship with is fixed.

The data read from the pickup 1 includes the preamplifier 3, the signal processing circuit 4, and the buffer RAM.
Through the changeover switch 9. Similarly, the data read from the pickup 2 is stored in the preamplifier 6,
It is input to the signal processing circuit 6 and the memory 8 having a relatively large storage capacity.

The memory 8 includes the pickups 1 and 2
The storage capacity is large enough to store the data corresponding to the time difference between. This memory 8 is a FIFO
Memory access is performed by the (first-in, first-out) method. In the figure, since it has a relatively large storage capacity as described above, it is shown in the form of a magnetic drum in order to clarify the distinction from the above buffer memory RAM. Is composed of a semiconductor memory such as a RAM.

In the memory 8 and the buffer RAM, data input and data output are performed by the FIFO method as described above by the address selection signal formed by the system control 10. That is, the system control 10 monitors the subcodes (data subinformation) of the data read from the pickups 1 and 2, respectively, and performs timing control so that the output data of the buffer RAM and the memory 8 are the same. , That match /
Watching for discrepancies.

The servo 13 controls the rotation of the disk motor and the movement of the pickup 1 by the preamplifier 3, the processing circuit 4 and the system controller 10. The servo 12 controls the movement of the pickup 2 by the preamplifier 6 processing circuit 7 and the system control 10.

The changeover switch 9 selects and outputs the data from the buffer RAM or the memory 8 according to the control signal from the system control 10. The data output through the change-over switch 9 is converted into an analog signal by the D / A converter 11, and an audio signal is output by driving a speaker or the like through an amplifier circuit provided in the output section. It should be understood that the amplifier circuit includes a left / right channel separation circuit for stereo reproduction and a corresponding audio output circuit.

The operation of the CD player system of this embodiment will be described below. During normal operation, the changeover switch 9 is connected to the buffer RAM side. Therefore,
The data read from the pickup 1 is output through the preamplifier 3, the signal processing circuit 4, and the buffer RAM.

In parallel with the data read from the pickup 1 as described above, data is read from the pickup 2 so as to precede it. The data read from the pickup 2 is taken into the memory 8 through the preamplifier 6 and the signal processing circuit 7, and the timing is adjusted so that the same data as the data output from the buffer RAM is also output from the memory 8. Is being done.

Although not particularly limited, the system control 10 monitors whether or not the data output from the buffer RAM and the data output from the memory 8 match / mismatch, and when they do not match, vibration or the like occurs. When it is determined that a sound skip has occurred, the changeover switch 9 is switched to the memory 8 side.

When the vibration is generated as described above, sound skipping is also generated in the pickups 1 and 2, but the memory 8 outputs the vibration about 2 to 3 seconds before that. Utilizing that it is data when not doing,
By comparing the data as described above, the sound skip can be easily detected. Then, by switching the switch 9, even if the pickups 1 and 2 are separated from the track, it is possible to continuously output continuous data.

Alternatively, the skipped state may be detected from the data temporarily stored in the buffer RAM. That is, it is also possible to determine that the continuity in the audio signal is interrupted by pattern recognition or the like and switch the changeover switch 9.
For such a sound skip detection, a conventional sound skip detection circuit may be used as it is.

Since the system control 10 stores correct data for 2 to 3 seconds in the memory 8, the current position information of the pickup 1 is obtained from the subcode data output from the pickup 1 using the interval. Is detected and the track jump (pickup movement) is repeated to correct the position. Then, when the correction of the track corresponding to the output data from the memory 8 that is currently output using the subcode data is completed, the system control 10 sets the changeover switch 9 to the buffer RAM.
Then, the data from the pickup 1 is output again.

The system control 10 performs correct track correction of the pickup 2 based on the track correction data for the pickup 1. As a result, the pickup 2 reads the data that precedes the pickup 1 by a predetermined time. During this time, the pickup 2 is reading data and stores the data in the memory 8 including the data corresponding to the skipped sound.

The data comparison operation is stopped until the track correction and the correct data are stored in the memory 8 as described above. As a result, it is possible to prevent the inconvenience that the changeover switch 9 is changed over to the memory 8 by the data corresponding to the skipped sound remaining in the memory 8.

The function of comparing data between the buffer RAM and the memory 8 may be used as a read error detection signal when used as a CD-ROM (read only memory). That is, when the system control 10 detects a mismatch of the above data, the pickup 1 is instructed to read the data of the same track again, the previous read data and the read data are compared again, and if they match, the same is output. If they match, it is possible to perform highly reliable data reading by signal processing such as a majority decision of the read data of the same track of the memory 8.

During the re-reading by the pickup 1 as described above, the pickup 2 stops the track movement and prohibits the data input to the memory 8. Don't get lost by entering new data.

The operational effects obtained from the above embodiment are as follows. (1) A second pickup for reading data ahead of the first pickup forming a read output signal by a predetermined time is provided to store data substantially corresponding to the difference in output time between the first and second pickups. The output signal of the second pickup is stored in the memory circuit for performing the operation, and the sound is output by the mismatch signal based on the read signal from the first pickup or by comparing it with the corresponding data stored in the memory circuit. Detects the flying state,
Output the data stored in the memory circuit,
Utilizing this interval, the track control is performed so that the data corresponding to the data output from the memory circuit is output from the first pickup, and then the data is output again from the first pickup, thereby improving vibration resistance. The effect that the high reliability can be improved is obtained.

(2) It is possible to achieve a highly reliable read operation by detecting a read error from the output signal of the data comparison circuit and performing the same data read operation again.

Although the invention made by the present inventor has been specifically described based on the embodiments, the invention of the present application is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say. For example, a pool area and a buffer area are provided for the preceding data in one memory device, and when data skip occurs, pooled data is output instead of the data in the buffer RAM area. For example, the memory may be provided with a switch function. By adopting such a configuration, since the control circuit for accessing the memory can be configured by a single circuit, the circuit can be simplified. However, while outputting one data, it is necessary to perform two data inputs to the pool area and the buffer area and two read operations to output the corresponding data.

INDUSTRIAL APPLICABILITY The present invention can be widely used for a CD control device for audio and a CD control device for reading an optical disk such as a CD-ROM for a personal computer with an optical pickup.

[0029]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows. That is, the first pickup forming the read output signal is provided with the second pickup for reading the data preceding by the predetermined time, and the first pickup is provided.
The output signal of the second pickup is stored in a memory circuit for storing data substantially corresponding to the output time difference between the first pickup and the second pickup, and based on the read signal from the first pickup, or with the memory circuit. By comparing with the corresponding stored data, the sound skip condition is detected by the disagreement signal, the data stored in the memory circuit is output, and the interval is used to correspond to the data output from the memory circuit. By performing the track control so that the above-described data is output from the first pickup, and then outputting the data from the first pickup again, it is possible to improve vibration resistance and high reliability.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a CD player system according to the present invention.

[Explanation of symbols]

1, 2 ... Pickup, 3, 6 ... Preamplifier, 4, 7 ...
Signal processing circuit, 5 ... Buttoffer RAM, 8 ... Memory, 9
… Changeover switch, 10… System control, 1
1 ... D / A converter, 12, 13 ... Servo.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kitohito Goto 5-22-1 Kamisuihoncho, Kodaira-shi, Tokyo Inside Hitachi Microcomputer System Co., Ltd. 22-22-1 Hitachi Microcomputer System Co., Ltd. (72) Inventor Akihiko Narita 5-221-1, Kamimizuhonmachi, Kodaira-shi, Tokyo Inside Hitachi Microcomputer System Co., Ltd.

Claims (3)

[Claims] 1. A first pickup for forming a read output signal, a second pickup for reading data which precedes the first pickup by a predetermined time, and outputs of the first and second pickups. A memory circuit that stores data that substantially corresponds to a time difference, a detection circuit that receives a read signal from the first pickup and detects skipping, and read data from the first pickup based on the detection signal of the detection circuit. Instead of outputting the data stored in the memory circuit, the track control is performed so that the data corresponding to the data output from the memory circuit is output from the first pickup, and the data is read from the first pickup again. A CD control device comprising a control circuit for outputting the output data. 2. A first pickup that forms a read output signal, a second pickup that reads data that precedes the first pickup by a predetermined time, and outputs of the first and second pickups. A memory circuit that stores data that substantially corresponds to the time difference, a data comparison circuit that compares the read signal from the first pickup with the corresponding data stored in the memory circuit, and a mismatch signal of the data comparison circuit. The data stored in the memory circuit is output instead of the read data from the first pickup, and the track control is performed so that the data corresponding to the data output from the memory circuit is output from the first pickup. And a control circuit for outputting the data read from the first pickup again. A CD control device characterized in that 3. The CD controller according to claim 2, wherein the output signal of the data comparison circuit is also used as a read error detection signal.