JPH0310188B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an access method for a CD player, particularly when tracking a pick-up, by performing coarse adjustment and then fine adjustment to place the pick-up at a predetermined position on a recording track. In an access method for a CD player that moves the top of the CD player, the fine adjustment is performed on the condition that the control result of the coarse adjustment has reached a predetermined control range. The present invention relates to an access method for a CD player that makes it possible to save time.

Recently, record players, or CD players (compact and
A disk player) was developed, and it suddenly came into the spotlight due to its excellent performance in terms of sound quality, storage stability, and operability. Compact disk used in the above CD player (hereinafter simply referred to as disk)
The information recorded on the track is recorded in the form of the presence or absence of pits on a spirally arranged track.
The track is composed of frames in which unit information is recorded separated by synchronization signals, and absolute time information is stored as address information in each frame. Therefore, for example, when selecting one song from a plurality of songs recorded on the disk, the absolute time information of the first frame of the desired song is accessed and the pick-up is performed at the starting position of the desired song. By moving it, you can select songs. In order to perform the above-mentioned access accurately and shorten the access time, generally, the above-mentioned access is performed based on specified absolute time information, and the absolute time is first adjusted by coarse adjustment control (fast forwarding) described later. An access method is used in which the pick-up is moved to a position close to a frame corresponding to information, and then the specified frame is accessed by fine adjustment control. It goes without saying that in order to shorten the access time, it is necessary to approach the designated access position as much as possible through the coarse adjustment control. Here, the above coarse adjustment control will be explained in relation to FIG. 1.

FIG. 1 is a diagram showing an example of a general coarse adjustment control mechanism, in which reference numeral 1 is a disk, 2 is a pick-up, and 3 is a pick-up position detector. 4 is a designated time input section that outputs a signal at a level corresponding to the position of the pick-up 2 (hereinafter referred to as a position detection signal);
For inputting absolute time information on the track, 5
is a D/A converter, 6 is a subtracter, 7 is an amplifier,
8 is a motor drive unit, and 9 is a motor, which operates the above-mentioned pick-up based on a drive signal from the motor drive unit 8.
It represents what moves Up2.

In FIG. 1, the absolute time information (digital signal, hereinafter referred to as the designated time) A _T input from the designated time input section 4 is converted to an analog signal (hereinafter referred to as the D/A output signal) by the D/A converter 5. (called _AV ) and sent to the subtraction unit 6. The subtraction unit 6 receives the position detection signal of the pick-up 2.
B _V is sent from the pick-up position detector 3 via an amplifier 7. The subtraction unit 6 performs a subtraction process of (A _V -B _V ), and outputs the subtraction result e. The motor drive section 8 drives the motor 9 based on the subtraction result e, and moves the pick-up 2 until the subtraction result e becomes "0". As a result of the coarse adjustment control, absolute time information (hereinafter simply referred to as absolute time) _BT read out from the disk 1 by the pick-up 2;
Ideally, it is desirable that the above-mentioned specified time A _T coincide with the absolute time B T, but due to manufacturing variations in the disk 1, changes in the chucking state, etc., the specified time A _T and the absolute time B _T may differ. generally do not match. In other words, the access error is too large with only the simple coarse adjustment control as described above, and it is difficult to perform fine adjustment control.
Even if this could be done, access would take a long time. Therefore, in order to shorten the access time, it is desirable to minimize the access error in the coarse adjustment control stage.

The present invention aims to meet the above-mentioned demands, and checks whether the access error of the coarse adjustment control result is within a desired control target range in a predetermined fine adjustment control, and When there is an access error exceeding the range, the control by the coarse adjustment control is corrected, and the control is shifted to fine adjustment control on the condition that the control result by the coarse adjustment control falls within the control target range, The object of the present invention is to provide an access method for a CD player that makes it possible to shorten access time. This will be explained below with reference to the drawings.

Figure 2 shows the configuration of one embodiment of the present invention, and Figure 3 shows the configuration of the second embodiment.
FIG. 3 shows a flow chart for explaining the operation of the illustrated embodiment. FIG. Reference numerals 1 to 9 in the figure correspond to those in FIG. 1, 10 is an access control section, and 11 is a coarse adjustment check section, which checks whether the coarse adjustment result is within a predetermined threshold value K. Reference numeral 12 is a correction control section which supervises the coarse adjustment control and corrects the coarse adjustment control based on the check result in the coarse adjustment check section 11. Reference numeral 13 is a fine adjustment control section. , 14 represents a selector, and 15 represents a fine adjustment servo circuit.

The operation of the embodiment shown in Fig. 2 is explained by the flowchart shown in Fig. 3.
I will explain this in relation to chat.

In FIG. 2, access control as described below is started by inputting a specified time A _T for specifying an access position from the specified time input unit 4 to the access control unit 10, but by chance the specified time A _T Needless to say, if the absolute time B _T read from the pick-up 2 matches, the access is considered to have ended. Therefore, in general, first, the rough adjustment check section 11 calculates, based on the specified time _AT and the absolute time B _T ,
The calculation is performed according to the following equation (1).

｜A _T −B _T ｜＞K ...(1) K in the above equation (1) is a predetermined threshold value, and if equation (1) is satisfied, the coarse adjustment control operation described later is started. However, if the left side of equation (1) is less than or equal to the threshold value K, the process shifts to fine adjustment control.

If the above equation (1) is satisfied, coarse adjustment control is performed with the selector 14 switched to the terminal α side. That is, first, the correction control unit 12 performs calculation according to the following equation (2), and the specified correction time A _T1 in the first coarse adjustment control becomes D/A.
It is sent to converter 55.

A _T1 = A _T + α (A _T − B _T ) ...(2) In addition, α in equation (2) is a predetermined correction coefficient, and the correction coefficient α is the specified correction time A _T1 The result of the first coarse adjustment control performed based on this is predetermined so as to satisfy the following equation (3).

A _T −B _T ＞A _T1 −B _T1 ...(3) However, B _T1 in equation (3) is the absolute time read out by the pick-up 2 as a result of the first coarse adjustment control. It represents.

When the first coarse adjustment control (the control operation is performed in the same manner as the operation described with reference to FIG. 1, detailed explanation will be omitted) is completed, the coarse adjustment check section 11 A check is performed using the above equation (1). Then, if the check result is that the left side of equation (1) is equal to or less than the threshold value K, the control shifts to fine adjustment control, but if equation (1) still holds true, the second rough adjustment control is performed. access is performed by That is, in the correction control unit 12, the specified correction time A _T2 in the second rough adjustment control is calculated by calculation based on the above equation (2). That is, A _T2 = A _T1 + α (A _T − B _T1 ) The above correction specified time A _T2 is sent to the D/A converter 5, and the second coarse adjustment control is performed based on the correction specified time A _T2 . .

In this way, the coarse adjustment control is repeated until the left side of the above equation (1) becomes equal to or less than the threshold value K, and then,
Shift to fine adjustment control.

Note that, generally, the correction designated time A _T i in the i-th rough adjustment control is determined as shown in the following equation. That is, A _T i=A _T (i-1)+α(A _T -B _T (i-1)) Note that if the condition A _T =B _T i is obtained during the above control, the access ends.

When the coarse adjustment control is completed, the selector 14 is switched to the terminal b side and fine adjustment control is performed. The fine adjustment control is carried out from the fine adjustment control section 13 via the fine adjustment servo circuit 15 and selector 14 to the designated time _AT and the pick up 2.
By sending a fine adjustment servo signal corresponding to the difference between the absolute time _BT read by and to the motor drive unit 8, the adjustment is performed until the specified time _AT and the absolute time _BT become equal. . That is,
Fine adjustment control ends when A _T = B _T ,
Accesses based on the specified time _AT end at the same time.

As explained above, according to the present invention, even if the result of one coarse adjustment is not within the desired error range, control is taken over to the fine adjustment under the condition that the result is within the desired error range. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a general coarse adjustment control mechanism, FIG. 2 is a diagram showing the configuration of an embodiment of the present invention, and FIG. 3 is a flowchart for explaining the operation of the embodiment shown in FIG.
Show chart. In the diagram, 1 is a disk, 2 is a pick-up, 3 is a
is a pick-up position detector, 4 is a specified time input section, 5 is a D/A converter, 6 is a subtraction section, 7 is an amplifier, 8 is a motor drive section, 9 is a motor, 10 is an access control section, 11 is a rough An adjustment check section, 12 a correction control section, 13 a fine adjustment control section, and 14 a selector.

Claims (1)

[Claims] 1 A coarse motor comprising a pick-up, a pick-up position detector that outputs a signal at a level corresponding to the position of the pick-up in conjunction with the pick-up, and a tracking motor that tracks the pick-up. An access method for a CD player that is equipped with an adjustment control mechanism and a fine adjustment control mechanism that performs fine adjustment control by reading absolute position information recorded on a track of a disk after coarse adjustment control by the coarse adjustment control mechanism. , a coarse adjustment check section for checking whether or not the coarse adjustment control result is within the desired control target range in the fine adjustment control; A correction control unit is provided for correcting the instruction information value in the coarse adjustment control based on the absolute position information, and when there is an error in the control result of the coarse adjustment control that exceeds the desired control target range in the fine adjustment control. The above-mentioned absolute adjustment is performed on the condition that the rough adjustment is repeated based on the instruction information value corrected by the correction control section, and the control result of the coarse adjustment control falls within the above-mentioned desired control target range in the above-mentioned fine adjustment control. An access method for a CD player, characterized in that the fine adjustment control described above is performed by reading position information.