JPS6378372A - Line speed measuring device - Google Patents

Abstract

PURPOSE:To attain quick information retrieval by setting a pickup to a prescribed radial position on a disk and calculating the moving distance of the pickup from number of revolutions and the radial degree while keeping the line velocity constant thereby reducing the feeding error of the pickup at the retrieval. CONSTITUTION:The pickup 5 is fixed to reproduce the innermost circumference of the disk 1 at the measurement of the line velocity and the radius of the reproduced position is discriminated. Moreover, the number of revolutions of the disk when the line velocity is constant is discriminated by a waveform shaping circuit 9 and a microcomputer 11. Thus, the line velocity of the disk is calculated by the microcomputer 11 and stored in a RAM (not shown) in the microcomputer 11. A command signal is fed from the microcomputer 11 to a pickup control circuit 10 in the timing when the discrimination signal is fed to the microcomputer from the signal processing circuit 7, the fixed pickup 6 is released and the normal reproduction is restored, and the moving distance (track number) of the pickup at the retrieval is calculated nearly accurately from the line velocity.

Description

DETAILED DESCRIPTION OF THE INVENTION B] Industrial Application Field The present invention relates to a linear velocity measuring device for a disk rotation drive device in which information signals are recorded at a constant linear velocity.

(El Prior Art Conventionally, for example, a compact disc is known as a disc on which information signals are recorded at a constant linear velocity.In such a compact disc (hereinafter referred to as an F disc), information signals are recorded in a spiral shape. An information track is formed by a string of such information signals.In addition to the information signal to be reproduced, an address signal indicating the position on the disk is recorded on this information track. The address signal represents the total playback time (absolute time J) from the most circumferential part of the disc.

A disc player that plays such a disc has a function of searching for a predetermined ff[- based on the address signal. For example, as a means of information retrieval,
As disclosed in Publication No. 7273 iC, the number of tracks that the pickup should cross during the search is calculated from the relationship between the absolute time and the number of tracks with the same diameter on the disk. There is a method.I will explain this in detail below.

As mentioned in the above-mentioned prior art, the relationship between the number of tracks n that is crossed by moving the playback position from the innermost R part toward the outer circumference and the above-mentioned absolute time t is almost exactly expressed by the following equation. approximated.

Here, P is the diameter of the innermost circumference of the RIVc disk, P is the track pitch, and V is the linear velocity of the disk.

When such a formula □ is expressed in Gutsu 7, it becomes as shown in Figure 12.

Now, in Figure 2, the pickup is at absolute time [t1]
Naru position fI: PI student, 4 hours, 6 vs. time [t! ], the corresponding number of tracks (nL) and (nl) are calculated from the first equation, and then (Ill-
nl), the number of tracks the pickup should cross is calculated.

By the way, in addition to the number of tracks (nl and absolute R time [t]), Equation 11 includes terms for the radius of the innermost circumference of the disc [&included track bin?CP], and the linear velocity (V) of the disc. These terms are determined by the disc specifications9, and are R1 25 [play], P 1.6 (fi ”)
v=1.2 to 1-4 (m/B).

In the conventional technology mentioned above, when calculating the number of trunks, the term of linear velocity in the first equation is set to a predetermined value within the range of 1.2 to 1.4. Since the number of tracks differs depending on the disk, an error may occur in the actual number of tracks calculated from the first equation. For example, how many tracks have absolute times between 0 and 20 minutes? Tsuki speed 1.2 (m/S) 1.4
When C'/S3, VCRN, and CJK are output, the difference in the number of tracks between them is more than 1000) racks. Such an error results in a pick-up feeding error during a search, resulting in problems such as a long search time.

Recently, in place of conventional disks, a disk called CL-ROM, in which information signals useful in computers are recorded, has been developed.
ROM allows for quick and accurate information retrieval! ! The shortcomings in search time mentioned above were a big problem.

Problems to be Solved by the Invention The present invention sets the rolling velocity Rk to a predetermined value in the approximate equation representing the relationship between the disk address (absolute time) and the number of tracks, including the linear velocity term, and picks it up at the time of search. When calculating the number of tracks that should be crossed from the disc's 7) "res", an error occurs in the number of tracks because the linear velocity differs depending on the disc, and this appears as a pickup feeding error, and n1 The problem that the search takes a long time is to be resolved.

B) Means for solving the problem In view of the above problems, the present invention provides a linear velocity measuring device that connects a rotary drive device for a disk on which information signals are recorded at a constant velocity, and is capable of detecting an ff A linear velocity vlJlf1 circuit that performs linear velocity control based on @, and a movement t of the pickup that moves along the disk.
l! tlJ The pick-up control circuit and the pink-up l1lt control circuit set the pickup at a predetermined position in the radial direction of the disk, and the linear velocity control circuit reaches a constant linear velocity at the time of 9 o'clock and 7 o'clock. The present invention is configured to include a rotational speed detection circuit that sends out a ratio signal in accordance with the rotational speed of the disk, and a linear velocity calculation circuit that calculates the linear speed of the disk based on the signal and the position of the pickup.

(E) Operation The pick-up is set at a predetermined position by the pitch 7711111m circuit, and thereby the information reading position is set at a position on the disc at a predetermined radius. When the linear velocity is made constant by the linear velocity ll11 control circuit at such a position, the rotational speed of the disk at that time is detected by the rotational speed detection circuit, and a corresponding signal is sent out. Then, the linear velocity of this disk is calculated by the linear velocity calculation circuit based on this signal and the radius 1ttI.

(f) Example One example of the present invention will be described below with reference to FIG.

(1) is the disk, (2) is the turntable on which the entire disk (1) is placed, (3) is the clamp member that presses the disk (1) onto the turntable (2), (4) is the turntable (2) t-rotation driven brushless motor, (5
) is a pickup that reads the information recorded on the disk (IJ) fully optically.16) i1 pickup (5
) to shape the waveform of the d-cut 't'Le signal and convert it to ff
Report number, focus error signal, tracking error signal? I-forming preamplifier, (7) is preamplifier (6
), and compares the synchronization signal read from the disk (1) with the reference signal and outputs No. 48 corresponding to the synchronization signal read from the disk (1).
This is a signal processing circuit. (8) is a motor control circuit that receives the comparison signal from the signal processing circuit (71) and controls the brushless motor (4); This is a waveform long circuit that converts the all-digital waveform tC of the alternating signal output from the Hall element (not shown) to be detected.The period of this current transformation is proportional to the number of rotations of the brushless motor (4). Since the signal changes, the waveform is shaped according to the frequency.The period of the digital signal also changes according to the rotation speed of the brushless motor (4).G receives the error signal formed by the preamplifier (6). Pick up (5) l1
1g! Pick up i! The IJ-circuit and αD apply the IIIJ# signal to the signal processing circuit (7) and the pickup + JIJ 'fi11 circuit a■, and receive the digital signal from the waveform rectangular circuit (9) to control the brushless motor (4). Determine the rotation IXt, and then calculate the resting speed R of the disc (1) from this rotation speed and the position of the pickup (5):
A micro combinatorial computer (hereinafter referred to as a microcomputer) calculates the following.

The operation of the four actual examples configured as above will be described below.

When the disc (1) is placed on the turntable (2) and is pressed against the turntable (support) by the ring part (3), the microcomputer (picks up from the ID)
A command signal is stamped on the control 11JQO, and the pickup (5) is fixed so that the reading position is located at the innermost circumference of the area where the signal is recorded on the disk.

Next, a command signal is applied from the microcomputer αD to the signal processing circuit (7), and in response, a start signal is applied from the signal processing circuit (7) to the motor 14 circuit (8), and the brushless motor (4) is driven. Disc (I) with this
J is rotationally driven, and an information signal and an error signal are generated by a preamplifier (6) via a pickup 153ft.

The circle of such a signal, E2-signal is the pickup control circuit a
1, big amplifier (5-inch to disk (1)
The pickup (5) is controlled so that the beam spot irradiated above is accurately positioned on the signal line on the disk. Further, the information signal is applied to the signal processing circuit (7), during which the jjA signal is compared in phase with the reference signal.

The synchronization signal is recorded on the information track of the disk at regular intervals, so the linear velocity of the disk is constant and n
For example, it can be detected at predetermined intervals. Therefore, if the synchronization signal and the reference signal having a predetermined period match in phase, it means that the disk (IJ) is being rotated at a constant speed a.

As mentioned above, the equal signal processing circuit (7) compares the phases of the synchronizing signal and the reference signal, detects the phase difference, and applies a corresponding signal to the motor control μs circuit (8). nru.

motor! 'II Misaki circuit (81) uses this signal to control the rotation of the brushless motor (4J). In this way, the disk (1) is rotated 1tl so that the synchronization signal and the reference signal are in phase.
lJ is controlled to keep the linear velocity constant.

On the other hand, the period of the father ftM from the Hall element changes due to the change in the rotation of the brushless motor (4) as described above, and correspondingly, the period of the digital signal output from the waveform shaping circuit (9) also changes. Change. This digital signal is then input to the microcomputer αυ to drive a brushless motor (4
) is determined.

Now, when the phase of the synchronization signal is compared with the reference signal by the signal processing circuit (7), that is, the disc O
5 When the speed becomes constant, this is determined and a determination signal is sent to the microcomputer 1υ.

By the way, when the disk is rotating at a predetermined rotational speed (fl), the linear velocity (l) at a position of the diameter (r) from the center of the disk is expressed by the following equation.

v −2x r t −・− (2) Therefore, the playback position on the disc that the pickup (4) is playing,
If the number of rotations of the disc at that time is known, the swing speed at the playback position can be determined from the above equation (2).

As mentioned above, the microcomputer σ11 has the function of calculating the linear velocity from the position of the disk and the pickup, that is, it has the calculation function of the above equation (2).

Now, as mentioned above, the pickup (5) is fixed so that it plays on the innermost circumference of the disc (1) during deceleration distance measurement, and the position is unified to a predetermined value according to the disc standard. Therefore, the radius of the playback position of the pickup (6) in such a state is known.

Further, the number of rotations of the disk (11) when the disk (1) is rotated and the degree of convergence becomes constant is determined by the shaping circuit (9) and the microcomputer dll. Therefore, the rotation speed determined by the waveform shaping circuit (9) is held at the timing when the above-mentioned determination signal is applied to the microcomputer σV, and from this rotation speed and the radius of the innermost circumference of the disk according to the unified standard, the above ( 2) The linear velocity of the disk is calculated by the microcomputer 111J based on the formula. Such a quick generation is unique to this disk (6), and the microcomputer ti
RAAi (not shown) of 11 yen is stored.

In this way, the deceleration of the disc is calculated at the first AA +' times 1IIra1
A command signal is applied to the n1 pickup (6) to fix or release it and return to normal playback operation. The moving distance (number of tracks) of the pickup at mW is as shown in the conventional example (1
), the microcomputer (11) oR
By applying the linear velocity Xt-(1) equation stored in the AM, a substantially accurate moving distance can be calculated.

In addition to the above-mentioned number of tracks, the means for indicating the moving distance ym of the disk can be changed in various ways, such as the number of steps of the stepping motor that moves the pickup in the full direction, or the number of steps.
It is.

Further, the motor for rotating the disk is not limited to a brushless motor, but may also be a DC servo motor, for example. In this case, in order to detect the rotational speed of the motor, a disk is mounted on the rotating shaft of fQ, a hole is drilled in the 51al edge of the disk, and a photocoupler is placed opposite to this hole. Therefore, a means for determining t from the period of the output pulse is required.

In addition, in order to reduce errors in linear velocity, it is possible to measure the coarse velocity several times at the beginning of playback and, for example, to make it fit with the average value, so that the pickup can be achieved with better FLR. Can be done.

(g) Effects of the invention Since the deceleration measuring device of the unexploded IA measures the corresponding decelerations of various discs with different decelerations,
For example, as a search means to search for disc tit information,
What is the relationship between the address information recorded on the disc and the displacement of the pickup in the disc radial direction? Among the approximation formulas shown below, using the formula that has one speed term (when performing a 1m search, if the above linear velocity corresponds to the gA velocity that differs depending on the disc, the approximately accurate amount of movement of the IC pickup during the search can be calculated. Therefore, it is possible to completely reduce the pickup feeding error during retrieval, making it possible to quickly retrieve information.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one example of the present invention, and FIG. 2 is a diagram showing the relationship between the disk address (8 vs. time leap) and the number of tracks in the radial direction (Equation 1). (1) ... Disk, (4) ... Brushless motor, (5) ... Pickup, (8) ... Motor control circuit, (9) ... Waveform shaping circuit (along with the Hall element of the brushless motor, the rotation speed Detection circuit t-configure), (1
G...Pickup control circuit, σV...Microcomputer<m speed calculation time i63°

Claims (1)

[Claims] (1) A linear velocity measuring device for a rotational drive device for a disk in which information signals are recorded at a constant linear velocity, the linear velocity control circuit controlling the linear velocity based on information read by a pickup; a pickup control circuit that controls the pickup moving along the disk; the pickup control circuit sets the pickup at a predetermined position in the radial direction of the disk; and the linear velocity control circuit makes the linear velocity constant. When I did,
It is characterized by having a rotational speed detection circuit that sends out a signal corresponding to the rotational speed of the disk at that time, and a linear velocity calculation circuit that calculates the linear velocity of the disk based on the signal and the position of the pickup. linear velocity measuring device.