JPH0519222B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a motor rotation control device that can be used mainly for compact disc players, video disc players, and the like.

Conventional configuration and its problems Conventionally, like a compact disc player,
In a system that detects motor rotation information from a disk using an optical pick-up and controls the speed and phase of the motor based on that rotation information, for example, information may be lost due to dust adhering to the disk surface, or information may be lost due to external If the information on the disk becomes undetectable due to a large mechanical disturbance from the motor, the motor is suddenly accelerated and goes into a runaway state, and as a result the rotation information cannot be detected by the pickup, the runaway state continues. Further, even if the motor is not in a runaway state, the motor is suddenly accelerated, resulting in a problem that it takes a long time to return to the original rotation speed after the disturbance factor has disappeared.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a motor rotation control device that can prevent sudden rotational fluctuations in the motor due to dust adhering to the disk surface or mechanical disturbances.

Composition of the Invention The motor rotation control device of the present invention is provided with a rotation speed sudden change detection means for detecting a state when the rotation speed of the motor suddenly changes, and detects the rotation speed by the output of the rotation speed sudden change detection means. The present invention is characterized in that the speed control loop and the phase control loop are opened for a certain period of time based on the dictionary that detects a sudden change in the speed. As a result, even if a situation occurs in which rotational information cannot be detected from the disk temporarily and the motor is about to accelerate suddenly, this situation can be detected and sudden fluctuations in the motor's rotation can be suppressed.
As soon as rotation information can be detected, normal rotation can be restored.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention is shown in FIGS. 1 to 4. That is, in FIG. 1, 1 is disk 2.
3 is a pick-up for reading the information on disk 2, 4 is a rotation speed that converts the longest cycle information in the output signal of pick-up 3 into voltage and uses it as the rotation speed information of disk 2 (motor 1). a detection circuit; 5 a clock extraction circuit that extracts the motor rotation clock signal included in the information recorded on the disk 2 when the disk 2 enters a predetermined rotational speed range; 6 a rotation reference; Clock signal _S and output signal _C of clock extraction circuit 5
7 is a motor drive circuit that receives an output signal from either the rotational speed detection circuit 4 or the phase comparison circuit 6 and supplies power to the motor 1. , 8 are switches controlled by an operating state signal S that determines the operating state of the clock extraction circuit 5 (whether clock extraction is being performed or not). 9 is a frequency generator that outputs a frequency _FG proportional to the rotational speed of the motor 1; 10 is a frequency generator that generates a control signal to open a switch 11 for a certain period of time from the point of sudden change in the output frequency of the frequency generator; This is a sudden change detection circuit for rotational speed.

In FIG. 1, when the rotation speed of the disk 2 is outside the range in which the clock extraction circuit 5 can operate, that is, when it is asynchronous, the switch 8 is connected to the contact a side by the operating state signal S of the clock extraction circuit 5. The control system constitutes a speed control loop consisting of a motor 1, a disk 2, a pickup 3, a rotation speed detection circuit 4, and a motor drive circuit 7. controlled within range. As a result of this operation, when the rotational speed of the motor 1 reaches a value at which the clock extraction rotation 5 operates, that is, when the clock is in a synchronized state, the operating state signal S of the clock extraction circuit 5 causes the switch 8 to be switched from the contact point a. Switching to contact b, a phase control loop consisting of motor 1, disk 2, pickup 3, clock extraction circuit 5, phase comparator circuit 6 and motor drive circuit 7 is formed, and disk 2 is thereafter reproduced.

In general, compact discs record information from the inner circumference to the outer circumference at a constant linear velocity (CLV), so the rotation speed of motor 1 changes depending on the playback position, but under normal playback conditions, the rate of change in rotation speed is small and can be ignored if considered in a short period of time. In other words, it can be said that a sudden change in the rotational speed of the motor 1 does not occur in a normal reproducing state.
FIG. 2 shows how the rotational speed of the motor 1 changes when it becomes temporarily impossible to detect disk information from the pickup 3 at time _t0 due to, for example, large disturbance vibration. Since this figure shows the phenomenon over a relatively short period of time, it is assumed that the normal rotation speed N ₀ shown in D is a constant value (in reality, playback is performed from the inner circumference of the disk to the outer circumference). Therefore, the graph of D has a very gentle negative slope). In FIG. 2, A can no longer detect disk information at time _t0 , and as a result, the rotation speed detection circuit 4 no longer receives input to the rotation speed detection circuit 4, and as a result, the rotation speed detection circuit 4 issues a very large acceleration command to the motor drive circuit 7. , the motor 1 is rapidly accelerated, and as a result of this acceleration, the rotation speed of the motor 1 increases so much that the pick-up 3 is unable to detect information even after the disturbance vibration has disappeared, and finally the motor 1 Limit rotation speed of
The case of deadlock reaching N _A is shown.
Similarly, in B, motor 1 is suddenly accelerated at time t ₀ , but
When the rotation speed N _B is reached, the disturbance vibration has already disappeared, and the pickup 3 can now detect the information on the disk 2. At this point, the rotation speed detection circuit 4 starts operating and the speed control loop is started. holds true, and then switches to the phase control loop as already explained, and at time t _B the steady state (rotational speed N ₀ ) is reached.
The figure shows the case where . C is frequency generator 9
When the sudden change in rotational speed detection circuit 10 detects that the rotational speed of the motor 1 has changed suddenly, the switch 11 is opened for a certain period of time τ, and the motor 1 is rotated by inertia alone.
This shows a state in which the steady state will be returned immediately if the disturbance vibration disappears. In other words, motor 1 is suddenly accelerated at time t ₀ , but at time t ₁ when the rotation speed reaches N _C (rotation speed ΔN higher than normal rotation speed), the sudden acceleration state is detected and the control loop opens, and the time During τ, that is, until time t ₂ , it rotates only by inertia (the rotational speed decreases very slowly due to lateral loss and other losses), and then switch 11 closes and the speed control loop or phase control loop is activated. is established, a retraction operation is performed, and the steady rotation speed is reached at time t _C. From the above, by operating the switch 11 using the output of the rotation speed change detection rotation 10, even if the rotation speed of the motor 1 suddenly changes for any reason, it can be suppressed, thereby preventing the motor from falling into a panic state. It can be seen that the control state can be returned to normal without any problems and in the shortest possible time.

FIG. 3 shows a specific configuration example of the rotational speed sudden change detection circuit ₁₀ shown in FIG. Terminal for selecting operation mode
UD, output terminals Q ₁ to Q _o , and clear terminal CL. Its counting mode depends on the level state of the control signal _M. When the terminal UD is at "H" level, it is an up counter, and when it is at "L" level, it is an up counter. is controlled to operate as a down counter. 13 is a comparison circuit that digitally compares the output of the up-down counter 12 with a previously set value and determines the magnitude thereof; 14 is a comparison circuit 13 at an optimal timing;
This is a gate circuit that transmits the output of the multivibrator 15 to the one-shot multivibrator 15. 16 is a one-shot multivibrator that detects the rising edge of signal _M and controls the gate circuit 14 at that timing; 17 is one-shot multivibrator 1;
This is a one-shot multivibrator that is triggered by the output of 6 and generates a pulse of a constant width, and the up-down counter 12 is reset by the output. In FIG. 3, when the control system in FIG. 1 constitutes a phase control loop and is in a steady regeneration state,
The signal _FG (having a frequency proportional to the rotation speed of the motor 1) is sent to the terminal by the up-down counter 12.
Up-counting and down-counting are repeated depending on the level of _{the M} signal input to UD. this
When the cycles of both the "H" and "L" levels of _{the M} signal are equal, the one-shot multivibrators 16 and 17 operate in sequence at the rising edge of the pulse of _{the M} signal, first controlling the gate circuit 14 and controlling the comparison circuit. 13
The output is transmitted to the one-shot multivibrator 15, and then the contents of the up-down counter 12 are reset. After the above operations, the up-down counter 12 starts counting up _{the FG} signal, and then switches the operation mode to the down-count mode and starts counting down from the point when the level state of _{the M} signal changes from "H" to "L". . Under steady playback conditions, if the period of _{the M} signal is set to a sufficiently short value (for example, about 0.01 to 1 second) relative to the total playback time, then _M
There is almost no change in the _FG frequency during one period of the signal (strictly speaking, the frequency decreases only slightly). Therefore, in one period of the _M signal, that is, in one cycle of the up-down counter 12, the count up number and the count down number are almost equal, and at the end of the one cycle operation, the count content is almost zero. At the same time, the output of the comparison circuit 13 is transmitted to the one-shot multivibrator 15 via the gate circuit 14. Since the one-shot multivibrator 13 does not output any output, the one-shot multivibrator 15 does not output any output.

On the other hand, if a large rotational fluctuation (for example, sudden acceleration ₎ occurs within one cycle of _{the M} signal, the number of up and down counts within one cycle of the up-down counter 12 will differ greatly, resulting in When the count does not become 0 at the end of the count and the difference between the count-up number and the count-down number exceeds the above-mentioned N, the comparison circuit 13 generates an output, which is sent via the gate circuit 14 to the one-shot multiplier. The vibrator 15 is triggered to generate a constant width pulse and its output interrupts the control loop.

FIG. 4 shows another embodiment of the rotational speed sudden change detection circuit 10, which has almost the same configuration as the embodiment shown in FIG.
A signal CK having a frequency sufficiently higher than the output frequency of the frequency generator 9 is applied to the terminal _CK of the up-down counter 12, and an _FG signal is applied to the terminal UD of the frequency dividing circuit 1.
The difference is that a frequency-divided signal obtained by dividing the frequency by 1/2 by 8 is input. Other configurations are the same. The embodiment shown in FIG. 4 differs from the case shown in FIG. 3 in that the relationship between the direction of rotation fluctuation (acceleration direction or deceleration direction) and the direction of increase/decrease in the contents of the counter is opposite. Since the operations are exactly the same, the explanation will be omitted. Furthermore, the frequency dividing circuit 18 in FIG. 4 does not need to be limited to 1/2 frequency division, and the frequency division ratio can be changed to N (an integer including 1) depending on the gradient of rotational fluctuation that is desired to be detected. The duty of the circumferential output must be 50%.

Effects of the Invention As described above, this invention is capable of suppressing sudden fluctuations in the rotation speed of the motor, and prevents information from being lost due to dust or the like adhering to the disk surface, or from large mechanical disturbances from the outside. This has an excellent effect in that even if the disk information cannot be detected, the motor will not run out of control, and the motor can immediately return to its normal state as soon as the disk information can be detected.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a motor rotation control device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of the motor rotation speed when disk information cannot be detected, and FIGS. 3 and 4 are respectively FIG. 7 is a block diagram showing a specific example of the configuration of a sudden change in rotational speed detection circuit according to another embodiment. 1...Motor, 2...Disk, 3...Pickup, 4...Rotational speed detection circuit (part of speed control loop), 5...Clock extraction circuit (part of phase control loop), 6...Phase Comparison circuit, 7...Motor drive circuit, 8, 11...Switch, 9...Frequency generator, 10... Sudden rotation speed change detection circuit (rotation speed sudden change detection means).

Claims (1)

[Scope of Claims] 1. A motor that drives a disk, a pickup means that detects information on the disk, and a speed control loop that detects rotational speed information of the disk from the pickup means and controls the speed of the motor. a phase control loop that controls the phase of the motor by comparing rotational phase information of the disk detected from the pickup means with a phase reference signal; and a speed control loop or a changeover switch means for selecting one of the phase control loops; and a sudden change in rotational speed for detecting a sudden change in the rotational speed of the motor and opening the speed control loop and the phase control loop for a predetermined period of time. A motor rotation control device comprising a detection means. 2. The rotation speed sudden change detection means includes an up-down counter that alternately repeats count-up and count-down at a constant period ratio using a frequency signal proportional to the rotation speed of the motor as a count input signal, and an output of this up-down counter. 2. The motor rotation control device according to claim 1, comprising a comparison circuit that compares the magnitude with a previously set reference value at a predetermined timing. 3. The rotational speed sudden change detection means includes a 1/N frequency dividing circuit (N is an integer including 1) that divides a frequency signal proportional to the rotational speed of the motor, and an external A patent claim consisting of an up-down counter that has two counting modes for counting up or down a clock signal, and a comparison circuit that compares the output of this up-down counter with a preset reference value at a predetermined timing. The motor rotation control device according to item 1.