JPS6346901B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital audio disc player, and more particularly to a rotation control circuit for a spindle motor provided to rotate a disc at a constant linear velocity.

Digital audio disc players play discs on which digitized audio signals and synchronization signals are recorded optically at high density at a constant linear velocity, and have the excellent feature of providing high-fidelity playback signals. are doing. In this case, the most important thing for high-fidelity playback is to control the rotation of the spindle motor according to the position of the pickup so that the rotation of the disk during playback accurately maintains a constant linear velocity. be.

Here, the rotation control of the spindle motor is performed by two systems: a coarse adjustment system and a fine adjustment system, and the coarse adjustment system is controlled using a signal obtained by F-V converting the spectrum of the reproduced signal. This allows coarse adjustment to within ±10% of the reference rotation, and the fine adjustment system is controlled using the phase comparison output between the bit clock generated in synchronization with the data included in the reproduced signal and the crystal-accurate reference clock. The rotation is finely adjusted to within ±1% of the reference rotation. The control signals for the coarse adjustment system and the fine adjustment system thus generated are added together and then supplied to a motor drive circuit to control the spindle motor.

In this case, in a digital audio disc player, the difference in the rotational speed of the spindle motor when playing the inner circumference of the disc and when playing the outer circumference is more than double, and the control range increases accordingly. has become extremely wide.

However, in the rotation control circuit of the spindle motor with the above-described configuration, the bit clock generation circuit with the phase lock loop configuration that generates the bit clock is ±10
Synchronization can only be achieved with respect to reproduction signals during rotation within a range of %. For this reason, when starting the motor, it is necessary to quickly adjust the rotation of the spindle motor to within ±10% of the specified value and accurately generate the bit clock used in the fine adjustment system. The problem is that the control characteristics of the coarse adjustment system using a signal obtained by FV-converting the spectrum of the reproduced signal become loose, resulting in a response delay, and the system becomes extremely vulnerable to external disturbances.

Therefore, an object of the present invention is to quickly control the rotation of the spindle motor to a range in which the bit clock generation circuit used in the fine adjustment system is synchronously driven when starting the spindle motor, and to obtain stable operation even in the face of external disturbances. An object of the present invention is to provide a digital audio disc player having a rotation control circuit.

In order to achieve this purpose, the digital audio disc player according to the present invention has the following features:
In a rotation control circuit composed of a coarse adjustment system and a fine adjustment system, after dividing the reproduction signal, the F-V
By performing rotation control using the converted signal, rapid and stable rotation control can be performed by utilizing the specificity of the frequency spectrum of the reproduced signal. Hereinafter, a digital audio disc player according to the present invention will be explained in detail using the drawings.

FIG. 1 is a circuit diagram showing one embodiment of a digital audio disc player according to the present invention, and in particular, one embodiment of a rotation control circuit. In the figure, reference numeral 1 denotes a frequency dividing circuit that divides the frequency of the reproduced signal A, and in this embodiment, a frequency dividing circuit that divides the frequency of the input signal by three is used. 3 is a frequency/voltage conversion circuit that generates an output obtained by F-V converting the spectrum of data included in the signal B supplied from the frequency dividing circuit 1, and is triggered by the input signal to generate a negative polarity of, for example, 0.25 μs. The mono-multivibrator circuit 3 generates a sexual pulse, and the low-pass filter 4 removes ripples in the negative output of the mono-multivibrator circuit 3 and converts it into direct current. 5 is an amplifier circuit that amplifies the output signal C of the frequency/voltage conversion circuit 2; 6 is a first level adjustment circuit that adjusts the level of the output signal of the amplifier circuit 5 to generate a coarse adjustment signal D; 7 is a reproduction signal A; A phase lock loop (PLL) that generates a bit clock E synchronized with the data contained in this reproduced signal as an input.
A bit clock generation circuit 8 is constructed of a bit clock signal E synchronized with the data of the reproduced signal A generated from the bit clock generation circuit 7, and a reference clock F supplied from a crystal oscillation circuit (not shown).
This is a phase comparator circuit that compares the phase between the two and generates an output signal G having a level corresponding to the phase difference. 9 is a second level adjustment circuit that adjusts the level of the output signal G of the phase comparison circuit 8 in relation to the level of the output signal D generated from the first level adjustment circuit 6; 10 is a second level adjustment circuit of the first level adjustment circuit 6; Output signal D
and the output signal H of the second level adjustment circuit 9, and 11 is a motor drive circuit that rotates the spindle motor 12 at a speed corresponding to the output signal I of the addition circuit 10.

In the motor rotation control circuit configured in this manner, when a reproduction signal A is supplied from a pickup (not shown), this reproduction signal A is transmitted to the frequency dividing circuit 1.
The frequency is divided by three and output as an output signal B. This frequency-divided output signal B is generated as an output signal C by subjecting the spectrum of data contained in the frequency/voltage conversion circuit 2 to F-V conversion. In this case, the reproduced signal A is a signal expressed by the non-zero return method (NRZ-I), and this signal includes, for example, an information signal expressed within the range of 3 to 11 bits, and 11 bits of "0" and "1". ” is a signal with a specificity consisting of a continuous synchronization signal, the spectrum of this reproduced signal A has a relatively smooth spectrum with a peak at about 480KHz, as shown in Figure 2a. have characteristics. On the other hand, when we measure the spectrum of a signal obtained by dividing the frequency of the reproduced signal A by 2, we find that it is approximately
It has a peak at 240KHz, and this peak part is slightly emphasized. Furthermore, when the spectrum of a signal obtained by dividing the input signal A by 4 is measured, it has a steep characteristic with a peak at about 120 KHz as shown in FIG. 2c. in this way,
It has been found that as the frequency division ratio for input signal A increases, the peak portion of the spectrum characteristics becomes steeper. Even if the content of the reproduced signal A changes, the peak portion of this spectrum characteristic only slightly fluctuates within 5%, and can be considered to be almost constant. Therefore, in the above embodiment, since the frequency divider circuit 1 has a frequency divider configuration of 4, the output signal B has a spectrum characteristic having a steep peak around 120 KHz as described above. There will be. The frequency-divided output signal B having such a spectrum characteristic is subjected to F-V conversion centered around the peak of the spectrum characteristic in the frequency/voltage conversion circuit 2. In this case, since the F-V conversion characteristic of the frequency/voltage conversion circuit 2 has the characteristic shown in FIG. 3, the output signal C of the frequency/voltage conversion circuit 2 is a component of the reproduced signal during normal rotation. The output has an S-shaped characteristic that peaks when the frequency signal B is supplied. That is, in the frequency/voltage conversion circuit 2, the mono multivibrator circuit 3 is triggered by the output signal B of the frequency dividing circuit 1, and generates a negative pulse of, for example, 0.25 μs. The ripples of the output signal of the mono-multivibrator circuit 3 are removed by the low-pass filter 4, so that a DC level output signal C having S-shaped characteristics with respect to the rotation of the disk is generated. Become. Therefore, when this output signal C is extracted as an output signal D via the amplifier circuit 5 and the first level adjustment circuit 6, and this output signal D is supplied to the motor drive circuit 11 via the adder circuit 10, the automatic frequency control circuit is configured, and the rotation of the spindle motor 12 is controlled so that the peak of the spectrum of the reproduced signal A becomes a predetermined DC voltage. Therefore, if the first level adjustment circuit 6 is adjusted to obtain normal rotation, the spindle motor 1
Even if the condition of constant linear velocity deviates significantly at startup of 2 or during fast forwarding of pick-up, the speed is quickly and coarsely adjusted to within 10% of the specified rotational speed in response to the output signal of the frequency/voltage conversion circuit 2. I can do it. Then, by dividing the frequency of the reproduced signal A,
Since the signal is converted into a signal having a spectrum characteristic with a steep peak and is supplied to the frequency/voltage conversion circuit 2, the S-curve characteristic of the output signal becomes steep, and rough adjustment of the spindle motor 12 can be performed more quickly. At the same time, it becomes stable against external disturbances.

In this way, coarse adjustments to the spindle motor 12 can be quickly made to ensure that its rotation is within the specified range.
When set in the 10% range, the phase lock loop (PLL) of the bit clock generating circuit 7 which receives the reproduced signal A as input is locked, and the bit clock signal E synchronized with the information bits included in the reproduced signal A is generated. And this bit clock signal E is
In the phase comparator circuit 8, the phase difference between the crystal level and the reference signal F supplied from an oscillation circuit (not shown) is determined, and an output signal G having a level corresponding to this phase difference is generated. This output signal G is level-adjusted in the second level adjustment circuit 9 in relation to the coarse adjustment signal D generated from the first level adjustment circuit 6, and is output as a fine adjustment signal H. . The fine adjustment signal H is added to the coarse adjustment signal D in the adder circuit 10 and supplied to the motor drive circuit 11, so that the rotation of the spindle motor 12 is matched to a specified value and the linear velocity is always constant. rotated accurately.

In the above embodiment, the case where the frequency dividing value of the frequency dividing circuit 1 was set to 3 was explained, but this frequency dividing ratio is not limited in any way, and as the frequency dividing value increases, the spectrum changes. The peak of the characteristic becomes steeper, and faster and more stable rotation control can be performed.

As explained above, the digital audio disc player according to the present invention divides the frequency of the reproduced signal to obtain the rough adjustment signal for the spindle motor by converting the frequency and voltage of the spectrum of the reproduced signal supplied from the pickup.・
By supplying the voltage to a voltage conversion circuit, the peak of the spectrum is made steeper. Then,
To quickly and coarsely adjust the rotation of the spindle motor to bring it within the control range of the fine adjustment system when the linear velocity deviates significantly from the specified value, such as when starting the spindle motor or during fast forwarding of a pick-up. I can do it. In addition, since the reproduced signal is frequency-divided to make the peak of the spectrum characteristic steeper and then supplied to the frequency/voltage conversion circuit to obtain the coarse adjustment signal for the spindle motor, the change in the coarse adjustment signal due to the linear velocity deviation is It has various excellent effects, such as the stability against disturbances being greatly improved due to the sharp increase in the stability.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of a spindle motor rotation control circuit used in a digital audio disc player according to the present invention, and Fig. 2 a to c are signals obtained by dividing the reproduction signal by changing the frequency division ratio. Figure 3 shows the spectrum characteristics of
FIG. 3 is an F-V characteristic diagram of the frequency/voltage conversion circuit shown in the figure. 1... Frequency divider circuit, 2... Frequency/voltage conversion circuit, 3... Mono multivibrator circuit, 4...
Low-pass filter, 5...Amplification circuit, 6, 9...
...first and second level adjustment circuits, 7...bit clock generation circuit, 8...phase comparison circuit, 10...addition circuit, 11...motor control circuit, 12...spindle motor.

Claims (1)

[Claims] 1. A voltage signal corresponding to the frequency of the reproduction signal supplied from the pickup is generated, and the voltage signal is used as a coarse adjustment signal for coarsely adjusting the rotation of a spindle motor for rotating a disk based on this voltage signal. In a digital audio disc player comprising a frequency/voltage conversion circuit that outputs a frequency/voltage conversion circuit and a circuit that controls rotation of the spindle motor using the coarse adjustment signal, the change in the coarse adjustment signal with respect to the change in the peak level of the reproduction signal is provided. In order to quickly and coarsely adjust the rotational deviation of the spindle motor by increasing the amount of rotation, the circuit that controls the rotation divides the frequency of the reproduction signal so that the peak in the frequency spectrum characteristic of the reproduction signal becomes steep. A digital audio disc player characterized in that it is provided with a frequency dividing circuit that supplies the frequency/voltage converter circuit with the frequency/voltage converter.