Apparatus for controlling reproduction speed for laser disc player

An apparatus for controlling the reproduction speed for laser disc player is disclosed. When audio and video signals recorded on a disc are reproduced by an optical pick-up, if an accelerating or decelerating signal is supplied from a speed controlling inputting part to a micro-processor, then the micro-processor outputs a speed control signal to the speed control part. The speed control part outputs a main clock (which is varied in accordance with the received control signal) to a video signal processing and pulse width modulation signal generating part. Then the video signal processing and pulse width modulation signal generating part outputs a modified spindle motor driving pulse width. Further, after receipt of the main clock, the video signal processing and pulse width modulation signal generating part supplies to an A/D converter the video signals which are extracted from the microwave signals which are outputted from the optical pick-up part. Then the A/D converter carries out a sampling on the received video signals based on A/D clocks to A/D convert them and to output them as digital data. The digital data signals are made to pass through an interpolator or a decimator to be outputted to the video signal processing part.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an apparatus for controlling a 
reproduction speed for a laser disc player, in which the data recorded on 
a disc is reproduced while controlling the revolution of the spindle motor 
by means of driving pulses for the spindle motor. 
2. Prior Arts 
Generally, in laser discs of a constant linear velocity type, the rotation 
speed of the spindle motor should be about 1800 rpm in its inner 
circumference, and about 600 rpm in its outer circumference. Therefore, 
the recorded amount of data per unit inner track and per unit outer track 
are different from each other, with the result that it is difficult to 
control the rotation speed of the spindle motor during the variation of 
the reproduction speed. 
Further, when a laser disc player carries out a low speed reproduction or a 
high speed reproduction for data in which the audio signals and the video 
signals are recorded on the laser disc in a standard type of a frequency 
modulation method, the signals have to be converted into the normal type 
again, this being a problem. 
U.S. Pat. No. 4,864,428 discloses an apparatus for adjusting the 
reproduction speed for a laser disc player. This patent provides a 
technique for controlling the rotation speed of the spindle motor of a 
laser disc player in accordance with the difference in the phase and 
frequency between reference synchronizing signals and the signals read 
from the laser disc. FIG. 1 is a block diagram showing the constitution of 
the reproduction speed adjustable laser disc player of U.S. Pat. No. 
4,864,428. 
As shown in FIG. 1, in the reproduction speed adjustable laser disc player, 
a disc 1 is driven by a spindle motor 2, and the data recorded on disc 1 
are read by an optical pick-up 3. The audio data which are read by optical 
pick-up 3 from disc 1 are amplified by a pre-amplifier 4, and then, are 
supplied to an audio demodulating circuit 5 to be demodulated before being 
supplied to an audio signal output terminal 6. Meanwhile, the video 
components are supplied to a video demodulating circuit 7 to be 
demodulated by it, and are supplied through a video memory 8 to a video 
output terminal 9. The output of video demodulating circuit 7 are also 
supplied to a synchronizing signal separating circuit 10 and to a write 
clock and address generating circuit 11. 
Horizontal synchronizing signal separating circuit 10 separates and 
extracts the horizontal synchronizing signals from the video signals to 
send them to a spindle servo circuit 12. Spindle servo circuit 12 compares 
the received horizontal synchronizing signals with a reference signal of 
the variable frequency which is generated by a variable frequency signal 
generating circuit 17. The variable frequency reference signal is used as 
a reference signal in spindle servo circuit 12 which controls the rotation 
speed of disc 1. 
Spindle servo circuit 12 detects the frequency and phase differences 
between the reference signal and the restored horizontal synchronizing 
signals so as to generate servo control signals which are varied in 
accordance with the detected frequency and phase differences. These servo 
control signals are used for controlling the driving of spindle motor 2 
through driving circuit 14, so as to ultimately control the rotation speed 
of the disc. 
In the apparatus of FIG. 1, the video data of disc 1 are stored into video 
memory 8 in a proper sequence in accordance with the write clocks and the 
address signals which are generated by write clock and address generating 
circuit 11 based on the reproduced video signals. The frequency of the 
video memory reading clocks which are generated by reference signal 
generating circuit 13 is decided in accordance with the reference signals, 
and therefore, the video signals which correspond to the television 
broadcasting standard appear on the video output terminal 9. 
As for the audio signals of disc 1, their demodulated output is supplied 
directly from audio demodulating circuit 5 to audio output terminal 6, and 
therefore, the pitches of the audio signals are varied proportionately to 
the rotation speed of the disc. 
However, in the spindle motor control method of FIG. 1 in which the speed 
of the spindle motor is controlled in accordance with the phase difference 
and the frequency difference between the reference synchronizing signals 
and the synchronizing signals read from the disc, an exact synchronization 
is not realized between the audio signals and the video signals, with the 
result that the picture reproducing speed and the audio reproducing speed 
do not correspond to each other. 
Further, in the case where the reproducing speed is fast, the capacity of 
the video memory should be larger compared with the normal reproduction, 
with the result that the manufacturing cost is increased. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide an apparatus for 
controlling the reproduction speed for a laser disc player, in which even 
when the reproduction speed is varied, the audio signals and the video 
signals are precisely synchronized, so that sounds and pictures would be 
reproduced in a good corresponding manner. 
To accomplish the above object of the present invention, there is provided 
an apparatus for controlling the reproduction speed for a laser disc 
player, including a speed controlling inputting part, a spindle motor 
driven by driving pulses, an optical pick-up part for reading out RF 
signals from a disc rotated by the spindle motor, and an audio signal 
processing part and a video signal processing part for detecting 
respectively audio signals and video signals from the RF signals read-out 
by the optical pick-up part, the apparatus comprising: 
a control means for outputting a plurality of control signals in accordance 
with signals received from the speed controlling inputting part; 
a memory control means for outputting control pulses to control a reference 
pulse and the video signal processing part upon receipt of a control 
signal from the control means; 
a speed control means for outputting a main clock which is varied in 
accordance with an inputted control signal upon receipt of a control 
signal from the control means; 
a video signal processing and pulse width modulation signal generating 
means for outputting a reference pulse same as the reference pulse 
received from the memory control means, video signals received from the 
optical pick-up part, a sampling pulse for sampling the video signals, and 
a spindle motor driving pulse for controlling a speed of the spindle 
motor; 
an A/D converter for receiving video signals and sampling pulses from the 
video signal processing and pulse width modulation signal generating means 
to convert the video signals to digital data; and 
an interpolating and decreasing means for interpolating or decreasing an 
data amount of the digital data signals to control an output supplied to 
the video signal processing part. 
According to the present invention, when the audio and video signals 
recorded on a disc which is rotated by a spindle motor are reproduced by 
an optical pick-up, if an accelerating or decelerating signal is supplied 
from a speed controlling input part to a micro-processor, then the 
micro-processor outputs a speed control signal to the speed control part. 
The speed control part outputs a main clock (which is varied in accordance 
with the received control signal) to a video signal processing and pulse 
width modulation signal generating part. Then the video signal processing 
and pulse width modulation signal generating part outputs a modified 
spindle motor driving pulse width. Further, after receipt of the main 
clock, the video signal processing and pulse width modulation signal 
generating part supplies to an A/D converter the video signals which are 
extracted from the microwave signals which are outputted from the optical 
pick-up part. Then the A/D converter carries out a sampling on the 
received video signals based on A/D clocks to A/D-convert them and to 
output them as digital data. The micro-processor discriminates the 
acceleration or deceleration for the signals which are supplied by a speed 
controlling input part. Based on the result of the discrimination, the 
switching part is controlled, and then, the digital data signals are made 
to pass an interpolator or a decimator to output them to the video signal 
processing part. Under this condition, an interpolating or decreasing is 
carried out on the data amount of the digital data signal. Accordingly, 
even when the reproduction speed is varied, the audio signals and the 
video signals are synchronized, with the result that the sounds and 
pictures are reproduced in a corresponding manner.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 2 is a block diagram showing a constitution of a laser disc player 
according to one embodiment of the present invention. FIGS. 3 and 4 
illustrate wave patterns of the signals generated from the different parts 
of FIG. 2. 
As shown in the drawings, if the power source is connected, a 
micro-processor 26 outputs a memory control signal (MECS). The MECS is 
used for activating a memory control part 31. Upon receipt of the MECS, 
memory control part 31 outputs video memory control (VMC) and 
digital-analogue control (DAC) signals, and a first reference pulse signal 
(STP1). The VMC and DAC signals control a D/A converter 32 and a video 
memory 30 of a video signal processing part 38, while the first reference 
pulse signal (STP1) is supplied to a video signal processing and pulse 
width modulation signal generating part 24. In accordance with the 
received first reference signal (STP1), video signal processing and pulse 
width modulation signal generating part 24 outputs a second reference 
signal (STP2) which is same as the first reference signal (STP1), and also 
outputs a sampling pulse (SAMP) for a sampling. 
Under the normal reproduction speed, micro-processor 26 outputs a switching 
control signal (SCS), so that first and second switching parts 36 and 37 
would be respectively connected to terminals NOR. For example, a speed 
control signal (SPCS1) which is illustrated in (A) of FIG. 3 is outputted 
through a line A to a speed control part 25. In accordance with the speed 
control signal (SPCS1), speed control part 25 outputs a signal e.g., a 
main clock (MAPS1) as shown in (B) of FIG. 3, through a line B to the 
video signal processing and pulse width modulation signal generating part 
24. In accordance with the received main clock (MAPS1), video signal 
processing and pulse width modulation signal generating part 24 outputs a 
pulse, e.g., a spindle motor driving pulse (PWM1) as shown in (C) of FIG. 
3 through a line D, so that the spindle motor would rotate at a normal 
speed. 
At first when the power source is connected, a spindle motor driving pulse 
(PWM1) is outputted from the video signal processing and pulse width 
modulation signal generating part 24 through the line D, so that the 
apparatus for controlling the reproduction speed for a laser disc player 
would rotate spindle motor 21 at the normal speed. Therefore, the RF 
signals recorded on disc 35 are read by optical pick-up part 22 at a 
normal speed. The RF signals thus read are inputted respectively into 
audio signal processing part 23 and video signal processing and pulse 
width modulation signal generating part 24, from which audio signals and 
video signals (NVS) are outputted. The video signal (NVS) which is 
illustrated in (B) of FIG. 4 passes through video memory 30 of video 
signal processing part 38 of A/D converter 27 and D/A converter 32 so as 
to be reproduced. 
Micro-processor 26 gives and receives clocks and data required for the 
current reproduction speed to and from audio signal processing part 23 and 
the video signal processing and pulse width modulation signal generating 
part 24. 
During such as normal speed reproduction of the disc data, if there is a 
manipulation of an accelerating or decelerating buttons (not shown) of a 
speed controlling inputting part 34, micro-processor 26 senses the 
accelerating or decelerating signals through line G. 
In the case where speed controlling inputting part 34 is first manipulated, 
micro-processor 26 senses the accelerating signal (ACCS) of (A) of FIG. 4 
through line G, and then, outputs a switching signal (SCS), so that first 
and second switching parts 36 and 37 would be connected to the respective 
terminals (INT). Interpolator 28 is connected between the terminals (INT) 
of first and second switching parts 36 and 37. 
Meanwhile, micro-processor 26 outputs for example a 3-bit code signal of 
(A) of FIG. 3 through line A to speed control part 25. Speed control part 
25 frequency-divides its own pulses based on the frequency dividing 
constant which is decided by the bit value of the speed control signal 
(SPCS2), so that the frequency-divided pulse and the second reference 
pulse (STP2) of video signal processing and pulse width modulation signal 
generating part 24 would be phase-locked-loop(PLL)-synchronized to each 
other, and that a main clock (MAPS2) of (B) of FIG. 3 would be outputted 
through line B. This main clock (MAPS2) is outputted to the video signal 
processing and pulse width modulation signal generating part 24 and to 
audio signal processing part 23. Video signal processing and pulse width 
modulation signal generating part 24 outputs a spindle motor driving pulse 
signal (PWM2) of (C) of FIG. 3 through line D, thereby increasing the 
speed of the spindle motor. Therefore the video signal output of video 
signal processing and pulse width modulation signal generating part 24 
which is based on the RF signals read by optical pick-up part 22 from disc 
35 has the form of the video signal (AVS) as shown in (C) of FIG. 3. 
The video signals (AVS) are supplied through line C to A/D converter 27, 
A/D converter 27 samples the received video signals (AVS) based on the 
sampling pulse (SAMP), and A/D converts to output them in the form of 
digital data signals. These outputted digital data signals are 
interpolated through interpolator 28, and then, are made to pass through 
video signal processing part 38 to be outputted in the form of analogue 
video signals. 
Meanwhile, during the time when RF signals recorded on the disc are 
reproduced at the normal speed, if a deceleration button of speed 
controlling inputting part 34 is pressed, then micro-processor 26 senses a 
deceleration signal (DECS) of (A) of FIG. 4 through the line G, and 
outputs a switching signal (SCS), so that first and second switching parts 
36 and 37 would be connected to terminals (DES) respectively. Decimator 29 
is connected between the terminals (DES) of first and second switching 
parts 36 and 37. 
Meanwhile, micro-processor 26 outputs for example a 3-bit code signal of 
(A) of FIG. 3 through the line A to speed control part 25. Speed control 
part 25 frequency-divides its own pulse based on a frequency dividing 
constant which is decided by the bit value of the speed control signal 
(SPCS3), so that the frequency-divided pulse and the second reference 
pulse STP2 of video signal processing and pulse width modulation signal 
generating part 24 would be PLL-synchronized with each other, and that it 
would be outputted through the line B in the form of the main clock MAPS3 
of (B) of FIG. 3. This main clock (MAPS3) is outputted to video signal 
processing and pulse width modulation signal generating part 24 and to 
audio signal processing part 23. Video signal processing and pulse width 
modulation signal generating part 24 outputs a spindle motor driving 
signal (PWM3) of (C) of FIG. 3, thereby decreasing the speed of spindle 
motor 21. Therefore, the video signal output of video signal processing 
and pulse width modulation signal generating part 24 (after the RF signals 
are read from disc 35 by optical pick-up part 22) has the form of video 
signal (DVS) of (C) of FIG. 3. 
These video signals (DVS) are inputted through the line C to A/D converter 
27. A/D converter 27 samples the received video signals (DVS) based on the 
sampling pulse (SAMP), and A/D converts to output them in the form of 
digital data. These outputted digital data undergo a reduction of the data 
amount while passing through decimator 29, and they pass through video 
signal processing part 38 to be outputted in the form of analogue signals. 
According to the present invention as described above, the constitution and 
action of the present invention makes it possible to interpolate or 
decrease the data amount, and therefore, the apparatus for controlling the 
reproduction speed for a laser disc player according to the present 
invention makes the audio signals and the video signals correspond with 
each other, even if the reproduction speed is varied, with the result that 
the sounds and pictures are reproduced in a well corresponding manner. 
While the present invention has been particularly shown and described with 
reference to particular embodiments thereof, it will be understood by 
those skilled in the art that various changes in form and details may be 
effected therein without departing from the spirit and scope of the 
invention as defined by the appended claims.