Disc playback apparatus for reproducing sequentially recorded digital data

• US 5,200,944 A
• Filed: 04/17/1991
• Issued: 04/06/1993
• Est. Priority Date: 04/18/1990
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Souma, Yasuhito
• Primary Examiner(s): Young, Wayne R.
• Application Number:
  US07/686,389
• Time in Patent Office: 720 Days
• Field of Search: 369/50, 369/32, 369/58, 369/59, 369/44.34, 369/44.28, 369/115, 369/124, 369/47, 369/48, 358/342, 358/907, 358/343, 358/338, 358/341, 360/73.01, 360/73.08, 360/73.05, 360/73.03, 360/78.04, 360/78.06, 360/78.08, 360/79, 360/75, 360/8, 360/9.1, 360/10.1
• US Class Current: 369/47.48
• CPC Class Codes: G11B 20/10 Digital recording or reproducing
• CPC Class Codes: G11B 2220/2545 CDs
• CPC Class Codes: G11B 2220/255 CD-I, i.e. CD-interactive
• CPC Class Codes: G11B 27/005 Reproducing at a different information rate from the information rate of recording for television signals H04N5/783
• CPC Class Codes: H04N 5/783 Adaptations for reproducing at a rate different from the recording rate
• CPC Class Codes: H04N 5/926 by pulse code modulation H04N5/919 takes precedence
• CPC Class Codes: H04N 5/945 for signals recorded by pulse code modulation

Abstract

A disc playback apparatus for reproducing data from a disc having digital data including at least image data or computer data recorded sequentially thereon includes: a spindle motor for rotating the disc; a pick-up assembly for reading and outputting data from the disc, as an electrical signal; waveshaping circuit for shaping the electrical signal into a pulse signal; a clock extracting circuit for extracting a playback clock signal from the pulse signal; a reference clock generating circuit controlled by a reference clock control circuit, for continuously varying and outputting a frequency of the reference clock signal; and a switching circuit which is switched on and off, the reference clock control circuit increasing the frequency of the reference clock signal when the switching circuit is switched on, and decreasing it when the switching circuit is switched off; a rotation servo circuit for controlling the spindle motor so that the frequency of the playback clock signal is consistent with the frequency of the reference clock signal; a digital signal processing circuit for receiving the pulse, playback clock and reference clock signals and for latching data from the pulse signal on the basis of the playback clock signal, and for processing and outputting the latched data according to the reference clock signal; and a processing and outputting circuit for receiving data outputted from the digital signal processing circuit and for processing and outputting attributes of the data.

Claims

1. A disc playback apparatus for reproducing data from a disc having recorded sequentially thereon digital data including at least image data or computer data as a main data, which comprises:

a single motor operable to rotate the disc;

a pick-up assembly operable to read the data from the disc and to output an electrical signal corresponding thereto;

a wave shaping means for shaping the electrical signal output from the pick-up assembly into a pulse signal and for outputting the pulse signal;

a clock extracting means for receiving the pulse signal from the wave shaping means and for extracting a playback clock signal from the pulse signal;

a reference clock generating means for outputting a reference clock signal and a reference clock signal control means for continuously varying a frequency of the reference clock signal;

a switching means adapted to be externally switched on and off;

wherein said reference clock control means controls the reference clock generating means so that the frequency of the reference clock signal is increased when the switching means is switched on, but is decreased when the switching means is switched off;

a rotation servo means for controlling the spindle motor so that the frequency of the playback clock signal outputted from the clock extracting means is consistent with the frequency of the reference clock signal outputted from the reference clock generating means;

a digital signal processing means for receiving the pulse signal outputted from the wave shaping means, the playback clock signal outputted from the clock extracting means and the reference clock signal outputted from the reference clock generating means and for latching data from the pulse signal on the basis of the playback clock signal, and for subjecting the latched data to a first process and to output the data after being processed by the first process, according to the reference clock signal; and

a processing and outputting means for receiving data outputted from the digital signal processing means and for subjecting the data attributes to a second process and then to output the data after being processed by the second process.

2. The disc playback apparatus as claimed in claim 1, wherein the reference clock generating means comprises a quartz oscillator, a digital-to-analog converter and a voltage-to-frequency converter, and wherein said reference clock control means selects a clock signal generated by the quartz oscillator as the reference clock signal during a normal playback, but selects a clock signal generated by the voltage-to-frequency converter as the reference clock signal during a varied speed playback.

3. A disc playback apparatus for reproducing data from a disc having recorded sequentially thereon digital data including at least image data or computer data as a main data, which comprises:

a spindle motor operable to rotate the disc;

a pick-up assembly operable to read the data from the disc and to output an electrical signal corresponding thereto

a wave shaping means for shaping the electrical signal output from the pick-up assembly into a pulse signal and for outputting the pulse signal;

a clock extracting means for receiving the pulse signal outputted from the wave shaping means and for extracting a playback clock signal from the pulse signal;

a reference clock generating means for outputting a reference clock signal and a reference clock signal control means for continuously varying a frequency of the reference clock signal;

a speed input means for externally inputting speed data in the form of a numerical value and then outputting such speed data;

wherein said reference clock control means controls the reference clock generating means so as to increase the frequency of the reference clock signal if a required playback speed is faster than a current playback speed and to decrease the frequency of the reference clock signal if the required playback speed is lower than the current playback speed, in accordance with the speed data outputted from the speed input means;

a rotation servo means for controlling the spindle motor so that the frequency of the playback clock signal outputted from the clock extracting means is consistent with the frequency of the reference clock signal outputted from the reference clock generating means;

a digital signal processing means for receiving the pulse signal outputted from the wave shaping means, the playback clock signal outputted from the clock extracting means and the reference clock signal outputted from the reference clock generating means and for latching data from the pulse signal on the basis of the playback clock signal, and for subjecting the latched data to a first process and to output the data after being processed by the first process, according to the reference clock signal; and

a processing and outputting means for receiving data outputted from the digital signal processing means and for subjecting the data attributes to a second process and then to output the data after being processed by the second process.

4. The disc playback apparatus as claimed in claim 3, wherein the reference clock generating means comprises a quartz oscillator, a digital-to-analog converter and a voltage-to-frequency converter, and wherein said reference clock control means selects a clock signal generated by the quartz oscillator as the reference clock signal during a normal playback, but selects a clock signal generated by the voltage-to-frequency converter as the reference clock signal during a varied speed playback.

5. A disc playback apparatus for reproducing data from a disc having recorded sequentially thereon digital data including at least image data or computer data as a main data, which comprises:

a spindle motor operable to rotate the disc;

a pick-up assembly operable to read the data from the disc and to output an electrical signal corresponding thereto;

a wave shaping means for shaping the electrical signal output from the pick-up assembly into a pulse signal and for outputting the pulse signal;

a clock extracting means for receiving the pulse signal outputted from the wave shaping means and for extracting a playback clock signal from the pulse signal;

a reference clock generating means for outputting a reference clock signal and a reference clock signal control means for continuously varying a frequency of the reference clock signal;

a speed input means for externally inputting speed data in the form of numerical value then outputting such speed data;

wherein said reference clock control means controls the reference clock generating means so as to increase the frequency of the reference clock signal if a required playback speed is faster than a current playback speed and to decrease the frequency of the reference clock signal if the required playback speed is lower than the current playback speed, in accordance with speed data outputted from the speed input means and for also monitoring the absolute value of a difference between the respective frequencies of the reference and playback clock signals so as to thereby prevent the absolute value from exceeding a predetermined value;

a rotation servo means for controlling the spindle motor so that the frequency of the playback clock signal outputted from the clock extracting means is consistent with the frequency of the reference clock signal outputted from the reference clock generating means;

a digital signal processing means for receiving the pulse signal outputted from the wave shaping means, the playback clock signal outputted from the clock extracting means and the reference clock signal outputted from the reference clock generating means for latching data from the pulse signal on the basis of the playback clock signal, and for subjecting the latched data to a first process and to output the data after being processed by the first process, according to the reference clock signal; and

a processing and outputting means for receiving data outputted from the digital signal processing means and for subjecting the data attributes to a second process and then to output the data after being processed by the second process.

6. The disc playback apparatus as claimed in claim 5, wherein the reference clock generating means comprises a quartz oscillator, a digital-to-analog converter and a voltage-to-frequency converter, and wherein said reference clock control means selects a clock signal generated by the quartz oscillator as the reference clock signal during a normal playback, but selects a clock signal generated by the voltage-to-frequency converter as the reference clock signal during a varied speed playback.