Miscellaneous active electrical nonlinear devices – circuits – and – Signal converting – shaping – or generating – Having specific delay in producing output waveform
Reexamination Certificate
1998-12-31
2001-01-16
Tran, Toan (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Signal converting, shaping, or generating
Having specific delay in producing output waveform
C327S276000, C327S287000, C327S553000
Reexamination Certificate
active
06175260
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a time delay apparatus for a system which requires time delay of a signal, and, more particularly, the present invention relates to a time delay apparatus including a transfer conductance portion which uses transfer conductance to control a signal from an external device and obtain a desirable time delay without influencing a frequency characteristic, by using a MOS (Metal-Oxide Semiconductor) transistor.
2. Description of the Related Art
Generally, in signal processing system, time delay of a signal is inevitably generated in a path between components. For example, a signal passing through a simple buffer generates a time delay of at least 2 nanoseconds (ns). Further, for example, a time delay dependent on holding time is generated in a sample-and-hold circuit installed in an analog to digital converter (A/D converter) for converting an analog signal to a digital signal.
However, in a system for processing an inputted multiplexed signal by using the time delay characteristics of each signal, the time delay between signals is different because the path for inputting and passing through each signal generated from an external device is not the same. Accordingly, adding a time delay according to the path through which the signal passes to the time characteristics of an ordinarily generated signal can produce a bad influence on the system.
A conventional time delay apparatus will be described hereinbelow with reference to a time delay control apparatus applied to a digital video disk player (DVDP) which is a system for processing a multiplexed signal and standardized as an alternative of a new video and voice storing device.
A block diagram of the conventional digital video disk player is shown in FIG.
1
. The digital video disk player includes: a data collecting portion
10
for collecting data from a high-density optical disk via a head; a data signal processing portion
20
which outputs the data as a bit stream by executing demodulation and error correction of the collected data from the data collecting portion
10
and feeds back the data to the data collecting portion
10
by detecting a tracking error; a signal reproducing portion
30
for generating audio and video outputs by decoding each audio, character and video signal among the bit streams inputted from the data signal processing portion
20
; and a system control portion
40
for inputting a control signal for display and operation and a control signal for a whole system into the data signal processing portion
20
and the signal reproducing portion
30
, thereby providing a user interface.
The data collecting portion
10
includes: an optical head
12
for directly collecting data from the high-density optical disk
14
which records data along a track; a disk motor
11
for rotating the optical head
12
at a constant speed; and a transporting motor
13
for transporting the optical head
12
to an exact position on the optical disk
14
.
Moreover, the data signal processing portion
20
includes: a signal amplifying portion
21
for outputting the signal received from the data collecting portion
10
as a safe signal by amplifying the same; a demodulating/error correcting portion
22
for applying the inputted signal from the signal amplifying portion
21
to the signal reproducing portion
30
as a bit stream by demodulating the inputted signal from the signal amplifying portion
21
and detecting and recovering the error generated during recording of the signal on the optical disk
14
by error correcting code; a servo control portion
23
which generates a track control signal of the data collecting portion
10
by using the track error of the data collecting portion
10
which is detected by using four (4) signals, such as a first, a second, a third and a fourth signal inputted from the signal amplifying portion
21
, and a control signal inputted from the demodulating/error correcting portion
22
; and a servo driving portion
24
for converting the track control signal inputted from the servo control portion
23
to a motor driving signal of the data collecting portion
10
.
The signal reproducing portion
30
includes: a system decoding portion
31
for separating the inputted signal bit stream from the demodulating/error correcting portion
22
of the signal processing portion
20
into video, character and audio signals according to data characteristics; a video decoding portion
32
for decoding the separated video signal stream from the system decoding portion
31
; a character decoding portion
33
for encoding the separated character signal stream from the system decoding portion
31
; an audio decoding portion
34
for decoding the separated audio signal stream from the system decoding portion
31
; a National Television Standard Committee (NTSC) decoding portion
35
for converting the inputted signal from the video decoding portion
32
and the character decoding portion
33
into a NTSC signal which is a displaying method of a broadcasting and a video player; and a Digital to Analog (D/A) converter
36
for converting the inputted signal from the audio decoding portion
34
into the audio signal.
The servo-control portion
23
will now be described in detail hereinbelow. The servo-control portion
23
receives and processes a multiplexed signal from the signal amplifying portion
21
and the demodulating/error correcting portion
22
. That is, to execute track error detection for a beam used for the digital video disk player, the four signals from the signal amplifying portion
21
are received and the phase difference between a first composite signal and a second composite signal is detected, wherein the first composite signal is a composite of the first and the third signals and the second composite signal is the composite of the second and the fourth signals. Accordingly, the signal track on the optical disk
14
is discriminated.
Then, respectively different time delays can be generated by an offset of a pickup process and a delay component of the signal amplifying portion
21
, etc., because each signal uses respectively different channels.
Accordingly, when the mechanism for correcting the exact position of the optical head portion
12
causes error because of the phase difference generated from the track error and the time delay according to the offset of the pickup process and the delay component of the signal amplifying portion
21
, deviation from the track can be generated at the servo-control portion
23
which detects the phase difference between the first composite signal and the second composite signal. Consequently, deviation from the track may cause discontinuous data collecting.
In addition to the above-described time delay, a time delay of the signal is needed for the general signal processing system for processing a single signal. The time delay can be obtained by using various methods, such as using a passive component or an active component. Generally, the time delay method can be roughly classified into a method using the passive component and a method using the active component.
The most simple time delay method using a passive element is to use a capacitor. By using the capacitor characteristics, that is, the capacitor charges to a predetermined value according to an inputted signal and discharges when the inputted signal is eliminated and the speed of charge and discharge is determined by the capacitance of the capacitor. Further, the time constant is changed by changing the capacitance of the capacitor and the required time delay can be obtained via change of the time constant.
Moreover, the active delay component having a naturally discrete time delay characteristic, such as a flip-flop, can delay time by continuously connecting the same in a serial manner. In the time delay method using a flip-flop, the degree of the time delay is determined by a the frequency of a clock applied to the delay component. By changing the clock frequency of an oscillator, the degree of the time delay i
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
Tran Toan
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