Oscilloscope intensity regulation apparatus

Details Oscilloscope intensity regulation apparatus Oscilloscope intensity regulation apparatus

1999-02-16

2001-07-17

Brier, Jeffery (Department: 2672)

Electric lamp and discharge devices: systems

Cathode ray tube circuits

Cathode-ray deflections circuits

C345S012000, C345S182000, C315S001000

Reexamination Certificate

active

06262543

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an oscilloscope intensity regulation apparatus.
The invention is particularly concerned with an apparatus of an oscilloscope for displaying wave-forms with a regulated intensity in spite of variations of repetition rates of the wave-forms and sweep velocities in the oscilloscope.
2. Description of the Prior Art
In an oscilloscope with a cathode-ray tube (CRT) for displaying wave-forms, low repetition rate wave-forms swept at high speed are displayed with insufficient intensity. It is, therefore, difficult to observe the wave-forms displayed with insufficient intensity on the CRT.
There is an oscilloscope with a charge coupled device (CCD) sensor on a surface of the CRT. The CCD sensor obtains a video signal for displaying the wave-forms. Wave-forms with enough strong intensity are observable by means of video signal via the CCD sensor without direct viewing on the CRT.
Shown in
FIG. 1
is a circuit block diagram of a prior art oscilloscope with a CCD sensor. A CRT
10
displays wave-forms to be observed on its surface. A Z-axis circuit
8
is connected with a cathode of the CRT
10
. The Z-axis circuit
8
controls a beam current of the CRT
10
in accordance with instructions from a central processing unit (CPU)
4
. An observer controls an intensity input
2
to obtain a desirable intensity of displayed wave-forms. The intensity input
2
is, for example, a variable register or a potentiometer delivering an intensity input signal
21
to the CPU
4
. The CPU
4
instructs the intensity to the Z-axis circuit
8
according to the signal
21
.
The CCD sensor
11
is on the surface of the CRT
10
. The CCD sensor
11
reads wave-forms on the surface of the CRT
10
to deliver a CCD output
28
to a video circuit
12
. The circuit
12
provides an analog to digital (A/D) converter
14
with a video signal
29
. A display
19
displays the video signal converted to digital.
In
FIG. 2
, there are shown the CRT
10
, the CCD sensor
11
and an output thereof. The output of the Z-axis circuit
8
is supplied between a cathode K and a grid G of the CRT
10
. The cathode K emits an electron current beam in accordance with the output of the Z-axis circuit
8
. The beam is deflected by deflection plates to display bright wave-forms on a fluorescent screen
9
of the CRT
10
. The CCD sensor
11
converts the bright wave-forms to an electrical signal.
A curve S shows a variation of an intensity I depending on X-position, in which the center of a bright trace is X
0
. The maximum intensity is shown at the center position X
0
of a width of the bright trace in view of an arrow
51
.
In
FIG. 3
, there are shown curves S
a
, S
b
, S
c
of (a) and curves D
a
, D
b
of (b).
In FIG.
3
(
a
), the curve S
a
is the same as the curve S of FIG.
2
. At the center position X
0
, the curves S
a
, S
b
, and S
c
show respectively the intensities I
a
, I
b
and I
c
, in which I
a
<I
b
<I
c
. The width of the bright trace of the curve S
b
is wider than that of the curve S
a
, In the same manner, the width of S
c
is wider than that of S
b
. The bright trace of S
c
shows a halation.
In FIG.
3
(
b
), there are curves D
a
and D
b
. Curves D
a
and D
b
show variations of intensities depending on outputs of the Z-axis circuit
8
. The curve D
a
is in case of low repetition rate of a wave-form to be observed and D
b
is in case of high repetition rate.
When an output Z
a
of the Z-axis circuit
8
is applied to the cathode K of the CRT
10
, a wave-form of a low repetition rate is displayed on the fluorescent screen
9
with an intensity I
a
on the curve D
a
. When output Z
b
or Z
c
of the Z-axis circuit
8
is applied to the cathode K of the CRT
10
, a wave-form of a high repetition rate is displayed on the fluorescent screen
9
with an intensity I
b
or I
c
on the curve D
b
. In spite of the fact that the outputs Z
a
, Z
b
and Z
c
are close in magnitude and show a relation of Z
b
<Z
a
<Z
c
, intensities I
a
, I
b
and I
c
show a relation of I
a
<I
b
<I
c
. Differences among intensities I
a
, I
b
and I
c
are quite big. It means that intensity differences depend considerably on repetition rates of wave-forms being displayed.
It is difficult to observe the low repetition rate wave-form displayed on the fluorescent screen
9
, because the intensity I
a
is not enough for observing with the naked eye. For resolving the problem, there is a method employing a high acceleration voltage of an electron beam in the CRT
10
to strongly excite the fluorescent screen
9
. In the method, there is problem that it requires a high acceleration voltage accompanying with the deterioration of the deflection sensitivity and the fluorescent screen
9
burnt up.
For avoiding those problems, the CCD sensor
11
of
FIGS. 1 and 2
is employed so as to obtain bright traces of wave-forms. As shown in
FIG. 3
, intensities significantly depend on repetition rates of wave-forms being displayed. Trace widths of displayed wave-forms vary in wide range with halations sometimes.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a novel oscilloscope intensity regulation apparatus to display wave-forms with substantially constant intensities.
Another object of the invention is to provide a novel oscilloscope with a CCD sensor on a CRT. An output of the CCD sensor is applied to a video circuit delivering a video signal.
A CPU instructs an intensity of an electron beam to a Z-axis circuit and an AGC (automatic gain control) revision signal to a AGC circuit in accordance with an intensity input signal.
The AGC circuit controls its gain for amplifying a video signal from the CCD sensor. When the video signal is small in its amplitude, the AGC circuit has a large gain. When the video signal is large, the circuit has a small gain. Therefore, an intensity of wave-forms being displayed is kept in the constant intensity desired, in spite of various repetition rates of the wave-forms or sweep velocities.


REFERENCES:
patent: 3829613 (1974-08-01), Melchior
patent: 3830970 (1974-08-01), Hurley et al.
patent: 3882359 (1975-05-01), Secher
patent: 3995197 (1976-11-01), Caswell
patent: 4215294 (1980-07-01), Taggart
patent: 4618254 (1986-10-01), Therrien et al.
patent: 4633145 (1986-12-01), Osawa et al.
patent: 5025196 (1991-06-01), Suzuki et al.
patent: 5315695 (1994-05-01), Saito et al.
patent: 5705891 (1998-01-01), Ishida et al.
patent: 1360534 (1974-07-01), None

Affiliated with

Also associated with

Rating

Oscilloscope intensity regulation apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Oscilloscope intensity regulation apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oscilloscope intensity regulation apparatus will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2562392