Computer graphics processing and selective visual display system – Display peripheral interface input device – Light pen for fluid matrix display panel
Reexamination Certificate
1998-08-13
2001-05-01
Liang, Regina (Department: 2774)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Light pen for fluid matrix display panel
C324S12100R
Reexamination Certificate
active
06225972
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to waveform display systems and, in particular, to automotive engine analyzers including such display systems.
Digital engine analyzers having digital oscilloscope display screens are well known, one such analyzer and the waveform display system therefor being disclosed in copending U.S. application Ser. No. 08/629,484, filed Apr. 10, 1996, and entitled “System for Reconfiguring Oscilloscope Screen in Freeze Mode”, the disclosure of which is incorporated herein by reference. Under some circumstances, a signal displayed on the oscilloscope screen of such an analyzer can be clipped or otherwise altered due to rails in the oscilloscope circuitry, resulting in a misleading waveform display. For example, the engine analyzer disclosed in the aforementioned application includes an analog-to-digital converter (“ADC”) which has rails, i.e., the voltages at which the ADC reaches its full negative or positive count. Any acquired waveform voltage exceeding the rail voltage level will cause no further change in the output of the ADC. When this occurs, it is said that the ADC is “railed” and that the acquired waveform is clipped at the rail level. It is sometimes possible for the operator to view a waveform display which is clipped in this manner, without being aware that the waveform is clipped. This may be particularly true in the case of some waveforms, such as square waves, wherein it is difficult to determine whether or not the waveform is clipped.
This can be illustrated in
FIGS. 2-5
.
FIG. 2
shows a zero to 3.5-volt sine wave acquired and plotted on a 5-volt scale. In the engine analyzer of the aforementioned application, the 5-volt scale uses a hardware channel which has a range of almost 32 volts, i.e., the ADC reaches its maximum count when the acquired incoming signal is close to 32 volts.
FIG. 2
shows the same waveform acquired and plotted on a 2-volt scale. This scale uses a hardware channel which has a much smaller range of about 3.2 volts. Thus, as can be seen in
FIG. 3
, the 3.5-volt sine wave extends beyond the plot area on a 2-volt scale.
FIG. 4
shows the same signal on a 2-volt scale with a 1.2-volt offset (i.e., the scale extends from 1.2 volts to 3.2 volts). As can be seen, the top of the waveform is clipped as it bumps up against the 3.2-volt rail level of the ADC. Since this rail level is at the top of the scale, it would be very difficult for an operator to determine whether the top of the waveform is removed simply because it is extending beyond the scale (as in
FIG. 3
) or because it is being clipped by encountering a rail level in the oscilloscope circuitry.
Also, engine analyzers of the type described in the aforementioned application have the capability of operating in a freeze mode, wherein a currently acquired and displayed waveform can be frozen on the screen. This analyzer is also capable of changing the display format in the freeze mode.
FIG. 5
illustrates the waveform of
FIG. 3
after the screen has been frozen and the display scale switched to the 5-volt scale. Since the waveform data was captured in the 2-volt scale (which has a 3.2-volt rail), switching to the 5-volt scale in freeze mode does not extend the range of the scale, as it would in live mode (FIG.
2
). Thus, the waveform in
FIG. 5
is clipped at the 3.2-volt rail level. While this is fairly apparent with the sine waveform of
FIG. 5
, it might be very difficult to determine with another waveform, such as a square wave.
SUMMARY OF THE INVENTION
It is a general object of the invention to provide an improved waveform display system which avoids the disadvantages of prior systems while affording additional structural and operating advantages.
An important feature of the invention is the provision of a waveform display system which provides an indication that a displayed waveform representation may be distorted or otherwise altered by internal circuitry of the display system.
In connection with the foregoing feature, another feature of the invention is the provision of a system of the type set forth, which, when a limit level imposed by the system circuitry is encountered by an acquired waveform signal, provides an indication of both the limit level and the fact that a displayed waveform representation may be altered by the limit level.
A still further feature of the invention is the provision of a system of the type set forth, which is of relatively simple and economical construction and permits a user to readily determine the existence and effect of rail levels encountered by an acquired waveform signal in the display system circuitry.
Certain ones of these and other features of the invention are attained by providing, in a waveform display system including a display screen, acquisition circuitry for acquiring a waveform signal and display control circuitry coupled to the acquisition circuitry and to the display screen for controlling the display on the screen of a waveform representation of the acquired waveform signal, the improvement comprising: a processor in the display control circuitry operating under stored program control and executing a program routine including: a first portion identifying a limit level for the waveform representation and determining whether an acquired waveform signal encounters the limit level, and a second portion controlling display on the screen of an indication of the limit level and/or an indication that the displayed waveform representation may be altered by the limit level.
The invention consists of certain novel features and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.
REFERENCES:
patent: 2570139 (1951-10-01), Maxwell
patent: 3543148 (1970-11-01), Martin
patent: 3891933 (1975-06-01), Suzuki et al.
patent: 4238727 (1980-12-01), Madni
patent: 4272719 (1981-06-01), Niki et al.
patent: 4399512 (1983-08-01), Soma et al.
patent: 4611164 (1986-09-01), Mitsuyoshi et al.
patent: 4628254 (1986-12-01), Bristol
patent: 4761640 (1988-08-01), Slavin
patent: 4763067 (1988-08-01), Fladstol
patent: 4975633 (1990-12-01), Toda et al.
patent: 5004975 (1991-04-01), Jordan
patent: 5025208 (1991-06-01), Danzeisen
patent: 5068620 (1991-11-01), Botti et al.
patent: 5119018 (1992-06-01), Katayama et al.
patent: 5365254 (1994-11-01), Kawamoto
patent: 5414635 (1995-05-01), Ohta
patent: 5430409 (1995-07-01), Buck et al.
patent: 5442316 (1995-08-01), Buck et al.
patent: 5453716 (1995-09-01), Person et al.
patent: 5543779 (1996-08-01), Aspesi et al.
patent: 5585819 (1996-12-01), Kazui
Taraki Yosuf M.
Trsar Dale A.
Liang Regina
Shaw Seyfarth
Snap-on Tools Company
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