Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2003-02-05
2004-03-09
Lee, Wilson (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C345S075100, C345S055000
Reexamination Certificate
active
06703789
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a multiplex anode driver circuit for chiefly driving a graphic fluorescent display device employing a multiplex (duplex, quadplex, or octuplex) anode matrix scheme and to a fluorescent display device using the same. The present invention can be used for driving conventional consumer, industrial, or in-vehicle fluorescent display devices. That is, the present invention can be used for fluorescent display devices in a simple anode matrix scheme, in addition to fluorescent display devices in a multiplex anode matrix scheme. The present invention is applicable in all time-proven fields of fluorescent display devices.
Fluorescent display devices in an anode multi-matrix scheme are well known as fluorescent display devices that can provide light emission with high intensity, with uniform brightness, and with less variation in brightness.
A fluorescent display device employing a quadplex anode matrix scheme as an anode multi-matrix scheme will be now explained as an example. In a fluorescent display device of this type, dot-like anodes are arranged in a matrix form which includes plural rows each formed of plural dot-like anodes. A fluorescent substance is coated on the surface of each anode. Four anode connection terminals are disposed to each row.
In each row, the anodes appearing every four places are connected to the common anode connection terminal. A grid is disposed above the anodes appearing every two columns so as to confront each other. A cathode, e.g. a filament cathode, which emits electrons, is suspended above each grid so as to confront each other.
FIG. 15
is a diagram illustrating the connection configuration of anodes in a fluorescent display device employing the quadplex anode matrix scheme.
FIG. 16
is shows a wiring diagram of the connection configuration shown in FIG.
15
. In the anode connection configuration of
FIGS. 15 and 16
, one row of anodes is schematically shown.
Referring to
FIG. 15
, the anode A
2
in the second column is connected to the anode A
2
a.
The anode A
3
in the third column is connected to the anode A
3
a.
The anodes A
2
and A
2
a
are light emitted simultaneously by a positive voltage applied to the anode connection terminal AT
1
-
2
. The anodes A
3
and A
3
a
are light emitted simultaneously by a positive voltage applied to the anode connection terminal AT
1
-
3
. At this time, other anodes do not glow because a negative voltage is applied to the anode connection terminals connected to them.
Moreover, the anode A
1
in the first column is connected to the anode A
1
a.
The anode A
4
in the fourth column is connected to the anode A
4
a.
The anodes A
1
and A
1
a
are light-emitted simultaneously by a positive voltage applied to the anode connection terminal AT
1
-
1
. The anodes A
4
and A
4
a
are light emitted simultaneously by a positive voltage applied to the anode connection terminal AT
1
-
4
. At this time, other anodes do not glow because a negative voltage is applied to the anode connection terminal connected to them.
In the above-mentioned configuration, the wiring pattern for the anode connection terminal AT
1
-
1
is disposed between the wiring pattern for the anode connection terminal AT
1
-
2
and the wiring pattern for the anode connection terminal AT
1
-
3
. When a positive voltage is applied to the anode connection terminals AT
1
-
2
and AT
1
-
3
, the anodes A
1
and A
1
a
associated with the anode connection terminal AT
1
-
1
are in a non-glow state.
The wiring pattern for the anode connection terminal AT
1
-
3
is disposed between the wiring pattern for the anode connection terminal AT
1
-
1
and the wiring pattern for the anode connection terminal AT
1
-
4
. When a positive voltage is applied to the anode connection terminals AT
1
-
1
and AT
1
-
4
, the anodes A
3
and A
3
a
associated with the anode connection terminal AT
1
-
3
is in a non-glow state.
In the connection configuration shown in
FIG. 15
, the wiring pattern for the anode connection terminal (AT
1
-
2
, AT
1
-
3
shown in FIG.
15
), to which anodes (A
2
, A
2
a,
A
3
, A
3
a
in
FIG. 15
) in a non-glow state are connected, is disposed between the wiring pattern for anode connection terminal (AT
1
-
1
in FIG.
15
), to which anodes (A
1
and A
1
a
in
FIG. 15
) in a glow state are connected, and the wiring pattern for anode connection terminal (AT
1
-
4
in FIG.
15
), to which anodes (A
4
and A
4
a
in
FIG. 15
) in a glow state are connected. That is, the wiring pattern for anode connection terminal to which a positive voltage is applied and the wiring pattern to which a negative voltage is applied are disposed alternately.
In the fluorescent display device employing the quadplex anode matrix scheme, each grid is wired so as to cover two columns of anodes. Grids are scanned such that a positive voltage is always applied to two adjacent grids. A positive voltage is applied to the two middle anodes among the four anodes, corresponding to two grids to which the positive voltage is applied. The negative voltage is applied to the remaining anodes. By doing so, the anode dot at a desired position in a desired row of anodes is selectively light emitted.
In the fluorescent display device employing the quadplex anode matrix scheme, the wiring pattern for the anode connection terminal accepting a positive voltage and the wiring pattern for the anode connection terminal accepting a negative voltage are arranged alternately. Anodes to be light emitted simultaneously are alternately connected to the anode connection terminals. For that reason, when a positive voltage is applied to the anode connection terminal to light emit an anode, a capacitance occurs between the wiring patterns for adjacent anode connection terminals. This causes the phenomenon where the current is charged into the capacitance.
In further explanation, a positive voltage is applied to the anode connection terminal AT
1
-
1
, AT
1
-
4
, the capacitance C, as shown in
FIG. 16
, occurs between the anode connection terminal AT
1
-
1
, AT
1
-
4
and the wiring pattern for the anode connection terminal AT
1
-
2
, AT
1
-
3
to which a negative voltage is applied. That is, the capacitance C occurs between all the anode connection terminals AT
1
-
1
, AT
1
-
2
, AT
1
-
3
, and AT
1
-
4
. Thus, a current is charged to each capacitance C.
The current charging the each capacitance C does not contribute to the light emission of the fluorescent display device. The peak current excessively heats the anode driver circuit that supplies the voltage to the anode connection terminals AT
1
-
1
, AT
1
-
2
, AT
1
-
3
, and AT
1
-
4
.
In the small fluorescent display devices, because the wiring pattern to each anode connection terminal is smaller and shorter, the capacitance between wiring conductors viewed from the anode driver circuit is not enough to heat the anode driver circuit. However, with the fluorescent display devices large-sized, the wiring pattern lengthened to each anode connection terminal tends to increase the influence due to heat generation, compared with the conventional small fluorescent display devices.
With the large-sized fluorescent display devices having the above anode connection configuration, the anode connection has the problem in that heat loss occurs in the anode driver circuit. That is, when two adjacent columns of anodes to a predetermined row glow, the capacitance produced between the wring patterns for all anode connection terminals is charged with current. The capacitance viewed from the anode driver circuit becomes large. The peak current of the charging current largely heats the anode driver circuit, thus causing a heat loss.
In order to solve that problem, the present applicant filed a fluorescent display device having an improved anode connection configuration (Japanese Patent Laid-open Publication No. Hei 10-55772).
FIG. 17
schematically shows the anode wiring in the fluorescent display device employing a quadplex anode matrix scheme, disclosed in the publication No. Hei 10-55772.
Referring to
FI
Eutaba Corporation
Lee Wilson
LandOfFree
Multiplex anode driver circuit and florescent display device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Multiplex anode driver circuit and florescent display device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multiplex anode driver circuit and florescent display device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3221097