JPH0755459Y2 - Fluorescent tube display - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to a fluorescent tube type display device in which a variable duty display signal is supplied to an anode electrode and a drive pulse signal is supplied to a filament electrode.

[Prior art]

As a conventional fluorescent tube type display device, for example, there is one as shown in FIG. In the figure, 1 is a dimming circuit that emits a dimming pulse signal with variable duty, 2 is an OR circuit to which one of the dimming pulse signals is supplied, and 3 is a knot circuit to which a light signal that is a day / night switching signal is supplied. The output of the knot circuit 3 is supplied to the other input of the OR circuit 2. 4 is the logical product of the segment signal and the display signal,
An AND gate circuit 5 for converting the anode signal according to the duty of the dimming pulse signal is an AND gate circuit 4.
Is a fluorescent display tube in which the anode signal which is the output of the fluorescent display tube 5 is supplied to the anode electrode 5a.
A filament signal, which is a drive pulse signal asynchronous with the dimming pulse signal, is supplied to 5b. Next, the operation will be described. An AND gate of each segment signal and the display signal is taken by the AND gate circuit 4 and applied to the fluorescent display tube 5. The display signal becomes high level when the write signal is low level, but is dimmed by the on-duty (25% to 0%) of the dimming pulse signal when the write signal is high level. The filament electrode 5b is pulse-driven by a pulse having an on-duty of 12.5% as shown in FIG. 4 (a).

[Problems to be solved by the device]

However, in such a conventional fluorescent tube type display device, when the filament signal is turned on, even if the segment signal is turned on, the anode electrode 5a and the filament electrode 5b are turned on.
Since the potential difference between the tube and the tube becomes small (see FIG. 4 (c)) and the display disappears, normally, there is F _i11 between the frequency F _i11 of the dimming pulse signal and the frequency Fr of the filament signal.
<< Fr is provided so that the ON time is asynchronous so that the segment signal does not turn ON when the filament signal turns ON. However, if the on-duty of the dimming pulse signal (see FIG. 4 (b)) is made extremely small and the on-time T _i11 of the dimming pulse signal and the on-time Tf of the filament signal have a relationship of T _i11 ≦ Tf. , There was a problem that the display disappeared or flickers. The present invention has been made to solve the above problems, and when the drive pulse signal and the display signal are supplied in synchronization, one of the signals is given priority, and the display disappears or flickers. It is an object of the present invention to provide a fluorescent tube type display device that does not wear.

[Means for Solving the Problems]

A fluorescent tube type display device according to the present invention is a fluorescent display tube in which a display signal is supplied to an anode electrode and a drive pulse signal which is asynchronous to the dimming pulse signal is supplied to a filament electrode, and the fluorescent display tube. The determination circuit for determining whether the dimming pulse signal and the drive pulse signal are synchronous or asynchronous and prioritizing one of the signals based on the determination output.

[Action]

The fluorescent tube type display device according to the present invention supplies a display signal to the anode electrode of the fluorescent display tube and a drive pulse signal asynchronous to the display signal to the filament electrode so that the display signal and the drive pulse signal are Whether the signal is synchronous or asynchronous, and based on the output of this determination, one of the signals is given priority so that the display does not disappear or flicker.

【Example】

The invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention.
In the figure, the same or equivalent components as those in FIG. 3 are designated by the same reference numerals, and a duplicate description will be omitted. In FIG. 1, 6 is a NAND circuit to which a write signal and a dimming pulse signal are input, 7 is an AND circuit to which a filament signal is supplied to one input and an output signal of the NAND circuit is supplied to the other input. The AND circuit 7 and the NAND circuit 6 constitute a discrimination circuit. Next, the operation will be described. A filament signal as shown in FIG. 2A is inputted to the filament electrode 5b from one input of the AND circuit 7. When either the write signal or the dimming pulse signal becomes high level, the output of the NAND circuit 6 becomes low level, so that the filament signal is not applied to the filament electrode 5b. However, when both the write signal and the dimming pulse signal become low level, the NAND circuit 6
Since the output of is high level, the AND circuit 7 applies a filament signal to the filament electrode. That is, when either the write signal or the dimming pulse signal becomes high level, the display signal may be synchronized with the filament signal. Therefore, the filament signal is canceled and either the write signal or the dimming pulse signal becomes low. When it is at the level, there is no fear that the filament signal will be synchronized with the display signal, so the filament signal is applied to the filament electrode. Therefore, the potential between the anode and the filament electrode is lowered, and the display disappears and flicker does not occur.

[Effect of device]

As described above, according to the present invention, the structure is such that the anode electrode to which the display signal of variable duty is supplied.
5a and a fluorescent display tube 5 having a filament electrode 5b to which a drive pulse signal asynchronous with the display signal is supplied, and whether the display signal and the drive pulse signal are synchronous or asynchronous, and based on this determination output Since the fluorescent tube type display device is provided with the discrimination circuits 6 and 7 that prioritize one of the signals, when the filament signal and the segment signal are supplied in synchronization, one of the signals is prioritized. ,
The effect that the display disappears and the flicker can be prevented is obtained.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing an embodiment of a fluorescent tube type display device according to the present invention, FIG. 2 is a waveform diagram for explaining the operation of FIG. 1, and FIG. 3 is a conventional fluorescent tube. FIG. 4 is a circuit diagram showing an example of a formula display device, and FIG. 4 is a waveform diagram for explaining the operation of FIG. 5 ... Fluorescent display tube, 5a ... Anode electrode, 5b ... Filament electrode, 6, 7 ... Discrimination circuit.

Claims (1)

[Scope of utility model registration request] 1. A fluorescent display tube 5 having an anode electrode 5a to which a duty-variable display signal is supplied and a filament electrode 5b to which a drive pulse signal asynchronous with the display signal is supplied, the display signal and the drive pulse. Sync with signal
A fluorescent tube type display device comprising discrimination circuits (6, 7) for discriminating non-synchronization and giving priority to either one of the signals based on the discrimination output.