JPS6315896Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a display circuit of a fluorescent display tube type display device, and after a certain time from the time when a voltage is applied to the filament of the fluorescent display tube (hereinafter referred to as FLT),
It is an object of the present invention to provide a display circuit capable of causing a display element to emit light with a predetermined brightness instantaneously by configuring the display circuit to display FLT.

In conventional FLT type digital watches, when a voltage is applied to the FLT filament by operating a switch at a certain time t ₀ as shown in Figure 2A in order to view the time display element, the FLT filament reaches a predetermined temperature. Since it takes a certain period of time for the time display to become bright, the time display element gradually increases in brightness from time _t0 , as shown in FIG. For this reason, the FLT display start state of conventional FLT type digital watches was unnatural and had drawbacks such as being difficult to see.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings.

In the embodiment shown in FIG. 1, a time display element drive circuit 1 consisting of an oscillator, a frequency divider, a counter, a decoder, a driver, etc. is applied with a voltage from a power supply +B, and a predetermined value is set in the display element of each digit by a well-known operation. A time display signal is taken out corresponding to the segment and supplied to one terminal of the AND circuit 2.

Here, when making the time display element emit light, when the switch S (in the case of a car watch, a switch linked to the ignition switch or a manual switch exclusively for FLT) is closed at time t ₀ shown in FIG. 2A, FLT3 A voltage is applied to the filament 4 to heat the filament 4, and at the same time, a voltage is applied to the delay circuit 5. At this time, if the delay time of the delay circuit 5 is selected to be approximately equal to the time required for the filament 4 to reach a predetermined temperature and emit sufficient thermoelectrons from the time t ₀ when the voltage is applied to the filament 4 of the FLT 3, the delay circuit 5 can be used. At time t ₁ when the filament 4 reaches a predetermined temperature, a voltage is taken out from the AND circuit 2 and supplied to the other terminal of the AND circuit 2 .

As a result, a signal that changes instantaneously at the above-mentioned time _t1 is taken out from the AND circuit 2, and the FLT3
The time display element of FLT3 emits light for the first time at time _t1 , as shown in FIG. 2C. Therefore, the time display element does not emit light while gradually increasing its brightness as in the past, but can emit light instantaneously with a predetermined brightness at time _t1 , giving an extremely natural feeling to the observer compared to conventional watches. can be given.

The drive circuit 1, AND circuit 2, and delay circuit 5 are built into the LSI, but elements that set the delay time of the delay circuit 5, such as capacitors and resistors, are not included.
If it is connected to the outside of the LSI and can be adjusted as appropriate, the light emission time _t1 of the element can be appropriately set, which is convenient.

Furthermore, the present invention is not limited to FLT type digital watches, but can be similarly applied to display devices using FLT.

As mentioned above, the display circuit of the FLT type display device according to the present invention includes a switch connected between the power source and the FLT filament to turn on and off the FLT, and an output of a drive circuit that drives the fluorescent display tube for display. A logic circuit is connected between the switch and the plate of the fluorescent display tube, and a switch is connected between the switch and one input of the logic circuit, and when the switch is closed and a filament voltage is applied, the filament of the FLT starts generating thermoelectrons. A logic circuit consisting of a delay circuit that delays and instantaneously changes the voltage applied to the plate of the FLT through a logic circuit until it reaches a predetermined temperature for sufficient release.From the time when the filament voltage is applied, after the delay time by the delay circuit described above. Since the FLT is configured to instantaneously display the FLT at a predetermined brightness through the It provides a more natural feeling to the observer than conventional ones, is easy to see, and uses a logic circuit, so it can be used to display multiple digits in fluorescent display type digital watches, etc.
It is easy to implement as an IC, and since the delay circuit is used to give a signal to one input terminal of the logic circuit, if a timer is used in the delay circuit, the timer itself requires less power, which makes it easy to implement as an IC. It has the following features.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the display circuit of a fluorescent display tube type display device according to the present invention, and Fig. 2 A to C are a circuit diagram of a conventional fluorescent display type digital watch and an embodiment of the display circuit of the present invention. FIG. 3 is a diagram showing the voltage applied to the filament and the brightness of the fluorescent display tube for explaining the operation. DESCRIPTION OF SYMBOLS 1... Time display element drive circuit, 2... AND circuit, 3... Fluorescent display tube, 4... Filament, 5
...delay circuit, 6...plate, S...switch.

Claims (1)

[Scope of utility model registration request] A switch connected between the power source and the filament of the fluorescent display tube for turning on and off the fluorescent display tube, and a switch between the output of the drive circuit for driving the display of the fluorescent display tube and the plate of the fluorescent display tube. A predetermined temperature that is connected between a connected logic circuit, the switch, and one input of the logic circuit, and at which the filament of the fluorescent display tube sufficiently emits thermionic electrons from the time when a filament voltage is applied by closing the switch. A delay circuit delays and instantaneously changes the voltage applied to the plate of the fluorescent display tube via the logic circuit, and after a delay time by the delay circuit from the time when the filament voltage is applied, the voltage is applied to the plate of the fluorescent display tube. A display circuit for a fluorescent display device configured to instantaneously cause the fluorescent display tube to display at a predetermined brightness via a logic circuit.