KR930000963Y1 - Apparatus for adjusting automatically illumination of digital display - Google Patents

Abstract

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Description

Digitron's automatic light control circuit

1 is a circuit diagram of a preferred embodiment according to the present invention.

* Explanation of symbols for main parts of the drawings

10: Micom 20: Digitron driver

30: digitron 40: roughness detection means

50: output feedback proportional level adjusting means 51: comparison means

52: gate means 53: counter means

54: digital analog conversion means 55: pulse generating means

60: switching means R1-R4: resistance

D1-D4: Diode G1-G4: Gate

The present invention relates to a circuit for automatically adjusting the brightness of a digitron, and more particularly to a circuit for automatically adjusting the brightness of a digitron according to external brightness.

Generally, a time display device is provided for home appliances such as VTRs and TVs to perform reservation recording or the like, and the time display is usually displayed using a digitron.

In the conventional digitron driving method, while the AC filament voltage Vp is supplied, the microcomputer supplies time data to the digitron driver and the digitron driver corresponds to the corresponding digitron grid voltage signal V _G and the segment selection signal ( S _N ) was fed to the digitron to display numbers or letters on the digitron. In the above method, DC is maintained at a constant potential difference between the grid voltage and the pillar voltage, so the display is always fixed at a constant brightness regardless of the external brightness. Therefore, the brightness of the digitron is higher than the external brightness at night. Relatively strong, there was a lung discomfort depending on the user.

Therefore, the purpose of the present invention is to solve the problems of the prior art such that the brightness of the digitron is automatically adjusted according to the external brightness to solve the sleep disturbance caused by the light during sleep, automatic adjustment circuit of the dimtron In providing.

In order to achieve the above object, the present invention has a digitron supplied with a filament voltage, and a digittron driver for supplying a corresponding grid voltage signal and a segment selection signal to the dztron according to a predetermined display command. In the display of numerals and letters, the illuminance detecting means outputs an illuminance detection signal proportional to the external brightness, and a feedback voltage signal which is raised in level when the output level is lower than that of the illuminance detection signal and lowered in level when the output level is low. And a switching means for switching the output feedback proportional level control means and a grid voltage signal or a feedback voltage signal to the digitron according to a voltage difference between the grid voltage signal and the feedback voltage signal.

When the present invention through the preferred embodiment shown in the accompanying drawings in more detail as follows.

In FIG. 1, the digittron display command is supplied to the digitron driver 20 by the microcomputer 10 as a strobe signal STROBE, a clock signal CLOCK, and a serial data signal DATA. The digitron driver 20 outputs a grid voltage signal V _G corresponding to the output port G0-G4 in accordance with the supplied serial data signal, thereby displaying a segment selection signal S _N corresponding to the output port S0-S6. )

The grid voltage signal V _G and the segment selection signal S _N are supplied to respective input ports _{G 0 -G 4} and S 0 -S 6 of the digitron 30 to which the AC filament voltage signal V _p is supplied. .

In this configuration, the present invention provides a phototransistor (PT) for outputting an emitter in proportion to the intensity of external light applied to a base, and a transistor for outputting an illuminance detection signal in proportion to external brightness by buffering the emitter output. The output pulse of the pulse generating means 55 by the output of the illuminance detecting means 40 of (Q), the comparison means 51 for level comparison of the illuminance detection signal, and the output returned; Gate means 52 for outputting clock pulses and up pulses or clock pulses and down pulses, and counting up or down by the output of the gate means 52 to output 8-bit parallel binary data. An output feedback proportional level adjusting means (50) comprising a counter means (53) and a digital analog conversion means (54) for analog-converting the binary data and outputting a feedback voltage signal (V _f ); The output V _F of the output feedback proportional level adjusting means 50 through the direction diodes D1-D4 and the grid voltage signal V _G through the resistors R1-R4 to the voltage difference between the two signals. The switching means 60 is combined with the switching means 60 to switch accordingly and to supply the input ports G0-G3 of the digitron 30.

Here, the gate means 52 is connected such that the output pulse of the pulse generating means 55 is supplied to one input terminal of the AND gates G2 and G3, and the output of the comparing means 51 is NOT connected to the AND gate G2. It is connected so as to be connected to the other input terminal through the gate G1, and is directly connected to the other input terminal of the AND gate G3, and the output of the AND gate G2 is down pulsed and the output of the AND gate G3 is uppulsed. Therefore, the output of the AND gates G2 and G3 through the OR gate G4 is connected to the counter means 53 by a clock pulse.

Reference numeral R5 is a resistor.

The operation and effects of the present invention constructed as described above are as follows. First, when the external brightness of the digitron is strong, such as during the day, the illuminance detection signal V _C becomes very high, and the output of the comparing means 51 becomes high, and the clock pulse and the up pulse are countered through the AND gate G3. Since it is supplied to 53 and counted up, the feedback voltage signal V _F output from the digital analog converting means 54 rises until the illuminance detection signal V _C becomes the same level. Therefore, the feedback voltage signal Vf becomes Vf > V _G -V _D (V _D is the diode forward voltage), and the diodes D1-D4 remain blocked, so the grid input port G0-G3 of the digitron 30 is maintained. ) Is supplied to the digitron grid voltage (V _G ) through the grid voltage signal (V _G ) through the resistors R1-R4.

Accordingly, the digitron 30 is driven at the brightness according to the grid voltage signal V _G.

If it is gradually darkened, the level of the illuminance detection signal V _C is lowered and the output of the comparing means 51 becomes low. Therefore, the output pulse of the pulse generating means 55 is clocked to the counter means 53 through the AND gate G2. The output level of the digital analog converting means 54 is down because the pulse and the down pulse are supplied and counted down. This operation is repeated so that the feedback voltage signal Vf continues to be lowered and thus V (Vf). When V _G -V _D is reached, the diodes D1-D4 are turned on.

Therefore, from this time, the grid input port G0-G3 of the digitron 30 is connected to a line for outputting a high signal, that is, a grid voltage signal V _G , to the output force G0-G3 of the digitron driver 20. When the diode is turned on, the grid voltage V _G is supplied to V _G = Vf + _{D. When the} external illuminance is lowered, the feedback voltage signal V _f falls in proportion as described above. Since the grid voltage V _G is also lowered according to the feedback voltage signal V _f , the brightness of the digitron 30 is automatically adjusted according to the external brightness.

As described above, in the present invention, the brightness of the digitron is changed according to the external brightness by driving the digitron by the grid voltage which is automatically adjusted according to the degree of external brightness, thus eliminating facial disturbances caused by the digitron brightness during sleep. You can do it.

Claims (2)

The digitron 30 to which the AC filament voltage V _p is supplied, and the grid voltage signal V _G and the segment selection signal S _K corresponding to the digitron 30 are supplied to the digitron 30 according to a predetermined display command. A display device having a digitron driver 20 for displaying numerals and letters by a selected segment combination, comprising: illumination detection means for outputting an illumination detection signal proportional to external brightness; Output feedback proportional level adjusting means (50) for outputting a feedback voltage signal (V _f ) that is raised in level when the output level is low by the level of the illuminance detection signal and is lowered when it is high; Switched according to the voltage difference between the grid voltage signal (V _G ) and the feedback signal (Vf) is switched according to the voltage difference between the grid voltage signal (V _G ) and the feedback signal (Vf) to grid voltage signal (V _G ) Or switching means 60 for supplying a feedback signal Vf to the digitron 20; Digitron automatic light control circuit, characterized in that provided with. 2. The control circuit according to claim 1, wherein the output feedback proportional level adjusting means (50) compares the illuminance detection signal (V _C ) and the feedback voltage signal (Vf) to output a gate signal, and the gate A gate means 52 for outputting a clock pulse and an up pulse, or a clock pulse and a down pulse by gated the output pulse of the pulse generating means 55 according to the signal, and counting up or according to the output of the gate means 52. A counting means 53 for counting down and outputting parallel binary data of a predetermined bit, and a digital analog converting means 54 for analog-converting the binary data and outputting a feedback voltage signal Vf. Digitron's automatic light control circuit.