JPH11167988A - Control method for el lighting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control method for which supplying a voltage to an electroluminescence(EL) from the moment of switching, and eliminating the occurrence of brightness nonuniformity, and the flickering of the EL in the case of the use of a zero cross switch for lessening a noise at the switching time of the EL. SOLUTION: When a zero-cross switch is used, at the switching time of the switches of ELs, time delay until voltages are actually applied to the ELs (EL1 to EL3 ) is caused. However, by forcibly reversing voltage outputs at the switching time to the next ELs, the voltages are crossed with zero volt soon after the switching of the ELs. Thereby, the time delay until the application of the voltages to the ELs after the EL switching is eliminated, the voltage application time per unit time is set to be a certain value for every EL so that the flickering of the ELs is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an illuminated key switch used as a display device, an input device, or a backlight using a plurality of electroluminescence (EL) or ELs divided into a plurality of portions. The present invention also relates to a method for controlling EL lighting in electric and electronic devices.

[0002]

2. Description of the Related Art Conventionally, fluorescent lamps, neon tubes, incandescent lamps, light emitting diodes (LEDs), cold cathode tubes, ELs and the like have been used as elements for illuminating.

However, fluorescent lamps, neon tubes, incandescent lamps, LE
Elements such as D and cold-cathode tubes have a large thickness, and the size of a display unit or an input unit illuminated using these elements is large.

[0004] In recent years, thinned LEDs have been developed and used for illumination.
The peripheral portion of the LED becomes particularly bright, and it is difficult to uniformly illuminate the entire illuminating portion, and illumination unevenness occurs.

[0005] Therefore, it is necessary to use an EL in order to reduce the thickness and to provide uniform illumination regardless of the shape and size of the illumination.

As shown in FIG. 1, this EL converts DC power by an EL lighting power supply (inverter), and emits light by applying an AC voltage of several hundred volts.

Japanese Patent Application Laid-Open No. 63-138691 discloses a control method for supplying power to each EL in a time-sharing manner in order to light a plurality of ELs with one EL lighting power supply. FIG. 2 shows the basic configuration, and FIG. 3 shows the waveform of the control signal. In this time-division lighting control method, only one EL is lit instantaneously (EL in FIG. 2).
₂ is turned on, and the other ELs are not turned on). The ELs to be turned on are sequentially changed every unit time, and this is repeated at a high speed.
This is a control method for making it appear that L is always lit.

[0008]

However, in this conventional time-division lighting control method, when a switch (zero-cross switch) having a built-in zero-cross circuit is used to reduce noise at the time of EL switching, the switch is turned on. However, the AC voltage is not output immediately, but is output once the AC voltage crosses 0 volt. At this time, the control signal waveform is not constant since the time from when the switch is switched as shown in FIG. 4 to when the voltage is actually supplied to the EL is not constant, as shown in FIG. The time during which a voltage is applied changes, so that the brightness becomes uneven, and the EL flickers.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a method for controlling an output voltage cycle of an EL lighting power supply and a cycle for switching EL in order to eliminate flickering caused when EL is lit by a time division method. Is provided. The basic configuration is the same as the time-division lighting method shown in FIG. 2, except that an EL lighting power supply whose cycle can be determined from the outside is used, and a switch for switching the EL is a zero-crossing switch. Using a switch. When a zero cross switch is used, a time delay actually occurs until the voltage is applied to the EL when the EL switch is switched, but the voltage output is forcibly inverted when the next EL is switched. As a result, the voltage is crossed with 0 volt immediately after switching the EL, and the voltage is applied to the EL. By doing so, there is no time delay from when the EL switch is switched to when the voltage is applied to the EL, and the time during which the voltage is applied per unit time is kept constant for any EL. And flicker can be eliminated. FIG. 6 shows the control signal waveform at this time.

[0010] By using such a control method,
It is possible to eliminate flickering of illumination of a display device such as a control panel of a car or a clock, and flickering of illumination of an input device such as a key of a remote controller, a key of a mobile phone, or a key of a medical device.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The voltage applied to the EL of the present invention is E
FIG. 7 shows a circuit block diagram of a control method of EL lighting for forcibly inverting when switching L.

In this circuit, a CPU is used as a control circuit.
(NEC uPD78054), a switch with a built-in zero-cross circuit to switch the EL applied voltage output from the EL lighting power supply to each EL (Toshiba Corporation photo triac TLP561G), and external EL
A power supply for EL lighting (D310, manufactured by DUREL) capable of controlling the cycle of the AC voltage applied to the device was used. The clock for determining the cycle of the output voltage of the EL lighting power supply used a timer inside the CPU. However, the devices used for these circuits are only examples, and for example, the power supply for EL lighting may be a power supply HEOP-0.6B50 manufactured by Matsusada Precision Co., Ltd.

FIG. 8 shows a control signal waveform of each EL when three ELs are used by using this circuit. Here, when the control signal waveform of each EL is High, the voltage output from the EL lighting power supply is applied to each EL. The EL lighting power source (DUREL D310) used this time is EL
When the power supply output cycle signal for lighting is high, a negative voltage is output, and when it is low, a positive voltage is output. FIG. 9 shows an EL lighting power supply output cycle signal and an output voltage waveform of the EL lighting power supply at this time.

When the EL is switched, the periodic signal of the output voltage of the EL lighting power source is forcibly inverted to thereby reduce the E signal.
Control is performed so that the voltage waveform applied to L crosses 0 volts. As a result, the application time becomes constant and the EL flicker disappears.

[0015] The time T from the EL ₁ to EL ₃ is lit.
Is too large, the switching of EL becomes visible to human eyes. In this embodiment, the value of the time T from EL ₁ to EL ₃ is lit 13.44 [mSec] (Frequency 74H
z).

The unit time TE at which each EL is turned on is the same for each EL, and T / 3 (the number of ELs) = 4.48
[MSec] (frequency 223Hz).

In the present embodiment, flickering caused by flickering condition with conventional method in the case where EL ₃ from EL ₁ is fixed time T (frequency) up lights, changing the period of the output voltage of the EL lightening power supply The condition is shown in Table 1. The EL size used at this time was 1.5 cm ² , and the applied voltage was 100 V.

[0018]

[Table 1] By using the control method of the present invention, the flickering light of a display device such as a car control panel, a clock character, an advertising sign, a remote control key, a telephone key, a medical device key, an audio switch, a vehicle audio,
It is possible to eliminate flickering of illumination of an input device such as an air conditioning switch.

[0019]

Embodiment 1 Next, a display device using the EL lighting control method of the present invention will be described with reference to a block diagram shown in FIG.

An operation confirmation lamp showing the operation state of each of the three motors was manufactured.

The EL ₁ , _2, and ₃ of the display section of the operation check lamp are powered by one EL lighting power source (D310 made by DUREL), using the time division method of the AC power supply according to the present invention. If not, it was displayed in a lighting pattern such as turning off.

The operation of the motor, the switching of the EL, the cycle of the output voltage of the EL lighting power supply, and the application of EL output from the EL lighting power supply are controlled by a CPU (uPD78054 manufactured by NEC Corporation) as a control circuit. A zero cross switch (Photo Triac TLP561G manufactured by Toshiba Corporation) was used as a switch for switching the voltage to each EL.

Regardless of the state of the motor, each EL illuminated without flicker.

[0024]

[Embodiment 2] An input device using a plurality of ELs or ELs arranged in a plurality of parts will be described with reference to a block diagram shown in FIG.

On the switch panel of the car audio, two switches 1 and 2 of "CD" and "TAPE" were illuminated by EL ₁ and EL ₂ , respectively. The CPU used was a uPD78054 made by NEC Corporation, the power supply for EL lighting was a D353 made by DUREL, and the zero cross switch was a photo triac (TLP561G) made by Toshiba Corporation. It was illuminated dark when not selected and brightly lit when selected. In both cases, the two switches illuminated without flicker.

[0026]

By using the control method according to the present invention, even if a plurality of ELs are lit by a time-division method in which a plurality of ELs are lit by a single EL lighting power source, flicker-free EL illumination is enabled. By changing the unit time at which the EL is turned on without changing the EL switching time, the brightness at the time of lighting can be controlled, so that illumination of several levels of brightness is possible. Furthermore, by setting the range of the unit time to be changed from 0 seconds, it is possible to turn off the light and to turn on several levels of brightness.

In a display device or an input device such as a watch or a car panel which always comes into view, the flickering of the illuminating part puts a burden on the eyes and causes fatigue. However, by using the control method according to the present invention, the flicker disappears, Can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a power supply for EL lighting and its wiring.

FIG. 2 is a configuration diagram of a time-division lighting method.

FIG. 3 is a control signal waveform of a time division lighting method when the number of ELs is three.

FIG. 4 is a control signal waveform when a zero cross switch is used.

FIG. 5 is a waveform of an applied voltage supplied to an EL element alone (a voltage is supplied to the EL in a solid line portion).

FIG. 6 shows a control signal according to the present invention.

FIG. 7 is a circuit block diagram used in the present embodiment.

FIG. 8 is a control signal waveform in the present embodiment.

FIG. 9 shows a relationship between an EL lighting power output cycle signal and an output voltage waveform of the EL lighting power supply.

FIG. 10 is a block diagram of a display device.

FIG. 11 is a block diagram of an input device.

[Explanation of symbols]

 EL Electroluminescence TE Unit lighting time

Claims (3)

[Claims] 1. A time-sharing control method for lighting a plurality of ELs or ELs arranged in a plurality of parts by one EL lighting power supply, wherein a zero-crossing circuit is incorporated for switching the lighting of the ELs. Using a switch and an EL lighting power supply for adjusting the period of the voltage applied to the EL from the outside,
What is claimed is: 1. An EL lighting control method, comprising: forcibly inverting the cycle of a voltage applied to an EL when switching EL in order to avoid flickering during EL lighting. 2. A switch having a built-in zero-cross circuit connected to an EL of an operation confirmation light or an indicator light such as an advertising display for controlling the operation of the target electronic component and indicating an operation state thereof, and further comprising: A control circuit for determining a frequency of a voltage to be applied to the EL and outputting a clock corresponding to the frequency, and an EL lighting power supply for receiving the clock signal, generating an AC voltage at the frequency, and lighting the EL. A display device using a plurality of ELs that employs the control method described in 1, or ELs that are separately arranged in a plurality of portions. 3. A lighting state of the EL is determined from an input signal from the switch, and a switch having a built-in zero cross circuit connected to the EL to be turned on is turned on / off.
A control circuit that determines the cycle of the AC voltage applied to L and outputs a clock corresponding to the frequency, and an EL lighting power supply that receives the output signal, generates an AC voltage at that frequency, and turns on the EL. An input device using a plurality of ELs or the ELs divided into a plurality of parts and adopting the control method according to claim 1.