JP2006302680A - Electroluminescence (el) display control circuit and controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EL display control circuit which an improves visual performance effects of an EL display panel by putting off an EL display element in a short period of time without fail, and its controlling method. <P>SOLUTION: In a controlling circuit for putting on/off of EL element 106, a controlled terminal of a first photo-isolator 102 is connected between a controlling terminal 107 of the EL element and a high-frequency inverter 103, and also a controlled terminal of a second photo-isolator 104 is connected between the controlling terminal 107 and a common terminal 108. In a controlling method for putting on/off of the EL element, a lighting control pulse signal 110 will be supplied to a lighting on/off switch 102 connected between the controlling terminal 107 of the EL display element and the high-frequency inverter 103, and also a reversed polarity signal of the above lighting on/off switch will be supplied to a short circuit switch 104 connected between the controlling terminal 107 of the EL display element and the common terminal 108. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  An EL (electroluminescence) light emitting display device is used in a place where the brightness of the surroundings where the display panel is installed, such as indoors or at night, is darker than the luminance of EL. The present invention relates to an EL light emitting display control circuit for controlling lighting and extinction of each display element of this EL light emitting display device and producing a visual dynamic display effect like a neon sign.

JP-A-6-222162

  A light emitting sheet or a light emitting tube made of an EL light emitter can be easily processed into an arbitrary shape by cutting or bending. For this reason, after processing into the shape which is going to emit light, as shown in FIG. 4, it is made to light by applying an alternating current, and the desired light emission display effect is acquired.

  As an example of producing a light-emitting display effect, Patent Document 1 discloses a technique for selectively emitting a plurality of EL elements in synchronization with the movement of a doll in a Karakuri watch. A device is described in which either an electrode for defining the light emission timing or a contact piece elastically contactable with the electrode is rotated, and an EL light emitting unit is blinked and issued according to the contact and separation of the electrode and the contact piece. With this device, it is possible to turn on the EL light emitting part with an inexpensive mechanism and with accurate timing, and it is possible to generate various light emission patterns by changing the arrangement of the contact part with the electrode contact piece on the arc. Is possible.

  In order to produce a display effect by repeating turning on and off in FIG. 4, a start / stop signal is generated at a very low frequency by the low frequency transmitter 404, and the operation and stop of the inverter 401 that generates an alternating current are performed. It can be realized by doing. When there are multiple EL display elements 408 to be lit, an AC current is individually supplied to each display element using a relay or rotary switch 406, and the temporal relationship between the energization or non-energization is controlled and displayed. An effect can be produced.

  However, when the blinking is performed by operating and stopping the inverter, the entire display panel blinks at the same time, so that the production effect is extremely monotonous. In addition, there is a problem in that the life of the inverter is shortened as a result of constant electrical stress applied to the inverter due to the operation and stop of the inverter.

  In addition, in the control of turning on and off by opening and closing the contact using a relay or rotary switch, there is a limit on the mechanical time response speed of the contact. Since the voltage required for light emission of the element is a high voltage of around 100V, there is a problem that the life is shortened due to contact consumption due to electric sparks.

  As a high-speed and long-life light-emission control element, the above-mentioned problems can be avoided by using a photoisolator generally called “photorelay” or “semiconductor relay” that has a property of conducting electricity in both directions when it is turned on. Since some types of photoisolators leak some current even when they are non-conductive, there is a problem that the EL light emitter cannot be completely turned off.

  The present invention enhances the visual effect of the EL display panel by reliably turning off the EL display element in a short time when the EL display element is blinked using a semiconductor such as a photoisolator. An object of the present invention is to provide an EL light emitting display control circuit and a control method capable of the above.

  In order to achieve the above object, an EL light emission display control circuit according to claim 1 is a circuit for controlling lighting and extinction of an EL display element, wherein the controlled terminal of the first photoisolator is connected to the control terminal of the EL display element. The control terminal of the second photoisolator is connected between the control terminal of the EL display element and the common terminal. Examples of the photo isolator include a photo MOSFET and a photo triac.

  The EL light emission display control method according to claim 2 is a control method for turning on and off the EL display element, wherein a lighting control pulse signal is applied to a blinking switch connected between the control terminal of the EL display element and the high frequency inverter. And a step of supplying a signal having a polarity opposite to that of the blinking switch to a short-circuiting switch connected between the control terminal and the common terminal of the EL display element.

  The EL light emission display control circuit according to claim 3 is characterized in that a delay circuit is inserted into control terminals of the first photoisolator and the second photoisolator. Here, examples of the delay circuit include a delay circuit constituted by an AND gate and a CR integration circuit.

  According to a fourth aspect of the present invention, there is provided an EL light emission display control method comprising a step of delaying an inversion time in a process in which the state of the EL display element is turned from off to off or from off to on. Here, as a method of delaying the inversion time, there are a method using a delay circuit, a method of generating a delay signal by a microcomputer program, and the like.

  According to the first or second aspect of the present invention, when the EL display element is turned off, an electrical short circuit is generated so that the EL display element can be reliably turned off in a short time. As a result, it is possible to enhance the visual effect of the EL light emitting display panel, and to produce a visual dynamic display effect like a neon sign.

  According to the invention according to claim 3 or claim 4, since the inversion time can be delayed in the process of inversion of the state of the EL display element from lighting to extinguishing or from extinguishing to lighting, between the controlled terminals of the two photoisolators Are not conducted at the same time, and the high frequency inverter can be prevented from being damaged by a short circuit.

  Next, the best mode for carrying out the present invention (hereinafter simply referred to as “embodiment”) will be described. In addition, this invention is not limited by this embodiment.

  Hereinafter, it demonstrates in detail based on drawing. FIG. 1 is a circuit diagram showing an embodiment of an EL light emission display control circuit of the present invention. The high frequency inverter 103 is connected to the control terminals PS1, PS2, PS3, and PS4 of the first photoisolator 102 corresponding to the control terminals 107, 1, 2, 3, and 4 of the EL display elements 106 of the EL display panel 105, respectively. The common terminal 108 of the EL display panel 105 is connected to the other end of the high frequency inverter output. At the same time, the controlled terminals of PS5, PS6, PS7, and PS8, which are the second photoisolators 104, are connected between the control terminals 107 1, 2, 3, and 4 of the EL display elements 106 and the common terminal 108, respectively. In addition, a NOT circuit 109 is inserted between the control terminals PS1 to PS4 and the corresponding control terminals PS5 to PS8 to make the pulse signal have a reverse polarity. Further, the control terminals of PS1 to PS4 are configured to conduct the controlled terminals of PS1 to PS4 in the order programmed in advance by, for example, a lighting control pulse signal 110 from the output port of the microcomputer 101.

  FIG. 2 shows an extracted circuit of one EL display element in FIG. One output terminal of the high-frequency inverter 201 is connected to the control terminal 208 of the EL display element 207 via the controlled terminals 3 and 4 of the first photoisolator 204 (PS1), and the other output terminal of the high-frequency inverter 201 is It is connected to the common terminal 209 of the EL display element 207. At the same time, the controlled terminal of the second photoisolator 205 (PS5) is connected between the control terminal 208 of the EL display element 207 and the common terminal 209.

  In FIG. 2, when the lighting control pulse signal 202 becomes high level, the internal light emitting diode connected to the control terminal (1-2) of the first photoisolator PS1 is turned on, and the controlled terminal (3-4) is conductive. To do. At this time, since a pulse signal having a polarity opposite to that of the lighting control pulse signal 202 is applied to the control terminal of the second photoisolator PS5 by the NOT circuit 203, the controlled terminals are in a non-conductive state. Yes. As a result, an AC voltage that is an output voltage of the high-frequency inverter 201 is applied between the control terminal 208 and the common terminal 209 of the EL display element 207, and the EL display element 207 is lit.

  Next, when the lighting control pulse signal 202 is inverted to a low level, the voltage between the control terminals (1-2) of the first photoisolator PS1 becomes a low level, and the controlled terminals (3-4) become non-conductive. At this time, the voltage between the control terminals of the second photoisolator PS5 is set to the high level by the NOT circuit 203, so that the controlled terminals are brought into conduction. As a result, the output of the high-frequency inverter 201 causes an alternating current of about the leakage current to flow through the parasitic output capacitance (Co) of the first photoisolator PS1, but the controlled terminal of the second photoisolator PS5 is conductive. As a result, the amount of the current flowing into the EL display element 207 can be extremely reduced. As a result, the EL display element 207 can be reliably turned off in a short time.

  Here, the EL display element 207 is electrically similar to a capacitor, and its capacitance is proportional to the light emitting area. As a result, since the EL display element having a smaller light emitting area has a smaller capacitance, the EL light emitting element is changed depending on the partial pressure ratio between the parasitic output capacitance (Co) of the first photoisolator PS1 and the capacitance of the EL display element itself. The applied voltage will increase. For this reason, if there is no second photoisolator PS5, it may not be possible to turn off the light even if PS1 is controlled to be non-conductive for turning off.

  Therefore, when PS5 which is the second photoisolator is provided between the control terminal 208 and the common terminal 209 of the EL display element 207 and operated with the polarity opposite to the control signal pulse of PS1, PS5 is not connected when PS1 is non-conductive. Since the electrical connection is established and the control terminal 208 and the common terminal 209 of the EL display element 207 are short-circuited, the output voltage of the high frequency inverter 201 is not applied to the EL display element 207, and the light can be reliably turned off.

  Further, in order to turn on or turn off the EL display element 207, when the lighting control pulse signal 202 is simply guided to the first photo isolator 204 and the inverted signal thereof is guided to the second photo isolator 205, the light is turned off or turned off. At the time when the state is reversed to lighting, a moment occurs in which the controlled terminals of both the first photoisolator 204 and the second photoisolator 205 are simultaneously conducted. As a result, the output of the high-frequency inverter 201 is short-circuited by the two photoisolators, and in the worst case, the photoisolator or high-frequency inverter located in this short-circuit route is destroyed.

  Therefore, by providing an inversion delay time at the timing when the pulse voltage applied to the control terminals of the two photoisolators changes from the low level to the high level, the first photoisolator is turned off at the timing when the EL display element is turned off. The controlled terminal of the second photoisolator 205 is turned on after the controlled terminal 204 is turned off. In addition, at the timing when the EL display element is turned on, the controlled terminal of the first photoisolator 204 is turned on after the controlled terminal of the second photoisolator 205 is turned off.

  FIG. 3 is a circuit diagram showing a timing chart of the inversion delay time and a delay circuit for realizing the inversion delay time. In order to provide an inversion delay time, a delay circuit composed of an AND gate and a CR integration circuit is inserted into the control terminals 303 of both the first photoisolator and the second photoisolator. As a result, at the timing when the display element is turned off, when the pulse voltage applied to the control terminal 303 of the first photoisolator changes to a low level, the delay more than the time delay that the non-control terminal 304 becomes non-conductive It is possible to change the pulse voltage applied to the control terminal 303 of the second photoisolator to a high level with time. In addition, when the display element is turned on, when the pulse voltage applied to the control terminal 303 of the second photoisolator changes to a low level, the delay time is longer than the time delay when the non-control terminal 304 becomes non-conductive. The pulse voltage applied to the control terminal 303 of the first photoisolator can be changed to a high level.

2A and 2B are diagrams illustrating an EL light emission display control circuit and a control method according to the present invention. FIG. 1 shows an extracted circuit of one EL display element in FIG. The figure explaining the delay circuit of this invention, and the timing chart of lighting and light extinction The figure explaining the conventional EL light emission display control

Explanation of symbols

101 Microcomputer 102 First photo isolator (flashing switch)
103 High-frequency inverter 104 Second photo isolator (short-circuit switch)
105 EL light emitting display panel 106 EL display element 107 control terminal 108 common terminal 109 NOT circuit 110 lighting control pulse signal 201 high frequency inverter 202 lighting control pulse signal 203 NOT circuit 204 first photo isolator 205 second photo isolator 206 EL light emitting display Panel 207 EL display element 208 Control terminal 209 Common terminal 210 Example: Photo MOSFET
301 Lighting control pulse signal 302 Photo isolator 303 Control terminal 304 Non-control terminal 401 High frequency inverter 402 DC power supply 403 High frequency AC power supply 404 Low frequency transmitter 405 Start / stop signal 406 Relay or rotary switch 407 EL light emitting display panel 408 EL display element 409 Control Terminal 410 Common terminal

Claims (4)

In the circuit for controlling the lighting and extinction of the EL display element, the controlled terminal of the first photoisolator is connected between the control terminal of the EL display element and the high frequency inverter, and the controlled terminal of the second photoisolator is connected An EL light emission display control circuit, wherein the EL display element is connected between a control terminal and a common terminal of an EL display element. In the control method for turning on and off the EL display element, a step of supplying a lighting control pulse signal to a blinking switch connected between the control terminal of the EL display element and the high frequency inverter, and a control terminal of the EL display element; An EL light emission display control method comprising a step of supplying a signal having a polarity opposite to that of the blinking switch to a shorting switch connected to a common terminal. 2. The EL light emission display control circuit according to claim 1, wherein a delay circuit is inserted into control terminals of the first photoisolator and the second photoisolator. 3. The EL light emission display control method according to claim 2, further comprising a step of delaying the inversion time in the process of reversing the state from turning on or off of the EL display element to turning on.

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