JPH01109693A - Driving method for el luminous element - Google Patents

Abstract

PURPOSE:To simplify the structure of a driving circuit and reduce the cost by applying the pulse voltage with the same voltage and the same phase to both electrodes pinching a layer not desired for the luminescence of an EL element with multiple luminous layers to suppress its luminescence. CONSTITUTION:In an EL element with two luminous layers EL1 and EL2, for example, when a circuit constituted of high-withstand voltage CMOS, A, B, C, switches SW1, SW2, SW3, SW4, SW5, photocouplers PC1, PC2, PC3, PC4, PC5 and resistors R1 and R2 is driven by a logic circuit, the luminous layers are optionally illuminated. The switches SW2 and SW4, photocouplers PC2 and PC4, and resistors R1 and R2 are eliminated in this complicated circuit, the channel (p) and (n) gates of CMOS, A, C are connected in common, the same voltage in the same phase is applied to both electrodes pinching the preset luminous layer, and its luminescence is suppressed. The driving circuit is simplified and the cost is reduced by omitting the constituting components.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to electroluminescence (hereinafter referred to as El).
A display device using , especially a display whose light emitting part is composed of multiple EL elements! This relates to a method of driving t@.

<Prior Art> FIG. 5 is a cross-sectional configuration diagram showing a conventional example of a multicolor light emitting body in which EL elements are arranged in W4 layers. In the figure, 1 is the board.

2 is a transparent electrode, 3.5.7.9 is an insulating layer, 4 is a lower light emitting layer, 6 is an intermediate transparent electrode, and 8 is an upper light emitting layer.

10 is a back electrode. Here, the upper light emitting layer 8 is, for example, z
A green EL element such as ns:Tl)Fa is used, and the lower light emitting layer 4 is a red EL element such as ZnS:SmF3. These light emitting layers are insulating layers 9 and 7. 5 and 3, the upper light emitting layer 8 is sandwiched between the back electrode 10 and the intermediate transparent single pole 6. The lower light emission M4 is connected between the intermediate transparent electrode 6 and the transparent electrode 2 from the power sources 11a and 11b. When a voltage is applied, each light-emitting layer emits visible light unique to it.

As a drive circuit for producing an intermediate color between green and red in the EL element and controlling the color tone, the present applicant applied for patent application No. 62-2.
No. 13627 is proposed.

FIG. 6 is a schematic electrical circuit described in the above-mentioned prior application, and in this example, three high-voltage CMOs 8 and A are connected.

B and C are connected in parallel, and the green element EL1 shown in Figure 5 is between the drain terminal of A and the drain terminal of 8, and the red element EL1 shown in the figure is between the drain terminal of B and the drain terminal of C. Element EL2 is connected, the source terminal side of the n channel of each 0MO8 is connected to the high voltage DC 'Fi source 2, and the source terminal of each n channel side is connected to the ground side. CLK is a clock signal that switches each of the 0MO8, and the gate terminal of the 0MO8 is connected to the 0MO8 of B via the switch SW+.
The gate terminal of 8 is connected via an inverter [n,
It is connected to the gate terminal of 0MO8 of C via a switch SW2.

FIG. 7 is a circuit diagram specifically representing the schematic diagram of FIG. 6. In the figure, the gate terminal of the p-channel of 0MO8 in A is connected to the CMO8 drive voltage through a load resistor R2, and at the same time, this gate is connected to a photocoupler P for separating the circuit driven by the voltage V+ and V2. The output terminal of C+ is connected. Further, a voltage v1 is applied to the input terminal of this P C+ via a load resistor R+ and SW+. The n-channel gate of MO3 of A is connected to the CMO8 drive voltage through a load resistor R2, and at the same time, this input terminal is connected to a photocoupler PC2 for isolating the circuit driven by the voltages V+ and v2. Output terminal is connected. Further, a voltage v1 is applied to the input terminal of this PC2 via a load resistor R+ and SW2.

The gates of B's 0MO8, in which the gates of the same <p, n channels are connected, are connected to the CMO8 drive voltage 2 through a load resistor R2, and at the same time, this gate terminal is driven by voltages 1 and V2. The output terminal of a photocoupler PC5 for isolating the circuit is connected. Further, a voltage 1 is applied to the input terminal of PO2 via load resistors R1 and SW5.

Also, the gate terminal of the p channel of C0MO8 has A
Similarly to the 0MO8, the CMO8 drive voltage is applied to the drive voltage through the load resistor R2, and at the same time, the voltage V+ is applied to this input terminal.
and an output terminal of a photocoupler PC3 for isolating the circuit driven by v2. Further, a voltage v1 is applied to the input terminal of this PO2 via a load resistor R+ and a SW. The CMO8 drive voltage is applied to the gate terminal of the n-channel of the C0MO8 through the load resistor R2, and at the same time, the voltage V is applied to this gate terminal.
The output terminal of a photocoupler PC4 for separating the circuits driven by 1 and 2 is connected. Further, a voltage V1 is applied to the input terminal of this PO2 via a load resistor R+ and SWa. Here, each voltage and resistance value is V, is 5V, V2 is 250V, R+ Gtl kΩ
, R2kL15 is approximately Ω. In addition, in this example, SW
A photocoupler that turns on when is on shall be used.

In the circuit with the above configuration, a signal based on the result of the operation of the control device (not shown) is synchronized with the clock to switch SW.
I'-SW5 is turned on and off as shown in FIG. In other words, for a certain clock, the green light emitting element E
To make L+ emit light, turn on SW+, SW2, and SW4, and turn off SW and SWs. In this state A
The p channel of 0MO8 of B is turned on and the n channel is turned off, the p channel of 0MO8 of B is turned off and the n channel is on, and both the p and n channels of 0MO8 of C are turned off. As a result, the voltage of power supply ■2 is A of 0 MO8 p
EL+ (green) is applied through the channel to emit light.

At the next clock, turn off S W + ~ S W 3, and turn off S
Turn on W a and S W s. In this state A
The p-channel of 0MO8 is off, the n-channel is on, and the p-channel of 0MO8 of 8 is on.

The n-channel is off, and the C 0MO84, tp, and n-channel remain off. As a result, p of 0MO8 of B
Voltage of power supply v2 via channel is EL+ (green)
is applied to emit light.

Furthermore, when the red light emitting element EL2 and both light emitting elements are caused to emit light, they can be caused to emit light by switching to the state shown in FIG. 8. Further, by driving these switches with a logic circuit (not shown), each color can be emitted arbitrarily.

<Problems to be Solved by the Invention> However, in the above driving method, both the p-channel and n-channel of 0MO8 are turned off for elements that are not desired to emit light. For this reason, a υ control circuit is required for each channel, resulting in a problem that the number of elements in the drive circuit increases.

The present invention has been made in view of the above-mentioned problems of the prior art, and it applies pulses of the same voltage and the same phase to both ends of the EL element without turning off the 0MO8 on one side of the EL element where light emission is not desired. By applying this voltage, the load on the drive circuit and logic section is reduced.

Furthermore, it is an object of the present invention to realize a method of driving an EL light emitting element that reduces costs by eliminating SW and photocoupler components.

Means to solve problems〉 The structure of the present invention for solving the above problems is as follows.

substrate,? i Bright electrode layer, 2? In a light-emitting element composed of a light-emitting layer and a back electrode consisting of i or more layers, the light-emitting layer and the insulating layer are alternately stacked.

The same voltage is applied to the layer that is not desired to emit light among the light emitting layers.

The device is characterized in that it is configured to apply pulse voltages of the same phase.

<Example> Figure 1 does not show an example of the present invention in which the conventional problems were solved using a stacked light emitting EL element having a configuration not shown in Figure 5. A's 0MO8 n-channel switching cable SW2, Fe2, R+ shown in the example
, R2 and C 0MO8 n-channel switching element SW4. Delete FCa, R+, R2, connect the p and n channel gate terminals of 0MO8 of A and C in common, and connect SW+, R+, R2 to the common connection point.
, FC+ and SW, 3, R+, R2, and Fe2 are connected, respectively.

In the above configuration, each switch performs switching as shown in FIG. In other words, if you want to make EL+ (green) emit light at a certain clock timing using a signal based on the calculation result, turn on SWl, and turn on SW3 and S.
Turn off each W5.

In this state, the p channel of A's 0MO8 is on,
n channel is off and p of B and C 0MO8
Channel is off and n channel is on. As a result, the voltage of the power supply (2) is applied to EL+ (green) through the p-channel of A's 0MO8, and light is emitted, but in this state, both ends of EL2 (red) are at the same potential, so no light is emitted.

At the next clock, SW+ is turned off, and SW3 and SW5 are each turned on. In this state, the p channel of the 0MO8 of A is turned off and the n channel is turned on, and the p channel of the 0MO8 of B, f5 and C is turned on and the n channel is turned off. As a result, the power supply v
The voltage of 2 is EL+ through the n channel of B's 0MO8.
However, even in this state, both ends of EL2 (red) are at the same potential, so no light is emitted.

As mentioned above, in the present invention, the switches SW+ and SW.

E using only 3 switches of SWs and not wanting 9 light emission
Light emission can be prevented by applying pulses of the same voltage and phase to the L elements. Therefore, the number of parts can be reduced, and the load on the logic (calculation) section is also reduced by reducing the number of control switches.

Figures 3 and 4 do not show other embodiments, and three EL elements are used.
It shows the layered electrical circuit and the operating status of each switch. In this way, by using three types of El elements and controlling the emission time of each element in a time-sharing manner, the mixed colors M, M'J4
can be controlled.

It should be noted that the EL element may have any structure as long as it is capable of applying an alternating voltage to the light emitting layer, and any structure of one light emitting layer (thin film, two dispersed films, etc.), lamination order, etc. may be used. Further, the drive circuit is not limited to the circuit shown in the figure, but may include an EL light emitting element,
High pressure switch part.

It is possible to operate if it consists of a high voltage power supply section and a switching control section. Further, the single display method may be for a fixed pattern display or for a matrix display, and the driving method may be switching an AC power supply or a refresh pulse drive method used in matrix panels.

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, according to the present invention, a pulse of the same voltage and potential is applied to both ends of an EL element that does not want to emit light, so that the number of switches is reduced. It is possible to realize a method for driving an EL light emitting element that reduces the amount of noise, reduces the burden on the drive circuit and logic section, and reduces costs.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing an embodiment of the present invention for driving two EL elements, Fig. 2 is a diagram showing the states of switches for driving two EL elements, Figs. 3 and 4. are the three E's
FIG. 5 is a cross-sectional configuration diagram showing an example of a multicolor light emitting body in which EL elements are laminated; FIG. 7 is a schematic diagram of a conventional EL element drive circuit, FIG. 7 is a specific electrical path diagram of FIG. 6, and FIG. 8 is a state of the switch for driving the two EL elements of FIG. 7. It is a diagram. 1... Substrate, 2... Transparent electrode, 3.5.7.9...
- Insulating layer, 4... Lower light emitting layer, 6... Open transparent electrode, 8... Upper light emitting layer, 10... Back electrode, A-D.
・・High voltage CMO8, SW 嘗～SW5...Switch,
FC+~FC4...Photo coupler. Figure 1 Tail Figure 2 Figure 5 Figure 6

Claims (1)

[Claims] In a light-emitting element composed of a substrate, a transparent electrode layer, a light-emitting layer consisting of two or more layers, and a back electrode, the light-emitting layer and the insulating layer are alternately laminated, and one of the light-emitting layers desired to emit light is 1. A method for driving an EL light emitting device, characterized in that pulse voltages of the same voltage and phase are applied to both electrodes sandwiching a layer between them.