JPH0650428B2 - EL panel drive - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matrix type EL panel driving device, and more particularly to an EL panel driving method suitable for high-speed scanning and low power consumption.

2. Description of the Related Art In the case of lighting EL elements arranged in a matrix at the intersections of scanning lines and data lines, for example, Japanese Patent Laid-Open No. 54-10
2898 and Japanese Unexamined Patent Publication No. 54-130898, a method of driving through pre-charging is known. However, in such a precharge type line-sequential driving, a fatal defect in terms of power consumption and high-speed scanning. Therefore, it was regarded as an important issue in this field. Further, it has been desired to develop a matrix type EL panel driving device having high-speed scanning performance and low power consumption by a direct line sequential driving system which eliminates preliminary charging.

DISCLOSURE OF THE INVENTION Accordingly, the present invention has been proposed in view of the above, and an object thereof is to provide a new and improved matrix-type EL panel drive device having high-speed scanning performance and power consumption consumption.

According to the present invention, a scan drive circuit for sequentially applying and scanning a first voltage required for light emission to a scan side electrode of an EL element connected to an intersection of a scan line and a data line, and a data side electrode of this element in a non-light emitting state A data driving circuit that applies a second voltage and changes the second voltage to a third voltage that obtains a light emitting state for the selected EL element, and a refresh voltage is applied to the data side electrode after scanning one frame. In a matrix type EL panel driving device including a refresh driving circuit, the scanning and data driving circuits each include a push-pull driver circuit, and when the scanning driving circuit scans one scanning line with the first voltage. Select and operate three states so that the scanning lines before and after that are maintained in the floating state or the grounded state, respectively, and Circuit is characterized in that to operate by selecting two states of the data voltage of each data line (V ₂₎ and a ground potential state (OV). As a result, the horizontal blanking period during scanning is shortened, the frame frequency can be set high, and high-speed scanning performance is achieved. Further, during the scanning period, the electric charges of all the panels are not discharged after the specific scanning line is selected and the floating state is maintained, so that it is possible to reduce the power consumption, especially when the data does not change in one frame. Appears prominently.

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 is a circuit configuration diagram of an EL panel driving device according to the present invention, in which scanning lines (S ₁ ) to (Sn) and data lines (d ₁ ) to
EL elements (EL ₁₁ ) to (ELmn) are connected to the respective intersections of (dm) to form a matrix type EL panel. Scan line (S ₁ ) ~
One end of (Sn) is connected with a scan drive circuit (11) consisting of a push-pull driver including push-switch elements (SP ₁ ) to (SPn) and pull-switch elements (SN ₁ ) to (SNn), and an EL element (EL
The first voltage V ₁ of the required light emission level (200 V) of ( ₁₁ ) to (ELmn) is supplied. On the other hand, one end of the data lines (d ₁ ) to (dm) has push-push switch elements (DP ₁ ) to (DPm) and diodes (Dd ₁ ) to
A data drive circuit (12) including a push-pull driver including (Ddm) and pull switch elements (DN ₁ ) to (DNm) is coupled. Further, a refresh drive circuit (13) including backflow prevention diodes (Dr ₁ ) to (Drm) and a switching element Tr is connected in parallel with the data drive circuit (12). Here, the data line voltage (60
Second and the voltage V ₂ is supplied to V), the Rifuretsushiyu drive circuit (13) is Rifuretsushiyu voltage V _R is supplied by the first voltage and the same level (200V).

The operation of the EL panel driving device having the above configuration will be described with reference to the time chart of FIG. First, scan drive circuit (11)
Are FET switch elements (SP ₁ ) to (SP _n ) and (SN ₁ ) to (SN ₁ ) which are push-pull drivers for each scanning line (S ₁ ) to (Sn).
_n ) are connected, and the first voltage V ₁ of the power supply is applied according to the gate signal of the push driver. The voltage V ₁ is selected to be a required light emission voltage of 200 V, which is sufficiently high to cause the EL elements (EL ₁₁ ) to (ELmn) to emit light. The pull driver is E
It functions to discharge the electric charge charged in the L element. In this way, the scanning with the first voltage V ₁ as shown in FIG. 3 is performed. On the other hand, in the data driving circuit (12), a push-pull driver is connected to each of the data lines (d ₁ ) to (dm) in the same manner as the scanning side, and the push-driver drives the second voltage V ₂ of the power source It is applied according to the gate signal of the switch element.
This second voltage V ₂ is the non-selection voltage 60V, and when this voltage is applied to the data side electrode of the EL element, even if the first voltage V ₁ required for light emission is applied to the scanning side electrode, E
Since only a voltage of 200-60 = 140V is applied between the terminals of the L element, the EL element does not emit light. Further, in order to cause the selected EL element to emit light, the pull driver supplies the control signal to set the second voltage V ₂ to the lower third voltage V ₃ . That is, the second that maintains the non-selected state
When the voltage V ₂ of the EL element is changed to the selected state and becomes the third voltage, for example, OV in the grounded state, a voltage equal to or higher than the light emission threshold of the EL elements (EL ₁₁ ) to (ELmn) (= V ₁ −V ₀ ). Is applied to both electrodes, and the selected EL element emits light. Therefore, the data line supplies a selection or non-selection data signal according to the scanning timing.

After the scanning period in which one frame is scanned by the scanning and data driving circuits (11) and (12) to form an image, all EL elements (E
L ₁₁ ) to (ELmn) must be refreshed and excited. This process is performed by applying a voltage having a polarity opposite to that of the applied voltage in the scanning period between both electrodes of the EL element, and this is achieved by the refresh drive circuit (13). That is,
The switching element Tr and the diode (D
r ₁₎ is performed by applying ~ a Rifuretsushiyu voltage V _R through (Drm) to the data side electrodes. Rifuretsushiyu voltage V _R is, for example, the first voltage and the same level of voltage 200V is used. Third
The figure shows a frame period including a scanning period T ₀ and a refreshing period T _3, and each scanning line (S ₁ ) to (Sn) is included in the scanning period.
On the other hand, the scanning voltage application period T ₁ and the horizontal blanking period are included respectively.

In another aspect of the present invention, the scan drive circuit (11) is a ground potential state (OV) for each scan line (S ₁ ) ~ (Sn),
The light emission required voltage (first voltage) is switched and driven into three states of a scanning state and a floating high impedance state. In such a driving method, the scanning driving circuit (11) is the first
As shown in the figure, this can be achieved by using a push-pull driver, which can further improve high-speed scanning and low power consumption.

FIG. 2 is a circuit diagram of a main part for operating the above-mentioned scanning drive circuit by switching between three types, and schematically shows the switching elements of the drive circuits (11) to (13). Here, the scan driving circuit (11) sets a certain scan line to a first voltage V ₁ by a push driver, charges the EL element of this scan line, and then discharges it by the pull driver, at which time the next scan line is discharged. Move on to. However, at this time, the other scanning lines are floated (in a high impedance state). FIG. 2 shows a state in which the second scan line has reached the first voltage V ₁ . When this is seen in a time chart, after the data line is set as shown in FIG. 4, the first voltage V ₁ is applied to the second scan line (S ₂ ) and the first scan line (S _{2 1} ) is set to OV to discharge the electric charge, and the third scan line (S
_{After 3} ), the floating state (high impedance) is maintained, and the voltage is maintained at the first voltage (200 V) or less and according to the switching of the data line.

In such a driving method, each operation from the selection of one scanning line to the selection of the next scanning line, that is, scanning line voltage OV point (x) → data rewriting point as shown in FIG.
(y) → Since the timing shift of the next line selection point (z) is required until stabilization of each operation, the horizontal blanking period T ₂ shown in FIG. 3 can be significantly shortened. Therefore, by shortening the horizontal blanking period, high-speed scanning can be realized and the frame frequency can be improved.

In addition, the effect of power consumption will be described. First, the power consumption of the entire display is the power consumed during scan driving in which the required light emission voltage V ₁ is applied to each scan line, the power consumed during refresh driving, and the data electrode. Is the sum of the power consumed during the data drive for selecting the light emission or non-light emission, and the power consumed during the write drive and the refresh drive in the present invention is the same as that in the conventional drive system for performing the precharge. However, the present invention has a significant improvement in the power consumed when driving data.

That is, in the conventional driving method that performs precharging, the light emission pattern that maximizes the power consumption during data driving is when the entire surface is non-light emitting, and at this time, the data voltage is 1/2, that is, 1/2 V ₂ As a result of performing precharging twice from the electrode and the scan electrode, every time one scan electrode is selected, 2 × C ₁ × (1 / 2V ₂ ) ² = 1 / 2C ₁ · V ₂ ²
(C1; total capacity of EL cell) is consumed.

On the other hand, in the driving method according to the present invention, the light emission pattern that maximizes the power consumption during data driving is when half of the EL cells of one scanning electrode emit light, and at this time, all EL cells are
Since it is charged with a voltage of 2V ₂ , power of C ₁ × (1 / 2V ₂ ) ² = 1 / 4C ₁ · V ₂ ² is consumed each time one scan electrode is selected. Conventional drive method 1
/ 2.

Generally, the power consumption during data driving varies depending on the voltage of the data line, the number of scanning lines, and the like, but since it occupies 70 to 80% of the power consumption of the entire display, when the power consumption during data driving becomes 1/2, In comparison of power consumption of the entire display, power consumption can be reduced by 30 to 40%.

In addition, except the selected scan line and the scan line immediately after it, the selected scan line is in the floating state, so that a considerable reduction in power consumption can be achieved. In particular, if the data of the data line does not change during one frame, after selecting one scan, almost only the charges of the selected scan line are discharged, and the charges charged in the other EL elements are not discharged. The low power consumption is more remarkable. It is clear that this is superior in low power consumption to the driving method in which the electric charges of all the panels are discharged at the end of selection of one scanning line.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an EL panel driving device according to the present invention, FIG. 2 is a timing characteristic diagram during operation of FIG. 1, and FIG. 3 is a main circuit for explaining a driving system by the driving device of FIG. Figure,
4 and FIG. 4 are timing characteristic diagrams of the scanning period in the circuit diagram of FIG. (11) …… Scan drive circuit (12) …… Data drive circuit (13) …… Refresh drive circuit (d ₁ ) to (dm) …… Data line (S ₁ ) to (Sn) …… Scan line (EL ₁₁ ) 〜 (ELmn) …… EL element

Claims (1)

[Claims] 1. A scan drive circuit for scanning while sequentially applying a first voltage to a scan-side electrode of an EL element connected to an intersection of a scan line and a data line, and a second voltage to a data-side electrode of the EL element or An EL panel drive having a data drive circuit that applies a third voltage to select non-light emission or light emission of the EL element, and a refresh drive circuit that applies a refresh voltage to the data-side electrode after frame scanning by the scan drive circuit In the device, the scan drive circuit includes a push-pull driver that selects each scan line into three states of a ground potential (OV) state, a light emission required voltage (first voltage) scan state, and a floating state. In addition, the data driving circuit selects each data line into _two states, that is, a data voltage (V ₂ ) state and a ground potential (OV) state. An EL panel drive device having a push-pull driver.