JP2001343932A - Temperature correcting circuit for organic el panel driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform optimum correction of VH voltage and VM voltage by providing a VH voltage setting circuit and a VM voltage setting circuit in the same circuit and allowing the circuit to have a temperature correcting function. SOLUTION: In a simple matrix drive type organic EL(electroluminescent) panel driving device in which anodes are arranged in a longitudinal direction and cathodes are arranged in a lateral direction, light emitting elements are arranged at respective intersections, voltage (VM) for preventing crosstalk and voltage (VH) for driving a constant current source are supplied respectively for every one line of cathode and for every one line of anode and respective cathode lines are successively scanned, a temperature correcting circuit in which the voltage (VM) which is to be applied to each cathode line in order to prevent crosstalk is set by dividing the voltage (VH) for driving a constant current source with resistances (R1, R3) and the voltage (VH) is set by detecting the VH whose voltage is divided and by comparing it with reference voltage and the VH is controlled by using a temperature sensor (Rth) is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anode, a cathode, and a light emitting element at each intersection.
A simple matrix drive type organic EL panel drive that supplies a voltage (VM) for preventing crosstalk for each line and a voltage (VH) for driving a constant current source for each anode line and sequentially scans each cathode line. The present invention relates to a temperature correction circuit of an organic EL panel driving device suitable for use in a device.

[0002]

2. Description of the Related Art FIG. 3 shows an organic EL (Electro Luminescenc).
e) Shows the panel drive circuit. (A) In-vehicle monitor,
(B) illustrates a drive circuit used in a mobile phone. On the anode side, a constant current circuit (VH
) And a switch between the terminal and GND,
The current is turned on when the scanning element emits light, the residual charge is discharged when the element is not emitting light, and the terminal is connected to the GND potential to reliably turn off the current.

On the cathode side, the terminal under scanning is set to GND, and the other terminals are opened. In this case, there is a danger that the drive current leaks depending on the residual voltage of the terminal that is in the open state, and crosstalk occurs. A voltage VM is applied to prevent crosstalk, and by setting VM ≒ VF (a forward voltage when the element emits light), the voltage can be reliably turned off. Here, when VM <VF, crosstalk occurs, and when VM> VF, a current for reverse bias charging flows, and current consumption increases.

By the way, the forward voltage VF at the time of light emission of the element is
Varies with temperature. FIG. 4 shows the voltage-temperature characteristics. In the figure, d is the minimum voltage required for the operation of the constant current source. If VM and VH are kept constant, crosstalk occurs at low temperatures, and power loss (VM system loss a at high temperatures).
And the loss b) of the VH system increases. Therefore, temperature correction is performed.

FIG. 5 shows this temperature correction circuit.
5A shows a VM setting circuit, and FIG. 5B shows a VH setting circuit. In the VM setting circuit, VH is divided by the resistors R1 and R2 to set VM. Here, VM =
R2 · VH / (R1 + R2). In the VH setting circuit, VH is set by comparing VH divided by a DC-DC converter with reference voltage Vref. A thermistor (Rth) is used in a circuit for setting VH, and VH is controlled by temperature. That is, the change R in VH
2 / (R1 + R2) is the change in VM.

FIG. 6 shows voltage-temperature characteristics. In FIG. 6, when VH is optimally corrected, VM becomes insufficiently corrected,
If VM is optimally corrected, VH will be overcorrected.

[0007]

As described above, the temperature correction circuit of the conventional organic EL panel driving device has a VH
The setting circuit and the VM setting circuit are provided independently, and the VH and VM are corrected by providing the VH setting circuit with a function for temperature correction. Therefore, the number of components is large, the cost is increased, and reliability is not preferable. Also,
As shown in FIG. 6, if the VH is properly corrected, the VM becomes insufficiently corrected. Conversely, if the VM is properly corrected, the VH becomes overcorrected, so that there is a disadvantage that the optimum correction cannot be performed.

The present invention has been made in view of the above circumstances. By providing a VH voltage setting circuit and a VM voltage setting circuit in the same circuit, and having this circuit with a temperature correction function, it is possible to optimize the VH and VM. It is an object of the present invention to provide a temperature correction circuit of an organic EL panel driving device capable of performing various corrections.

[0009]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises an anode in the vertical direction, a cathode in the horizontal direction, a light emitting element at each intersection, and a cathode line. In a simple matrix driving type organic EL panel driving apparatus which supplies a voltage (VM) for preventing crosstalk and a voltage (VH) for driving a constant current source for each anode line and sequentially scans each cathode line, VH And a voltage control circuit that performs temperature correction by sharing a circuit for setting each of the VMs. As a result, since the circuits for VH setting and VM setting are provided in the same circuit, the number of components constituting the circuit can be reduced, and VH and VM can be reduced.
Temperature correction can be performed optimally.

According to a second aspect of the present invention, in the temperature correction circuit of the organic EL panel driving device according to the first aspect, the voltage control circuit sets the VM by dividing the voltage of VH, and uses the temperature sensor. While controlling the VM, the divided VH is detected, compared with the reference voltage, and the VH is set.
A temperature control circuit for controlling VH using the temperature sensor. With the above configuration, a temperature sensor is used in a circuit for setting VH, and VH is temperature-corrected by controlling VH with temperature, and VM is further corrected by a temperature change of VH. It is possible to provide a temperature correction circuit for an organic EL panel driving device that can perform correction and reduce the number of components.

[0011]

FIG. 1 is a circuit diagram showing an embodiment of a temperature correction circuit of an organic EL panel driving device according to the present invention. In the temperature correction circuit of the organic EL panel driving device according to the present invention, the VH voltage setting circuit and the VM voltage setting circuit are realized by the same circuit, and the VH voltage is set by adding the temperature correction function.
, And a voltage control circuit that corrects the VM based on the change in VH. This voltage control circuit converts a voltage (VH) for driving a constant current source into a resistor R1 and a temperature sensor R
th, a voltage setting circuit for setting the voltage (VM) applied to each cathode line to prevent crosstalk by dividing the voltage by the resistor R3, and detecting the divided VH here to obtain a temperature sensor such as a thermistor (Rth) And a temperature correction circuit that controls the VH using the VH and reflects the change in the VH on the VM.

Here, VH · R3 / (R1 + Rth + R3) = Vref∴VH = (R1 + Rth + R3) · Vref / R3 = Vref · Rth / R3 + (R1 + R2) · Vref / R3 (1) VM = VH · (Rth + R3) / (R1 + Rth + R3) = (R1 + Rth + R3) · Vref (Rth + R3) / R3 (R1 + Rth + R3) = (Rth + R3) · Vref / R3 = (Vref · Rth / R3) + (R3 · Vref / R3) (1) ) As is clear from (2), VH and VM
Change with respect to temperature becomes equal.

FIG. 2 is a diagram showing a temperature-correction circuit voltage-temperature characteristic of the organic EL panel driving device of the present invention shown in FIG. In the figure, d is the minimum voltage required for the constant current source to operate. As shown in FIG. 2, VH and VF ≒ VM do not intersect due to a temperature change, and a temperature correction close to ideal can be performed.

As described above, according to the present invention, the VH voltage setting circuit and the VM voltage setting circuit are provided in the same circuit, and this circuit is provided with a temperature correction function, so that optimum correction of VH and VM can be performed. And a temperature correction circuit for the organic EL panel driving device.

[0015]

According to the first aspect of the present invention, since the circuits for setting the VH voltage and the VM voltage are provided in the same circuit, the number of components constituting the circuit can be reduced. Further, it is possible to perform optimal temperature correction on VH and VM. According to the second aspect of the present invention, a temperature sensor is used in a circuit for setting VH, and VH is temperature-corrected by controlling VH with temperature, and VM is corrected by a temperature change of VH. In addition, it is possible to provide a temperature correction circuit of an organic EL panel driving device which can perform optimal temperature correction of the VM and the VM and reduce the number of parts.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a temperature correction circuit of an organic EL panel driving device according to the present invention.

FIG. 2 is a diagram showing voltage-temperature characteristics of a temperature correction circuit of the organic EL panel driving device according to the present invention shown in FIG.

FIG. 3 is a diagram showing an example of a conventional driving circuit configuration of an organic EL panel.

FIG. 4 shows a voltage of a conventional organic EL panel driving device.
It is a figure which shows a temperature characteristic.

FIG. 5 is a diagram showing a circuit configuration of a temperature correction circuit of a conventional organic EL panel driving device.

6 is a diagram showing voltage-temperature characteristics of a temperature correction circuit of the organic EL panel driving device shown in FIG.

[Explanation of symbols]

VH: constant current source drive voltage, VM: crosstalk prevention reverse bias voltage, VF: forward voltage of the light emitting element, R1 (R
3)… Division resistor, Rth… Temperature sensor (Thermistor)

Claims (2)

[Claims] An anode is arranged in a vertical direction, a cathode is arranged in a horizontal direction, and a light emitting element is arranged at each intersection. A voltage (VM) for preventing crosstalk is provided for each cathode line, and a constant current source is provided for each anode line. In a simple matrix drive type organic EL panel driving device that supplies a driving voltage (VH) and sequentially scans each of the cathode lines, a circuit for setting each of the VH and VM is shared,
A temperature correction circuit for an organic EL panel driving device, comprising a voltage control circuit for performing temperature correction. 2. The voltage control circuit sets the VM by dividing the VH, controls the VM using a temperature sensor, detects the divided VH, and compares the detected VH with a reference voltage. 2. The temperature correction circuit according to claim 1, further comprising: a temperature control circuit that sets VH by using a temperature sensor and controls the VH using the temperature sensor.