JP2004145026A - Driving gear for light emission element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving circuit for driving with a low voltage capable of miniaturizing even when a driving gear is mounted onto a chip or the like. <P>SOLUTION: In an organic EL (electroluminescence) panel 10, thin film transistors TFT and light emission elements (E) are connected at each crossing point of address scanning electrode lines (A) and data electrode lines (B) arranged in a matrix shape, field effect transistors (Tr<SB>nA</SB>) 11 are arranged at the tops of each of the arranged data electrode lines (B). Reference currents (i) supplied to the data electrode lines (B) are adjusted by the transistors (Tr<SB>nA</SB>) 11. The transistors (Tr<SB>nA</SB>) 11 are disposed on a semiconductor chip different from that of on a driving gear 100. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention belongs to the technical field of a drive circuit of an organic EL display in which a display is constituted by organic EL elements.
[0002]
[Prior art]
Electroluminescence (EL) elements include an inorganic light emitting element using a thin film of an inorganic compound such as selenium or zinc as a light emitting material, and an organic EL light emitting element using an organic compound as a light emitting material.
[0003]
The organic EL light-emitting device can display (1) high luminous efficiency, (2) low drive voltage, (3) various colors (green, red, blue, yellow, etc.) by selecting a light-emitting material, (4) The display is clear and does not require a backlight because it is a self-luminous type. (5) Surface emission and has no viewing angle dependence. (6) Thin and lightweight. (7) Maximum temperature of the manufacturing process is low. Therefore, there is an excellent feature that a soft material such as a plastic film can be used as a substrate material.
[0004]
Therefore, in recent years, a display using an organic EL light emitting element (hereinafter, referred to as an organic EL display) has attracted attention as a display device such as an in-vehicle AV device, a portable device such as a PDA and a mobile phone, instead of a CRT or LCD. I have.
[0005]
When an organic EL element is applied to a display, a dot matrix display is generally used. There are a passive system and an active system for driving the organic EL display of the dot matrix display.
[0006]
In the former active method, a switching element composed of a thin film transistor (TFT) is connected to each of the organic EL light emitting elements constituting a pixel, and when driving, a so-called static drive is performed, which is always lit. (For example, see Patent Document 1).
[0007]
On the other hand, in the latter passive method, each of the yin and yang electrodes is formed as a matrix line electrode group composed of a plurality of rows and columns, and is sequentially selected by scanning the lines of each of the yin and yang electrodes. That is, so-called duty driving is performed, which is lit only when the row line is selected.
[0008]
Among the above two types of displays, the passive type display has a simpler manufacturing process and can be manufactured at low cost as compared with the active type display, whereas the active type requires TFTs and is expensive, but has a low cost. It has a point that it can be driven with power consumption and a point that there is little crosstalk in pixel sense, and is particularly suitable for a large screen display and a display with high definition.
[0009]
[Patent Document 1]
JP 2001-117534 A
[Problems to be solved by the invention]
However, when driving an active type display, it is necessary to apply a high voltage to the light emitting element in order to emit light from the organic EL light emitting element, and a driving device for driving the display needs to have a high breakdown voltage. Therefore, when the driving device is mounted on a semiconductor chip or the like, there is a problem that miniaturization of the driving circuit becomes difficult.
[0011]
The present invention has been made in view of the above-described problems, and an example of the problem is to provide a driving circuit that can be driven by a low voltage that can be miniaturized even when a driving device is mounted on a semiconductor chip or the like. Is to do.
[0012]
[Means for Solving the Problems]
According to an aspect of the present invention, there is provided a driving apparatus for a light emitting element, wherein a plurality of light emitting elements are formed in a matrix, and a light emitting element is driven by scanning the light emitting element. A first driving unit that supplies a reference current serving as a reference when each of the light emitting elements is driven, for each scanning line in a first scanning direction that is a scanning direction of one scanning line in the display unit. A second driving unit for applying a predetermined voltage for each scanning line in a second scanning direction, which is the other scanning direction in the display unit, and the first driving unit based on an input voltage input from the outside. Adjusting means for adjusting each reference current supplied by the driving means, wherein at least the first driving means is provided on one semiconductor chip, and the adjusting means is provided on a semiconductor chip different from the one semiconductor chip. It has the only configuration.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present application will be described with reference to the drawings.
[0014]
An organic EL panel (hereinafter simply referred to as an organic EL panel) in an active type organic EL display and a driving device thereof will be described with reference to FIGS.
[0015]
FIG. 1 is a configuration diagram showing a schematic configuration of an organic EL panel and its driving device, and FIG. 2 is a diagram showing a partial configuration of the organic EL panel and its driving device.
[0016]
In the present embodiment, the organic EL panel having the field-effect transistor for controlling the reference current of the data electrode line and the driving device are provided on different semiconductor chips.
[0017]
Further, in the present embodiment, description will be made on the assumption that 256 data electrode lines and 64 address scanning electrode lines are provided.
[0018]
In the organic EL panel 10, as shown in FIGS. 1 and 2, address scanning electrode lines (B) to which address signals are supplied and data electrode lines (A) to which data signals are supplied are arranged in a matrix (lattice). In the organic EL panel 10, the light emission of each light emitting element (E) is provided at each intersection of the address scanning electrode lines (A) and the data electrode lines (B) arranged in a matrix. A thin film transistor TFT (hereinafter simply referred to as TFT) for performing switching control is connected to a light emitting element (E). The light emitting element (E) is connected to the data electrode line (A) and the address scanning electrode line (B) via the TFT. ) And connected.
[0019]
Specifically, when the TFT is a P-type transistor, the gate of the TFT is connected to the data electrode line (A) corresponding to the TFT, and the source of the TFT is connected to the TFT corresponding to the TFT. Address scanning electrode lines to be connected, and a current corresponding to the gate voltage applied by the data electrode (A) is caused to flow between the source and the drain of the TFT via the address scanning electrode lines. Has become.
[0020]
The drain of the TFT is connected to the light emitting element (E) via a current mirror circuit composed of a P-type transistor Tr, and the current mirror circuit is connected to a power supply voltage V _DD connected to each transistor Tr. The current flowing between the source and the drain of the TFT is accurately supplied to the light emitting element (E) by using.
[0021]
For example, in this embodiment, the gates of the transistors Tr forming the current mirror circuit are connected to the drains of the TFTs _n and _n via switches (SW), and the source of one of the transistors Tr _nnA is connected to the power supply. being adapted to the voltage _{V DD} is connected to the drain of the other field effect transistor _{Tr NNB,} together with the power supply voltage _{V DD} is connected, the light-emitting element (E) is connected to the source of the transistor _{Tr NNB} It is supposed to be.
[0022]
Further, the gate of each transistor Tr constituting the current mirror circuit is connected to the power supply voltage _VDD via a capacitor (C). In this capacitor (C), TFTs _n and _n operate. when, i.e., when data is written, holds the written charge, in accordance with the held charge (voltage), so as to turn oN the transistor Tr _NNA and the transistor Tr _NNB constitute a current mirror circuit Has become.
[0023]
The switch (SW) connected to the gate of each transistor Tr suppresses the leakage of the electric charge held in the capacitor (C), and is turned ON only during writing scan by external control. ing.
[0024]
In the present embodiment, in the organic EL panel 10, a field-effect transistor (Tr _nA ) 11 is provided at the head of each data electrode line provided, and the transistor (Tr _nA ) 11 provides a data electrode line. To adjust the reference current (i) supplied to.
[0025]
More specifically, the transistor _(Tr nA) 11, together with the n-type transistors are used, the gate of the transistor _(Tr nA) 11 is connected the power supply voltage _{V DD,} a drain, each of the data electrodes source It is designed to connect to a wire.
[0026]
Incidentally, the power supply voltage VDD, along with the power supply voltage VDD supplied to the drain of the transistor Tr ₀ of the data electrode line drive circuit 120 as will be described later, it is connected to an external power supply voltage VDD.
[0027]
In the present embodiment, by _adopting such a configuration, the voltage is supplied to each data electrode line in accordance with the gate voltage applied to the gate of the transistor (Tr _nA ) 11, that is, the power supply voltage _VDD supplied from the outside. The reference current (i) can be adjusted.
[0028]
In addition, for example, the transistor (Tr _nA ) 11 of the present embodiment constitutes an adjusting unit and a switching circuit according to the present invention.
[0029]
As shown in FIGS. 1 and 2, the driving device 100 drives an address scanning electrode line driving circuit 110 that sequentially selects and scans the address scanning electrode lines (B) at regular time intervals, and drives a current source that is a driving source. By doing so, the data electrode line drive circuit 120 for causing the light emitting element (E) at an arbitrary intersection to emit light, the address scan electrode line drive circuit 110, and the light emission control circuit 130 for controlling the data electrode line drive circuit 120 Have.
[0030]
Note that, for example, the address scanning electrode line driving circuit 110 forms a second driving unit according to the present invention, and the data electrode line circuit 120 forms a first driving unit according to the present invention.
[0031]
The address scan electrode line drive circuit 110 sequentially scans each address scan electrode line (B) by controlling the application of a voltage for each address scan electrode. For example, a power supply voltage of a voltage and a ground potential Is switched for each address scanning electrode, thereby sequentially scanning each address scanning electrode line (B).
[0032]
Specifically, the address scan electrode line drive circuit 110 includes scan switches 111 _{1 to} 111 ₆₄ for sequentially scanning the address scan electrode lines (B ₁ ) to (B ₆₄ ). one terminal of _{1-111 64} is connected to the supply voltage, the other terminal, are connected to the ground potential.
[0033]
The data electrode line drive circuit 120 has a drive source for each data electrode scan line (A), and controls supply of a reference current from each drive source for each data electrode scan line (A). ing.
[0034]
Specifically, the data electrode line drive circuit 120 includes current sources 121 _{1 to} 121 ₂₅₆ having the field-effect transistors Tr ₀ and a drive switch 122 for selecting each of the data electrode lines (A ₁ ) to (A ₂₅₆ ). _{1 to} 122 ₂₅₆ , and the drive current sources 121 _{1 to} 121 ₂₅₆ are connected to the data electrode lines (A) by turning on the respective drive switches 122 _{1 to} 122 _256. Has become.
[0035]
The drain of the transistor Tr _0, together with the power supply voltage _{V DD} supplied to the drain of the field effect transistor _(Tr nA) 11 of the organic EL panel 10 described above, is connected to an external power supply voltage _{V DD.}
[0036]
In the present embodiment, by a common and _{V DD} supply thus the transistor Tr ₀ to supply the power supply voltage _{V DD} and the field effect transistor _(Tr nA) 11, the data electrode line drive circuit 120 side If the power supply voltage V _DD is applied to the FET (Tr _nA ), a potential higher than the power supply voltage V _DD is not applied to the data electrode line drive circuit 120, so that low-voltage driving can be performed as described later. ing.
[0037]
The light emission control circuit 130 switches the voltage or supplies the reference current (i) to the address scan electrode line drive circuit 110 and the data electrode line drive circuit 120 for each scanning line based on the input light emission data. It is made to make.
[0038]
Light emitting operation of the pixel is, for example, when the light emission of the light emitting element (E1, ₁₎ is indicated by the light emission control circuit 130, the address scanning electrode line drive circuit 110, for scanning the address scanning electrode line B ₁ the scan switch 111 ₁ to oN, a predetermined voltage is applied to the TFT _{1, 1} a gate adapted to the TFT _{1, 1} to the oN state.
[0039]
On the other hand, the data electrode line drive circuit 120, the light emission of the light-emitting element _{(E1, 1)} is indicated by the light emission control circuit 130, a reference to a drive switch (SW) 122 ₁ a in the ON data electrode lines _{(A 1)} The current (i) is supplied.
[0040]
Therefore, when the reference current (i) is supplied to the data electrode line (A ₁ ), a predetermined power supply voltage V _DD is applied to the transistor (Tr _1A ) 11 in the organic EL panel 10 in advance. A reference current (i) corresponding to the power supply voltage _VDD flows between the drain and the source of the transistor (Tr _1A ) 11, and the adjusted reference current (i) is applied to the data electrode line (A) in the organic EL panel 10. Will be supplied.
[0041]
Also, when a reference current (i) flows between the drain and the source of the transistor (Tr _1A ) 11, a reference current (i) flows between the source and the drain of the TFTs 1 and ₁ , and the TFT ₁ via the transformer mirror circuit. , ₁ is supplied with the reference current (i) to the light emitting element (E), whereby the light emitting element (E) emits light.
[0042]
As described above, according to the present embodiment, for each scanning line of the data electrode line in the display unit, the data electrode line driving circuit 120 that supplies a reference current that is used as a reference when driving each light emitting element; For each scanning line of the electrode line, an address scanning electrode line driving circuit 110 for applying a predetermined voltage, and a reference current supplied by the data electrode line driving circuit 120 based on a power supply voltage input from the outside. And a field effect transistor Tr11 to be adjusted. At least the data electrode line drive circuit 120 is provided on one semiconductor chip, and the transistor Tr11 is provided on a semiconductor chip different from the semiconductor chip on which the data electrode line drive circuit 120 is mounted. It has a configuration.
[0043]
With this configuration, in the present embodiment, since the reference current for driving the light emitting element (E) is adjusted by the field effect transistor, it is not necessary to drive the data electrode line drive circuit with a high voltage, and the low voltage is not required. Since driving can be performed, a semiconductor chip in which the driving device is incorporated can be miniaturized.
[0044]
That is, since the conventional driving device does not include the transistor 11 for adjusting the reference current (i) supplied from the data electrode line driving circuit as described above, the data electrode line driving circuit 120 includes the organic EL element. When driving, a high voltage of at least about 7 V to 8 V is required.
[0045]
Normally, in the case of a 0.35 μ process for manufacturing a semiconductor chip signal line with 0.35 μm, the maximum rated voltage is 3.3 V, and in the case of a 0.25 μ process for manufacturing a semiconductor chip signal line with 0.25 μm. Has a maximum rated voltage of 2.5V.
[0046]
However, in the present embodiment, the reference current (i) is adjusted by a high voltage in the data electrode line drive circuit by configuring the reference electrode (i) with a semiconductor chip different from the semiconductor chip of the data electrode line drive circuit. Even if the reference current (i) is not generated, the generated reference current (i) can be adjusted to the reference current (i) that drives the light emitting element (E) by a field effect transistor provided on a different semiconductor chip. Need not be driven at a high voltage, and the data electrode line drive circuit can be driven at a low voltage.
[0047]
Therefore, when the driving device is mounted on a semiconductor chip or the like, the width of the signal line can be reduced, so that the driving circuit can be miniaturized.
[0048]
A semiconductor chip having a field-effect transistor for adjusting a reference current has a configuration in which a TFT for controlling a light-emitting element and a light-emitting element are provided.
[0049]
With this configuration, in the present embodiment, the TFT and the light emitting element are provided on a semiconductor chip different from the semiconductor chip on which the driving device is mounted, so that the organic EL panel and the driving device can be realized with a small number of semiconductor chips. In the embodiment, a P-type TFT is provided at each intersection of the address scanning electrode line (A) and the data electrode line (B) of the organic EL panel 10. However, instead of the P-type TFT, an N-type TFT is provided. A type TFT may be provided.
[0050]
In this case, since the voltage applied by the address scan electrode line drive circuit 110 does not need to be set to a high voltage (eg, about 5 V), the address scan electrode drive circuit 110 does not need to have a high withstand voltage specification. Thus, the address scan electrode drive circuit 110 can be driven at a low voltage.
[0051]
As a result, when the drive device is mounted on a semiconductor chip or the like, the width of the signal line can be reduced, so that the drive circuit can be miniaturized.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating a schematic configuration of an organic EL panel and a driving device thereof.
FIG. 2 is a diagram showing a configuration of an organic EL panel and a part of a driving device thereof.
[Explanation of symbols]
E: Light-emitting element (organic EL)
10… Organic EL panel (TFT panel)
11: Transistor Tr _nA
100: drive device 110: address scan electrode line drive circuit 120: data electrode line drive circuit

Claims (3)

A plurality of light emitting elements are formed in a matrix, a driving device of a light emitting element to drive a display unit that emits light by scanning the light emitting element,
A first driving unit that supplies a reference current serving as a reference when each of the light emitting elements is driven, for each scanning line in a first scanning direction that is a scanning direction of one of the scanning lines in the display unit;
A second driving unit that applies a predetermined voltage to each scanning line in a second scanning direction that is the other scanning direction in the display unit;
Adjusting means for adjusting each reference current supplied by the first driving means based on the input voltage input from the outside;
With
A driving device for a light emitting element, wherein at least the first driving means is provided on one semiconductor chip, and the adjusting means is provided on a semiconductor chip different from the one semiconductor chip. The driving device for a light emitting device according to claim 1,
The adjusting means comprises a switching circuit for adjusting a reference current supplied to each scanning line by the first driving means based on the input voltage inputted from the outside for each scanning line in the first scanning direction. A driving device for a light-emitting element, characterized in that: The light-emitting element driving device according to claim 1 or 2,
A driving device for a light-emitting element, wherein a display unit that scans the light-emitting element and emits light is provided on a semiconductor chip having the adjusting unit.

Images