JP2004094232A - Driving circuit of active matrix organic el (electroluminescent) panel and organic el display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL (electroluminescent) driving circuit of an active matrix organic EL panel in which a mounting area of a driver for the active matrix organic EL panel is reduced and brightness of an organic EL display element is improved and to provide an organic EL display device. <P>SOLUTION: This organic EL display device is provided with a driving current generation circuit which generates driving current corresponding to each of R, G, B in a prescribed order on receiving an RGB switching signal and a current switching circuit having first, second and third output terminals, which selects one of the first, second and third output terminals in a prescribed order according to the RGB switching signal on receiving the driving current and the RGB switching current, generates current for charging capacitors of pixel circuits of each of R, G, B according to the driving circuit and outputs the current to the output terminals. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a drive circuit for an active matrix type organic EL panel and an organic EL display device, and more particularly, it is possible to reduce a mounting area of a driver for an active matrix type organic EL panel in a device such as a cellular phone, a PHS, and the like. The present invention relates to an active matrix type organic EL display device suitable for high luminance color display capable of improving luminance.

The organic EL display device is capable of high-luminance display by self-emission, so it is suitable for small-screen display, and is a next-generation display device mounted on a mobile phone, a PHS, a DVD player, a PDA (portable terminal device), and the like. It is currently attracting attention. In this organic EL display device, when voltage driving is performed as in a liquid crystal display device, control is performed because luminance variation increases and there is a sensitivity difference between R (red), G (green), and B (blue). There is a problem that becomes difficult.
Therefore, recently, an organic EL display device using a current-driven driver has been proposed. For example, Japanese Patent Application Laid-Open No. H10-112391 discloses a technique for solving the problem of luminance variation by current driving.

As an organic EL display panel of an organic EL display device for mobile phones and PHSs, an organic EL display panel having 396 (132 × 3) terminal pins and 162 terminal pins as row lines has been proposed. , The terminal pins of the low line tend to increase more than this.
The output stage of the current drive circuit of such an organic EL display panel is provided with a drive circuit of a current source, for example, an output circuit of a current mirror circuit, corresponding to the terminal pin, whether of an active matrix type or a simple matrix type.

In the active matrix type, a pixel circuit including a capacitor and a current-driven transistor is provided for a display cell (pixel). The transistor is driven according to the voltage stored in the capacitor, and the organic EL element is connected via the transistor. (Hereinafter referred to as an OEL element) is driven by current. The driving method includes digital driving for controlling the OEL element with binary values of ON / OFF and analog driving for controlling the driving current of the OEL element with analog input data. In the case of digital driving, a display area is controlled by providing a sub-pixel in a pixel, or a light-emitting time is time-divided to control a gradation of a display pixel based on a difference in driving time. In the case of analog driving, there are a voltage designation type (voltage program method) and a current designation type (current program method). In the case of the voltage designation type, the terminal voltage of the capacitor of each pixel circuit is set by a voltage signal, In the case of the current designation type, the terminal voltage of the capacitor is set by a current signal.
Meanwhile, a driving circuit of an EL element which drives currents of EL elements arranged in a matrix and resets the EL element by dropping its anode and cathode to the ground is known as Patent Document 1. Further, a technique for driving an EL element with low power consumption by using a DC-DC converter is known as Patent Document 2.

JP-A-9-232074 JP 2001-143867 A

By the way, a current drive circuit of a simple matrix type organic EL display panel uses a drive current having a peak current in order to initially charge an OEL element having a characteristic of a capacitive load to emit light early and to suppress luminance unevenness. Can be In this regard, in the active matrix type, a voltage value corresponding to a drive current value is once written and stored in a capacitor of a pixel circuit, and then a drive current value corresponding to the stored voltage value is generated. Therefore, the active matrix type OEL element is not driven by the peak current. The OEL element is driven in the order of writing the drive current value and emitting light, and the writing period is required before the light emitting period. As a result, the active matrix type does not allow the OEL element to emit light as early as the simple matrix type, and has a disadvantage that the light emission period is shorter than that of the simple matrix type.
The writing of the driving current value is usually performed by charging the capacitor of the pixel circuit of several hundred pF with a current of about 0.1 μA to 10 μA. Therefore, the writing time to the capacitor of the pixel circuit is 10% of the entire scanning period. It accounts for a relatively large proportion of the order of magnitude or more. As a result, the light emission period is shortened and the luminance is reduced. In particular, when the number of display pixels becomes high, for example, VGA, SVGA, XGA, etc., the above-mentioned drawbacks are caused by the need to perform timing control within a limited time in a circuit of the current programming system. It becomes a problem.

Further, in the case where an active matrix type OEL element is driven by a drive circuit provided outside the organic EL display panel, a high luminance color display and a high density such as VGA, SVGA, XGA, etc. Since a large number of drive circuits are provided in the periphery of the organic EL display panel corresponding to G and B, there is a disadvantage that the mounting area of the driver becomes large.
In order to reduce the mounting area of the driver, in a liquid crystal display device or the like, one driving circuit is provided corresponding to three pixels of R, G, and B, and the R, G, and B pixel circuits are provided in a time-division manner. There is something to drive. In this method, one of the three pixels of R, G, and B is selected and driven by voltage through time-division driving via an analog switch (transmission gate). Even if this analog switch method is applied to current driving of an active matrix type OEL element, there is a problem that a voltage drop in the analog switch becomes large and a highly accurate drive current cannot be generated.
SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem of the related art, and it is possible to reduce a mounting area of a driver for an active matrix type organic EL panel and to improve a luminance of an OEL element. An object of the present invention is to provide a drive circuit of an active matrix type organic EL panel suitable for luminance color display and an organic EL display device.

A feature of the drive circuit of the active matrix type organic EL panel and the organic EL display device of the present invention for achieving the above object is that a drive current corresponding to each of R, G, and B is determined by receiving an RGB switching signal. And a first, second, and third output terminals having the first, second, and third output terminals, receiving the drive current and the RGB switching signal, and receiving the driving current and the RGB switching signal in a predetermined order according to the RGB switching signal. 2. A current switching circuit for selecting one of the third output terminals, generating a current for charging the capacitors of the R, G, and B pixel circuits in accordance with the drive current and outputting the current to the output terminal Is provided.

As described above, according to the present invention, the current switching circuit receives the drive current from one drive current generation circuit and stores the drive current value in the R, G, and B pixel circuits for charging the capacitors with the RGB. Since the current is generated in a time-sharing manner in accordance with the switching signal, the current driving circuit can be substantially reduced to one third. Moreover, since the charging current is generated by the current switching circuit, a voltage drop such as that of an analog switch (transmission gate) does not need to occur, and a charging current having a high current value can be generated.
Further, the drive current values of R, G, and B can be sequentially and continuously written without taking the order of writing the drive current values and emitting light individually for R, G, and B. Can be overlapped, and the emission driving period of the R, G, B OEL elements can be lengthened. In addition, it is possible to write R, G, and B collectively at a high speed, and it is possible to shorten the total write time of R, G, and B. Accordingly, the light emission period can be lengthened.
As a result, the present invention can realize a drive circuit and an organic EL display device for an active matrix type organic EL panel that can reduce the mounting area of the driver for the organic EL panel and improve the luminance of the OEL element.

FIG. 1 is a block diagram of an embodiment to which an active matrix type organic EL display device of the present invention is applied, and FIG. 2 is an explanatory diagram of driving timings of R, G, and B in an RGB current switching output circuit. FIG. 3 is an explanatory diagram of a drive timing in which writing of R, G, and B drive current values in an R, G, and B current switching output circuit is performed twice for one line of horizontal scanning, and FIG. FIG. 4 is an explanatory diagram of a switching circuit that implements the drive timing in FIG. 3.
In FIG. 1, reference numeral 1 denotes an organic EL panel of an active matrix type organic EL display device, which includes a data electrode driver 2, an R, G, and B switching control circuit 3, a pixel circuit 4, a control circuit 5, and a low-side scan. It comprises a circuit 6, an MPU 7, and the like.
Although a large number of pixel circuits 4 are provided corresponding to the respective intersections of the X and Y matrix wirings, one R, G, and B is assumed to be one of pixel circuits 4G1, 4R1, and 4B1 in FIG. The internal circuit is shown. The pixel circuits 4G2, 4R2, 4B2,... Are pixel circuits following the pixel circuits 4G1, 4R1, 4B1 forming horizontal lines, but the internal circuits are the same, and are omitted.
Hereinafter, the pixel circuits 4G1, 4R1, and 4B1 will be mainly described. However, horizontal pixel circuits are provided corresponding to the R, G, and B horizontal display pixels, respectively.

XG1, XR1, XB1,... Are part of data lines (or lines connected to respective column pins, hereinafter the same) provided for display pixels in the horizontal direction (column direction) of R, G, and B, respectively. XG1, XR1, and XB1 are data lines connected to the respective pixel circuits 4G1, 4R1, and 4B1. The data lines XG1, XR1, and XB1 are commonly connected to a number of pixel circuits arranged in the vertical direction (row direction) in addition to the respective pixel circuits 4G1, 4R1, and 4B1. In addition, 4a is an OEL element provided in each pixel circuit.
The data electrode driver 2 includes R, G, and B current drive circuits 10-1, 10-2,... Are the column drivers (drivers in the horizontal scanning direction) of a so-called organic EL driving circuit, and each of the R, G, and B current driving circuits 10-1, 10-2,... Are provided in common for each of three pixels consisting of one pixel in the horizontal direction of R, G, and B. Therefore, the number of R, G, and B current drive circuits 10-1, 10-2,... Is 1/3 of the total number of data lines obtained by adding R, G, and B, and each has the same configuration. In other words, one pixel is provided in common for each pixel of R, G, and B, and a number corresponding to the number of pixels in the horizontal scanning direction of each of R, G, and B is provided.

The relationship between the pixel circuits 4G1, 4R1, 4B1 and the RGB current driving circuit 10-1 will be described below as representatives of the pixel circuit and the RGB current driving circuit. Each of the pixel circuits 4G1, 4R1, and 4B1 includes a driving P-channel MOS transistor Tr whose source and drain are connected between the anode side of the OEL element 4a and the power supply line + Vcc, and a gate and a source ( And a capacitor C connected between the power supply line + Vcc) and storing a drive current value as a voltage value. The gate of the transistor Tr of each of the pixel circuits 4G1, 4R1, and 4B1 has data corresponding to R, G, and B, respectively. They are connected to lines XG1, XR1, and XB1, respectively.
The data lines XG1, XR1, and XB1 are connected to input terminals IG1, IR1, and IB1, and the input terminals IG1, IR1, and IB1 are output terminals OG1 of G, R, and B of the R, G, and B current switching output circuit 11. , OR1, OB1.

The cathode side of the OEL element 4a for one horizontal line is commonly connected to the switch circuit 6a of the low-side scanning circuit 6 via the low-side line 8. After the drive current value is written to the capacitor C of each pixel circuit for one line in the horizontal direction, the low side scanning circuit 6 switches the switch circuit 6a to which the cathode side of the OEL element 4a for one line in the horizontal scanning direction is connected. Turn ON. As a result, the OEL elements 4a for one line in the horizontal scanning direction are simultaneously driven with a current value determined by the voltage value written to each capacitor C.
A large number of switch circuits 6a are provided corresponding to the number of vertical scanning lines in the low-side scanning circuit 6, and the switch circuits 6a connected to the preceding low-side line are turned off in response to the vertical scanning, and the current scanning is performed. When the switch circuit 6a connected to the target low-side line is turned on, the switch circuit 6a is sequentially turned on / off in response to low-side scanning (vertical scanning).

The R, G, and B current drive circuit 10-1 includes an R, G, and B current switching output circuit 11 and a drive current generation circuit 12. The R, G, and B current switching output circuit 11 includes an input stage current mirror circuit 11a including P-channel MOS transistors Tr1, Tr2, Tr3, and Tr4, and an output stage current switching circuit 11g, 11r, 11b.
The transistor Tr1 of the current mirror circuit 11a is an input-side transistor, and the transistors Tr2, Tr3, and Tr4 are output-side transistors provided corresponding to R, G, and B. The sources of these transistors are connected to the power supply line + Vcc, and the drain of the input transistor Tr1 receives the drive current from the drive current generation circuit 12 via the input terminal IN of the RGB current switching output circuit 11. Driven. The current mirror circuit 11a generates a mirror current equal to the drive current at the drains of the output transistors Tr2, Tr3, and Tr4, and provides a corresponding current switching circuit provided for R, G, and B. 11g, 11r, and 11b.

Each of the current switching circuits 11g, 11r, and 11b has the same configuration, and includes a current mirror output circuit including N-channel MOS transistors Tr5 and Tr6, and a transistor Tr7 provided in parallel with the input-side transistor Tr5. The sources of the transistors Tr5 to Tr7 are grounded. The gate width ratio between the transistor Tr5 and the transistor Tr6 is N: 1 (where N is a positive number of 2 or more), and the output current to each of the output terminals OG1, OR1, and OB1 of R, G, and B is Here, 1 / N is set. As a result, noise is reduced, and a highly accurate output current can be generated. In this current switching circuit, the drains of the input side transistors Tr5 and Tr7 are commonly connected, and both transistors receive a drive current. When the transistor Tr7 is turned on, the input-side transistor Tr5 is turned off, and the drive current flowing through the input-side transistor Tr5 is switched to the transistor Tr7. When the transistor Tr7 is turned off, the transistor Tr5 is turned on, and the reverse current switching is performed. Is

In the current switching circuit 11g, a commonly connected drain of the transistors Tr5 and Tr7 is connected to a drain of the transistor Tr2 of the current mirror circuit 11a, and receives a driving current from the transistor Tr2. The drain of the transistor Tr6 of the current switching circuit 11g is connected to the output terminal OG1, and a charging current (sinking current) is input to the input terminal IN of the capacitor C of the pixel circuit 4G1 corresponding to the terminal OG1. Output according to the drive current at that time.
Similarly, in the current switching circuit 11r, the commonly connected drains of the transistors Tr5 and Tr7 are connected to the drain of the transistor Tr3 of the current mirror circuit 11a, and receive the driving current from the transistor Tr3. The drain of the transistor Tr6 of the current switching circuit 11r is connected to the output terminal OR1, and the charging current (sinking current) to the capacitor C of the pixel circuit 4R1 corresponding to R is input to the input terminal IN. It outputs according to the drive current at that time.
Further, in the current switching circuit 11b, the commonly connected drains of the transistors Tr5 and Tr7 are connected to the drain of the transistor Tr4 of the current mirror circuit 11a, and receive the driving current from the transistor Tr4. The drain of the transistor Tr6 of the current switching circuit 11b is connected to the output terminal OB1, and a charging current (sinking current) is input to the input terminal IN of the capacitor C of the pixel circuit 4B1 corresponding to B at the terminal OB1. Output according to the drive current at that time.

The transistor Tr7 of each of the current switching circuits 11g, 11r, and 11b has a switching control signal Sg, Sr, and Sb from the R, G, and B switching control circuit 3 at the gate, respectively, and inverters 3g, 3r, 3b, control lines 13g, 13r, Received via 13b. In each of the current switching circuits 11g, 11r and 11b, when the switching control signals Sg, Sr and Sbr are at the high level (hereinafter "H"), "L" is applied to the gate of the transistor Tr7 by the inverter, so that the transistor Tr7 is turned off. , Low level (hereinafter "L"), "H" is applied to the gate of the transistor Tr7, so that the transistor Tr7 is turned on.
Then, when the switching control signals Sg, Sr, Sb are "L", the transistors Tr7 are turned on and the current switching circuits 11g, 11r, 11b turn on the input side of the current mirror output circuits of the current switching circuits 11g, 11r, 11b. The current flowing through the transistor Tr5 is switched to the transistor Tr7 so that no current flows through the transistor Tr5, and no output current is generated in the output transistor Tr6 that is connected to the transistor Tr5 by a current mirror. Conversely, when the switching control signals Sg, Sr, Sb are at "H", the transistor Tr7 is turned off and the output transistor Tr6 outputs a charging current.

As shown in FIG. 2, the switching control signals Sg, Sr, and Sb are control signals that become “H” in a predetermined order according to the driving timings of R, G, and B. Here, G, R, and B are used.
In the order of “H” for a certain period. When the switching control signals Sg, Sr, Sb attain "H", respectively, the output currents appear in the output transistors Tr6 of the current switching circuits 11g, 11r, 11b. Output at the specified output terminal. This output current is a charging current for the capacitor C of each of the R, G, and B pixel circuits.
Here, the switching control signals Sg, Sr, and Sb are, respectively, a G pixel circuit and a R pixel that constitute one horizontal display pixel arranged in the horizontal scanning direction via the control lines 13g, 13r, and 13b. Since the current is supplied to the pixel circuit B and the pixel circuit B, the writing of the drive current value to the capacitor C of the pixel circuits R, G, and B is performed simultaneously for one horizontal line. The RGB switching control circuit 3 is controlled by the control circuit 5 and generates switching control signals Sg, Sr, Sb.

The output currents of the current switching circuits 11g, 11r, 11b are determined by the driving current input from the driving current generation circuit 12 to the input terminal IN of the RGB current switching output circuit 11. The drive current generation circuit 12 includes a D / A conversion circuit 12a, a reference current generation circuit 12b, a display data register 12c, and a data selection circuit 12d.
The D / A conversion circuit 12a is driven by receiving the reference current Iref from the reference current generation circuit 12b, receives display data from the display data register 12c, and generates a drive current corresponding to the display data value based on the reference current Iref. . The generated drive current is input to the input terminal IN.
The display data register 12c has storage areas DR, DG, and DB corresponding to R, G, and B, respectively, and stores the switching control signals Sg, Sr, and Sb in the inverters 3g, 3r, and 3b. It is selected by the data selection circuit 12d received through it. When any of the switching control signals Sg, Sr, Sb is "H", the data selection circuit 12d selects one of R, G, B data corresponding to the "H" control signal, and / A conversion circuit 12a.

Therefore, the drive current generation circuit 12 adjusts the timing of the switching control signal Sg, Sr, or Sb to R when the input signal to the data selection circuit 12d becomes L. , G, and B display data, and the D / A conversion circuit 12a generates drive currents corresponding to the R, G, and B display data in accordance with respective timings, and generates the generated drive currents by R · G. -Input to the input terminal IN of the B current switching output circuit 11. As a result, the output terminals OG1, OR1, OB1 of R, G, B are supplied with R, G in accordance with the drive timing of R, G, B in which one of the switching control signals Sg, Sr, Sb becomes "H". , B, respectively.
When the switching control signals Sg, Sr, Sb are all "L", the input value of the D / A conversion circuit 12a is "0", and the drive current value generated by the D / A conversion circuit 12a is "0". It becomes. As a result, the currents generated in the current switching circuits 11g, 11r, 11b also become "0", and wasteful power consumption does not substantially occur.

FIG. 2 is an explanatory diagram of R, G, and B drive timings in the R, G, and B current switching output circuit.
The switching control signals Sg, Sr, and Sb become "H" during the writing period T to the capacitor C in the order of G, R, and B at the timings shown in FIGS. 2A, 2B, and 2C. Become. .., G, R, and B, the charge switching currents are simultaneously generated by the number of pixels in the horizontal direction in a time-division manner from the current switching circuits 11g, 11r, 11b,. The driving current value is stored as a voltage value in each capacitor C of. Next, in the display period D, the low-side switch circuit 6a to be scanned is turned ON, and the R, G, and B OEL elements 4a for one horizontal line as shown in FIG. , And the G, R, and B OEL elements 4a for one horizontal line of the pixel circuits 4G1, 4R1, 4B1, 4G2, 4R2, 4B2,. Before the writing period T, there is a line switching period for low-side scanning (shaded area).

In this manner, the drive current value is stored in each capacitor C in one horizontal line portion of R, G, and B for one horizontal scan in a time-division manner, so that the pixel circuit 4 Is separated from the drive current value writing period T and the light emission period D provided in the capacitor C, the drive current value can be stored in the capacitor C at high speed. Note that, here, the writing period of each drive current value of G, R, and B is T / 3, but these periods of G, R, and B need not be equal.
In this embodiment, the time-division writing control is performed on the writing of the driving current value in this manner. Specifically, the current driving circuit of the pixel circuit for R, G, and B corresponding to the display pixel is time-divisionally controlled. By performing the switching operation, the current drive circuit can be substantially reduced to 1/3, and the mounting area of the driver for the organic EL panel of the current drive circuit can be reduced.

The present invention is not limited to the case where the drive current value is stored in each of the capacitors C of R, G, and B of the pixel circuit in a time-division manner. The driving current value may be sequentially written for each of the pixel circuits, stored as a voltage value, and the R, G, and B pixels may emit light simultaneously. Even in such a case, according to the present invention, the writing of R, G, and B can be performed sequentially and continuously in units of display pixels, so that the light emission periods of R, G, and B can be lengthened collectively in units of pixels. . Further, since writing of the drive current values of R, G, and B can be performed continuously, the writing period is shorter and faster than in the case where the writing periods are individually provided for R, G, and B, respectively. This also makes it possible to extend the light emission period.
Further, in the embodiment, the drive current value is stored in each of the capacitors C of R, G, and B for one horizontal scanning line in a time-sharing manner. The drive current value may be sequentially written to the capacitor C of the pixel circuit in a time-division manner, and thereafter, control may be performed such that one screen of each of R, G, and B is simultaneously emitted.
FIG. 2E shows a driving example in which the writing period is n times as large as that in such a case.
Assuming that the total number of pixel circuits for one screen including R, G, and B is n, writing of n capacitors C and light emission of n OEL elements are separated. As a result, as shown in FIG. 2E, the writing period T becomes n × T, and the light emitting period D becomes n × D.

FIG. 3 shows an example of drive timing in which writing of R, G, and B drive current values in the R, G, and B current switching output circuit is performed twice for one horizontal scanning line.
In this embodiment, the horizontal scanning line is divided into two parts before and after, and the driving current value is written to the capacitors C of the R, G, and B pixel circuits in the first half of the horizontal scanning line in the first half of the writing period T. Do with. Then, writing of the drive current value to the capacitor C of the pixel circuit of R, G, B in the latter half of the horizontal scanning line is performed in the latter half of the writing period T. FIG. 4 shows a switching circuit for that purpose.

In FIG. 4, each changeover switch of the changeover circuit 9 is provided corresponding to each output terminal. Output terminals OG1 to OBi correspond to the output terminals of the first half of one horizontal line, and output terminal OGi + 1. OBn correspond to the output terminals of the latter half of one horizontal line. As shown in FIG. 3 (e), during the period of the pulse P which is "L" in the first half of the writing period T, as shown, the switches of the output terminals OG1 to OBi are ON. , Output terminals OG1-OBi are connected to input terminals IG1-IOBi, respectively. At this time, the switches of the output terminals OGi + 1 to OBn in the latter half are OFF, and the output terminals OGi + 1 to OBn are not connected to the input terminals IGi + 1 to IBn. In the latter half of the writing period T, the pulse P becomes "H", and in this period, the ON / OFF of the switch is reversed, the output terminals OGi + 1 to OBn are connected to the input terminals IGi + 1 to IBn, and the output terminal OG1-OBi are not connected to the input terminals IG1-IOBi.

In this embodiment, the switching circuit 9 shown in FIG. 4 is added to FIG. A switching circuit 9 shown in FIG. 4 is provided between output terminals OG1, OR1, OB1... Of R, G, B and input terminals IG1, IR1, IB1. The switching circuit 9 connects each output terminal of the first half of the horizontal one line to the capacitor C of each of the pixel circuits of R, G and B of the first half of the horizontal one line at the first half timing of the writing period T, At the timing of the latter half of the writing period T, the output terminals of the latter half of the horizontal one line are connected to the capacitors C of the R, G, B pixel circuits of the latter half of the horizontal one line. The switching circuit 9 receives the pulse P rising at the latter half of the writing period T from the RGB switching control circuit 3 as shown in FIG.
On the other hand, as shown in FIGS. 3A, 3B, and 3C, the switching control signals Sg, Sr, and Sb each have a period T / 2 and a pulse width T / 6 of “H”. A pulse is generated twice during the writing period T.
As a result, as shown in FIG. 3D, the light emission drive is performed after the drive current value is written to the R, G, and B OEL elements 4a for one horizontal line, as shown in FIG. The G, R, B OEL elements 4a for one horizontal line of the pixel circuits 4G1, 4R1, 4B1, 4G2, 4R2, 4B2,.
In FIG. 4, writing is performed twice in the writing period T separately for the first half output terminal and the second half output terminal to be subjected to horizontal scanning. May be divided into m (m is an integer of 2 or more), and writing may be performed m times in the writing period T.

As described above, the current switching circuit according to the embodiment has an N-channel input-side transistor Tr5 and an N-channel transistor Tr7 whose drains are connected in common and both of these transistors receive a drive current. The present invention is not limited to such a current switching circuit. For example, current switching may be performed by coupling sources of P-channel transistors. Further, a bipolar transistor may be used. The present invention may be any switching circuit that performs a current switching operation according to ON / OFF of a transistor or a diode.
Further, the current switching circuits 11g, 11r, and 11b of the embodiment are provided outside the pixel circuit of the organic EL panel 1, but may be integrated in the organic EL panel similarly to the pixel circuit.
In the embodiment, the MOSFET transistor is mainly used, but it is needless to say that a bipolar transistor may be mainly used. Further, the N-channel transistor (or npn type) of the embodiment can be replaced with a P-channel (or pnp) transistor, and the P-channel transistor can be replaced with an N-channel (or npn) transistor. In this case, the power supply voltage becomes negative, and the transistor provided upstream is provided downstream.

FIG. 1 is a block diagram of an embodiment to which an active matrix type organic EL display device of the present invention is applied. FIG. 2 is an explanatory diagram of R, G, and B drive timings in the R, G, and B current switching output circuit. FIG. 3 is an explanatory diagram of the drive timing for writing the R, G, and B drive current values twice for one horizontal scanning line in the R, G, and B current switching output circuit. FIG. 4 is an explanatory diagram of a switching circuit that implements the drive timing in FIG.

Explanation of reference numerals

1: Organic EL panel,
2 ... data electrode driver, 3 ... RGB switching control circuit,
4,4G1,4R1,4B1 ... pixel circuit,
4a: organic EL element, 4b: inverter,
5 ... Control circuit,
6. Low side scanning circuit,
7 MPU, 9 switching circuit,
10, 10a-1 ... RGB current drive circuit,
11 ... RGB output switching circuit
11g, 11r, 11b ... current switching output circuit,
12 ... Drive current generation circuit,
12a ... D / A conversion circuit,
12b: Reference current generating circuit,
12c: display data register,
12d: data selection circuit,
C… Capacitor,
Tr1 to Tr7: transistors.

Claims (15)

A pixel circuit including an organic EL element, a capacitor storing a voltage value corresponding to a current value of a drive current of the organic EL element, and a transistor for outputting the drive current to the organic EL element according to the voltage value is provided. In an active matrix type organic EL panel driving circuit for driving an active matrix type organic EL panel provided corresponding to each of R, G, B display colors,
A drive current generating circuit that receives a RGB switching signal and generates a drive current corresponding to each of the R, G, and B in a predetermined order;
The first, second, and third output terminals having first, second, and third output terminals and receiving the drive current and the RGB switching signal in the predetermined order in response to the RGB switching signal. And a current switching circuit for generating a current for charging the capacitors of the R, G, and B pixel circuits in accordance with the drive current and outputting the current to the output terminal. Drive circuit for active matrix type organic EL panel. The current switching circuit includes first, second, and third current switching circuits provided corresponding to the R, G, and B respectively receiving the driving currents corresponding to the R, G, and B, respectively. The RGB switching signal comprises first, second, and third control signals generated in the predetermined order, and the first current switching circuit receives the first control signal and performs current switching. Operates and outputs a current corresponding to the drive current received from the drive current generation circuit to the first output terminal as the charging current, and the second current switching circuit outputs the second control signal Receiving a current switching operation and outputting a current corresponding to the driving current received from the driving current generation circuit to the second output terminal as the charging current; The current switching operation is performed in response to the control signal of Driving circuit of an active matrix type organic EL panel according to claim 1, wherein for outputting a current corresponding to the driving current received from the flow generator as the charging current to the third output terminal. 3. The drive circuit of an active matrix type organic EL panel according to claim 2, wherein the RGB switching signal is generated during a writing period for storing the voltage value in the capacitor. The current for charging the capacitor is a current drawn from the pixel circuit to the selected output terminal, and a driving circuit including the driving current generating circuit and the current switching circuit is configured to drive each of the R, G, and B circuits. 4. The drive circuit for an active matrix type organic EL panel according to claim 3, wherein one drive circuit is provided in common with one pixel, the number corresponding to the number of pixels in the horizontal scanning direction of R, G and B. The drive current generation circuit includes a register for storing data for generating the drive current corresponding to the R, G, and B, and the register stores the data in accordance with the first, second, and third control signals. A D / A conversion circuit for receiving the respective data corresponding to the R, G, and B, and D / A converting the received data to generate the drive current in the predetermined order; 4. The drive circuit for an active matrix type organic EL panel according to claim 3, wherein the second and third current switching circuits are respectively connected to the pixel circuits via data electrodes. The first, second, and third current switching circuits each include a first current mirror circuit and a first transistor provided in parallel with an input-side transistor of the first current mirror. The drive current sent from the / A conversion circuit is received by the input side transistor and the first transistor, and between the input side transistor and the first transistor according to ON / OFF of the first transistor. 6. The drive circuit for an active matrix type organic EL panel according to claim 5, wherein the current is switched by: The data selection circuit further includes a data selection circuit that selects each data corresponding to the R, G, and B from the register according to the first, second, and third control signals, and The first, second, and third current switching circuits receive the first, second, and third control signals, and turn the first transistor on or off, respectively. The driving circuit for an active matrix type organic EL panel according to claim 6. The current switching circuit further includes a second current mirror circuit having output transistors corresponding to the R, G, and B with respect to the input-side transistor, respectively. Receiving the drive current from the D / A conversion circuit and applying the drive current to each of the first current mirror circuits of the first, second, and third current switching circuits via the respective output transistors. 8. The driving circuit for an active matrix type organic EL panel according to claim 7, which sends out. 7. A switching control circuit for generating the first, second, and third control signals, and a current for charging the capacitor is generated simultaneously for the number of pixels in the horizontal scanning direction. Active matrix type organic EL panel drive circuit. 7. The active matrix type organic EL panel according to claim 6, further comprising: dividing the entirety of the plurality of output terminals to be subjected to horizontal scanning into m (m is an integer of 2 or more) and writing m times in the writing period. Drive circuit. The current switching circuit connects one of the R, G, and B drive currents and one of the first, second, and third output terminals in a predetermined order in response to the RGB switching signal. And selecting a current in order to charge the capacitors of the pixel circuits of the R, G, and B in accordance with the drive current, and outputting the generated current to the selected output terminal. 2. A drive circuit for an active matrix type organic EL panel according to item 1. The current switching circuit includes first, second, and third current switching circuits provided corresponding to the R, G, and B respectively receiving the driving currents corresponding to the R, G, and B, respectively. The RGB switching signal comprises first, second, and third control signals generated in the predetermined order, and the first current switching circuit receives the first control signal and performs current switching. Operates and outputs a current corresponding to the drive current received from the drive current generation circuit to the first output terminal as the charging current, and the second current switching circuit outputs the second control signal Receiving a current switching operation and outputting a current corresponding to the driving current received from the driving current generation circuit to the second output terminal as the charging current; The current switching operation is performed in response to the control signal of Driving circuit of an active matrix type organic EL panel according to claim 11, wherein outputting a current corresponding to the driving current received from the flow generator as the charging current to the third output terminal. 13. The drive circuit of an active matrix type organic EL panel according to claim 12, wherein the RGB switching signal is generated during a writing period for storing the voltage value in the capacitor. An organic EL display device having a drive circuit for an active matrix type organic EL panel according to any one of claims 1 to 13. 15. The organic EL display device according to claim 14, further comprising the organic EL panel and a controller, wherein the controller controls the switching signal generation circuit.

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