JP2004126139A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a hold type display device which resolves the occurrence of blur of moving images to display images of high quality by the same sort of driving as the conventional method. <P>SOLUTION: A relatively high resistor 180 is connected in parallel to a data holding capacitance 170, and electric charge corresponding to image data held in the data holding capacitance 170 by the CR time constant of the capacity value of the data holding capacitance 170 and the resistance value of the resistor 180 is discharged within a period shorter than one frame period, and thereby, black is inserted before the next frame and a hold type display element is made closer to an impulse type element and is driven. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a display device, and more particularly to a display device capable of displaying a high-quality moving image by eliminating moving image blur.
[0002]
[Prior art]
In recent years, with the advent of the advanced information society, the demand for personal computers, car navigation systems, portable information terminals, information communication devices, or composite products thereof has been increasing. As a display means for these products, a thin, lightweight, low power consumption display device is suitable, and a liquid crystal display device or an image display device using a self-luminous electro-optical element such as a light emitting diode is used. . Also, a plasma display device has been put to practical use as a self-luminous image display device.
[0003]
A display device using a self-luminous electro-optical element has features such as good visibility, a wide viewing angle characteristic, and high-speed response, which is suitable for displaying moving images. It is considered. Particularly, in recent years, image display devices using an organic EL display device using an organic substance as a light-emitting layer are expected to be put to practical use due to the rapid improvement in luminous efficiency and the development of network technology that enables video communication. BACKGROUND ART An organic electroluminescence (organic EL) light emitting device (OLED) has a diode structure in which an organic light emitting layer (organic EL layer) is sandwiched between two electrodes. In a display device configured using such an organic EL light emitting element, active drive using a switching element such as a thin film transistor (hereinafter, also referred to as a TFT) for pixel selection is often adopted.
[0004]
The display device using the organic EL performs a display by a so-called hold type light emitting mechanism like the liquid crystal display device, and the impulse type light emission characteristics (response characteristics) of the cathode ray tube (CRT) shown in FIG. Therefore, when a moving image is displayed, for example, blurring (moving image blurring) due to blurred outlines occurs, resulting in image quality deterioration.
[0005]
For example, Non-Patent Documents 1 and 2 disclose methods for evaluating the image quality of a moving image in a hold-type display device.
[0006]
A switching thin film transistor for inputting a blanking signal to a gate terminal in parallel with a storage capacitor for providing a gate voltage of the organic EL driving thin film transistor; Patent Document 1 discloses that a blanking signal is turned on in a predetermined period immediately before the start of the next one frame period to blank the light emission of the organic EL element.
[0007]
Regarding the liquid crystal display device, Non-Patent Document 3 discloses a blink backlight system in which a backlight lamp (cold cathode fluorescent lamp, CFL) is intermittently turned on in synchronization with a vertical synchronization signal Vsync.
[0008]
Patent Literature 2 describes that a moving image display performance is improved by separately providing a period in which a gradation voltage corresponding to a video signal is applied to a liquid crystal panel and a period in which a black gradation voltage is applied to a liquid crystal panel. Have been.
[0009]
Patent Document 3 discloses that only writing of display data to a liquid crystal pixel (display data writing operation) is performed and a backlight is kept off in a period of ２ of a one-field period, and then a one-field period In the remaining 1/3 of the time, the display data written with the backlight turned on is displayed (panel emission display operation), and this operation is repeated for each field.
[0010]
Patent Literature 4 discloses that a liquid crystal display device using a thin film transistor for selecting a pixel has a structure in which a high resistance is generated between electrodes of a storage capacitor used for holding a gray scale voltage, so that a data line can be connected. The charge accumulated in the liquid crystal pixel capacitance (liquid crystal capacitance) and the storage capacitance via the drain and source of the thin film transistor is gated by the CR time constant determined by the liquid crystal pixel capacitance and the auxiliary storage capacitance C and the resistance R between the storage capacitances. By discharging the charge to the side or the storage capacitor line side, the image data is brought closer to the impulse type such as CRT from the hold type where the data is constant during one frame period, and black is automatically generated between frames. It is inserted.
[0011]
[Patent Document 1]
JP 2000-221942 A
[0012]
[Patent Document 2]
JP-A-11-109921
[0013]
[Patent Document 3]
JP 2000-293142 A
[0014]
[Patent Document 4]
JP-A-2002-14372
[0015]
[Non-patent document 1]
IEICE Technical Report, EID96-4, pp. 19-26, “Study on Moving Picture Quality of Hold-Emission Display Using 8x CRT”
[0016]
[Non-patent document 2]
Published by the Institute of Electrical Engineers of Japan, “Research Papers of the Institute of Electrical Engineers of Japan”, EDD-00-48, pp. 135-139, “Evaluation Method of Moving Image Quality on Hold-Type Display”
[0017]
[Non-Patent Document 3]
SID DIGEST 35.2, pp 990-993 "Super-TFT-LCD for Moving Picture Images with the Link Backlight System"
[0018]
[Problems to be solved by the invention]
In the hold-type display devices described in Non-Patent Documents 1 and 2, since the display data is held for one frame period, the above-described image quality degradation occurs when displaying a moving image. In the blink backlight system of Non-Patent Document 3, the transient response time of the rise of luminance when the CFL is turned on and the transient response time of the fall of the luminance when the CFL is turned off are long, and the transition of the transmittance of the liquid crystal is long. When the response period overlaps with the transient response period of the rising or falling edge of the CFL, light emission with low luminance occurs once, and then light emission with high luminance occurs. When a moving image is displayed on the liquid crystal display device, the outline becomes double. There is a problem that it can be seen.
[0019]
Further, the method described in Patent Document 1 requires an extra thin film transistor, and a period for generating a blanking signal and applying the signal to the thin film transistor must be created. Further, in the method described in Patent Document 2, the longer the period during which the black gradation voltage is applied to the liquid crystal panel, the lower the screen brightness. In a hold type display device such as a thin film transistor type liquid crystal display device, the moving image display performance is not improved unless black is used for a period of 1/2 or more of one frame. However, if the black display period is set to 1/2 of one frame, Since the display period of the video signal is １ ／, the luminance is １ ／.
[0020]
The driving method described in Patent Literature 3 requires high-speed writing of display data, and has a disadvantage that the luminance is reduced because the lighting period of the backlight is 1/3 of one field. Further, in Patent Document 4, since the response of the liquid crystal is slow, charges are released while the response of the liquid crystal is in a transient state, and the luminance is not sufficiently increased. Although it is possible to solve such problems by providing a complicated drive circuit, it is not desirable to incorporate a large number of circuit elements in one pixel.
[0021]
SUMMARY OF THE INVENTION An object of the present invention is to provide a hold-type display device capable of displaying a high-quality image by eliminating the occurrence of moving image blur by the same drive as in the related art.
[0022]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method for connecting a relatively high resistance in parallel between a data storage capacitor (or a data storage capacitor, or simply a storage capacitor or a storage capacitor), and The charge corresponding to the image data held (held) in the data holding capacitor by the CR time constant of the capacitance value of the resistor and the resistance value of the resistor is released (discharged) within a period shorter than one frame period to discharge the next. Black was inserted between frames to drive the hold type display element closer to the impulse type.
[0023]
In a basic configuration of the present invention, a data holding capacitor for holding image data to be displayed on a display element, a first thin film transistor for charging (accumulating) electric charge corresponding to image data in the data holding capacitor, A display device including a second thin film transistor for supplying a charge held in a data holding capacitor to a display element is characterized in that a resistor having a relatively high resistance is connected in parallel with the data holding capacitor. . The first thin film transistor is for writing input image data (for pixel switching), and is not limited to one, and may be composed of a plurality of thin film transistors.
[0024]
Assuming that the capacitance value of the data holding capacitor is C and the resistance value of the resistor is R, the charge corresponding to the image data held in the data holding capacitor is a CR time constant in a short period within one frame period. The resistance value of the resistor is set so as to be discharged by the above.
[0025]
With this configuration, image data can be supplied as impulse-type data to a hold-type display element in which charges corresponding to image data are held constant during one frame period, and a display device including the hold-type display element can be supplied to an impulse-type display device. It can be driven by a mold. As a result, high-quality moving image display can be performed without using a new driving method for eliminating moving image blur in driving the hold-type display device.
[0026]
The present invention is suitable for a display device using an organic EL display element or a light emitting diode with a high response speed, but can also be provided for a liquid crystal display device with a relatively low response speed.
[0027]
It should be noted that the present invention is not limited to the above configuration and the configuration of the embodiment described later, and it is needless to say that various modifications can be made without departing from the technical idea of the present invention. Other objects and configurations of the present invention will become apparent from the description of the embodiments below.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram of a first embodiment of a display device according to the present invention, and is an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using an organic EL as a display element. One pixel is a unit pixel, and in the case of color display, a color pixel is composed of three unit pixels of R, G, and B. In the figure, reference numeral 51 indicates a scanning line, 52 indicates a data line, and 53 indicates a power supply line. Reference numeral 130 denotes a first thin film transistor (data writing or switching thin film transistor). Reference numeral 140 denotes a second thin film transistor (driving thin film transistor), 160 denotes an organic EL element, 170 denotes a data holding capacity, and 180 denotes a data holding capacity (capacitance value C, hereinafter also referred to as a storage capacity or simply as a storage capacity) 170. Are connected in parallel (resistance value R).
[0029]
The first thin film transistor 130 selected by the scanning line 51 holds (holds) the current Ic corresponding to the gradation voltage corresponding to the image data supplied from the data line 52 in the storage capacitor 170 as electric charge. The second thin film transistor 140 supplies a current corresponding to the charge corresponding to the image data stored in the storage capacitor 170 from the power supply line 53 to the organic EL element 160 to emit light.
[0030]
At this time, the resistor 180 connected in parallel with the storage capacitor 170 forms a CR time constant circuit (discharge circuit) with the resistance value and the capacitance value C of the storage capacitor 170, and the storage capacitor 170 is determined by the CR time constant. Is discharged through the power supply line 53. In the figure, the discharge current is indicated by Id. The resistance value R of the resistor 180 is set to a value that discharges the charge accumulated in the storage capacitor 170 within one frame and inserts a black display between the next frame and the next frame.
[0031]
FIG. 2 is an explanatory diagram of the response characteristics of the organic EL in the pixel circuit shown in FIG. The electric charge stored in the storage capacitor 170 is discharged in a short time within one frame, and a black display is inserted between the next frame and the next frame. The luminance is a relative value, and the CR time constant is set so that black display is inserted between the next frame and the highest luminance. This discharge period is practically about 1/2 to 1/4 of one frame. The same applies to the following embodiments.
[0032]
According to the configuration of this embodiment, image data supplied to the hold-type display element can be close to the impulse-type, and moving image blur in moving image display can be eliminated to obtain a high-quality moving image. .
[0033]
FIG. 3 is an explanatory diagram of an equivalent circuit of one pixel of an active matrix type display device using a conventional organic EL as a display element for comparing the effects of the first embodiment of the present invention. FIG. 4 is an explanatory diagram of the response characteristics of the organic EL in FIG. 3, the same reference numerals as those in FIG. 1 correspond to the same functional parts. In FIG. 3, the storage capacitor 170 does not have the resistance shown in FIG. Accordingly, the charge stored in the storage capacitor 170 holds the charge corresponding to the image data for one frame period, and the current corresponding to the charge of the image data of the previous frame is maintained until the writing of the image data of the next frame is started. It continues to flow from the power supply line 53 to the organic EL element 160. For this reason, the screen on which the image of the previous frame was displayed immediately before the next frame is immediately switched to the image display of the next frame. When a moving image is displayed on a screen that can change the display image for each frame, the movement of the image is jerky and unsightly.
[0034]
On the other hand, according to the first embodiment shown in FIG. 1, since black is automatically inserted between frames, a jerky image is not displayed, and a high-quality moving image can be obtained. it can.
[0035]
5A and 5B are explanatory diagrams of a second embodiment of the display device according to the present invention. FIG. 5A is a conventional circuit for comparison, and FIG. 5B is a circuit diagram of the second embodiment of the present invention. Show. This embodiment is also an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using an organic EL as a display element. In the figure, the same reference numerals as those in FIG. 1 or 2 correspond to the same functional parts.
[0036]
In this embodiment, the present invention is applied to a configuration in which the storage capacitor line 54 is provided and one electrode of the storage capacitor 170 is connected to the storage capacitor line 54. In the conventional circuit shown in FIG. 5A, charges corresponding to image data are accumulated in the storage capacitor 170 by the first thin film transistor 130. A current corresponding to the accumulated charge flows through the second thin film transistor 140 to the organic EL element 160. The charge stored in the storage capacitor 170 holds the charge corresponding to the image data for one frame period, and the current corresponding to the charge of the image data of the frame is supplied from the power supply line 53 until the image data of the next frame is written. It continues to flow to the organic EL element 160. For this reason, since the screen displaying the image of the previous frame up to immediately before the next frame is immediately switched to the image display of the next frame, the moving image is displayed jerky and unsightly.
[0037]
On the other hand, in the second embodiment of the present invention, as shown in FIG. 5B, a resistor 180 is connected in parallel with the storage capacitor 170, and the electric charge accumulated in the storage capacitor 170 is converted to the CR time constant. To discharge to the storage capacitor line 54. The time constant of CR is set in the same manner as in the above embodiment, and black is automatically inserted between the next frame as shown in FIG. Also according to the configuration of the present embodiment, the image data can be close to the impulse type, and moving image blur in moving image display can be eliminated, and a high-quality moving image can be obtained.
[0038]
6A and 6B are explanatory views of a third embodiment of the display device according to the present invention. FIG. 6A is a circuit diagram of a conventional circuit for comparison, and FIG. 6B is a circuit diagram of a third embodiment of the present invention. Show. This embodiment is also an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using an organic EL as a display element. In the drawing, the same reference numerals as those in the drawings of the embodiment correspond to the same functional portions.
[0039]
In this embodiment, three thin film transistors 131, 132, and 133 are connected between adjacent scanning lines for switching in order to store charges corresponding to image data in the storage capacitor 170. The circuit configuration shown in FIG. 6A suppresses the variation in the current flowing through the organic EL element 160 due to the variation in the characteristics of the thin film transistor in the display device.
[0040]
The adjacent thin film transistor 133 and the driving thin film transistor (second thin film transistor) 140 have substantially the same characteristics. First, the thin film transistor 133 and the second thin film transistor 140 are turned on, and a current corresponding to a gradation voltage corresponding to image data is supplied from the data line 52 selected by the scanning line 51n to the storage capacitor 170 as a charge determined by the gate voltage of the thin film transistor 133. Stored. Next, a current is supplied to the organic EL element 160 through the second thin film transistor 140 which is turned on by the electric charge accumulated in the storage capacitor 170 with the thin film transistor 133 turned off, and the organic EL element 160 emits light.
[0041]
In this circuit, as shown in FIG. 6B, a resistor 180 is connected in parallel with the storage capacitor 170. The electric charge accumulated in the storage capacitor 170 is discharged within one frame by the CR time constant of the resistor 180 and the storage capacitor 170. Also according to the configuration of the present embodiment, the image data can be close to the impulse type as shown in FIG. 2, and the moving image blur in the moving image display can be eliminated to obtain a high-quality moving image.
[0042]
FIGS. 7A and 7B are explanatory diagrams of a fourth embodiment of the display device according to the present invention. FIG. 7A is a conventional circuit for comparison, and FIG. 7B is a circuit diagram of a fourth embodiment of the present invention. Show. This embodiment is also an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using an organic EL as a display element. In the drawing, the same reference numerals as those in the drawings of the embodiment correspond to the same functional portions.
[0043]
In this embodiment, the switching single-gate thin film transistor (first thin film transistor) in FIG. 5 is a dual gate, and the other configuration is the same as that of FIG. . In the present embodiment, as shown in FIG. 7B, a resistor 180 is connected in parallel with the storage capacitor 170. Also according to the configuration of the present embodiment, the image data can be close to the impulse type as shown in FIG. 2, and the moving image blur in the moving image display can be eliminated to obtain a high-quality moving image.
[0044]
8A and 8B are explanatory diagrams of a fifth embodiment of the display device according to the present invention. FIG. 8A is a circuit diagram of a conventional circuit for comparison, and FIG. 8B is a circuit diagram of a fifth embodiment of the present invention. Show. This embodiment is also an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using an organic EL as a display element. In the drawing, the same reference numerals as those in the drawings of the embodiment correspond to the same functional portions.
[0045]
In the present embodiment, the switching single-gate thin film transistor (first thin film transistor) in FIGS. 3 and 1 is a dual gate, and the other configuration is the same as that of FIGS. 3 and 1. A repeated description is omitted. In the present embodiment, as shown in FIG. 8B, a resistor 180 is connected in parallel with the storage capacitor 170. Also according to the configuration of the present embodiment, the image data can be close to the impulse type as shown in FIG. 2, and the moving image blur in the moving image display can be eliminated and a high-quality moving image can be obtained.
[0046]
FIG. 9 is an explanatory view of a sixth embodiment of the display device according to the present invention. FIG. 9 (a) is a conventional circuit for comparison, and FIG. 9 (b) is a circuit diagram of the sixth embodiment of the present invention. Show. This embodiment is also an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using an organic EL as a display element. In the drawing, the same reference numerals as those in the drawings of the embodiment correspond to the same functional portions.
[0047]
In FIG. 9A, the first thin film transistor is a dual gate thin film transistor, reference numeral 11 denotes a gate, 13d denotes a drain, and 13s denotes a source. In addition, 41 of the second thin film transistor 140 indicates a gate, 43d indicates a drain, and 43s indicates a source. The organic EL element 160 includes an anode 61, a cathode 66, and a light emitting layer 65. One electrode 55 of the storage capacitor 170 is connected to the gate 41 of the second thin film transistor 140, and the other electrode 54 is connected to the power supply line 53 at a connection point 173. Reference numeral 150 indicates a terminal of the power supply line 53.
[0048]
This circuit configuration is the same as that of FIG. 8, and the driving method of the organic EL element 160 is the same as that of FIG. In the present embodiment, the resistor 180 is connected in parallel with the storage capacitor 170, so that the image data can be close to the impulse type as shown in FIG. 2, and the moving image blur in the moving image display is eliminated. A high-quality moving image can be obtained.
[0049]
FIG. 10 is a plan view of a conventional circuit for explaining a sixth embodiment of the display device according to the present invention, FIG. 11 is a cross-sectional view taken along line AA of FIG. 10, and FIG. 12 is line BB of FIG. 13 is a plan view of a circuit according to a sixth embodiment of the present invention in which the present invention is applied to the circuit of FIG. 10, and FIG. 14 is a cross-sectional view taken along line AA of FIG. This embodiment is also an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using an organic EL as a display element. In the drawing, the same reference numerals as those in the drawings of the embodiment correspond to the same functional portions.
[0050]
First, in FIGS. 10 to 12, pixels are formed in a region surrounded by a scanning line (gate signal line) 51, a data line (drain signal line) 52, and a power supply line (drive power supply line) 53. A first thin film transistor 130 is formed near an intersection of a scanning line (gate signal line) 51 and a data line (drain signal line) 52, and its source electrode 13 s is connected to a storage capacitor electrode line (storage capacitor line) 54. The capacitor also serves as a capacitor electrode 55 constituting a storage capacitor, is connected to the anode 61 of the organic EL element, and the drain 43 d of the second thin film transistor 140 is connected to the drive power supply line 53.
[0051]
The storage capacitor line 54 forms a storage capacitor for storing electric charge between the capacitor electrode 55 connected to the source 13 s of the thin film transistor 130 via the gate insulating film 12. The storage capacitor holds a voltage applied to the gate electrode 41 of the second thin film transistor 140. Reference numeral 13 denotes an active layer of a p-Si film, 13LD denotes a low concentration region, 13d denotes a drain, 14 denotes a stopper insulating film, 15 denotes an interlayer insulating film, 16 denotes a drain electrode, 17 denotes a planarizing insulating film, and 41 denotes a gate electrode. , 43 denotes an active layer, 43c denotes a channel, 43s denotes a source electrode, and 43d denotes a drain electrode. Reference numeral 61 denotes an anode, 62 denotes a first hole transport layer, 63 denotes a second hole transport layer, 64 denotes a light emitting layer, 65 denotes a light emitting element layer, and 66 denotes a cathode 10 as a substrate.
[0052]
In the display device shown in FIGS. 10 to 12, the charge stored in the storage capacitor holds the charge corresponding to the image data for one frame period, and the image data of the previous frame is written until the image data of the next frame is written. The electric current corresponding to the electric charge continues to flow from the power supply line 53 to the organic EL element. For this reason, the image of the next frame is immediately superimposed on the screen on which the image of the previous frame is displayed up to immediately before the next frame, and the outline of the moving object or person between the frames is doubled. In addition, the movement of a person in this object is displayed like a frame advance, and is unsightly.
[0053]
On the other hand, as shown in FIGS. 13 and 14, in the sixth embodiment of the present invention, a resistance hole is provided in the gate insulating film 12 to connect the electrodes constituting the storage capacitor with the resistance material 181. A time constant circuit of CR was constituted by the resistance value R of the resistance material and the capacitance value C of the storage capacitor. The operation of the CR time constant circuit is the same as in each of the above embodiments. Also according to the present embodiment, the image data can be close to the impulse type as shown in FIG. 2, and the moving image blur in the moving image display can be eliminated and a high-quality moving image can be obtained.
[0054]
FIGS. 15A and 15B are explanatory diagrams of a seventh embodiment of the present invention. FIG. 15A shows a conventional circuit for comparison, and FIG. 15B shows a circuit diagram of a seventh embodiment of the present invention. FIG. 16 is a plan view of FIG. 15, and FIG. 16A corresponds to FIG. 15A, and FIG. 16B corresponds to FIG. This embodiment is an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using an organic EL as a display element. In the drawings, the same reference numerals as those in the drawings of the above embodiments correspond to the same functional portions.
[0055]
15A and FIG. 16A, the pixel having the organic EL element 251 has a gate line (scanning line) gl connected to the gate driver and a drain line (data line) dl connected to the drain driver. It is composed of a first thin-film transistor 254 for selection (for switching), a second thin-film transistor 252 for driving, and a capacitor (holding capacity, storage capacity) 253 provided at the intersection. The thin film transistor 252 is an nMOS transistor, whereas the driving thin film transistor in the drawings describing the above embodiments is a pMOS transistor.
[0056]
In the conventional display device shown in FIGS. 15A and 16A, the charge stored in the storage capacitor 253 holds the charge corresponding to the image data for one frame period, and the image of the next frame is displayed. A current corresponding to the charge of the image data of the previous frame continues to flow through the organic EL element until data is written. For this reason, the screen displaying the image of the previous frame up to immediately before the next frame is immediately switched to the image of the next frame, and the moving image becomes jerky and unsightly.
[0057]
On the other hand, in the present embodiment shown in FIGS. 15B and 16B, a circuit in which a resistance 256 is connected in parallel with the storage capacitor 253 is used. As shown in FIG. 16B, the resistor 256 is formed by providing a hole 255 penetrating between electrodes forming the storage capacitor 253, and filling the hole 255 with a resistance material. A time constant circuit of CR was constituted by the resistance value R of the resistance material and the capacitance value C of the storage capacitor 253. The operation of the CR time constant circuit is the same as in each of the above embodiments. Also according to the present embodiment, the image data can be close to the impulse type as shown in FIG. 2, and the moving image blur in the moving image display can be eliminated and a high-quality moving image can be obtained.
[0058]
Next, an embodiment in which the present invention is applied to a liquid crystal display device using a thin film transistor (referred to as a TFT-LCD in the drawings referred to in the following description) will be described. The response characteristic of the display light of the liquid crystal display device is a hold type as shown in FIG. That is, almost all periods of one frame are used for image display. The broken line in FIG. 18 indicates the ideal luminance (relative luminance) characteristic of the display light, and the solid line indicates the luminance (relative luminance) characteristic of the actual display light.
[0059]
19A and 19B are explanatory diagrams of a seventh embodiment of the display device according to the present invention. FIG. 19A is a conventional circuit for comparison (for example, see Patent Document 4 described above), and FIG. FIG. 13 is a circuit diagram of a seventh embodiment of the present invention, and is an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using a liquid crystal display element. In the figure, reference numeral 61 denotes a gate line, 62 denotes a drain line, 63 denotes a thin film transistor, 64 denotes a liquid crystal capacitor, 65 denotes a storage capacitor, 66 denotes a common electrode, and 67 denotes a storage capacitance line.
[0060]
In the conventional circuit shown in FIG. 19A, a current corresponding to image data flows from the data line 62 through the thin film transistor 63 selected by the gate line 61, and a charge corresponding to the current is held in the storage capacitor 65. Then, an electric field corresponding to the accumulated charge is applied between the liquid crystal capacitors, and an image is displayed. The accumulated charge is held until the next frame. For this reason, the screen that displayed the image of the previous frame until immediately before the next frame was immediately switched to the next frame image display, and as a result, a blurred phenomenon occurred in the moving image, and the movement of objects and people in the screen was jerky. It will be unsightly.
[0061]
On the other hand, in the seventh embodiment of the present invention, as shown in FIG. 19B, a resistor 68 is connected in parallel with the storage capacitor 65, and the charge stored in the storage capacitor 65 is converted into a time constant of CR. To discharge to the storage capacitance line 67. The time constant of CR based on the capacitance value C of the storage capacitor 65 and the resistance value R of the resistor 68 is set in the same manner as in the previous embodiment, and black is automatically inserted between the next frame as shown in FIG. Is done. With the configuration of the present embodiment, the image data can be closer to the impulse type, and moving image blur in moving image display can be eliminated, and a high-quality moving image can be obtained.
[0062]
FIG. 21 is an explanatory view of an eighth embodiment of the display device according to the present invention. FIG. 21 (a) is a conventional circuit for comparison (for example, see Patent Document 4 described above), and FIG. 21 (b) is the present invention. FIG. 14 is a circuit diagram of an eighth embodiment of the present invention, and is an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using a liquid crystal display element. In the figure, reference numeral 61n denotes an n-th gate line, 61n-1 denotes an (n-1) th gate line, 62 denotes a drain line, 63 denotes a thin film transistor, 64 denotes a liquid crystal capacitor, 65 denotes a storage capacitor, and 66 denotes a common electrode. Is shown. This pixel has a configuration in which a thin film transistor 63 and a storage capacitor 65 are connected between an n-th gate line 61 and an (n-1) -th gate line 61n-1.
[0063]
In the conventional circuit shown in FIG. 21A, a current corresponding to image data flows from the data line 62 through the thin film transistor 63 selected by the n-th gate line 61n, and a charge corresponding to the current is stored in the storage capacitor. 65, an image is displayed by applying an electric field corresponding to the accumulated electric charges between the liquid crystal capacitors. The accumulated charge is held until the next frame. Therefore, the image of the next frame appears immediately on the screen displaying the image of the previous frame until immediately before the next frame, and as a result, a jerky and unsightly moving image is displayed.
[0064]
On the other hand, in the eighth embodiment of the present invention, as shown in FIG. 21B, a resistor 68 is connected in parallel with the storage capacitor 65, and the electric charge accumulated in the storage capacitor 65 is converted into a time constant of CR. To discharge to the (n-1) th gate line 61n-1. The time constant of CR based on the capacitance value C of the storage capacitor 65 and the resistance value R of the resistor 68 is set in the same manner as in the previous embodiment, and black is automatically inserted between the next frame as shown in FIG. Is done. With the configuration of the present embodiment, the image data can be closer to the impulse type, and moving image blur in moving image display can be eliminated, and a high-quality moving image can be obtained.
[0065]
In the liquid crystal display device, since the response speed of the liquid crystal is slower than that of the organic EL, if the charge held in the storage capacitor is discharged during the transient state, the luminance cannot be sufficiently secured. By adjusting the time constant, it is possible to secure an allowable luminance.
[0066]
FIG. 22 is a plan view schematically showing an overall configuration example of the active matrix substrate of the display device according to the present invention. In the organic EL display device, a sealing can or a glass substrate is attached so as to cover the active matrix substrate. In the case of a liquid crystal display device, depending on the method, a glass substrate with or without a color filter may be a liquid crystal layer. , But not shown.
[0067]
In FIG. 22, reference numeral 500 denotes an active matrix substrate, and a large number of pixels (R, G, B) having any one of the above-described embodiments are arranged in a matrix in a display area AR. . R is red, G is green, and B is blue. Each pixel is formed in a portion surrounded by a scanning line 51 connected to a scanning drive circuit (a gate driver in the case of using a thin film transistor as an active element) 510 and a data line 52 connected to a data driving circuit (same drain driver) 520. I have.
[0068]
Reference numeral 53 denotes a power supply line for supplying a current to the organic EL element in the organic EL display device. The reference numeral 53 is a counter electrode or a common electrode in a liquid crystal display device. Reference numeral 530 indicates a power line bus line for supplying a current to the organic EL element in an organic EL display device, and a bus line of a counter electrode or a common electrode in a liquid crystal display device. Reference numeral 600 denotes a terminal for connecting to an external signal source.
[0069]
【The invention's effect】
As described above, according to the present invention, blurring of an outline when displaying a moving image on a hold-type display device, that is, occurrence of so-called moving image blurring is avoided, and is equivalent to an impulse-type display device represented by a cathode ray tube. Can provide a display device capable of displaying a high quality image.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a first embodiment of a display device according to the present invention.
FIG. 2 is an explanatory diagram of a response characteristic of an organic EL in the pixel circuit shown in FIG.
FIG. 3 is an explanatory diagram of an equivalent circuit of one pixel of an active matrix display device using a conventional organic EL as a display element for comparing the effects of the first embodiment of the present invention.
4 is an explanatory diagram of a response characteristic of the organic EL in FIG.
FIG. 5 is an explanatory diagram of a second embodiment of the display device according to the present invention.
FIG. 6 is an explanatory view of a third embodiment of the display device according to the present invention.
FIG. 7 is an explanatory view of a fourth embodiment of the display device according to the present invention.
FIG. 8 is an explanatory diagram of a fifth embodiment of the display device according to the present invention.
FIG. 9 is an explanatory view of a sixth embodiment of the display device according to the present invention.
FIG. 10 is a plan view of a conventional circuit for explaining a sixth embodiment of the display device according to the present invention.
FIG. 11 is a sectional view taken along the line AA in FIG. 10;
FIG. 12 is a sectional view taken along the line BB of FIG. 10;
FIG. 13 is a plan view of a circuit according to a sixth embodiment of the present invention in which the present invention is applied to the circuit of FIG. 10;
FIG. 14 is a sectional view taken along line AA of FIG.
FIG. 15 is an explanatory diagram of a seventh embodiment of the present invention.
FIG. 16 is a plan view of FIG.
FIG. 17 is an explanatory diagram of emission characteristics of an impulse type represented by a cathode ray tube.
FIG. 18 is an explanatory diagram of response characteristics of display light of the liquid crystal display device.
FIG. 19 is an explanatory view of a seventh embodiment of the display device according to the present invention.
FIG. 20 is an explanatory diagram of response characteristics of display light of a liquid crystal display device that has taken measures against moving image blur.
FIG. 21 is an explanatory view of an eighth embodiment of the display device according to the present invention.
FIG. 22 is a plan view schematically showing an overall configuration example of an active matrix substrate of a display device according to the present invention.
[Explanation of symbols]
51: scanning line, 52: data line, 53: power line, 130: first thin film transistor, 140: second thin film transistor, 160: organic EL element, 170 data storage capacitor, 180 resistance.

Claims (4)

A scanning line for selecting a pixel, a data line for supplying image data to the selected pixel, a first thin film transistor provided at an intersection of the scanning line and the data line, and image data through the first thin film transistor And a power supply line to which one electrode of the storage capacitor is connected, a second thin film transistor whose conduction amount is controlled by the charge stored in the storage capacitor, A display device in which unit pixels each including an organic EL element supplied with a current according to a conduction amount of the second thin film transistor from the power supply line are arranged in a matrix,
A display device, comprising: a resistor connected in parallel to each storage capacitor of the unit pixel and having a resistance value R constituting a CR time constant circuit together with a capacitance value C of the storage capacitor. A scanning line for selecting a pixel, a data line for supplying image data to the selected pixel, a first thin film transistor provided at an intersection of the scanning line and the data line, and image data through the first thin film transistor A storage capacitor for storing and holding a charge corresponding to the storage capacitor line, a storage capacitor line to which one electrode of the storage capacitor is connected, and a second thin film transistor whose conduction amount is controlled by the charge stored in the storage capacitor. A display device in which unit pixels each having an organic EL element to which a current according to a conduction amount of the second thin film transistor is supplied are arranged in a matrix,
A display device, comprising: a resistor connected in parallel to each storage capacitor of the unit pixel and having a resistance value R constituting a CR time constant circuit together with a capacitance value C of the storage capacitor. The display device according to claim 1, wherein the resistor has a resistance value such that a time constant of the time constant circuit of the CR is shorter than one frame period. 4. The display device according to claim 3, wherein the resistor has a time constant of the time constant circuit of the CR that is ２〜 to ４ of one frame period. 5.

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