CN109272938B - Display screen, pixel circuit unit and control method thereof - Google Patents

Display screen, pixel circuit unit and control method thereof Download PDF

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Publication number
CN109272938B
CN109272938B CN201811405996.9A CN201811405996A CN109272938B CN 109272938 B CN109272938 B CN 109272938B CN 201811405996 A CN201811405996 A CN 201811405996A CN 109272938 B CN109272938 B CN 109272938B
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pixel
pixel compensation
circuit unit
gray scale
pixel circuit
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CN109272938A (en
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王博
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BOE Technology Group Co Ltd
Ordos Yuansheng Optoelectronics Co Ltd
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BOE Technology Group Co Ltd
Ordos Yuansheng Optoelectronics Co Ltd
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    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • G09G3/3233—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
    • G09G3/3241—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror
    • G09G3/325—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element the current through the light-emitting element being set using a data current provided by the data driver, e.g. by using a two-transistor current mirror the data current flowing through the driving transistor during a setting phase, e.g. by using a switch for connecting the driving transistor to the data driver
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G09G3/3208—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED]
    • G09G3/3225—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix
    • G09G3/3233—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED] organic, e.g. using organic light-emitting diodes [OLED] using an active matrix with pixel circuitry controlling the current through the light-emitting element
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0271—Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Electroluminescent Light Sources (AREA)
  • Control Of El Displays (AREA)

Abstract

The invention discloses a display screen, a pixel circuit unit and a control method thereof, wherein the pixel circuit unit comprises: a light emitting device, further comprising: at least two simple pixel compensation circuits are connected with the light-emitting device and provide driving current for the light-emitting device; the simple pixel compensation circuit refers to a pixel compensation circuit with the number of elements less than a set value. The invention can improve the PPI of the display screen, in particular to the PPI of the display screen of the wearable device.

Description

Display screen, pixel circuit unit and control method thereof
Technical Field
The invention relates to the technical field of display, in particular to a display screen, a pixel circuit unit and a control method thereof.
Background
At present, the requirements of users for mobile terminal devices are higher and higher, and the requirements of users are still the requirements of most users, however, by virtue of the characteristic of autonomous light emission of an organic light-emitting diode (OLED), the OLED can realize a display function without a backlight source, and becomes a preferred display with lighter and thinner characteristics. Meanwhile, the requirements of the display on the market at present are no longer only the requirement of a plane, and the display technology with opposite properties, curved surfaces, transparent display and the like makes the OLED become the most widely applied display technology in the future.
However, since an AMOLED (Active-matrix organic light-emitting diode) belongs to current driving, the process requirement is relatively high, and in order to achieve the purpose of current uniformity, a pixel compensation circuit for an AMOLED display is also diversified, and the development is made from a simple 2T1C circuit (a pixel compensation circuit based on 2 transistors and 1 capacitor) as shown in fig. 1 to 7T1C (a pixel compensation circuit based on 7 transistors and 1 capacitor) and 8T1C (a pixel compensation circuit based on 8 transistors and 1 capacitor) as shown in fig. 2, which are commonly used at present.
Although a uniform current can be realized based on the commonly used 7T1C and 8T1C circuits, the complicated pixel compensation circuit makes the PPI of the AMOLED display not slow and cannot realize the display of 600 or above.
Disclosure of Invention
In view of the above, the present invention is directed to a display panel, a pixel circuit unit and a control method thereof, which are used to improve the PPI of the display panel, especially the PPI of a display panel of a wearable device.
The present invention provides a pixel circuit unit based on the above object, including: a light emitting device, further comprising:
at least two simple pixel compensation circuits are connected with the light-emitting device and provide driving current for the light-emitting device; wherein the content of the first and second substances,
the simple pixel compensation circuit refers to a pixel compensation circuit with the number of elements less than a set value.
The number of the simple pixel compensation circuits is 3, and the number of the light emitting devices is 1.
Preferably, the simple pixel compensation circuit is a pixel compensation circuit based on 2 transistors and 1 capacitor, and includes: a first transistor, a driving transistor, and a first capacitor;
in each simple pixel compensation circuit, the source electrode and the drain electrode of the driving transistor of the simple pixel compensation circuit, and the anode and the cathode of the light-emitting device are connected in series between a circuit working voltage VDD and a common ground terminal voltage VSS; one end of a first capacitor of the simple pixel compensation circuit is connected to a grid electrode of a driving transistor of the simple pixel compensation circuit, and the other end of the first capacitor is connected to VDD; one of a source electrode and a drain electrode of the first transistor of the simple pixel compensation circuit is connected with a grid electrode of the driving transistor of the simple pixel compensation circuit, and the other one is connected with a Data line; the grid electrode of the first transistor of the simple pixel compensation circuit is connected with the scanning line.
Or the number of the light-emitting devices is the same as that of the simple pixel compensation circuits, and each simple pixel compensation circuit provides a driving current for one light-emitting device; wherein the content of the first and second substances,
the light emitting devices belonging to the same pixel circuit unit have the same color and are adjacent in position, and the distance between the adjacent light emitting devices belonging to the same pixel circuit unit is smaller than the distance between the light emitting devices of the adjacent different pixel circuit units.
Preferably, the number of the light emitting devices is 3, and the number of the simple pixel compensation circuits is 3, and the simple pixel compensation circuits are respectively and correspondingly connected to the light emitting devices.
Preferably, the simple pixel compensation circuit is a pixel compensation circuit based on 2 transistors and 1 capacitor, and includes: a second transistor, a driving transistor, and a second capacitor;
in each simple pixel compensation circuit, the source and the drain of the driving transistor of the simple pixel compensation circuit, and the anode and the cathode of the light-emitting device corresponding to the simple pixel compensation circuit are connected in series between VDD and VSS; one end of a second capacitor of the simple pixel compensation circuit is connected to a grid electrode of a driving transistor of the simple pixel compensation circuit, and the other end of the second capacitor is connected to VDD; one of a source and a drain of the second transistor of the simple pixel compensation circuit is connected with a gate of the driving transistor of the simple pixel compensation circuit, and the other is connected with a Data line; the grid electrode of the second transistor of the simple pixel compensation circuit is connected with the scanning line.
The invention also provides a control method of the pixel circuit unit, which comprises the following steps:
determining a gray scale range of the current brightness gray scale of a pixel circuit unit to be scanned currently;
determining the starting number of the simple pixel compensation circuits in the pixel circuit unit according to the gray scale range;
calculating the device brightness control voltage V of the pixel circuit unit based on the gray scale and the determined turn-on numberdataA value;
providing scanning signals for the simple pixel compensation circuits with corresponding numbers in the pixel circuit units according to the determined starting number, and controlling the voltage V according to the calculated device brightnessdataThe value provides a device brightness control voltage for the pixel circuit cell.
Preferably, the number of the simple pixel compensation circuits in the pixel circuit unit is 3.
Wherein, the determined gray scale range is specifically as follows: low, medium, or high gray scale range; and
the determining the number of the simple pixel compensation circuits in the pixel circuit unit according to the gray scale range specifically includes:
if the determined gray scale range is the low gray scale range, determining the number of the simple pixel compensation circuits in the pixel circuit unit to be started to be 1;
if the determined gray scale range is the middle gray scale range, determining that the number of the simple pixel compensation circuits in the pixel circuit unit is 2;
and if the determined gray scale range is the high gray scale range, determining that the number of the simple pixel compensation circuits in the pixel circuit unit is 3.
The present invention also provides a display screen, comprising: a plurality of pixel circuit units and control modules thereof; wherein the content of the first and second substances,
the control module is used for determining the gray scale range of the current brightness gray scale of the pixel circuit unit for the pixel circuit unit to be scanned; determining the starting number of the simple pixel compensation circuits in the pixel circuit unit according to the gray scale range; calculating the device brightness control voltage V of the pixel circuit unit based on the gray scale and the determined turn-on numberdataA value; providing scanning signals for the simple pixel compensation circuits with corresponding numbers in the pixel circuit units according to the determined starting number, and calculating VdataThe value provides a device brightness control voltage for the pixel circuit cell.
In the technical scheme of the invention, at least two simple pixel compensation circuits (such as 2T1C circuits) are adopted in one pixel circuit unit to be connected with a light-emitting device so as to provide driving current for the light-emitting device; therefore, the gray scales of the light-emitting device are increased, and meanwhile, as the simple pixel compensation circuits (such as the 2T1C circuit) are few in elements and simple in wiring, a plurality of simple pixel compensation circuits are convenient to arrange in a unit area, the number of pixels in the unit area of the display screen can be increased, namely the PPI of the display screen is increased; in addition, also because the simple pixel compensation circuit (such as 2T1C circuit) has few components and simple wiring, the Mask process in the display screen production process can be simplified, the current 9Mask process is not needed, and it is actually proved that the number of masks can be reduced to 5-6, which is very helpful for improving the productivity and reducing the cost.
Drawings
FIGS. 1 and 2 are circuit diagrams of prior art pixel circuit cells based on 2T1C and 7T1C circuits, respectively;
fig. 3 is a circuit diagram of a pixel circuit unit according to an embodiment of the invention;
FIG. 4 is a schematic diagram of low, medium and high gray scale display of a light emitting device in a pixel circuit unit having 3 simple pixel compensation circuits according to an embodiment of the present invention;
fig. 5 is a circuit diagram of a pixel circuit unit according to a second embodiment of the present invention;
fig. 6 is a schematic layout diagram of light emitting devices in a pixel circuit unit having 3 light emitting devices according to a second embodiment of the present invention;
fig. 7 is a schematic diagram of low, medium and high gray scale display of the light emitting device in the pixel circuit unit having 3 light emitting devices and 3 simple pixel compensation circuits according to the second embodiment of the present invention;
fig. 8 is a block diagram of an internal structure of a display screen according to a third embodiment of the present invention;
fig. 9 is a flowchart of a control method of a pixel circuit unit according to a third embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to specific embodiments and the accompanying drawings.
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative only and should not be construed as limiting the invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or wirelessly coupled. As used herein, the term "and/or" includes all or any element and all combinations of one or more of the associated listed items.
It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are used for distinguishing two entities with the same name but different names or different parameters, and it should be noted that "first" and "second" are merely for convenience of description and should not be construed as limitations of the embodiments of the present invention, and they are not described in any more detail in the following embodiments.
The inventor of the invention analyzes the existing pixel circuit unit and finds that the pixel circuit unit based on 7T1C or 8T1C can better realize uniform current, but the complicated circuit makes the pixel density more difficult to improve; the pixel circuit unit based on 2T1C is simple in circuit, and is beneficial to greatly increasing the number of pixels in a unit area in a display screen, but cannot meet the display requirement due to less gray scale of the control light-emitting device. For convenience of description, the pixel compensation circuit with less elements than a predetermined value is referred to as a simple pixel compensation circuit, for example, the 2T1C circuit is a simple pixel compensation circuit; wherein the set value can be 4 or 5 or other values, which can be set empirically by a person skilled in the art.
Therefore, the inventor of the present invention considers that at least two simple pixel compensation circuits (such as 2T1C circuits) are used in one pixel circuit unit to increase the gray scale of the light emitting device, and at the same time, since the simple pixel compensation circuits (such as 2T1C circuits) have fewer elements and simple wiring, it is convenient to arrange a plurality of simple pixel compensation circuits in a unit area, so as to increase the number of pixels in the unit area of the display screen, i.e. increase the PPI of the display screen; in addition, also because the simple pixel compensation circuit (such as 2T1C circuit) has few components and simple wiring, the Mask process in the display screen production process can be simplified, the current 9Mask process is not needed, and it is actually proved that the number of masks can be reduced to 5-6, which is very helpful for improving the productivity and reducing the cost.
Especially for wearing products such as a bracelet and a watch, the products do not need to display more complicated pictures like mobile phone products, pads and computer monitors. At present, most of the display functions used for wearing products have the functions of displaying text information and simple pictures; therefore, the OLED display screen does not need to use a complex pixel compensation circuit to achieve the display effect of a lot of gray scales. Then, the gray scale of one pixel circuit unit with a plurality of simple pixel compensation circuits can meet the requirement. Therefore, the display gray scale requirement can be met, the PPI of the display screen of the wearable device can be improved, and the Mask process in the production process can be simplified.
The technical solution of the embodiments of the present invention is described in detail below with reference to the accompanying drawings. The present invention provides the following two embodiments of the pixel circuit unit.
Example one
A circuit diagram of a pixel circuit unit according to an embodiment of the present invention is shown in fig. 3, and includes: a light emitting device 302, and at least two simple pixel compensation circuits 301.
The number of the light emitting devices 302 is one, and the at least two simple pixel compensation circuits 301 are connected to the light emitting devices 302 to provide driving current for the light emitting devices 302.
Preferably, the simple pixel compensation circuit 301 is embodied as a 2T1C circuit, i.e. a pixel compensation circuit based on 2 transistors and 1 capacitor.
Preferably, the number of the simple pixel compensation circuits 301 is 3. Fig. 4 shows a schematic diagram of low, medium and high gray scale display of the light emitting device in the pixel circuit unit having 3 simple pixel compensation circuits 301.
In fact, a pixel circuit cell having 3 2T1C circuits may have 64 gray levels; the pixel circuit unit having 2T1C circuits can have 16 gray levels.
The pixel circuit unit shown in fig. 3 includes 3 2T1C circuits 301 and 1 OLED light emitting device 302; wherein, each 2T1C circuit includes: a first transistor T31, a driving transistor T32, and a first capacitor C33.
In each simple pixel compensation circuit, the source and drain of the driving transistor T32 of the simple pixel compensation circuit, and the anode and cathode of the light emitting device 302 are connected in series between the circuit operating voltage VDD and the common ground voltage VSS; for example, one of the source and the drain of T32 of the simple pixel compensation circuit is connected to VDD (circuit operating voltage), and the other is connected to the anode of the OLED light emitting device 302 in the pixel circuit unit, so as to provide driving current for the OLED light emitting device 302; the cathode of the OLED light emitting device 302 is connected to VSS (common ground voltage); one end of C33 of the simple pixel compensation circuit is connected to the grid of T32 of the simple pixel compensation circuit, and the other end is connected to VDD; one of the source and drain of the T31 of the simple pixel compensation circuit is connected with the gate of the T32 of the simple pixel compensation circuit, and the other is connected with a Data (Data) line for receiving a brightness control voltage Vdata(ii) a The gate of T31 of the simple pixel compensation circuit is connected to the scan line for receiving the scan signal. The data lines and the scan lines can be connected to the control module. The control module is used for outputting a scanning signal and a brightness control voltage V to the simple pixel compensation circuit of the pixel circuit unit through a data line and a scanning linedataThereby controlling the brightness of the OLED light emitting device 302. The function of the control module will be described in detail later.
Example two
A circuit diagram of a pixel circuit unit according to a second embodiment of the present invention is shown in fig. 5, and includes: a light emitting device 501, and at least two simple pixel compensation circuits 502;
at least two simple pixel compensation circuits 502 are connected to the light emitting device 501 to provide driving current for the light emitting device 501. Specifically, there are a plurality of light emitting devices 501, and the number of the light emitting devices 501 is the same as that of the simple pixel compensation circuits 502, and each simple pixel compensation circuit 502 provides a driving current for one light emitting device 501.
Preferably, the simple pixel compensation circuit 502 is embodied as a 2T1C circuit, i.e. a pixel compensation circuit based on 2 transistors and 1 capacitor.
Preferably, there are 3 light emitting devices 501, and there are 3 simple pixel compensation circuits 502, which are respectively connected to the light emitting devices 501. That is, one pixel corresponding to one pixel circuit unit may be composed of 3 small pixels, for example, as shown in fig. 6; and 3 small pixels are respectively provided with 3 light emitting devices 501 for emitting light.
In the second embodiment of the present invention, the light emitting devices in the pixel circuit unit are arranged such that the light emitting devices belonging to the same pixel circuit unit have the same color and are adjacent in position, and the distance between the adjacent light emitting devices belonging to the same pixel circuit unit is smaller than the distance between the light emitting devices of the adjacent different pixel circuit units.
For example, fig. 6 shows a layout of light emitting devices in a pixel circuit unit having 3 light emitting devices 501; it can be seen that 3 red light emitting devices belonging to the same pixel circuit unit are adjacently and closely arranged; that is, the pitch between the adjacent light emitting devices belonging to the same pixel circuit unit is smaller than the pitch between the adjacent light emitting devices of different pixel circuit units.
Fig. 7 shows a schematic diagram of low, medium and high gray scale display of light emitting devices in a pixel circuit unit having 3 light emitting devices 501 and 3 simple pixel compensation circuits 502.
The 2T1C circuit shown in fig. 2 is applied to a wearable product, and the pixels are shown in fig. 6. For OLED light emitting devices, the formula for luminance and current density is as follows L ═ K × Eff × J; where K is a coefficient, Eff is the luminous efficiency of the OLED light emitting device, and J is the current density. Drive current I of light emitting device: (1/2) Un × Cox × (W/L) × (Vgs-Vth)2(ii) a Wherein Un is the migration rate of electrons, Cox is the capacitance of a gate oxide layer in unit area, W/L is the width-to-length ratio, and Vgs-Vth is the overdrive voltage.
A maximum current when one of the three small pixels of the pixel circuit unit operates is I ═ (1/2) ucox (W/L) k; the maximum current is I ═ UnCox (W/L) k when the two work; the maximum current is 3/2ox (W/L) k when three are in operation.
For current density, when the area of the OLED light emitting device is fixed to S, the current density is calculated as J ═ I/S. That is, when one pixel operates, the luminance of the light emitting unit is different from that when three pixels operate simultaneously. As shown in fig. 7.
According to such a calculation method, 2 can be realized2×22×2264 gray levels; that is, a pixel circuit unit having 3 2T1C circuits may have 64 gray scales; the pixel circuit unit with 2T1C circuits can have 16 gray levels, and can completely meet the display requirements of wearing products.
The pixel circuit unit shown in fig. 5 includes 3 2T1C circuits 501 and 3 OLED light emitting devices 502; wherein, each 2T1C circuit includes: a second transistor T51, a driving transistor T52, and a second capacitor C53.
In each simple pixel compensation circuit, the source and drain of the driving transistor T52 of the simple pixel compensation circuit, and the anode and cathode of the light emitting device 502 corresponding to the simple pixel compensation circuit are connected in series between VDD and VSS; for example, one of the source and the drain of T52 of the simple pixel compensation circuit is connected to VDD (circuit operating voltage), and the other is connected to the anode of the OLED light emitting device 502 corresponding to the simple pixel compensation circuit in the pixel circuit unit, so as to provide the OLED light emitting device 502 with driving current; the cathode of the OLED light emitting device 502 is connected to VSS (common ground voltage); one end of C53 of the simple pixel compensation circuit is connected to the grid of T52 of the simple pixel compensation circuit, and the other end is connected to VDD; one of the source and drain of the T51 of the simple pixel compensation circuit is connected with the gate of the T52 of the simple pixel compensation circuit, and the other is connected with a Data (Data) line for receiving a brightness control voltage Vdata(ii) a The gate of T51 of the simple pixel compensation circuit is connected to the scan line for receiving the scan signal. The data lines and the scan lines can be connected to the control module. The control module is used for outputting scanning signals and brightness control voltage V to each simple pixel compensation circuit of the pixel circuit unit through the data line and the scanning linedataThereby controlling the turn-on and brightness of each OLED light emitting device 502. The function of the control module will be described in detail later.
EXAMPLE III
Based on the pixel circuit unit in the first embodiment or the second embodiment, a third embodiment of the present invention provides a display panel, as shown in fig. 8, including: a plurality of pixel circuit units 801 and a control module 802 thereof.
The specific circuit of the pixel circuit unit 801 may be the circuit of the pixel circuit unit of the first embodiment described above, or may be the circuit of the pixel circuit unit of the second embodiment described above.
The control module 802 may be disposed in the signal processing chip, and is connected to each pixel circuit unit 801: the control module 802 may provide a scan signal to each simple pixel compensation circuit in each pixel circuit unit 801 through a scan line, and the control module 802 may provide a brightness control voltage V to each simple pixel compensation circuit in each pixel circuit unit 801 through a data linedata。
Specifically, the control module 802 determines, for a currently to-be-scanned pixel circuit unit 801, a gray scale range in which a gray scale of current brightness of the pixel circuit unit is located; determining the starting number of the simple pixel compensation circuits in the pixel circuit unit according to the gray scale range; calculating the device brightness control voltage V of the pixel circuit unit based on the gray scale and the determined turn-on numberdataA value; providing scanning signals for simple pixel compensation circuits with corresponding numbers in the pixel circuit units through scanning lines according to the determined starting number, and calculating VdataThe pixel circuit unit is supplied with a device brightness control voltage through a data line.
The specific control method of the pixel circuit unit by the control module 802 in the display screen according to the third embodiment of the present invention has a flow as shown in fig. 9, and includes the following steps:
step S901: the control module 802 determines, for a currently to-be-scanned pixel circuit unit, a gray scale range in which a gray scale of a current brightness of the pixel circuit unit is located.
Specifically, in the process of scanning one pixel circuit unit, the control module 802 determines, for a pixel circuit unit to be scanned currently, a gray scale range in which a gray scale of the current brightness of the pixel circuit unit is located. For example, for the case that the number of the simple pixel compensation circuits in the pixel circuit unit is 3, the gray scale range determined by the control module 802 may be a low, medium, or high gray scale range.
For example, 3 2T1C circuits in the pixel circuit unit have 64 gray scales, and if the gray scale of the current brightness is 0-20, the determined gray scale range is a low gray scale range; if the gray scale of the current brightness is 21-42, determining the gray scale range as a middle gray scale range; and if the gray scale of the current brightness is 43-63, determining the gray scale range as a high gray scale range.
Step S902: the control module 802 determines the number of the simple pixel compensation circuits in the pixel circuit unit according to the gray scale range.
For example, in the case that the number of the simple pixel compensation circuits in the pixel circuit unit is specifically 3, if the gray scale range determined by the control module 802 is the low gray scale range, it is determined that the number of the simple pixel compensation circuits in the pixel circuit unit that are turned on is 1; if the determined gray scale range is the middle gray scale range, determining that the number of the simple pixel compensation circuits in the pixel circuit unit is 2; and if the determined gray scale range is the high gray scale range, determining that the number of the simple pixel compensation circuits in the pixel circuit unit is 3.
Step S903: the control module 802 calculates the device brightness control voltage V of the pixel circuit unit based on the gray scale and the determined turn-on numberdataThe value is obtained.
Specifically, the control module 802 calculates the device brightness control voltage V of the pixel circuit unit based on the gray scale and the determined turn-on numberdataThe value is usually between 3 and 5V.
Step S904: the control module 802 provides the scan signals for the corresponding number of simple pixel compensation circuits in the pixel circuit unit according to the determined number of turned-on pixels, and calculates VdataThe value provides a device brightness control voltage for the pixel circuit cell.
Specifically, the control module 802 is connected to each simple pixel compensation circuit in the pixel circuit unit through a scan line, so as to provide a scan signal for each simple pixel compensation circuit to turn on the simple pixel compensation circuit.
The control module 802 also provides a device brightness control voltage for all the simple pixel compensation circuits in the pixel circuit unit.
In this way, after determining the number of the simple pixel compensation circuits to be turned on, the control module 802 may provide the scanning signals for the corresponding number of the simple pixel compensation circuits in the pixel circuit unit, and may calculate V according to the calculated VdataThe value provides the device brightness control voltage for all simple pixel compensation circuits in the pixel circuit unit.
For example, for the case that the number of the simple pixel compensation circuits in the pixel circuit unit is specifically 3, after determining that the number of the simple pixel compensation circuits to be turned on is 2, the control module 802 may provide scanning signals for 2 simple pixel compensation circuits in the pixel circuit unit to turn on the two simple pixel compensation circuits; at this time, the control module 802 provides the brightness control voltage for the pixel circuit unit, and the light emitting device in the pixel circuit unit can be finally driven by the two simple pixel compensation circuits.
In the technical scheme of the invention, at least two simple pixel compensation circuits (such as 2T1C circuits) are adopted in one pixel circuit unit to be connected with a light-emitting device so as to provide driving current for the light-emitting device; therefore, the gray scales of the light-emitting device are increased, and meanwhile, as the simple pixel compensation circuits (such as the 2T1C circuit) are few in elements and simple in wiring, a plurality of simple pixel compensation circuits are convenient to arrange in a unit area, the number of pixels in the unit area of the display screen can be increased, namely the PPI of the display screen is increased; in addition, also because the simple pixel compensation circuit (such as 2T1C circuit) has few components and simple wiring, the Mask process in the display screen production process can be simplified, the current 9Mask process is not needed, and it is actually proved that the number of masks can be reduced to 5-6, which is very helpful for improving the productivity and reducing the cost.
Those skilled in the art will appreciate that the present invention includes apparatus directed to performing one or more of the operations described in the present application. These devices may be specially designed and manufactured for the required purposes, or they may comprise known devices in general-purpose computers. These devices have stored therein computer programs that are selectively activated or reconfigured. Such a computer program may be stored in a device (e.g., computer) readable medium, including, but not limited to, any type of disk including floppy disks, hard disks, optical disks, CD-ROMs, and magnetic-optical disks, ROMs (Read-Only memories), RAMs (Random Access memories), EPROMs (Erasable Programmable Read-Only memories), EEPROMs (Electrically Erasable Programmable Read-Only memories), flash memories, magnetic cards, or optical cards, or any type of media suitable for storing electronic instructions, and each coupled to a bus. That is, a readable medium includes any medium that stores or transmits information in a form readable by a device (e.g., a computer).
It will be understood by those within the art that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions. Those skilled in the art will appreciate that the computer program instructions may be implemented by a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, implement the features specified in the block or blocks of the block diagrams and/or flowchart illustrations of the present disclosure.
Those of skill in the art will appreciate that various operations, methods, steps in the processes, acts, or solutions discussed in the present application may be alternated, modified, combined, or deleted. Further, various operations, methods, steps in the flows, which have been discussed in the present application, may be interchanged, modified, rearranged, decomposed, combined, or eliminated. Further, steps, measures, schemes in the various operations, methods, procedures disclosed in the prior art and the present invention can also be alternated, changed, rearranged, decomposed, combined, or deleted.
Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the invention, also features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity. Therefore, any omissions, modifications, substitutions, improvements and the like that may be made without departing from the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (8)

1. A pixel circuit cell, comprising: a light emitting device, characterized by further comprising:
at least two simple pixel compensation circuits are connected with the light-emitting device and provide driving current for the light-emitting device;
the simple pixel compensation circuit refers to a pixel compensation circuit with the number of elements less than a set value, and the number of the simple pixel compensation circuits is 3;
the control module is used for determining the gray scale range of the current brightness gray scale of the pixel circuit unit for the pixel circuit unit to be scanned; determining the starting number of the simple pixel compensation circuits in the pixel circuit unit according to the gray scale range; calculating the device brightness control voltage Vdata value of the pixel circuit unit based on the gray scale and the determined turn-on number; and providing scanning signals for the simple pixel compensation circuits with corresponding numbers in the pixel circuit units according to the determined starting number, and providing device brightness control voltage for the pixel circuit units according to the calculated Vdata value.
2. The pixel circuit unit according to claim 1, wherein the simple pixel compensation circuit is a pixel compensation circuit based on 2 transistors and 1 capacitor, and comprises: a first transistor, a driving transistor, and a first capacitor;
in each simple pixel compensation circuit, the source electrode and the drain electrode of the driving transistor of the simple pixel compensation circuit, and the anode and the cathode of the light-emitting device are connected in series between a circuit working voltage VDD and a common ground terminal voltage VSS; one end of a first capacitor of the simple pixel compensation circuit is connected to a grid electrode of a driving transistor of the simple pixel compensation circuit, and the other end of the first capacitor is connected to VDD; one of a source electrode and a drain electrode of the first transistor of the simple pixel compensation circuit is connected with a grid electrode of the driving transistor of the simple pixel compensation circuit, and the other one is connected with a Data line; the grid electrode of the first transistor of the simple pixel compensation circuit is connected with the scanning line.
3. The pixel circuit unit according to claim 1, wherein the number of the light emitting devices is the same as that of the simple pixel compensation circuits, and each simple pixel compensation circuit provides a driving current for one light emitting device;
the light emitting devices belonging to the same pixel circuit unit are same in color and adjacent in position, and the distance between the adjacent light emitting devices belonging to the same pixel circuit unit is smaller than the distance between the light emitting devices of different adjacent pixel circuit units.
4. The pixel circuit unit according to claim 3, wherein the simple pixel compensation circuits are respectively connected to the light emitting devices.
5. The pixel circuit unit according to claim 4, wherein the simple pixel compensation circuit is a pixel compensation circuit based on 2 transistors and 1 capacitor, and comprises: a second transistor, a driving transistor, and a second capacitor;
in each simple pixel compensation circuit, the source and the drain of the driving transistor of the simple pixel compensation circuit, and the anode and the cathode of the light-emitting device corresponding to the simple pixel compensation circuit are connected in series between VDD and VSS; one end of a second capacitor of the simple pixel compensation circuit is connected to a grid electrode of a driving transistor of the simple pixel compensation circuit, and the other end of the second capacitor is connected to VDD; one of a source and a drain of the second transistor of the simple pixel compensation circuit is connected with a gate of the driving transistor of the simple pixel compensation circuit, and the other is connected with a Data line; the grid electrode of the second transistor of the simple pixel compensation circuit is connected with the scanning line.
6. The pixel circuit unit according to any of claims 1-5, wherein the set value is 4.
7. A control method of a pixel circuit unit includes:
determining a gray scale range of the current brightness gray scale of a pixel circuit unit to be scanned currently;
determining the starting number of the simple pixel compensation circuits in the pixel circuit unit according to the gray scale range;
calculating the device brightness control voltage Vdata value of the pixel circuit unit based on the gray scale and the determined turn-on number;
providing scanning signals for the simple pixel compensation circuits with corresponding numbers in the pixel circuit units according to the determined starting number, and providing device brightness control voltage for the pixel circuit units according to the calculated device brightness control voltage Vdata value;
the determined gray scale range is specifically as follows: low, medium, or high gray scale range; and
the determining the number of the simple pixel compensation circuits in the pixel circuit unit according to the gray scale range specifically includes:
if the determined gray scale range is the low gray scale range, determining the number of the simple pixel compensation circuits in the pixel circuit unit to be started to be 1;
if the determined gray scale range is the middle gray scale range, determining that the number of the simple pixel compensation circuits in the pixel circuit unit is 2;
and if the determined gray scale range is the high gray scale range, determining that the number of the simple pixel compensation circuits in the pixel circuit unit is 3.
8. A display screen, comprising: a plurality of pixel circuit units according to any one of claims 1-6 and control modules therefor; wherein the content of the first and second substances,
the control module is used for determining the gray scale range of the current brightness gray scale of the pixel circuit unit for the pixel circuit unit to be scanned; determining the starting number of the simple pixel compensation circuits in the pixel circuit unit according to the gray scale range; calculating the device brightness control voltage Vdata value of the pixel circuit unit based on the gray scale and the determined turn-on number; and providing scanning signals for the simple pixel compensation circuits with corresponding numbers in the pixel circuit units according to the determined starting number, and providing device brightness control voltage for the pixel circuit units according to the calculated Vdata value.
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