CN217485073U

CN217485073U - Display screen

Info

Publication number: CN217485073U
Application number: CN202221307688.4U
Authority: CN
Inventors: 周国华; 杨杰; 洪荣辉; 林阳腾
Original assignee: Fujian Qiangli Photoelectricity Co Ltd
Current assignee: Fujian Qiangli Photoelectricity Co Ltd
Priority date: 2022-05-26
Filing date: 2022-05-26
Publication date: 2022-09-23
Anticipated expiration: 2032-05-26

Abstract

The utility model discloses a display screen, include: a light emitting element; the light emitting elements are arranged in an array; the first end of each light-emitting element is electrically connected with the first level output end; a plurality of constant current drive circuits; the second end of at least one light-emitting element is connected with at least two different constant current driving circuits, so that at least one of the at least two different constant current driving circuits provides constant current for the light-emitting element; the amplitude of the constant current output by different constant current driving circuits is different. The technical scheme provided by the utility model, can improve the fine and smooth degree of grey level when realizing high refresh rate.

Description

Display screen

Technical Field

The utility model relates to a show technical field, especially relate to a display screen

Background

The current Light Emitting Diode (LED) screen has been widely used in various electronic devices due to its advantages of low power consumption, power saving, long service life, environmental protection, etc. As the resolution of the LED panel is increased, the light emitting diodes may be driven using a constant current source chip for multi-line scanning.

The method for controlling the brightness of the LED by the constant current source chip generally comprises the following steps: a Pulse Width Modulation (PWM) method, that is, controlling the bright/dark time of the LEDs to represent the display effect of different brightness. Illustratively, in a fixed time, the time for turning on the LED is increased, so that the display brightness of the LED can be effectively improved. The constant current output by the constant current source is integrated in a fixed time during the LED lighting time, so that the brightness value of the LED can be represented.

However, in the PWM control method, when the time interval between adjacent light emitting periods of the LED is long, human eyes can easily perceive the flicker problem, and when the gray scale value is low, the fineness of the gray scale is insufficient, which affects the display effect of the picture.

SUMMERY OF THE UTILITY MODEL

An embodiment of the utility model provides a display screen to when realizing high refresh rate, improve the fine and smooth degree of low grey level.

An embodiment of the utility model provides a display screen, include:

a light emitting element; the light emitting elements are arranged in an array; the first end of each light-emitting element is electrically connected with the first level output end;

a plurality of constant current drive circuits; the second end of at least one light-emitting element is connected with at least two different constant current driving circuits, so that at least one of the at least two different constant current driving circuits provides constant current for the light-emitting element; the amplitude of the constant current output by different constant current driving circuits is different.

The utility model discloses in, at least one light emitting component to on the display screen is provided with the constant current drive circuit of a plurality of differences and drives, and the amplitude of the constant current drive circuit output of difference is different, then this embodiment can set for the behavior of the constant current drive circuit of a plurality of differences that light emitting component connects according to light emitting component's target grey value, that is, it is great as required target grey value, can set up a plurality of constant current drive circuit and export constant current value light emitting component simultaneously, light emitting component charges very fast, can reach the target grey value fast, effectively reduce every line of light emitting component's scan time, and then reduce the frame cycle of every frame picture of display screen, avoid the problem of picture scintillation. In addition, when the target gray value is smaller, the light-emitting element is driven only by the constant current driving circuit with smaller constant current amplitude, so that the problem of too short charging time caused by larger constant current amplitude is effectively avoided, the fine degree of the low-gray-scale picture is improved, and the picture display effect is improved.

Drawings

FIG. 1 is a schematic diagram of PWM modulation in the prior art;

fig. 2 is a schematic view of a partial structure of a display screen according to an embodiment of the present invention;

fig. 3 is a schematic partial structure diagram of another display screen provided by an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a display screen according to an embodiment of the present invention;

fig. 5 is a schematic diagram of PWM modulation provided by an embodiment of the present invention;

fig. 6 is a schematic flowchart of a driving method for a display screen according to an embodiment of the present invention;

fig. 7 is a schematic flowchart of another driving method for a display panel according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

In the prior art, when the brightness of the light emitting device of the display screen is controlled, PWM modulation is performed by a single constant current, as shown in fig. 1, fig. 1 is a schematic diagram of PWM modulation in the prior art, and the brightness value L of each gray level is an integral of the brightness of the light emitting device driven by the constant current I in the time T direction:

L＝f(I*T)；

T＝g*t0；

where g is the gray scale value (integer), t0 is the minimum pulse width that can be realized by the circuit, and f () is a function of the inherent luminous efficiency of the light emitting element. The unfilled portion in fig. 1 is luminance at g gray scale value, and the hatched portion is luminance at minimum gray scale (e.g., g 1). Because the display driving method of the current display screen is the determinant scanning, and high grey scale (g >16384 is often required) and high refresh rate and low grey scale are fine, the following difficulties exist: first, in the case of a high gray level, g × T0 is large, and the time T taken to form the gray level of each row is large, so that it is difficult to achieve a high refresh rate; secondly, when the lowest gray level g is 1, the circuit physical limitation of t0 cannot be reduced any more, which affects the fine gray level.

In order to solve the above problem, the embodiment of the utility model provides a display screen is provided, as shown in fig. 2, fig. 2 is the embodiment of the utility model provides a local structure schematic diagram of a display screen, the display screen includes:

a light emitting element 11; the light emitting elements 11 are arranged in an array; a first end of each light emitting element 11 is electrically connected with the first level output end 12;

a plurality of constant current drive circuits 13; a second end of at least one light emitting element 11 is connected with at least two different constant current driving circuits 13, so that at least one of the at least two different constant current driving circuits 13 provides a constant current for the light emitting element 11; the constant currents output from the different constant current drive circuits 13 are different in magnitude.

Because the light emitting elements 11 are scanned line by line, in the prior art, the second end of each light emitting element 11 is connected to one constant current driving circuit 13, in this embodiment, the second ends of one or more light emitting elements 11 in the display screen may be connected to two different constant current driving circuits 13, and in each line scanning time, at least one constant current driving circuit 13 may exist in the plurality of constant current driving circuits 13 connected to the light emitting elements 11 to charge the light emitting elements 11 through a constant current, because each constant current driving circuit 13 may be controlled independently, the charging current of the light emitting elements 11 may be controlled independently, and thus the scanning time of the light emitting unit may be controlled, and further the duration of the frame period may be controlled. Moreover, because the constant currents of different constant current driving circuits 13 have different amplitudes, when the target gray scale is too small, the constant current driving circuit 13 with the smaller amplitude can be selected, so that the situation that the charging time of the constant current in each line of scanning time is too short is avoided, and the situation that a low-gray-scale picture is not fine and smooth enough is avoided. Optionally, in order to further control the duration of the frame period and avoid the situation that the low-gray level image is not fine enough, the second ends of all the light emitting elements 11 may be controlled to be connected to at least two different constant current driving circuits 13, so as to enhance the display effect. In addition, the number of light emitting elements 11 connected to the plurality of constant current driving circuits 13 in the display panel may be set as needed, and the number of light emitting elements 11 connected to the plurality of constant current driving circuits 13 is not particularly limited in this embodiment.

Alternatively, the light-emitting element 11 may be any one of a red light-emitting element R, a green light-emitting element G, and a blue light-emitting element B for realizing full-color display. Optionally, the light emitting element 11 is an organic light emitting diode. The display screen is a full-color LED display screen formed by arranging a plurality of red light-emitting elements R, green light-emitting elements G and blue light-emitting elements B, and one red light-emitting element R, one green light-emitting element G and one blue light-emitting element B form one pixel point. The scanning mode of the LED display screen refers to a ratio of the number of lines to be simultaneously lit to the number of lines in the whole area in a certain display area.

The embodiment of the utility model provides an in, be provided with a plurality of different constant current drive circuit to at least one light emitting component on the display screen and drive, and the amplitude of the constant current drive circuit output of difference is different, then the working condition of a plurality of different constant current drive circuit that light emitting component connects can be set for according to light emitting component's target grey scale value to this embodiment, that is, it is great as required target grey scale value, can set up a plurality of constant current drive circuit and export constant current value light emitting component simultaneously, light emitting component charges fastly, can reach the target grey scale value fast, effectively reduce every line light emitting component's scan time, and then reduce the frame cycle of every frame picture of display screen, avoid the problem of picture scintillation. In addition, when the target gray value is smaller, the light-emitting element is driven only by the constant current driving circuit with smaller constant current amplitude, so that the problem of too short charging time caused by larger constant current amplitude is effectively avoided, the fine degree of the low-gray-scale picture is improved, and the picture display effect is improved.

Above is the core thought of the utility model, will combine the attached drawing in the embodiment of the utility model below, to the technical scheme in the embodiment of the utility model clearly, describe completely. Based on the embodiments in the present invention, under the premise that creative work is not done by ordinary skilled in the art, all other embodiments obtained all belong to the protection scope of the present invention.

Fig. 3 is a schematic partial structure diagram of another display screen provided by the embodiment of the present invention, fig. 4 is a schematic structural diagram of a display screen provided by the embodiment of the present invention, it is optional, and the display screen further includes: a switching tube 14 and a grid drive circuit 15; the switch tubes 14 are arranged in one-to-one correspondence with the light-emitting elements 11; the switch tube 14 is used for connecting the first level output end 12 and a first end of the corresponding light-emitting element 11; the gate driving circuit 15 is electrically connected to the control terminal of the switching tube 14, and is configured to turn on the switching tube 14 line by line. In this embodiment, the light-emitting units of multiple colors are combined to form a full-color LED lamp bead 11a, and in this embodiment, the full-color LED lamp bead 11a includes a red light-emitting element R, a green light-emitting element G, and a blue light-emitting element B. The gate driving circuit 15 includes row driving units having the same number of rows, each of the row driving units may drive the switching tube 14 of the light emitting element 11 of the corresponding row, during the row scanning time, the switching tube 14 is turned on, and the first level output terminal 12 may output the first level to the first terminal of the light emitting element 11, at this time, if the constant current driving circuit outputs the constant current to the light emitting element 11, the light emitting element 11 emits light.

Optionally, the display screen further includes: a control chip 16; the control chip 16 is electrically connected to the plurality of constant current driving circuits 13, respectively, and is configured to control a time when the constant current driving circuits 13 output a constant current. The control chip 16 can control the number of constant current driving circuits 13 connected to the same light emitting element to output constant current in the line scanning time.

With continued reference to fig. 3, optionally, the second terminals of at least one light emitting element 11 are connected to the first constant current driving circuit 131 and the second constant current driving circuit 132; the first constant current driving circuit 131 is for outputting a first constant current to the light emitting element 11; the second constant current driving circuit 132 is for outputting a second constant current to the light emitting element 11; the magnitude of the first constant current is larger than that of the second constant current.

Consider that LED's electric current and luminance are very close linear relation, the utility model discloses a two constant current sources connect the drive LED in parallel simultaneously and combine the PWM mode, represent as the following formula:

L＝L1+L2；

L1＝f(I1*T)＝f(I1*GH*t0)；

L2＝f(I2*T)＝f(I2*GL*t0)；

as shown in fig. 5, fig. 5 is a schematic diagram of PWM modulation provided by the embodiment of the present invention, and the above control manner can effectively reduce the duration of each line scanning time, and avoid the problem that t0 is too small when the gray value is too small. Optionally, the amplitude of the second constant current is smaller than or equal to 0.1 times the amplitude of the first constant current, although other multiple relationships may exist between the second constant current and the first constant current, which is not particularly limited in this embodiment.

With continued reference to fig. 5, the total luminance of the LED is the sum of two integrated areas, I1 is a large current, I2 is a small current, and assuming that I1 is X times of I2 and the luminance L1 is X times of luminance L2, g can be decomposed into a high-order gray-scale value GH (integer) and a low-order gray-scale value GL (integer), and the display gray-scale value g of the LED is X GH + GL. When the required gray value g is small, the charging is mainly carried out through I2, the situations that the charging time is short and the picture is not fine and smooth enough are avoided, when the required gray value g is large, the charging is carried out through I1, or the charging is carried out through I1 and I2 simultaneously, the problem that the scanning time is too long is avoided, the picture flicker is avoided, and the high refresh rate is achieved.

Based on the same conception, the embodiment of the utility model provides a still provide a drive method of display screen. Fig. 6 is a schematic flowchart of a driving method for a display screen according to an embodiment of the present invention, as shown in fig. 6, the method of this embodiment includes the following steps:

and S101, controlling at least one of at least two different constant current driving circuits connected with the light-emitting element to provide constant current for the light-emitting element in the line scanning time of the light-emitting element.

The embodiment of the utility model provides an in, at least one light emitting component to on the display screen is provided with the constant current drive circuit of a plurality of differences and drives, and the amplitude of the constant current drive circuit output of difference is different, then this embodiment can set for the behavior of the constant current drive circuit of a plurality of differences that light emitting component connects according to light emitting component's target grey level, namely, it is great as required target grey level value, can set up a plurality of constant current drive circuit and export constant current value light emitting component simultaneously, light emitting component charges very fast, can reach the target grey level value fast, effectively reduce every line light emitting component's scan time, and then reduce the frame cycle of every frame picture of display screen, avoid the problem of picture scintillation. In addition, when the target gray value is smaller, the light-emitting element is driven only by the constant current driving circuit with smaller constant current amplitude, so that the problem of too short charging time caused by larger constant current amplitude is effectively avoided, the fine degree of the low-gray-scale picture is improved, and the picture display effect is improved.

On the basis of the above embodiment, at least one light emitting element is connected to a first constant current driving circuit and a second constant current driving circuit; the amplitude of the first constant current that first constant current drive circuit exported is greater than the amplitude of the second constant current that second constant current drive circuit exported, as shown in fig. 7, fig. 7 does the embodiment of the utility model provides a flow chart of the drive method of another kind of display screen, control at least one of the at least two different constant current drive circuits that light emitting component connects and provide the constant current for light emitting component, include the following step:

step S201, when the target gray-scale value of the light emitting element is greater than the first set threshold, controlling the first constant current driving circuit and the second constant current driving circuit to output a constant current for the light emitting element at the same time.

Step S202, when the target gray-scale value of the light emitting device is greater than the second set threshold and smaller than the first set threshold, the first constant current driving circuit is controlled to output a constant current to the light emitting device.

Step S203, when the target gray-scale value of the light emitting device is smaller than the second set threshold, the second constant current driving circuit is controlled to output a constant current to the light emitting device.

In this embodiment, the second set threshold is smaller than the first set threshold.

Each constant current driving circuit can be independently controlled, so that the charging current of the light-emitting element can be independently controlled, the scanning time of the light-emitting unit can be controlled, and the duration of a frame period can be controlled. Moreover, because the amplitude values of the constant currents of different constant current driving circuits are different, when the target gray scale is too small, the constant current driving circuit with the smaller amplitude value can be selected, so that the situation that the charging time of the constant current in each line of scanning time is too short is avoided, and the situation that a low-gray-scale picture is not fine and smooth enough is avoided.

It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.

Claims

1. A display screen, comprising:

2. The display screen according to claim 1, wherein a second end of at least one of the light-emitting elements is connected to a first constant current drive circuit and a second constant current drive circuit;

the first constant current driving circuit is used for outputting a first constant current to the light emitting element; the second constant current driving circuit is used for outputting a second constant current to the light-emitting element;

the magnitude of the first constant current is larger than the magnitude of the second constant current.

3. The display panel according to claim 2, wherein the magnitude of the second constant current is less than or equal to 0.1 times the magnitude of the first constant current.

4. The display screen of claim 1, further comprising: a control chip; the control chip is respectively electrically connected with the constant current driving circuits and is used for controlling the time for the constant current driving circuits to output the constant current.

5. The display panel according to claim 1, wherein the light-emitting element is any one of a red light-emitting element, a green light-emitting element, and a blue light-emitting element.

6. The display screen of claim 1, wherein the light emitting elements are organic light emitting diodes.

7. The display screen of claim 1, further comprising: a switching tube and a grid driving circuit;

the switch tubes and the light-emitting elements are arranged in a one-to-one correspondence manner; the switch tube is used for connecting the first level output end and the first end of the corresponding light-emitting element;

the grid driving circuit is electrically connected with the control end of the switch tube and used for conducting the switch tube line by line.