Patent Publication Number: US-2022216183-A1

Title: Display substrate and display device

Description:
TECHNICAL FIELD 
     At least one embodiment of the present disclosure relates to a display substrate and a display device. 
     BACKGROUND 
     With the development of display technology, people&#39;s requirements for the resolution of the display device have gradually improved. Compared with a liquid crystal display device (LCD) and an organic light emitting diode (OLED) display device, an inorganic light emitting display device, such as Mini LED or Micro LED, has the advantages of ultra-high resolution display. The application of Mini LED or Micro LED to 3D display technology can also improve the 3D display effect. 
     SUMMARY 
     At least an embodiment of the present disclosure provides a display substrate and a display device. 
     At least an embodiment of the present disclosure provides a display substrate, which includes a backplane including a plurality of pixel regions; and a plurality of light emitting units arranged in one-to-one correspondence with the plurality of pixel regions. Each of the plurality of light emitting units includes light emitting sub-units arranged in a plurality of rows and a plurality of columns, each row of light emitting sub-units includes a plurality of light emitting sub-units arranged along a row direction, each column of light emitting sub-units includes one light emitting sub-unit, and orthographic projections of light emitting regions of two adjacent columns of light emitting sub-units on a first straight line extending along a column direction are not overlapped; and in each of the plurality of light emitting units, there is no gap between orthographic projections of the light emitting regions of the two adjacent columns of light emitting sub-units on a second straight line extending along the row direction. 
     For example, in an embodiment of the present disclosure, the orthographic projections of the light emitting regions of the two adjacent columns of light emitting sub-units on the second straight line are overlapped, or, endpoints, which are close to each other, of the orthographic projections of the light emitting regions of the two adjacent columns of light emitting sub-units on the second straight line coincide. 
     For example, in an embodiment of the present disclosure, a distance between light emitting regions of any two light emitting sub-units located in a same row and adjacent to each other is equal. 
     For example, in an embodiment of the present disclosure, the light emitting sub-units arranged in the plurality of rows and the plurality of columns include N rows of light emitting sub-units, and an orthographic projection of light emitting regions of an n-th row of light emitting sub-units on the second straight line is located between an orthographic projection of light emitting regions of an (n−1)-th row of light emitting sub-units on the second straight line and an orthographic projection of light emitting regions of an (n+1)-th row of light emitting sub-units on the second straight line, or the orthographic projection of the light emitting regions of the n-th row of light emitting sub-units on the second straight line is located between the orthographic projection of the light emitting regions of the (n−1)-th row of light emitting sub-units on the second straight line and an orthographic projection of light emitting regions of a first row of light emitting sub-units on the second straight line, where N&gt;1 and 1&lt;n≤N. 
     For example, in an embodiment of the present disclosure, each of the plurality of pixel regions includes first contact pads arranged in a plurality of rows and a plurality of columns and at least one second contact pad, and the at least one second contact pad is located at one side of the first contact pad distributed at an edge of the each of the plurality of pixel regions away from the first contact pad distributed at a center of the each of the plurality of pixel regions; each of the plurality of light emitting units includes a plurality of first electrodes and at least one second electrode located at a same side, and each of the light emitting sub-units includes one first electrode, at least parts of the plurality of first electrodes are configured to be respectively connected with the first contact pads arranged in the plurality of rows and the plurality of columns, and the second electrode is configured to be connected with the second contact pad. 
     For example, in an embodiment of the present disclosure, each of the plurality of light emitting units further includes a plurality of first conductive type semiconductor layers, a second conductive type semiconductor layer and a light emitting layer located between the plurality of first conductive type semiconductor layers and the second conductive type semiconductor layer, the plurality of first conductive type semiconductor layers are respectively connected with the plurality of first electrodes in one-to-one correspondence, and the second conductive type semiconductor layer is connected with the second electrode. 
     For example, in an embodiment of the present disclosure, in each of the plurality of light emitting units, the second electrode is a common electrode shared by the plurality of light emitting sub-units, and the second conductive type semiconductor layer is a continuous film. 
     For example, in an embodiment of the present disclosure, in each of the plurality of light emitting units, each of the plurality of light emitting sub-units includes a plurality of nano-pillar structures arranged at intervals, each of the plurality of nano-pillar structures at least includes the light emitting layer, the first conductive type semiconductor layer and the first electrode which are stacked, and the light emitting region of each of the plurality of light emitting sub-units is at least partially overlapped with each of the plurality of first contact pads. 
     For example, in an embodiment of the present disclosure, each row of first contact pads includes a plurality of first contact pads arranged along the row direction, each column of first contact pads includes one first contact pad, and orthographic projections of two adjacent columns of first contact pads on the first straight line are not overlapped; and in each of the plurality of pixel regions, there is no gap between orthographic projections of the two adjacent columns of first contact pads on the second straight line. 
     For example, in an embodiment of the present disclosure, the orthographic projections of the two adjacent columns of first contact pads on the second straight line are overlapped, or, endpoints, which are close to each other, of the orthographic projections of the two adjacent columns of first contact pads on the second straight line coincide. 
     For example, in an embodiment of the present disclosure, a distance between any two first contact pads located in a same row and adjacent to each other is equal. 
     For example, in an embodiment of the present disclosure, a pitch of the plurality of nano-pillar structures along the row direction is less than a distance between adjacent first contact pads arranged along the row direction. 
     For example, in an embodiment of the present disclosure, the magnitude of the pitch along the row direction is in a range from 200 nanometers to 100 micrometers, the distance between adjacent first contact pads arranged along the row direction is in a range from 5 micrometers to 1000 micrometers, and the size of each of the plurality of nano-pillar structures along the row direction is in a range from 100 nanometers to 50 micrometers. 
     For example, in an embodiment of the present disclosure, in each of the plurality of light emitting units, the light emitting layer is a continuous film. 
     For example, in an embodiment of the present disclosure, the backplane is located at a light exiting side of the plurality of light emitting units, and a light shielding layer is disposed at least one of between adjacent light emitting units, at a side of the plurality of light emitting units away from the backplane and between adjacent first electrodes. 
     For example, in an embodiment of the present disclosure, the display substrate further includes: a light splitting device, located at a light exiting side of the plurality of light emitting units, and configured to split light emitted from the plurality of light emitting sub-units into different viewpoint regions. 
     For example, in an embodiment of the present disclosure, the light splitting device includes a plurality of lenses arranged along the row direction, and an orthographic projection of each of the plurality of lens on the base substrate is overlapped with an orthographic projection of one column of light emitting units on the base substrate. 
     For example, in an embodiment of the present disclosure, each of the plurality of light emitting units is a micro light emitting diode or a mini light emitting diode. 
     At least an embodiment provides a display device, including the display substrate as mentioned above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to clearly illustrate the technical solutions of the embodiments of the disclosure, the drawings of the embodiments will be briefly described in the following; it is obvious that the described drawings are only related to some embodiments of the disclosure and thus are not limitative to the disclosure. 
         FIG. 1  is a partial structural view of a backplane of a display substrate according to an embodiment of the present disclosure; 
         FIG. 2  is a partial cross-sectional structural view of a display substrate according to an embodiment of the present disclosure; 
         FIG. 3  is a view of visual effect of a light emitting region corresponding to one pixel region shown in  FIG. 1 ; 
         FIG. 4  is a principle diagram of visual effect of adjacent three columns of light emitting regions corresponding to one pixel region shown in  FIG. 3 ; 
         FIG. 5  is a schematic diagram of 3D display in the case where there is a gap between adjacent light emitting regions in a light emitting unit; 
         FIG. 6  is a schematic diagram of 3D display in the case where there is no gap between adjacent light emitting regions in a light emitting unit; 
         FIG. 7A  is a partial cross-sectional structural view of normal bonding between a light emitting unit and a backplane; 
         FIG. 7B  is a schematic diagram of the case where bonding deviation occurs between the light emitting unit and the backplane shown in  FIG. 7A ; 
         FIG. 8A  is a partial cross-sectional structural view of normal bonding between the light emitting unit and the backplane shown in  FIGS. 1-3 ; 
         FIG. 8B  is a schematic diagram of the case where bonding deviation occurs between the light emitting unit and the backplane shown in  FIG. 8A ; 
         FIG. 9  is a partial structural view of a light emitting unit of a display substrate according to another embodiment of the present disclosure; 
         FIG. 10  is a planar structural view of the light emitting unit of the display substrate shown in  FIG. 9 ; 
         FIG. 11  is a partial structural view of a light emitting unit of a display substrate according to another embodiment of the present disclosure; 
         FIG. 12  is a planar structural view of the light emitting unit of the display substrate shown in  FIG. 11 ; 
         FIG. 13  is a planar structural view of a display substrate according to an embodiment of the present disclosure; 
         FIG. 14  is a partial cross-sectional structural view taken along line BB shown in  FIG. 13 ; 
         FIG. 15  is a schematic diagram of arranging a light splitting device at a light exiting side of the light emitting unit shown in  FIG. 9 ; 
         FIG. 16  is a schematic diagram of arranging a light splitting device at a light exiting side of the light emitting unit shown in  FIG. 11 ; 
         FIG. 17  is a schematic diagram of a light path of the display substrate shown in  FIGS. 14-16 ; 
         FIG. 18  is a cross-sectional structural view of a lens and a planarization layer shown in  FIG. 17 ; 
         FIG. 19  is a schematic diagram of a driving mode of a display substrate according to an embodiment of the present disclosure; and 
         FIG. 20  and  FIG. 21  are schematic diagrams of driving modes of a display substrate according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In order to make objects, technical details and advantages of the embodiments of the disclosure apparent, the technical solutions of the embodiments will be described in a clearly and fully understandable way in connection with the drawings related to the embodiments of the disclosure. Apparently, the described embodiments are just a part but not all of the embodiments of the disclosure. Based on the described embodiments herein, those skilled in the art can obtain other embodiment(s), without any inventive work, which should be within the scope of the disclosure. 
     Unless otherwise defined, all the technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the present disclosure belongs. The terms “first,” “second,” etc., which are used in the description and the claims of the present disclosure, are not intended to indicate any sequence, amount or importance, but distinguish various components. Also, the terms “comprise,” “comprising,” “include,” “including,” etc., are intended to specify that the elements or the objects stated before these terms encompass the elements or the objects and equivalents thereof listed after these terms, but do not preclude the other elements or objects. 
     The embodiments of the present disclosure provide a display substrate and a display device. The display substrate includes: a backplane, including a plurality of pixel regions; a plurality of light emitting units arranged in one-to-one correspondence with the plurality of pixel regions. Each light emitting unit includes light emitting sub-units arranged in a plurality of rows and a plurality of columns, each row of light emitting sub-units includes a plurality of light emitting sub-units arranged along a row direction, each column of light emitting sub-units includes one light emitting sub-unit, and orthographic projections of light emitting regions of two adjacent columns of light emitting sub-units on a first straight line extending along a column direction are not overlapped; and in each light emitting unit, there is no gap between orthographic projections of the light emitting regions of the two adjacent columns of light emitting sub-units on a second straight line extending along the row direction. In the embodiments of the present disclosure, by setting the positional relationship of the light emitting regions of two adjacent columns of light emitting sub-units on the display substrate, there may be no black region between the light emitting regions of two adjacent columns of light emitting sub-units, so as to improve the display effect. 
     Hereinafter, the display substrate and the display device provided by the embodiments of the present disclosure will be described with reference to the accompanying drawings. 
       FIG. 1  is a partial structural view of a backplane of a display substrate according to an embodiment of the present disclosure. As shown in  FIG. 1 , the backplane includes a base substrate  100  and a plurality of pixel regions  200  located on the base substrate  100 , and each pixel region  200  includes first contact pads  210  arranged in a plurality of rows and a plurality of columns. For example, as shown in  FIG. 1 , in the embodiment of the present disclosure, the row direction is the X direction and the column direction is the Y direction. The embodiment of the present disclosure illustratively shows that the row direction and the column direction are substantially perpendicular to each other, but is not limited thereto, and the row direction and the column direction may not be perpendicular to each other. For example, the plurality of pixel regions  200  can be arrayed along the row direction and the column direction, but are not limited thereto. For example,  FIG. 1  illustratively shows that each pixel region  200  can include three rows of first contact pads  210 , but is not limited thereto. Each pixel region can include two rows of first contact pads, or each pixel region can include four or more rows of first contact pads, the embodiment of the present disclosure is not limited thereto. The number of rows and columns of the first contact pads can be determined according to the requirement and size of the actual product. 
     As shown in  FIG. 1 , in each pixel region  200 , each row of first contact pads  210  includes a plurality of first contact pads  210  arranged along the row direction, and each column of first contact pads  210  includes one first contact pad  210 . For example, in each pixel region  200 , the number of the first contact pads  210  arranged in the row direction is multiple, and the number of the first contact pads  210  arranged in the column direction is one, that is, each first contact pad  210  is a single column of first contact pads  210 . 
     As shown in  FIG. 1 , the orthographic projections of two adjacent columns of first contact pads  210  on a first straight line extending along the column direction are not overlapped; in each pixel region  200 , there is no gap between the orthographic projections of two adjacent columns of first contact pads  210  on a second straight line extending along the row direction. For example, as shown in  FIG. 1 , the base substrate  100  includes a first side  101  extending along the column direction and a second side  102  extending along the row direction. For example, the first straight line described above is the straight line in which the first side  101  of the base substrate  100  is located, and the second straight line described above is the straight line in which the second side  102  of the base substrate  100  is located. For example, as shown in  FIG. 1 , in each pixel region  200 , the orthographic projections of two adjacent columns of first contact pads  210  on the first side  101  are not overlapped, and there is no gap between the orthographic projections of two adjacent columns of first contact pads  210  on the second side  102 . The “two adjacent columns of first contact pads” described above refers to two first contact pads located in two adjacent columns, the two first contact pads are located in different rows, and there is not any other first contact pad between the two columns of first contact pads. 
     For example, as shown in  FIG. 1 , the orthographic projections of two adjacent columns of first contact pads  210  on the second straight line are overlapped, so that there is no gap between the orthographic projections of the two adjacent columns of first contact pads on the second straight line. For example, the orthographic projections of two adjacent columns of first contact pads  210  on the second side  102  of the base substrate  100  are overlapped. For example, the size of the overlapping part of the orthographic projections of two adjacent columns of first contact pads  210  on the second straight line is relatively small, and the size is not greater than  1 / 20  of the size of each first contact pad  210  in the row direction. 
     For example, as shown in  FIG. 1 , the endpoints, which are close to each other, of the orthographic projections of two adjacent columns of first contact pads  210  on the second straight line coincide. For example, the endpoints, which are close to each other, of the orthographic projections of two adjacent columns of first contact pads  210  on the second side of the base substrate  100  coincide. For example, as shown in  FIG. 1 , taking that the shape of each first contact pad  210  is rectangular as an example, the edge of the first column of first contact pads  210  close to the second column of first contact pads  210  and extending in the Y direction is in a straight line with the edge of the second column of first contact pads  210  close to the first column of first contact pads  210  and extending in the Y direction, the edge of the second column of first contact pads close to the third column of first contact pads  210  and extending in the Y direction is in a straight line with the edge of the third column of first contact pads  210  close to the second column of first contact pads  210  and extending in the Y direction, and so on. 
     For example, as shown in  FIG. 1 , the distance between any two first contact pads  210  located in the same row and adjacent to each other is equal. For example, two first contact pads  210  located in the same row and adjacent to each other are respectively located in non-two adjacent columns. For example, as shown in  FIG. 1 , the distance between two first contact pads  210  located in the first row and adjacent to each other is equal to the distance between two first contact pads  210  located in the second row and adjacent to each other, the distance between two first contact pads  210  located in the second row and adjacent to each other is equal to the distance between two first contact pads  210  located in the third row and adjacent to each other, and so on. 
     For example, as shown in  FIG. 1 , the first contact pads  210  arranged in the plurality of rows and the plurality of columns include N rows of first contact pads  210 , and the orthographic projection of the n-th row of first contact pads  210  on the second straight line is located between the orthographic projection of the (n−1)-th row of first contact pads  210  on the second straight line and the orthographic projection of the (n+1)-th row of first contact pads  210  on the second straight line, or the orthographic projection of the n-th row of first contact pads  210  on the second straight line is located between the orthographic projection of the (n−1)-th row of first contact pads  210  on the second straight line and the orthographic projection of the first row of first contact pads  210  on the second straight line, where N&gt;1 and 1&lt;n≤N. 
     For example, as shown in  FIG. 1 , taking N=3 as an example, the orthographic projection of the second row of first contact pads  210  on the second straight line is located between the orthographic projection of the first row of first contact pads  210  on the second straight line and the orthographic projection of the third row of first contact pads  210  on the second straight line, the orthographic projection of the third row of first contact pads  210  on the second straight line is located between the orthographic projection of the second row of first contact pads  210  on the second straight line and the orthographic projection of the first row of first contact pads  210  on the second straight line. 
     For example, taking adjacent N columns of first contact pads  210  as one contact pad group, each contact pad group includes the first to N-th rows of first contact pads  210 , and the first contact pads  210  having a count of N in each contact pad group are arranged in a stepped shape. For example, the orthographic projections of the first contact pads  210  having a count of N in each contact pad group on the second straight line are sequentially arranged in the order from the first row to the n-th row. 
     For example, as shown in  FIG. 1 , each pixel region  200  further includes at least one second contact pad  220 , and the second contact pad  220  is located at one side of the first contact pad  210  distributed at the edge of each pixel region away from the first contact pad  210  distributed at the center of each pixel region. For example, the second contact pad  220  can be located at one side of the last row of first contact pads  210  away from the first row of first contact pads  210 , but is not limited thereto, and the second contact pad  220  can be located at one side of the first row of first contact pads away from the last row of first contact pads  210 . For example, the second contact pad  220  is not distributed between adjacent first contact pads  210  in the same row, and the second contact pad  220  is not distributed between adjacent rows of first contact pads  210 . 
     For example, as shown in  FIG. 1 , each pixel region  200  can also include two second contact pads  220 , and the two second contact pads  220  can be located at two diagonal positions close to the each pixel region  200 . 
       FIG. 2  is a partial cross-sectional structural view of a display substrate according to an embodiment of the present disclosure, and  FIG. 2  shows a partial cross-sectional structural view taken along line AA shown in  FIG. 1 . As shown in  FIG. 2 , the display substrate includes the backplane shown in  FIG. 1  and a plurality of light emitting units  300  arranged in one-to-one correspondence with the plurality of pixel regions  200 , each light emitting unit  300  includes a plurality of first electrodes  310  and a second electrode  320  located at the same side, at least parts of the first electrodes  310  are configured to be respectively connected with the first contact pads  210  arranged in the plurality of rows and the plurality of columns, and the second electrode  320  is configured to be connected with the second contact pad  220 . The plurality of first electrodes described above are arranged at intervals. For example, as shown in  FIG. 2 , the first electrodes  310  and the second electrode  320  of each light emitting unit  300  are located at one side of the light emitting unit  300  facing the backplane, so as to be electrically connected with the first contact pads  210  and the second contact pad  220  on the backplane, respectively. 
     For example, the number of the first electrodes  310  included in each light emitting unit  300  can be greater than the number of the first contact pads  210  included in the corresponding pixel region  200 . For example, the first electrodes  310  included in each light emitting unit  300  can be arranged in an array, and a light emitting sub-unit  301  is formed at the position where the first electrode  310  contact with the first contact pad  210 , so the position arrangement of the light emitting sub-units  301  is determined by the position arrangement of the first contact pads  210 , and the position and the size of the light emitting region of the light emitting sub-unit  301  are also respectively determined by the position and the size of the first contact pad  210 . 
     For example, a tapered or tubular protruding structure can be formed at one side of the first electrode  310  facing the first contact pad  210 , or a hard metal structure with protrusions can be additionally provided at one side of the first electrode  310  facing the first contact pad  210 , or a conductive particle can be provided at one side of the first electrode  310  facing the first contact pad  210 , and so on, so that a non-conductive adhesive can be coated on the first electrode  310  or the first contact pad  210  when the first electrode  310  is bonded to the first contact pad  210 , thus ensuring the alignment and physical connection therebetween; then, the protruding structure or conductive particle at one side of the first electrode  310  facing the first contact pad  210  are pressed onto the first contact pad  210  by external force such as pressure, thereby realizing the electrical connection between the first electrode  310  and the first contact pad  210 . Accordingly, a tapered or tubular protruding structure can be formed at one side of the first contact pad  210  facing the first electrode  310 , or a hard metal structure with protrusions can be additionally provided at one side of the first contact pad  210  facing the first electrode  310 , or a conductive particle can be provided at one side of the first contact pad  210  facing the first electrode  310 , and so on, so that a non-conductive adhesive can be coated on the first electrode  310  or the first contact pad  210  when the first electrode  310  is bonded to the first contact pad  210 , thus ensuring the alignment and physical connection therebetween; then, the protruding structure or conductive particle at one side of the first electrode  310  facing the first contact pad  210  are pressed onto the first contact pad  210  by external force such as pressure, thereby realizing the electrical connection between the first electrode  310  and the first contact pad  210 . 
     The embodiments of the present disclosure are not limited thereto. When the first electrode is bonded to the first contact pad, an anisotropic conductive adhesive can also be coated on the first electrode or the first contact pad, and then a conductive path in the vertical direction can be realized under the pressure, so as to realize electrical connection and adhesive bonding between the first electrode and the first contact pad. For example, the first electrode  310  in part of light emitting units  300  can include indium tin oxide (ITO) and a metal material located at one side of ITO facing the first contact pad  210 , such as titanium, aluminum, nickel, gold, copper, indium, zinc, silver or zinc alloy, etc., and the metal material is electrically connected with the first contact pad. For example, after the light emitting unit is transferred onto the backplane by means of laser, machinery, etc., the light emitting units can be fixed on the backplane under certain pressure and temperature, or by means of ultraviolet irradiation. 
     For example, the plurality of light emitting units can include a blue light emitting unit, a green light emitting unit and a red light emitting unit, the blue light emitting unit is configured to emit blue light, the green light emitting unit is configured to emit green light, and the red light emitting unit is configured to emit red light. The distribution manner of light emitting sub-units in each color light emitting unit is the same, that is, the distribution manner of first contact pads in the pixel region corresponding to each color light emitting unit is the same. 
     As shown in  FIG. 2 , each light emitting unit  300  further includes a plurality of first conductive type semiconductor layers  330 , a second conductive type semiconductor layer  350  and light emitting layers  340  located between the plurality of first conductive type semiconductor layers  330  and the second conductive type semiconductor layer  350 , the plurality of first conductive type semiconductor layers  330  are respectively connected with the plurality of first electrodes  310  in one-to-one correspondence, and the second conductive type semiconductor layer  350  is connected with the second electrode  320 . The plurality of first conductivity type semiconductor layers described above are arranged at intervals. 
     It should be noted that the above-mentioned “conductivity type” includes n type or p type. For example, the first conductivity type semiconductor layer can be an n-type semiconductor layer and the second conductivity type semiconductor layer can be a p-type semiconductor layer. Of course, the embodiments of the present disclosure include but are not limited thereto, and the first conductivity type semiconductor layer can be a p-type semiconductor layer and the second conductivity type semiconductor layer can be an n-type semiconductor layer. For example, in the case where the light emitting unit is a blue light emitting unit or a green light emitting unit, the first conductive type semiconductor layer is a p-type semiconductor layer and the second conductive type semiconductor layer is an n-type semiconductor layer; and in the case where the light emitting unit is a red light emitting unit, the first conductive type semiconductor layer is an n-type semiconductor layer and the second conductive type semiconductor layer is a p-type semiconductor layer. 
     For example, the first electrode  310  is a p-electrode, the first conductive type semiconductor layer  330  is a p-type semiconductor layer, the second electrode  320  is an n-electrode, and the second conductive type semiconductor layer  350  is an n-type semiconductor layer. Holes and electrons are injected into the second conductive type semiconductor layer  350  and the first conductive type semiconductor layer  330  from the second electrode  320  and the first electrode  310 , respectively, and then recombine in the light emitting layer  340 , which is expressed by releasing energy in the form of photons. The luminescent wavelength depends on the band gap of the luminescent material The present embodiment is not limited thereto, and the first electrode can be an n-electrode, the first conductive type semiconductor layer can be an n-type semiconductor layer, the second electrode can be a p-electrode, and the second conductive type semiconductor layer can be a p-type semiconductor layer. 
     For example, in some examples, the first conductive type semiconductor layer  330  is an n-type gallium nitride layer and the second conductive type semiconductor layer  350  is a p-type gallium nitride layer. Of course, the embodiments of the present disclosure include but are not limited thereto, and the first conductive type semiconductor layer  330  can be a p-type gallium nitride layer and the second conductive type semiconductor layer  350  can be an n-type gallium nitride layer. 
     For example, in the case where the light emitting unit is configured to emit blue light or green light, the first conductive type semiconductor layer and the second conductive type semiconductor layer can adopt gallium nitride (GaN) as described above. In the case where the light emitting unit is configured to emit red light, the first conductive type semiconductor layer and the second conductive type semiconductor layer can adopt gallium phosphide (GaP), aluminum gallium arsenide (AlGaAs) or aluminum gallium indium phosphide (AlGaInP). Of course, the embodiments of the present disclosure include but are not limited to these case, and the first conductive type semiconductor layer and the second conductive type semiconductor layer can also be made of other suitable materials. 
     For example, in some examples, the light emitting layer  340  described above includes a multi-quantum well layer (MQW), and the multi-quantum well layer includes a plurality of quantum wells, so that the luminous intensity and luminous efficiency of the light emitting unit can be improved. Of course, the embodiments of the present disclosure include but are not limited thereto, and the light emitting layer described above can also be any other suitable light emitting layer such as a quantum well layer or a PN junction. 
     For example, as shown in  FIG. 2 , the orthographic projections of the first electrode  310  and the second electrode  320  in each light emitting unit  300  on the base substrate  100  are overlapped with the orthographic projection of the second conductive type semiconductor layer  350  on the base substrate, and both the first electrode  310  and the second electrode  320  are located at one side of the second conductive type semiconductor layer  350  facing the base substrate  100 . 
     For example, as shown in  FIG. 2 , the orthographic projection of the first conductive type semiconductor layer  330  on the base substrate  100  is substantially coincident with the orthographic projection of the first electrode  310  on the base substrate  100 . The light emitting region of each light emitting sub-unit is related to a contact region between the first conductive type semiconductor layer and the light emitting layer, and a contact region between the first electrode and the first contact pad. 
     For example, as shown in  FIG. 2 , a buffer layer  360  is further disposed at one side of the second conductive type semiconductor layer  350  away from the first electrode  310 , and the buffer layer can improve the quality of the second conductive type semiconductor layer  350 . 
     For example, the light emitting unit provided by the embodiments of the present disclosure can be formed on a sapphire substrate, and the sapphire substrate is located at one side of the buffer layer away from the second conductive type semiconductor layer; and after the light emitting unit is transferred onto the backplane, the sapphire substrate can be lifted off to increase light exiting amount (in the case where the second conductive type semiconductor layer is located at the light exiting side). 
     For example, as shown in  FIG. 2 , in each light emitting unit  300 , each light emitting sub-unit  301  includes one first electrode  310  and one first conductive type semiconductor layer  330 , and the first electrode  310  in each light emitting sub-unit  301  is configured to be connected with one first contact pad  210 . In each light emitting unit  300 , the second electrode  320  is a common electrode shared by the plurality of light emitting sub-units  301 , the second conductive type semiconductor layer  350  is a continuous film, and the second electrode  320  is configured to be connected with the second contact pad  220 . 
     In the light emitting unit provided by the embodiments of the present disclosure, one first electrode, one first conductive type semiconductor layer, the light emitting layer, the second conductive type semiconductor layer and the second electrode can form one light emitting sub-unit. The second electrode can be a common electrode shared by at least two light emitting sub-units. Because the light emitting unit includes at least two first conductivity type semiconductor layers and at least two first electrodes, the light emitting unit can be formed with at least two light emitting sub-units which can emit light independently. 
     In the embodiments of the present disclosure, in the case where one light emitting unit includes a plurality of light emitting sub-units which can emit light independently, the plurality of light emitting sub-units can be transferred at one time in the process of transferring the light emitting unit onto the backplane, thereby improving the transfer efficiency. 
     For example, the light emitting unit in the embodiments of the present disclosure can be a micro LED or a mini LED. For example, the maximum size of each light emitting unit in the direction parallel to the base substrate can be 30 microns to 600 microns. For example, the maximum size of each light emitting unit in the direction parallel to the base substrate can refer to the diagonal length, side length or diameter, etc., of the planar shape of the light emitting unit parallel to the base substrate. For example, in the case where the shape of the light emitting unit is polygonal, the maximum size of each light emitting unit in the direction parallel to the base substrate can be the diagonal length of the polygon. For example, in the case where the shape of the light emitting unit is circular, the maximum size of each light emitting unit in the direction parallel to the base substrate can be a diameter. 
     On the one hand, in the case where the overall size of the light emitting diode remains unchanged, the size of a single light emitting sub-unit can be reduced by forming a plurality of light emitting sub-units in the light emitting diode. For example, light emitting diode chips with smaller size can be manufactured with existing process accuracy. Therefore, the light emitting unit provided by the embodiments of the present disclosure can reduce the manufacturing difficulty and cost of small-sized light emitting diodes by arranging a plurality of light emitting sub-units, and can also realize higher pixels per inch. 
     For example, as shown in  FIG. 2 , in each light emitting unit  300 , each first electrode  310  connected with each first contact pad  210  includes a plurality of sub-electrodes  311  spaced apart from each other, the first conductive type semiconductor layer  330  includes a plurality of sub-semiconductor layers  331  spaced apart from each other, the plurality of sub-semiconductor layers  331  are in one-to-one correspondence with the plurality of sub-electrodes  311 , and the light emitting layer  340  includes a plurality of sub-light emitting layers  341  spaced apart from each other, and the plurality of sub-light emitting layers  341  are in one-to-one correspondence with the plurality of sub-electrodes  311 . 
     For example, as shown in  FIG. 2 , the orthographic projection of each sub-light emitting layer  341  on the base substrate  100  basically coincides with the orthographic projection of each sub-electrode  311  on the base substrate  100 . For example, the orthographic projection of each sub-semiconductor layer  331  on the base substrate  100  basically coincides with the orthographic projection of each sub-electrode  311  on the base substrate  100 . For example, each light emitting sub-unit  301  includes a plurality of nano-pillar structures  134 , and each nano-pillar structure  134  at least includes one sub-electrode  311 , one sub-semiconductor layer  331  and one sub-light emitting layer  341  which are stacked.  FIG. 2  illustratively shows that one nano-pillar structure  134  includes one sub-electrode  311 , one sub-semiconductor layer  331  and one sub-light emitting layer  341  which are stacked, but is not limited thereto. The nano-pillar structure in at least one light emitting unit can also include a part of the second conductive type semiconductor layer, that is, the second conductive type semiconductor layer can include a plurality of protrusions, each protrusion is a part of one nano-pillar structure, and a concave portion between adjacent protrusions is the concave portion between adjacent nano-pillar structures. 
     For example, the sizes of each sub-electrode  311  in the row direction and column direction are respectively smaller than the sizes of each first contact pad  210  in the row direction and column direction. For example, the orthographic projection of one first contact pad  210  on the base substrate  100  is overlapped with the orthographic projections of a plurality of sub-electrodes  311  on the base substrate  100 . For example, the number of nano-pillar structures in contact with each first contact pad  210  is the same or there is little difference in the number of nano-pillar structures in contact with each first contact pad  210 , so that the area of the light emitting region of each light emitting sub-unit is basically the same. For the nano-pillar structures in contact with one first contact pad, because the sizes of the nano-pillar structures and the distance between adjacent nano-pillar structures are small, in the case where the nano-pillar structures are in contact with one first contact pad, the contact region between each nano-pillar structure and the first contact pad emits light. And the contact region between each nano-pillar structure and the first contact pad covers at least a part of the gap between adjacent nano-pillar structures, so that in the case where the nano-pillar structures are electrically connected with the first contact pad, the light emitting region is an entire region covering the first contact pad, and the area of the light emitting region is basically equal to or even slightly greater than the area of the first contact pad. For example, for the plurality of nano-pillar structures in contact with one first contact pad, the light emitting region refers to a region when each nano-pillar structure works normally so that the light emitting layer corresponding to each nano-pillar structure can emit light normally; and when one nano-pillar structure fails to emit light normally among the nano-pillar structures in contact with one first contact pad, the light emitting region still represents the light emitting region when all nano-pillar structures in contact with one first contact pad work normally. 
     For example, as shown in  FIG. 2 , the distance between adjacent sub-electrodes  311  can be in a range from 100 nanometers to 50 micrometers. For example, the sizes of each sub-electrode  311  in the row direction and the column direction can be in a range from 100 nanometers to m50 micrometers. 
     In the embodiments of the present disclosure, the shape and size of the light emitting region of each light emitting sub-unit are determined by the shape and size of the contact region between the plurality of nano-pillar structures and each first contact pad. Because the size of each nano-pillar structure and the distance between adjacent nano-pillar structures are small, the light emitting region of each light emitting sub-unit is determined by the shape and size of the contact region between the plurality of nano-pillar structures and each first contact pad. Therefore, the size and position of the light emitting region of each light emitting sub-unit can be set by setting the size and position of the first contact pad. 
     For example, as shown in  FIG. 1  and  FIG. 2 , each light emitting unit  300  includes light emitting sub-units  301  arranged in a plurality of rows and a plurality of columns, and each light emitting sub-unit  301  includes one first electrode  310 , that is, each light emitting sub-unit  301  is configured to be connected with one first contact pad  210 . For example, each row of light emitting sub-units  301  includes a plurality of light emitting sub-units  301  arranged along the row direction, and each column of light emitting sub-units  301  includes one light emitting sub-unit  301 , and the orthographic projections of light emitting regions  3001  of two adjacent columns of light emitting sub-units  301  on the first straight line extending along the column direction are not overlapped; and in each light emitting unit  300 , there is no gap between orthographic projections of the light emitting regions  3001  of the two adjacent columns of light emitting sub-units  301  on the second straight line extending along the row direction. In an embodiment of the present disclosure, the positional relationship of the plurality of first contact pads on the backplane is basically consistent with the positional relationship of light emitting regions of the plurality of light emitting sub-units on the display substrate including the backplane, so the size and position of the first contact pads  210  shown in  FIG. 1  can also represent the size and position of the light emitting regions  3001  of the sub-light emitting units  301 . 
     For example, the orthographic projections of the light emitting regions  3001  of the two adjacent columns of light emitting sub-units  301  on the second straight line are overlapped, or, the endpoints, which are close to each other, of the orthographic projections of the light emitting regions  3001  of the two adjacent columns of light emitting sub-units  301  on the second straight line coincide. For example, as shown in  FIG. 1  and  FIG. 2 , in each light emitting unit  300 , the orthographic projections of the light emitting regions  3001  of the two adjacent columns of light emitting sub-units  301  on the first side  101  are not overlapped, and there is no gap between the orthographic projections of the light emitting regions  3001  of two adjacent columns of light emitting sub-units  301  on the second side  102 . The “light emitting regions of two adjacent columns of light emitting sub-units” mentioned above refers to two light emitting regions located in two adjacent columns, the two light emitting regions are located in different rows, and there is not any other light emitting region between the two columns of light emitting regions. 
     For example, as shown in  FIG. 1  and  FIG. 2 , the distance between the light emitting regions  3001  of any two light emitting sub-units  301  located in the same row and adjacent to each other is equal. 
     For example, as shown in  FIG. 1  and  FIG. 2 , the light emitting sub-units  301  arranged in the plurality of rows and the plurality of columns include N rows of light emitting sub-units  301 , and the orthographic projection of the light emitting regions  3001  of the n-th row of light emitting sub-units  301  on the second straight line is located between the orthographic projection of the light emitting regions  3001  of the (n−1)-th row of light emitting sub-units  301  on the second straight line and the orthographic projection of the light emitting regions  3001  of the (n+1)-th row of light emitting sub-units  301  on the second straight line, or the orthographic projection of the light emitting region  3001  of the n-th row of light emitting sub-units  301  on the second straight line is located between the orthographic projection of the light emitting region  3001  of the (n−1)-th row of light emitting sub-units  301  on the second straight line and the orthographic projection of the light emitting region  3001  of the first row of light emitting sub-units  301  on the second straight line, where N&gt;1 and 1&lt;n≤N. 
     For example, as shown in  FIG. 1  and  FIG. 2 , taking N=3 as an example, the orthographic projection of the light emitting regions  3001  of the second row of light emitting sub-units  301  on the second straight line is between the orthographic projection of the light emitting regions  3001  of the first row of light emitting sub-units  301  on the second straight line and the orthographic projection of the light emitting regions  3001  of the third row of light emitting sub-units  301  on the second straight line, and the orthographic projection of the light emitting regions  3001  of the third row of light emitting sub-units  301  on the second straight line is located between the orthographic projection of the light emitting regions  3001  of the second row of light emitting sub-units  301  on the second straight line and the orthographic projection of the light emitting regions  3001  of the first row of light emitting sub-units  301  on the second straight line. The embodiments of the present disclosure illustratively shows that each light emitting unit can include three rows of light emitting sub-units, but is not limited thereto. Each light emitting unit can include two rows of light emitting sub-units, or each light emitting unit can include four or more rows of light emitting sub-units, which is not limited in the embodiments of the present disclosure. The row number and column number of the light emitting sub-units can be determined according to the requirement and size of the actual product. 
       FIG. 3  is a view of visual effect of a light emitting region corresponding to one pixel region shown in  FIG. 1 . As shown in  FIGS. 1-3 , according to the resolution limit of human eyes in terms of angle, the viewing effect presented by the arrangement of the light emitting region corresponding to each pixel region at a certain viewing distance is basically the same as the viewing effect of the light emitting regions  3001  arranged in a continuous row as shown in  FIG. 3 , and in the case where there is no gap between the orthographic projections of the light emitting regions  3001  of two adjacent columns of light emitting sub-units  301  on the second side  102 , the light emitting regions  3001  of the light emitting sub-units  301  in each light emitting unit  300  are arranged as a line of light emitting regions  3001  without gaps in visual effect, so as to form a plurality of viewpoints which are continuous and have no black region in a horizontal direction. 
       FIG. 4  is a principle diagram of visual effect of adjacent three columns of light emitting regions corresponding to one pixel region shown in  FIG. 3 . As shown in  FIG. 4 , assuming that the light emitting region  1 , the light emitting region  2  and the light emitting region  3  shown in  FIG. 1  are arranged as a column of the light emitting region  1 ′, the light emitting region  2 ′ and the light emitting region  3 ′ along the Y direction, that the size of each light emitting region in the Y direction is 10 microns, and that the distance between two adjacent light emitting regions (e.g., the light emitting region  2 ′ and the light emitting region  3 ′, or the light emitting region  2 ′ and the light emitting region  1 ′) is 2 microns, the total size h of the three light emitting regions in the Y direction is 34 microns. The minimum visual angle α of human eyes in the Y direction is 1 arc minute, and according to the formula tan(α/2)=h/2d, when the distance d between human eyes and the light emitting regions is greater than 116.88 mm, the positions of the light emitting region  1 ′, the light emitting region  2 ′ and the light emitting region  3 ′ which are arranged in three rows cannot be distinguished by human eyes. For example, the light emitting region  1 ′, the light emitting region  2 ′ and the light emitting region  3 ′ are overlapped in the same position in human eyes. In the case where the light emitting region  1 ′, the light emitting region  2 ′ and the light emitting region  3 ′ located in different rows are staggered in the row direction, such as the light emitting region  1 , the light emitting region  2  and the light emitting region  3  which are respectively located in different columns as shown in  FIG. 1 , when the distance d between human eyes and the light emitting regions  3001  is greater than 116.88 mm, the light emitting regions  3001  located in different rows cannot be distinguished by human eyes, and the light emitting region  1 , the light emitting region  2  and the light emitting region  3  will be arranged as light emitting regions in the same row and without gaps in visual effect. That is, the light emitting regions  3001  in each light emitting unit  300  is arranged as light emitting regions in one row and without gaps in visual effect. 
     In the case where the backplane shown in  FIG. 1  is applied to display, the contact region between the first contact pad and the corresponding light emitting unit is a light emitting region. For example, the size of the first contact pad is the same as the size of the light emitting region, and a relatively small light emitting region can meet the brightness requirement. In the case where there is no gap between the orthographic projections of two adjacent columns of first contact pads on the second side of the base substrate, in the case of a certain viewing distance, the two adjacent columns of light emitting regions are arranged as a line of light emitting regions without gaps in visual effect, which can prevent moire during display, thus improving display effect. 
     Compared with arranging the first contact pads in each pixel region directly in the arrangement structure shown in  FIG. 3 , the embodiment of the present disclosure arranges the first contact pads in each pixel region into a multi-row structure, which can reduce the bonding accuracy between the light emitting units and the first contact pads on the backplane, and is beneficial to reducing the transfer accuracy of the light emitting units. 
     For example, in an example of the embodiments of the present disclosure, a light splitting device  400  is provided at the light exiting side of the light emitting units, so as to split light emitted from the plurality of light emitting units to different viewpoint regions, thereby forming different display information in space. And when human eyes receive different display information in space, 3D display effect can be perceived. For example, the light splitting device can include a cylindrical mirror or a lens to control the light direction. 
     For example,  FIG. 5  is a schematic diagram of 3D display in the case where there is a gap between adjacent light emitting regions in the light emitting unit, and  FIG. 6  is a schematic diagram of 3D display in the case where there is no gap between adjacent light emitting regions in a light emitting unit. As shown in  FIG. 5 , there are gaps  3002  between the plurality of light emitting regions  3001  of the plurality of light emitting sub-units included in each light emitting unit; when the display substrate including the light emitting unit is applied to 3D display, the existence of the gaps  3002  between adjacent light emitting regions will cause black regions to be formed between the plurality of viewpoint regions formed after light passes through the light splitting device  400 , and when human eyes switch among different viewpoint regions, moire will be observed, thus affecting the viewing experience. As shown in  FIG. 6 , in the case where the plurality of light emitting regions  3001  of the plurality of light emitting sub-units included in each light emitting unit are arranged in the arrangement manner shown in  FIGS. 1-3 , there is basically no gap between adjacent light emitting regions  3001 ; when the display substrate including the light emitting unit is applied to 3D display, no black region will be formed between the plurality of viewpoint regions formed after the image light emitted from adjacent light emitting regions  3001  passes through the light splitting device  400 , thus solving the problem that human eyes observe moire when switching among different viewpoint regions and improving the viewing experience. 
     For example, in the case where the orthographic projections of two adjacent columns of first contact pads on the second straight line are overlapped, there may also exist cases of partial overlapping between two adjacent light emitting regions among the light emitting regions arranged in a line in visual effect, but the subsequent display is basically not affected. In the case where the endpoints, which are close to each other, of the orthographic projections of two adjacent columns of first contact pads on the second straight line coincide, the edges of two adjacent light emitting regions in the light emitting regions arranged in a line in visual effect also basically coincide. 
     For example, as shown in  FIG. 2 , the pitch a of adjacent sub-electrodes  311  (i.e., nano-pillar structures) along the row direction is less than the distance b between adjacent first contact pads  210  arranged along the row direction. The pitch of the sub-electrodes arranged along the row direction includes the size of one sub-electrode along the row direction and the distance between two adjacent sub-electrodes. Because the size of the first contact pad on the backplane determines the size of the light emitting region, by setting the pitch of the sub-electrodes to be less than the distance between adjacent first contact pads, it can prevent the same sub-electrode from contacting with the two first contact pads, resulting in interference between different sub-electrodes. 
     For example, the magnitude of the pitch a along the row direction is in a range from 200 nm to 100 microns, and the distance b between adjacent first contact pads  210  arranged along the row direction is in a range from 5 microns to 1000 microns. 
       FIG. 7A  is a partial cross-sectional structural view of normal bonding between a light emitting unit and a backplane;  FIG. 7B  is a schematic diagram of the case where bonding deviation occurs between the light emitting unit and the backplane shown in  FIG. 7A ;  FIG. 8A  is a partial cross-sectional structural view of normal bonding between the light emitting unit and the backplane shown in  FIGS. 1-3 ,  FIG. 8B  is a schematic diagram of the case where bonding deviation occurs between the light emitting unit and the backplane shown in  FIG. 8A . As shown in  FIG. 7A  and  FIG. 7B , the plurality of light emitting sub-units in each light emitting unit share the second electrode  32  and the second conductive type semiconductor layer  35 , and a buffer layer  36  is provided at one side of the second conductive type semiconductor layer  35  away from the backplane. The first electrodes  31  in different light emitting sub-units are spaced apart from each other, the first conductive type semiconductor layers  33  in different light emitting sub-units are spaced apart from each other, and the light emitting layers  34  in different light emitting sub-units are spaced apart from each other. In the case where the first electrode  31  in each light emitting sub-unit has a continuous structure, both the first conductive type semiconductor layer  33  and the light emitting layer  34  in each light emitting sub-unit have a continuous structure. 
     For example, the shape of each first electrode  31  can be substantially the same as the shape of the first contact pad  21 , and the size of each first electrode  31  can be substantially the same as the size of the first contact pad  21 . For example, as shown in  FIG. 7A , in the case where the light emitting unit is normally bonded to the backplane, the orthographic projection of the first electrode  31  on the base substrate  10  of the backplane substantially coincides with the orthographic projection of the first contact pad  21  on the base substrate  10 , so as to realize electrical connection, or the orthographic projection of each first electrode  31  on the base substrate  10  of the backplane is only overlapped with the orthographic projection of a corresponding first contact pad  21  on the base substrate  10 , so as to realize electrical connection. For example, as shown in  FIG. 7B , in the case where bonding deviation occurs between the light emitting unit and the backplane, the first electrode  31  of each light emitting sub-unit may be misaligned with a corresponding first contact pad  21 . For example, the orthographic projections of the first electrode  31  and the corresponding first contact pad  21  on the base substrate  10  are not overlapped, or the overlapping area between the orthographic projections of the first electrode  31  and the corresponding first contact pad  21  on the base substrate  10  is small, which leads to connection failure between the light emitting sub-unit and the corresponding first contact pad  21 . Similarly, in the case where bonding deviation occurs between the light emitting unit and the backplane, the second electrode  32  and the second contact pad  22  may also be misaligned, resulting in the problem of electrical connection failure. 
     For example, as shown in  FIG. 8A , in the case where the backplane and the light emitting unit provided by an embodiment of the present disclosure is normally bonded, the effect thereof is basically the same as the effect of the case that the light emitting unit is normally bonded to the backplane as shown in  FIG. 7A . As shown in  FIG. 8B , the nano-pillar structures in the light emitting unit provided by an embodiment of the present disclosure are small in size and independent of each other, by adjusting the distance between the first electrode closest to the second electrode in the light emitting unit and the second electrode to be greater than the transfer accuracy of the equipment, the requirements for the transfer accuracy in the process of bonding the light emitting unit to the backplane can be effectively reduced. 
     For example, as shown in  FIG. 1 ,  FIG. 2 ,  FIG. 8A  and  FIG. 8B , the second electrode  320  in each light emitting unit  300  is a continuous entire electrode, and the alignment accuracy between the second electrodes  320  and the second contact pads  220  can be reduced by arranging each second contact pad  220  electrically connected with each second electrode  320  on the backplane to include a plurality of second sub-contact pads  221  (e.g., the size of the second sub-contact pad  221  is as small as possible). For example, the size of the second sub-contact pad  221  can be 2.5 μm*2.5 μm. 
       FIG. 9  is a partial structural view of a light emitting unit of a display substrate according to another embodiment of the present disclosure, and  FIG. 10  is a planar structural view of the light emitting unit of the display substrate shown in  FIG. 9 .  FIG. 9  is a partial cross-sectional structural view taken along line CC shown in  FIG. 10 . As shown in  FIG. 9  and  FIG. 10 , the display substrate in the present embodiment is different from the embodiment shown in  FIG. 1  and  FIG. 2  in that: the light emitting layer  340  in each light emitting unit  300  of the display substrate is a continuous film, that is, the display substrate does not include a plurality of sub-light emitting layers spaced apart from each other; the first electrodes  310  in the light emitting sub-units  301  included in each light emitting unit  300  are an entire electrode, that is, light emitting unit  300  does not include a plurality of sub-electrodes spaced apart from each other; and the first conductivity type semiconductor layer  330  in each light emitting sub-unit  301  is an entire film, that is, the first conductivity type semiconductor layer  330  does not include a plurality of sub-semiconductor layers spaced apart from each other. That is, each light emitting sub-unit does not include the nano-pillar structure. 
     For example, as shown in  FIG. 9  and  FIG. 10 , in the display substrate, each light emitting unit  300  includes light emitting sub-units  301  arranged in a plurality of rows and a plurality of columns, and each light emitting sub-unit  301  includes one first electrode  310 , that is, each light emitting sub-unit  301  is configured to be connected with one first contact pad. 
     For example, the light emitting region  3001  of each light emitting sub-unit  301  is a region where each first conductivity type semiconductor layer  330  is in contact with the light emitting layer  340 . For example, each row of light emitting sub-units  301  includes a plurality of light emitting sub-units  301  arranged along the row direction, and each column of light emitting sub-units  301  includes one light emitting sub-unit  301 , and the orthographic projections of light emitting regions  3001  of two adjacent columns of light emitting sub-units  301  on a first straight line extending along the column direction are not overlapped; and in each light emitting unit  300 , there is no gap between orthographic projections of the light emitting regions  3001  of the two adjacent columns of light emitting sub-units  301  on a second straight line extending along the row direction. 
     For example, as shown in  FIG. 9  and  FIG. 10 , the distance between the light emitting regions  3001  of any two light emitting sub-units  301  located in the same row and adjacent to each other is equal. 
     For example, as shown in  FIG. 9  and  FIG. 10 , taking that the plurality of light emitting sub-units  301  in each light emitting unit  300  are arranged in three rows as an example, the orthographic projection of the light emitting regions  3001  of the second row of light emitting sub-units  301  on the second straight line is between the orthographic projection of the light emitting regions  3001  of the first row of light emitting sub-units  301  on the second straight line and the orthographic projection of the light emitting regions  3001  of the third row of light emitting sub-units  301  on the second straight line, and the orthographic projection of the light emitting regions  3001  of the third row of light emitting sub-units  301  on the second straight line is located between the orthographic projection of the light emitting regions  3001  of the second row of light emitting sub-units  301  on the second straight line and the orthographic projection of the light emitting regions  3001  of the first row of light emitting sub-units  301  on the second straight line. 
     The light emitting regions in the display substrate in the embodiment of the present disclosure are substantially arranged in the same way as the first contact pads (which are also light emitting regions) in the display substrate shown in  FIG. 1 , and therefore, the viewing effect of the light emitting regions of the light emitting sub-units in the display substrate at a certain viewing distance is basically the same as the viewing effect of the light emitting regions arranged in a continuous row as shown in  FIG. 3 , which can prevent moire during display, thus improving display effect. 
     For example, as shown in  FIG. 9  and  FIG. 10 , a first electrode contact pad  302  connected with the first electrode  310  is provided at one side of the first electrode  310  away from the second conductivity type semiconductor layer  350 , and the first electrode contact pad  302  is configured to be connected with the first contact pad to realize the connection between the first electrode and the first contact pad when the light emitting unit is bonded to the backplane. A second electrode contact pad  303  connected with the second electrode  320  is provided at one side of the second electrode  320  away from the second conductive type semiconductor layer  350 , and the second electrode contact pad  303  is configured to be connected with the second contact pad to realize the connection between the second electrode and the second contact pad when the light emitting unit is bonded to the backplane. 
     For example, as shown in  FIG. 9 , an insulating layer  304  is provided at one side of the first electrode  310  away from the second conductive type semiconductor layer  350 , the first electrode contact pad  302  is connected with the first electrode  310  through a via hole in the insulating layer  304 , and the second electrode contact pad  303  is connected with the second electrode  320  through a via hole in the insulating layer  304 . 
     For example, as shown in  FIG. 10 , the distance d 1  between the first electrode contact pads  302  in two adjacent columns of light emitting sub-units  301  along the Y direction is the difference between the pitch of the light emitting sub-units  301  and the size of the first electrode contact pad  302  along the Y direction, where the pitch includes the length of the light emitting region  3001  of the light emitting sub-unit  301  along the Y direction and the distance between the two adjacent columns of light emitting regions  3001 ; the distance d 2  between the first electrode contact pads  302  in two adjacent light emitting units  301  of the same row along the X direction is, for example, greater than or equal to the sum of the widths of the light emitting regions  3001  of the two light emitting units  301 . 
     Compared with arranging the plurality of light emitting sub-units in each light emitting unit directly in the arrangement structure shown in  FIG. 3 , the embodiment of the present disclosure arranges the plurality of first electrode contact pads in each pixel region into a multi-row structure, so that the distance between the first contact pad and the second contact pad, the distance between two adjacent first electrode contact pads in the same row, and the distance between two adjacent columns of first electrode contact pads, can all be adjusted. For example, the distances as mentioned above can all be arranged relatively large, thereby reducing the requirement of transfer accuracy. In this case, the equipment used for picking up and transferring, for example, LEDs with a size of above 100 μm, can be adopted to realize picking up and transferring, for example, LEDs with a size of below 100 μm, and the transfer efficiency is effectively improved. 
     For example, the light emitting sub-unit can be a light emitting diode, and its size can be 15 μm×25 μm. For example, the bonding between the first electrode contact pad and the contact pad on the backplane, and the bonding between the second electrode contact pad and the contact pad on the backplane can be carried out by means of eutectic bonding, solder paste or anisotropic conductive adhesive, without being limited here. For example, the above bonding process can adopt a flip chip bonding method. 
     For example, as shown in  FIG. 9 , the display substrate further includes a substrate  370  located at one side of the light emitting layer  340  away from the first electrode  310 . The substrate  370 , is, for example, a sapphire substrate located at the light exiting side of the light emitting sub-units, that is, the light emitted from the light emitting layer  340  can pass through the substrate and then enter the eyes of an observer, and after the light emitting diode is bonded onto the backplane, whether or not to remove the sapphire substrate can be determined as needed, without being limited here. 
     In the embodiment of the present disclosure, one first electrode, one first conductive type semiconductor layer, the second conductive type semiconductor layer and the light emitting layer can form one light emitting sub-unit. Because the light emitting unit includes at least two first conductivity type semiconductor layers and at least two first electrodes, the light emitting unit can be formed with at least two light emitting sub-units which can emit light independently. 
     In the embodiments of the present disclosure, in the case where one light emitting unit includes a plurality of light emitting sub-units which can emit light independently, the plurality of light emitting sub-units can be transferred at one time in the process of transferring the light emitting unit onto the backplane, thereby improving the transfer efficiency. 
     In the embodiments of the present disclosure, the light emitting region of the light emitting sub-unit is determined by the contact region between the first conductive type semiconductor layer and the light emitting layer, so the distribution manner of the first contact pads on the backplane can be the same as or different from the distribution manner of the first contact pads shown in  FIG. 1 , as long as each first electrode can be electrically connected with the corresponding first contact pad through the first electrode contact pad. 
       FIG. 11  is a partial structural view of a light emitting unit of a display substrate according to another embodiment of the present disclosure, and  FIG. 12  is a planar structural view of the light emitting unit of the display substrate shown in  FIG. 11 .  FIG. 11  is a partial cross-sectional structural view taken along line DD shown in  FIG. 12 . As shown in  FIG. 11  and  FIG. 12 , the display substrate in the present embodiment is different from the embodiment shown in  FIG. 9  and  FIG. 10  in that: the light emitted from the light emitting layer  340  of the display substrate passes through the first electrode  310  and then is incident to the eyes of the observer, so the first electrode  310  needs to have better light transmittance. 
     For example, the material of the first electrode  310  can be indium tin oxide (ITO). For example, the first electrode contact pad  302  disposed at one side of the first electrode  310  away from the light emitting layer  340  is electrically connected with the first electrode  310  through a through hole located at the edge of the first electrode  310  and in the insulating layer  304 . For example, the material of the first electrode contact pad  302  can be titanium, aluminum, nickel, gold, copper, indium, zinc, silver, or zinc alloy, etc., the embodiments of the present disclosure are limited thereto. 
     For example, as shown in  FIG. 11  and  FIG. 12 , in the display substrate, each light emitting unit  300  includes light emitting sub-units  301  arranged in a plurality of rows and a plurality of columns, and each light emitting sub-unit  301  includes one first electrode  310 , that is, each light emitting sub-unit  301  is configured to be connected with one first contact pad. 
     For example, the light emitting region  3001  of each light emitting sub-unit  301  is a region where each first conductivity type semiconductor layer  330  is in contact with the light emitting layer  340 . For example, each row of light emitting sub-units  301  includes a plurality of light emitting sub-units  301  arranged along the row direction, and each column of light emitting sub-units  301  includes one light emitting sub-unit  301 , and the orthographic projections of light emitting regions  3001  of two adjacent columns of light emitting sub-units  301  on a first straight line extending along the column direction are not overlapped; and in each light emitting unit  300 , there is no gap between orthographic projections of the light emitting regions  3001  of the two adjacent columns of light emitting sub-units  301  on a second straight line extending along the row direction. 
     For example, as shown in  FIG. 11  and  FIG. 12 , the distance between the light emitting regions  3001  of any two light emitting sub-units  301  located in the same row and adjacent to each other is equal. 
     For example, as shown in  FIG. 11  and  FIG. 12 , taking that the plurality of light emitting sub-units  301  in each light emitting unit  300  are arranged in three rows as an example, the orthographic projection of the light emitting regions  3001  of the second row of light emitting sub-units  301  on the second straight line is between the orthographic projection of the light emitting regions  3001  of the first row of light emitting sub-units  301  on the second straight line and the orthographic projection of the light emitting regions  3001  of the third row of light emitting sub-units  301  on the second straight line, and the orthographic projection of the light emitting regions  3001  of the third row of light emitting sub-units  301  on the second straight line is located between the orthographic projection of the light emitting regions  3001  of the second row of light emitting sub-units  301  on the second straight line and the orthographic projection of the light emitting regions  3001  of the first row of light emitting sub-units  301  on the second straight line. 
     The light emitting regions in the display substrate in the embodiment of the present disclosure are substantially arranged in the same way as the first contact pads (which are also light emitting regions) in the display substrate shown in  FIG. 1 , and therefore, the viewing effect of the light emitting regions of the light emitting sub-units in the display substrate at a certain viewing distance is basically the same as the viewing effect of the light emitting regions arranged in one continuous row as shown in  FIG. 3 , which can prevent moire during display, thus improving display effect. 
     Compared with arranging the plurality of light emitting sub-units in each light emitting unit directly in the arrangement structure shown in  FIG. 3 , the embodiment of the present disclosure arranges the plurality of first electrode contact pads in each pixel region into a multi-row structure, so that the distance between the first contact pad and the second contact pad, the distance between two adjacent first electrode contact pads in the same row, and the distance between two adjacent columns of first electrode contact pads, can all be adjusted. For example, the distances as mentioned above can all be arranged relatively large, thereby reducing the requirement of transfer accuracy. In this case, the equipment used for picking up and transferring LEDs with a size of above 100 μm, can be adopted to realize picking up and transferring LEDs with a size of below 100 μm, and the transfer efficiency is effectively improved. 
     In the embodiments of the present disclosure, the light emitting region of the light emitting sub-unit is determined by the contact region between the first conductive type semiconductor layer and the light emitting layer, so the distribution manner of the first contact pads on the backplane can be the same as or different from the distribution manner of the first contact pads shown in  FIG. 1 , as long as each first electrode can be electrically connected with the corresponding first contact pad through the first electrode contact pad. 
       FIG. 13  is a planar structural view of a display substrate according to an embodiment of the present disclosure, and  FIG. 14  is a partial cross-sectional structural view taken along line BB shown in  FIG. 13 .  FIG. 14  is a schematic diagram of arranging a light splitting device at a light exiting side of the light emitting unit shown in  FIG. 2 ,  FIG. 15  is a schematic diagram of arranging a light splitting device at a light exiting side of the light emitting unit shown in  FIG. 9 , and  FIG. 16  is a schematic diagram of arranging a light splitting device at a light exiting side of the light emitting unit shown in  FIG. 11 . As shown in  FIGS. 13-16 , the display substrate further includes a light splitting device  400  located at the light exiting side of the plurality of light emitting units to split light emitted from the plurality of light emitting sub-units to different viewpoint regions, and the light splitting device  400  is the light splitting device  400  shown in  FIG. 5 . For example, the light splitting device  400  includes a plurality of lenses  410  arranged along the row direction, and the orthographic projection of each lens  410  on the base substrate  100  is overlapped with the orthographic projection of one column of pixel regions  200  on the base substrate  100 . For example, the orthographic projection of each lens  410  on the base substrate  100  is overlapped with the orthographic projection of one column of light emitting units on the base substrate  100 . For example, the width of each lens  410  is basically consistent with the width of the light emitting regions of one column of light emitting units, so that the light emitted from each column of light emitting units can exit through the corresponding lens. 
     For example, as shown in  FIG. 13 , one column of light emitting units corresponding to one lens  410  can include a blue light emitting unit, a green light emitting unit, and a red light emitting unit which are arranged in sequence. For example, one row of light emitting units arranged along the row direction can be light emitting units emitting light of the same color. 
     For example, as shown in  FIGS. 13-16 , the row number of light emitting sub-units in each light emitting unit can be determined according to the required number of viewpoint regions for 3D display. For example, in the case where the number of viewpoint regions is 90, the number of light emitting sub-units in each light emitting unit is 90, the light emitting sub-units can be arranged in 3 rows, and the number of light emitting sub-units in each row is 30; or, the light emitting sub-units can be arranged in 9 rows, and the number of light emitting sub-units in each row is 10, which is not limited in the embodiment of the present disclosure. 
     For example, as shown in  FIG. 14  and  FIG. 15 , a planarization layer  500  is further provided between the light emitting units and the light splitting device  400  to realize a planarization treatment of the light emitting units. For convenience of illustration,  FIG. 15  illustratively shows the second conductivity type semiconductor layer and the buffer layer  360  as an integral structure layer  3560 . 
     For example, as shown in  FIG. 16 , the light splitting device  400  is arranged at one side of the base substrate  100  of the backplane away from the light emitting units  300 . In order to effectively avoid the problem of crosstalk caused by reflection and refraction of light emitted from the light emitting sub-units in each film, a light shielding layer  700  can be disposed at least one of between adjacent light emitting units  300 , at one side of the light emitting units  300  away from the backplane and between adjacent first electrodes  310 , so as to effectively absorb unnecessary reflected light and refracted light. In some cases, a light absorbing structure can be arranged between adjacent light emitting units, and a reflective layer can be arranged at one side of the light emitting units away from the backplane to improve the light efficiency of the display substrate. 
     For example, as shown in  FIG. 13  and  FIG. 14 , in the case where each light emitting sub-unit includes a plurality of first electrodes  310 , that is, in the case where each light emitting sub-unit includes a plurality of nano-pillar structures, the position of the light emitting region  3001  of each light emitting sub-unit is determined by the position of the first contact pad  210  on the backplane. When aligning the light emitting region  3001  with the lens  410 , the lens  410  can be directly aligned with the first contact pad  210  to improve the alignment accuracy. Compared with a display substrate in which the light emitting region is determined by the position of the light emitting unit, the embodiment of the present disclosure directly aligns the lens with the first contact pad on the backplane, so that the alignment deviation between the lens and the light emitting region will not occur due to the alignment deviation during the transfer process of the light emitting unit. 
       FIG. 17  is a schematic diagram of a light path of the display substrate shown in  FIGS. 14-16 . As shown in  FIG. 17 , taking that each light emitting unit includes four light emitting sub-units  301  as an example, the light emitted from the four light emitting sub-units  301  forms four viewpoint regions after passing through lenses  410 , and each lens  410  has a certain shrinkage relationship with respect to the size of a corresponding light emitting unit, and the shrinkage ratio satisfies a relationship of D x /x=W lens /W panel =L/(L+f)=99.979%. L is the optimal viewing distance, for example, 350 mm; f is the focal length of the lens  410 ; D x  is the aperture of the lens  410 ; x is the size of the light emitting unit along the X direction; W lens  is the length of the lens array along the X direction; W panel  is the length of the display substrate along the X direction. For example, the light emitting unit is located on the focal plane of the lens. 
     For example, as shown in  FIG. 17 , the light emitted from the light emitting sub-unit  301  has a width a x  along the X direction at the optimal viewing distance after passing through the lens  410 , and the width of the light emitting sub-unit  301  along the X direction is t x , and they satisfy the following relationship: a x /t x =L/f, then a x =t x *L/f. For example, a x  needs to be smaller than the interpupillary distance of human eyes, so as to ensure that the two eyes of the observer are in different viewpoint regions, thus generating parallax and realizing 3D viewing effect. 
       FIG. 18  is a cross-sectional structural view of a lens and a planarization layer shown in  FIG. 17 . As shown in  FIG. 17 , the lens  410  includes a curved surface away from the light emitting unit and a planar surface facing the light emitting unit, the refractive index of the lens  410  is n, the curvature radius r of the curved surface and the focal length f of the lens  410  satisfy r=f*(n−1), and the thickness k of the lens  410  satisfies k=r−[r 2 −(D x /2) 2 ] 1/2 . As shown in  FIG. 18 , a planarization layer  500  is provided between the lens  410  and the light emitting unit, and the thickness of the planarization layer  500  is h and the refractive index thereof is n 0 , so that the optical path of light emitted from the light emitting unit in the planarization layer satisfies l=n 0 *h, and the focal length f of the lens  410  is equal to the above optical path l. For example, the lens  410  and the planarization layer  500  can be made of the same material, and the refractive index n of the lens  410  is equal to the refractive index no of the planarization layer  500 . Therefore, the distance between the lens and the light emitting unit can be determined according to the width and focal length of the lens, and the focal length of the lens can be determined by the processing ability of the lens. 
       FIG. 19  is a schematic diagram of a driving mode of a display substrate according to an embodiment of the present disclosure. As shown in  FIG. 19 , the display substrate can adopt passive matrix (PM) driving, and the display substrate further includes a first signal line  610  extending along the column direction and a second signal line  620  extending along the row direction. For example, as shown in  FIG. 19 , in the case where each light emitting unit includes two second electrodes connected with two second contact pads  220 , the second signal lines  620  respectively electrically connected with the two second electrodes, are configured to input the same common signal, and the second signal lines  620  can be connected with the second electrodes, which serve as a common electrode, of the light emitting unit through via holes. For example, each first signal line  610  is connected with the first electrodes of one column of light emitting sub-units in the light emitting unit, respectively, so as to control the light emitting region of each light emitting sub-unit to emit light. 
       FIG. 20  and  FIG. 21  are schematic diagrams of driving modes of a display substrate according to another embodiment of the present disclosure, and  FIG. 20  is a schematic diagram of a driving circuit of each light emitting sub-unit. As shown in  FIG. 20 , the driving circuit of each light emitting sub-unit can have a 2T1C structure, and the driving circuit can include a light emitting control transistor T 1 , a driving transistor T 2 , and a storage capacitor C. The present embodiment includes but is not limited thereto. For example, the driving circuit  210  can also have a structure of, for example, 5T1C, 6T1C, 7T1C or 8T2C, etc. 
     As shown in  FIG. 20  and  FIG. 21 , the display substrate further includes a gate line  630 , a data line  640 , a first power signal line  650 , and a second power signal line  660 . For example, the gate line  630  and the data line  640  can both extend along the column direction, and the first power signal line  650  and the second power signal line  660  can both extend along the row direction. The embodiment of the present disclosure is not limited thereto, and one of the gate line  630  and the data line  640  can also extend along the row direction, and the specific arrangement can be designed according to the space of the actual product, which is not limited in the embodiment of the present disclosure. 
     Each light emitting sub-unit in the light emitting unit is connected with one corresponding gate line  630 , and the gate line  630  provides a gate driving signal Gate for the light emitting sub-unit; each light emitting sub-unit in the light emitting unit is connected with one corresponding data line  640 , and the data line  640  provides a data signal Date for the light emitting sub-unit; each light emitting sub-unit in the light emitting unit is connected with one corresponding first power signal line  650 , and the first power signal line  650  provides a first voltage signal VDD for the light emitting sub-unit; the light emitting sub-units in the light emitting unit are connected with the same second power signal line  660 , and the second power signal line  660  provides a second voltage signal VSS for each light emitting sub-unit. It should be noted that, for the sake of clarity,  FIG. 21  only illustratively shows one pixel region, a light emitting unit corresponding to the pixel region, and a gate line, a data line, a first power signal line and a second power signal line which are connected with the light emitting unit. 
     For example, in the case where the light emitting unit includes N light emitting sub-units, N first power signal lines  650  need to be provided. 
     For example, one of the first voltage signal VDD and the second voltage signal VSS is a signal output from a high voltage terminal, and the other of the first voltage signal VDD and the second voltage signal VSS is a signal output from a low voltage terminal. For example, in the embodiment shown in  FIG. 21 , the first voltage signal VDD can be a positive voltage and the second voltage signal VSS can be a negative voltage. 
     Another embodiment of the present disclosure provides a display device, which includes the display substrate provided by any of the above embodiments. In the embodiments of the present disclosure, by setting the positional relationship of the light emitting regions of two adjacent columns of light emitting sub-units in the display device, there may be no black region between the light emitting regions of two adjacent columns of light emitting sub-units, so as to improve the display effect. 
     For example, the display device can be a 3D display device. 
     The following statements should be noted: 
     (1) The accompanying drawings related to the embodiment(s) of the present disclosure involve only the structure(s) in connection with the embodiment(s) of the present disclosure, and other structure(s) can be referred to common design(s). 
     (2) In case of no conflict, features in one embodiment or in different embodiments of the present disclosure can be combined. 
     What have been described above are only specific implementations of the present disclosure, and the protection scope of the present disclosure is not limited thereto. Therefore, the protection scope of the present disclosure should be determined based on the protection scope of the appended claims.