CN111048700A

CN111048700A - Printing device for preparing OLED film and printing method thereof

Info

Publication number: CN111048700A
Application number: CN201911299237.3A
Authority: CN
Inventors: 郝鹏
Original assignee: Shenzhen China Star Optoelectronics Semiconductor Display Technology Co Ltd
Current assignee: Shenzhen China Star Optoelectronics Semiconductor Display Technology Co Ltd
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2020-04-21

Abstract

The application discloses a printing device for preparing an OLED film and a printing method thereof. The printing device for preparing the OLED film comprises a printing head and a shielding plate. The printhead is configured to eject droplets containing a luminescent material. The shielding plate is arranged below the printing head and is used as a pre-ejection area and configured to accommodate the liquid drops containing the luminous materials ejected when the printing head performs pre-printing. The printing device and the printing method for preparing the OLED film can improve the printing performance.

Description

Printing device for preparing OLED film and printing method thereof

Technical Field

The application relates to the technical field of display, in particular to the technical field of display panels, and particularly relates to a printing device and a printing method for preparing an OLED film.

Background

Organic Light Emitting Diodes (OLEDs) have the advantages of self-luminescence, full solid state, high contrast, and the like, and thus become the most potential display devices in recent years. The method for preparing the OLED device by using the evaporation equipment is a mainstream mode of the current production, but the defects of low material utilization rate and poor uniformity of the evaporation process are always lack of an effective solution. The solution method for preparing the OLED film has the advantages of high material utilization rate, low equipment cost and the like, and shows obvious advantages.

The solution process includes spin coating, printing, etc., and a method in which a solution containing a light-emitting (or functional) material is dropped in the form of fine droplets onto a predetermined position and then a solvent is evaporated to remove the solvent, leaving only a thin film formed of a solute (light-emitting or functional material), which is called ink-jet printing (IJP), is currently the most suitable process for the OLED light-emitting device.

However, when the printing head of the current IJP is paused for a while and printing is resumed, the drop velocity of the discharged droplets is reduced to some extent, and then, after several tens of droplets, the droplet velocity is gradually returned to the original velocity. This causes a drop of a relatively slow velocity to land at a position other than the predetermined landing point, causing a printing deviation and a printing defect. The print defect is liable to occur at the print start position. In addition, some nozzles of current printheads fall above the non-open area of the panel and must remain disabled during printing. Disabled nozzles can have an impact on the print volume and accuracy of adjacent nozzles on either side.

Therefore, there is a need to provide a printing apparatus for preparing an OLED thin film and a printing method thereof to solve the problems of the prior art.

Disclosure of Invention

The embodiment of the application provides a printing device for preparing an OLED film and a printing method thereof, which can solve the problems in the prior art and improve the printing performance.

The embodiment of the application provides a printing device for preparing an OLED film, which comprises:

a printhead configured to eject droplets containing a luminescent material; and

a shielding plate disposed below the print head as a pre-ejection region and configured to accommodate the droplet containing the light-emitting material ejected when the print head performs pre-printing.

In some embodiments, the shield plate is a strip-shaped shield plate.

In some embodiments, the strip-shaped shielding plate is disposed on two sides of an active region of a substrate, when the printhead performs pre-printing, the printhead continuously ejects a plurality of droplets containing the light-emitting material above the strip-shaped shielding plate, and when the ejection quality of the printhead is stable, the printhead moves to above the active region of the substrate to perform printing.

In some embodiments, the printhead includes a plurality of groups of nozzles, each group of nozzles including N nozzles, N being greater than 1, the pitch of each group of nozzles being equal to the pitch of the sub-pixels.

In some embodiments, the pitch of each set of nozzles is movably adjusted to equal the pitch of the subpixels.

In some embodiments, N-4.

In some embodiments, when the printhead is printing, the printhead is parallel to the long axis of the openings of the sub-pixels, and each set of nozzles falls within a respective row of pixels.

In some embodiments, after the main printing of the print head is finished, the print head is used for performing auxiliary supplementary printing according to the detection result, so as to reduce the difference between the actual printing volume and the target volume in each sub-pixel.

The embodiment of the application provides a printing method for preparing an OLED film, which comprises the following steps:

performing preprinting by using a printing head, and enabling the printing head to continuously eject a plurality of droplets containing luminous materials above a shielding plate, wherein the shielding plate is arranged below the printing head and is used as a preprinting area and is configured to accommodate the droplets containing the luminous materials ejected when the printing head performs preprinting; and

and when the pre-printed ejection quality of the printing head is stable, the printing head moves to the position above the active area of the substrate for printing.

The embodiment of the application provides a printing device for preparing an OLED film and a printing method thereof. The printing device for preparing the OLED film comprises a printing head and a shielding plate. The printhead is configured to eject droplets containing a luminescent material. The shielding plate is arranged below the printing head and is used as a pre-ejection area and configured to accommodate the liquid drops containing the luminous materials ejected when the printing head performs pre-printing. The printing device and the printing method for preparing the OLED film can improve the printing performance.

Drawings

The technical solution and other advantages of the present application will become apparent from the detailed description of the embodiments of the present application with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of a printing apparatus for preparing an OLED thin film according to an embodiment of the present application.

Fig. 2 is a schematic structural diagram of a printing apparatus for preparing an OLED film according to an embodiment of the present application.

Fig. 3 is a schematic flow chart of a printing method for preparing an OLED thin film according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present application and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and are not to be construed as limiting the present application. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; may be mechanically connected, may be electrically connected or may be in communication with each other; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In this application, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact of the first and second features, or may comprise contact of the first and second features not directly but through another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the application. In order to simplify the disclosure of the present application, specific example components and arrangements are described below. Of course, they are merely examples and are not intended to limit the present application. Moreover, the present application may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, examples of various specific processes and materials are provided herein, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.

Specifically, referring to fig. 1 and fig. 2, the embodiment of the present application provides a printing apparatus 10 for preparing an OLED film. The printing apparatus 10 for preparing the OLED thin film includes a print head 12 and a shielding plate 14. The print head 12 is configured for ejecting droplets 20 containing a luminescent material. The shielding plate 14 is disposed below the print head 12 and serves as a pre-ejection area configured to accommodate the droplet 20 containing the light-emitting material ejected when the print head 12 performs pre-printing. The printing device 10 for preparing the OLED film can improve the printing performance.

In some embodiments, the shield plate 14 is a strip-shaped shield plate. In some embodiments, the strip-shaped shielding plate is disposed on two sides of the active area of the substrate 30, when the printhead 12 performs pre-printing, the printhead 12 continuously ejects a plurality of droplets 20 containing the light-emitting material above the strip-shaped shielding plate, and when the ejection quality of the printhead 12 is stable, the printhead 12 moves to above the active area of the substrate 30 for printing.

In some embodiments, the printhead 12 includes multiple sets of nozzles 122, each set of nozzles 122 including N nozzles 124, N being greater than 1, the pitch of each set of nozzles 122 being equal to the pitch of the sub-pixels 40. In some embodiments, the pitch of each set of nozzles 122 is movably adjusted to equal the pitch of the subpixels 40. In some embodiments, N-4.

In some embodiments, when the printhead 12 is printing, the printhead 12 is parallel to the long axis of the opening of the sub-pixel 40, and each set of nozzles 122 falls within a corresponding row of pixels.

In some embodiments, after the main printing is completed by the print head 122, the print head 12 is used to perform auxiliary supplemental printing according to the detection result, so as to reduce the difference between the actual printing volume and the target volume in each sub-pixel 40.

Referring to fig. 3, a printing method S300 for preparing an OLED thin film is provided in the present disclosure. The printing method S300 for preparing the OLED thin film includes a step S310 of performing pre-printing by using a printing head, and enabling the printing head to continuously eject a plurality of droplets containing the light-emitting material above a shielding plate, where the shielding plate is disposed below the printing head and serves as a pre-ejection area configured to accommodate the droplets containing the light-emitting material ejected when the printing head performs pre-printing, and a step S320 of moving the printing head to above an active area of a substrate for printing when ejection quality of the pre-printing by the printing head is stable. The printing method S300 for preparing the OLED film can improve the printing performance.

In some embodiments, the shield plate is a strip-shaped shield plate. In some embodiments, the strip-shaped shielding plate is disposed on two sides of an active region of a substrate, when the printhead performs pre-printing, the printhead continuously ejects a plurality of droplets containing the light-emitting material above the strip-shaped shielding plate, and when the ejection quality of the printhead is stable, the printhead moves to above the active region of the substrate to perform printing.

In some embodiments, the printhead includes a plurality of groups of nozzles, each group of nozzles including N nozzles, N being greater than 1, the pitch of each group of nozzles being equal to the pitch of the sub-pixels. In some embodiments, the pitch of each set of nozzles is movably adjusted to equal the pitch of the subpixels. In some embodiments, N-4.

In some embodiments, the printing method S300 for preparing the OLED film includes a step S330 in which, when the print head prints, the print head is parallel to the long axis of the opening of the sub-pixel, and each group of nozzles falls in a corresponding pixel row.

In some embodiments, the printing method S300 for preparing an OLED film includes step S340, after the main printing of the print head is completed, performing auxiliary supplemental printing by using the print head according to a detection result, so as to reduce a difference between an actual printing volume and a target volume in each sub-pixel.

In some embodiments, the main steps of ink-jet printing (IJP) to prepare the OLED thin film include:

(1) a precise volume of the droplet is dropped into a specified location, i.e., a sub-pixel opening of the panel.

(2) The droplets were dried to a film by vacuum drying under reduced pressure.

(3) And (4) heating and annealing treatment to improve the quality of the obtained OLED film.

In order to ensure the uniformity of the entire light-emitting area of the screen, the organic film thickness of each sub-pixel is required to be the same. That is, in the printing process, it is required to accurately ensure that the volumes of the organic solvents injected into the openings of the sub-pixels are the same, so that no film thickness difference is generated after the dry film is formed.

In some embodiments, the printhead may employ, for example, a piezoelectric ceramic as a trigger, which may enable individual driving of each nozzle and control of drop volume and drop velocity for each drop by adjusting the waveform of the voltage.

In some embodiments, the printing device for preparing the OLED film and the printing method thereof remove the forbidden nozzle, and can solve the problem that the initial dropping speed of the nozzle is low when the nozzle is started, so that the nozzle can work at a stable discharge speed all the time, and the risk of printing defects on the panel caused by the stable discharge speed is avoided. Also, the pre-printing buffer set for this problem can be eliminated.

In some embodiments, the design of the sub-pixel apertures of the panel is kept constant in mass production practice. Therefore, for the printing head as a consumable, the nozzle pitch should be adjusted according to the requirement of the printing position of the product, so that each nozzle is located at a position where printing can be performed.

In some embodiments, assuming that N nozzles can be accommodated (as illustrated in fig. 2, N is 4), the N nozzles are defined as 1 group, and each group has a pitch equal to the pitch of the sub-pixels, according to the size of the sub-pixel opening and the nozzle pitch. 100% utilization of the print head nozzles can be achieved. This printhead is defined as the master printhead.

In some embodiments, the volume of drops ejected by each nozzle of the printhead is tested prior to printing. The tester can simultaneously test the volume of the liquid drops ejected by the same group of N nozzles and record the volume. The sum of the ejection volumes of each group is made to be close to or slightly lower than the target volume by adjusting the voltage waveform. And the difference between each group and the target volume is recorded.

In some embodiments, the print head is parallel to the long axis of the sub-pixel openings and each set of nozzles falls within a corresponding row of pixels to maximize print efficiency of the print head. Only 1 scan is needed to complete the entire print.

In some embodiments, after the main print head finishes printing, the auxiliary print head with 1pl level is used for performing supplementary printing according to the detected result, so as to reduce the difference between the actual printing volume and the target volume in each sub-pixel.

In some embodiments, to solve the problem that the state of each nozzle at the beginning of printing is unstable, strip-shaped shielding plates are arranged on two sides of the active area of the substrate to serve as a pre-ejection area, and the printing head continuously ejects 50 drops above the shielding plates and then moves to the position above the active area of the substrate for printing.

In some embodiments, the difference in film thickness is reduced by adding an auxiliary printhead to supplement the print volume deviation of the main printhead. In some embodiments, by adding a pre-printed mask, unstable droplets when the printhead is just starting to print are prevented from landing on the active area of the substrate, causing non-uniformity, such as mura. In some embodiments, the disabled nozzles are eliminated and the spacing of the nozzles is arranged as desired for the product. The printing effect is improved, and the printing defects caused by the disablement/enablement of the nozzles are eliminated. This improves the problem of poor print quality of adjacent nozzles due to nozzle disablement.

In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

The foregoing describes in detail an electronic device provided in an embodiment of the present application, and a specific example is applied to illustrate the principle and the implementation of the present application, and the description of the foregoing embodiment is only used to help understanding the technical solution and the core idea of the present application; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the present disclosure as defined by the appended claims.

Claims

1. A printing apparatus for preparing an OLED film, comprising:

a printhead configured to eject droplets containing a luminescent material; and

2. The printing apparatus for manufacturing an OLED film as claimed in claim 1, wherein the shielding plate is a strip-shaped shielding plate.

3. The printing apparatus for preparing the OLED film according to claim 2, wherein the strip-shaped shielding plates are disposed on two sides of an active area of a substrate, when the print head performs preprinting, the print head continuously ejects a plurality of droplets containing the light-emitting material above the strip-shaped shielding plates, and when the ejection quality of the print head is stable, the print head moves to above the active area of the substrate for printing.

4. The printing apparatus for preparing an OLED film according to claim 1, wherein the print head includes a plurality of sets of nozzles, each set of nozzles including N nozzles, N being greater than 1, and a pitch of the nozzles of each set being equal to a pitch of the sub-pixels.

5. The printing apparatus for manufacturing an OLED film as claimed in claim 4, wherein a pitch of each group of nozzles is movably adjusted to be equal to a pitch of the sub-pixels.

6. The printing apparatus for manufacturing an OLED film as claimed in claim 4, wherein N-4.

7. The printing apparatus for preparing an OLED film as claimed in claim 4, wherein when said print head prints, said print head is parallel to the long axis of the openings of said sub-pixels, and each set of nozzles falls within a corresponding pixel row.

8. The printing apparatus for preparing the OLED film as claimed in claim 4, wherein after the main printing of the print head is completed, the print head is used to perform the auxiliary complementary printing according to the detection result, so as to reduce the difference between the actual printing volume and the target volume in each sub-pixel.

9. A printing method for preparing an OLED film is characterized by comprising the following steps:

10. The printing method for preparing an OLED film according to claim 9, wherein the print head includes a plurality of sets of nozzles, each set of nozzles including N nozzles, N being greater than 1, and a pitch of each set of nozzles being equal to a pitch of the sub-pixels.