Patent Description:
OLED display devices have a series of excellent characteristics such as self-luminescence, no backlight module, high contrast and definition, wide viewing angle, fully-cured state, capability of adopting flexible panels, good temperature characteristics, low power consumption, fast response speed, and low manufacturing cost, and therefore have become one of key development trends of new-generation flat display devices and attract more and more attentions.

At present, all kinds of OLEDs have been applied to mobile phones and become rapidly widespread as products. Also, TVs using the OLEDs have gradually begun to prevail with great popularity. However, the TVs using the OLEDs have a drawback in terms of display. To be specific, when a viewer gradually increases his/her viewing angle from a center of a large-screen display panel with the viewing angle of zero towards an edge position of the display panel, a wavelength of light observed by the viewer may shift, which results in color inconsistency between the central position and the edge position of the display panel, thereby adversely affecting viewing experience.

<CIT> discloses an OLED display device with thickness of the encapsulating film being increased inside out and a method of manufacturing the same.

<CIT> discloses an organic EL display device with the film thickness of the sealing film being reduced at the bend portion.

<CIT> discloses an organic EL light-emitting device having two substrates, an organic EL element, and a sealing member.

<CIT> and <CIT> disclose display devices wherein pixel defining layers or spacers have a thickness gradually increasing from the center of the display device to the edge of the display device.

The present disclosure provides a display panel, an OLED display device and a method for manufacturing the OLED display panel, as defined in the appended set of claims.

In order to illustrate the technical solutions in the embodiments of the present disclosure or in the related art more clearly, the accompanying drawings necessary for the description of the embodiments will be briefly described below. It is obvious that the drawings in the following description relate to only some of the embodiments of the present disclosure, and based on these drawings, other drawings can be obtained by those having ordinary skills in the art without any inventive effort.

To make the technical problems to be solved, technical solutions, and advantages of the present disclosure more apparent, detailed description will be made below in conjunction with the drawings and specific embodiments.

<FIG> are schematic diagrams showing variations in viewing angles when a viewer views large-screen display panels in the related art. <FIG> shows a flat screen, and <FIG> shows a curved screen. When the viewer gradually increases his/her viewing angle from a center of the large-screen display panel with the viewing angle of zero towards an edge position of the display panel, a wavelength of light observed by the viewer may shift, which results in color inconsistency between the central position and the edge position of the display panel, thereby badly affecting the viewing experience. Embodiments of the present disclosure provide an OLED display panel, capable of effectively suppressing the phenomenon of a blue shift of a luminescence peak position of pixels at the edge of the display panel.

<FIG> is a schematic diagram showing a structure of an OLED display panel according to an embodiment of the present disclosure. <FIG> is a schematic diagram showing a portion of the structure of the OLED display panel corresponding to an A-A section in <FIG>. As shown in <FIG> and <FIG>, an embodiment of the present disclosure provides an OLED display panel, including a base substrate <NUM>, pixel units <NUM> located on the base substrate <NUM>, and an encapsulation layer <NUM> covered on the pixel units <NUM>. Further, the encapsulation layer <NUM> on the pixel units <NUM> has a gradually increasing thickness in a direction from a central position of the display panel to an edge position of the display panel. That is to say, the thickness of the encapsulation layer <NUM> on the pixel units <NUM> becomes larger in the direction from the central position of the display panel to the edge position of the display panel.

The expression "the encapsulation layer <NUM> on the pixel units <NUM> has a gradually increasing thickness" herein means that in the direction from the central position of the display panel to the edge position of the display panel, the thickness of the encapsulation layer <NUM> on the pixel units <NUM> tends to increase and that regions of the encapsulation layer covered on some adjacent pixel units can have an equal thickness. According to an optional embodiment of the present disclosure, the thickness of the encapsulation layer <NUM> covered on the pixel units <NUM> is the smallest at the central position of the display panel, and is sequentially increased based on a predetermined increment in the direction from the central position of the display panel to the edge position of the display panel. For example, the predetermined increment can be set to satisfy a linear, exponential, logarithmic, square, square root or other relationship as desired. For example, in a horizontal direction of the display panel, the central position of the display panel is a position of the display panel where a line which passes through a center point of the display panel and which is perpendicular to the horizontal direction (I2 in <FIG>) is located. Among the pixel units <NUM> on the same horizontal line, a region of the encapsulation layer <NUM> covered on the pixel unit <NUM> at the central position has the smallest thickness, and another region of the encapsulation layer <NUM> covered on the pixel unit at the edge position of the display panel has the largest thickness. The encapsulation layer <NUM> is implemented by using a Thin-Film Encapsulation (TFE) technology, for example.

In this embodiment, the center point of the display panel is not limited to a geometric center of the display panel, and a point on a central line of the display panel may be any point within a predetermined range of the geometric center of the display panel. In addition, the center point of the display panel can be selected as a geometric center point of the display panel, such as a center of gravity or a center of a circle. Moreover, there may be one, or a group, of the pixel units <NUM> at the central position of the display panel.

In addition, in a vertical direction of the display panel, the central position of the display panel is a position of the display panel where a line which passes through the center point a of the display panel and which is parallel to the horizontal direction (I1 in <FIG>) is located. Among a plurality of pixel units <NUM> on the same vertical line (i.e., a line perpendicular to the horizontal direction), a region of the encapsulation layer <NUM> covered on the pixel unit(s) <NUM> at the central position has the smallest thickness, and another region of the thickness of the encapsulation layer <NUM> covered on the pixel unit <NUM> at the edge position of the display panel has the largest thickness, for example.

Similarly, in the horizontal direction of the display panel, the central position of the display panel is a position of the display panel where a line which passes through the center point of the display panel and which is parallel to the vertical direction is located. Among the pixel units <NUM> on the same horizontal line (i.e., a line perpendicular to the vertical line), a region of the encapsulation layer <NUM> covered on the pixel unit(s) <NUM> at the central position has the smallest thickness, and another region of the encapsulation layer <NUM> covered on the pixel unit <NUM> at the edge position of the display panel has the largest thickness, for example.

According to an optional embodiment of the present disclosure, regions of the encapsulation layer <NUM> covered on the respective pixel units <NUM> at the central position have an identical thickness.

According to an optional embodiment of the present disclosure, the central position may also be the center point of the display panel. In this case, in directions radiating from the central position as a starting point towards edges of the display panel, the thickness of the encapsulation layer <NUM> on the pixel units <NUM> gradually increases.

In the OLED display panel in the embodiments of the present disclosure, the thickness of the encapsulation layer <NUM> on the pixel units <NUM> gradually increases in the direction from the central position of the display panel to the edge position of the display panel, which results in an increase in a resonant cavity length of the pixel units <NUM> at the edge position of the display panel, allowing a gradual increase in the wavelength of a luminescence spectrum peak of the organic light-emitting diode, and thus effectively suppressing the blue shift of the luminescence peak position of the pixels at the edge of the display panel.

Further, as shown in <FIG>, according to the claimed invention, the display panel further includes a pixel-defining layer <NUM> which has a gradually increasing thickness in the direction from the central position of the display panel to the edge position of the display panel. Since the encapsulation layer <NUM> needs to cover the entire pixel-defining layer <NUM> (the encapsulation layer <NUM> needs to cover a top of the pixel-defining layer <NUM>), the larger the thickness of the pixel-defining layer <NUM> is, the larger the thickness of the encapsulation layer <NUM> is required to be. In other words, the thickness of the encapsulation layer <NUM> is associated with the thickness of the pixel-defining layer <NUM>.

As shown in <FIG> which is a schematic top view showing a part of the pixel units, the pixel-defining layer <NUM> is configured to define a light-emitting element <NUM>, and a reference numeral <NUM> indicates an aperture of the pixel-defining layer.

The thickness of the pixel-defining layer <NUM> on the pixel units <NUM> is the smallest at the central position of the display panel, and can be sequentially increased based on a predetermined increment in the direction from the central position of the display panel to the edge position of the display panel, so that the thickness of the encapsulation layer <NUM> covered on the pixel units <NUM> can be sequentially increased based on the predetermined increment. For example, in the horizontal direction of the display panel, the central position of the display panel is a position of the display panel where a line which passes through the center point of the display panel and which is perpendicular to the horizontal direction is located. Among the pixel units <NUM> on the same horizontal line, a region of the pixel-defining layer <NUM> of the pixel unit(s) <NUM> at the central position has the smallest thickness, and another region of the pixel-defining layer <NUM> of the pixel unit <NUM> at the edge position of the display panel has the largest thickness, for example.

In addition, in the vertical direction of the display panel, the central position of the display panel is a position of the display panel where a line which passes through the center point of the display panel and which is parallel to the horizontal direction is located. Among the pixel units <NUM> on the same vertical line (i.e., a line perpendicular to the horizontal direction), a region of the pixel-defining layer <NUM> of the pixel unit(s) <NUM> at the central position has the smallest thickness, and another region of the pixel-defining layer <NUM> of the pixel unit <NUM> at the edge position of the display panel has the largest thickness, for example.

Further, in another embodiment of the present disclosure, the OLED display panel further includes a spacer <NUM> disposed on the pixel-defining layer <NUM>, which has an equal or gradually increasing thickness in the direction from the central position of the display panel to the edge position of the display panel.

When the spacer <NUM> provided on the pixel-defining layer <NUM> has a constant thicknesses, the thickness of the encapsulation layer <NUM> covered on the pixel units <NUM> is associated with the thickness of the pixel-defining layer <NUM>. When the thickness of the one or more spacers <NUM> provided on the pixel-defining layer <NUM> is not consistent, the thickness of the encapsulation layer <NUM> covered on the pixel units <NUM> is associated with the thicknesses of the pixel-defining layer <NUM> and the spacer <NUM>. As shown in <FIG>, at the pixel unit <NUM> where the encapsulation layer has the smallest thickness, only the pixel-defining layer <NUM> is shown, but the pixel-defining layer <NUM> at this position can also by covered by the spacer <NUM>.

<FIG> is a schematic diagram showing a variation in a viewing angle when a viewer views an OLED display panel according to an embodiment of the present disclosure, in which Δh is a difference in thickness between a combination layer of the pixel unit(s) <NUM> at the central position and a combination layer of the pixel unit <NUM> at the edge position. Here, as a non-limiting example, the combination layer includes the pixel-defining layer <NUM> and the spacer <NUM>. Correspondingly, a light-emitting center in <FIG> is the pixel unit.

In the direction from the central position of the display panel to the edge position of the display panel, the thickness of the encapsulation layer <NUM> on the pixel units <NUM> gradually increases.

Further, in a further embodiment of the present disclosure, in the horizontal direction of the display panel, a difference in thickness between the combination layers of adjacent pixel units <NUM> is Δh<NUM>; <MAT> where the combination layer includes the pixel-defining layer <NUM> and the spacer <NUM>, H<NUM> is a thickness of the combination layer of the pixel units <NUM> on a center line of the display panel perpendicular to the horizontal direction, Hn-<NUM> is a thickness of the combination layer of the pixel unit <NUM> at an edge position of the display panel in the horizontal direction, and n is the number of the pixel units <NUM> of the display panel in the horizontal direction.

Specifically, the center line of the display panel perpendicular to the horizontal direction is a line which is perpendicular to the horizontal direction and which passes through the center point of the display panel. The difference in thickness between the combination layers of the adjacent pixel units <NUM> located on the same horizontal line is Δh<NUM>. According to an optional embodiment of the present disclosure, the combination layers of the respective pixel units <NUM> on the same vertical line are equal in thickness so as to reduce the manufacturing complexity.

Further, in an embodiment of the present disclosure, the difference in thickness between the combination layers of adjacent pixel units <NUM> in the vertical direction of the display panel is Δh<NUM>; <MAT> where the combination layer includes the pixel-defining layer <NUM> and the spacer <NUM>, H<NUM> is a thickness of the combination layer of the pixel units <NUM> on a center line of the display panel parallel to the horizontal direction, Hm-<NUM> is a thickness of the combination layer of the pixel unit <NUM> at an edge position of the display panel in the vertical direction, and m is the number of the pixel units <NUM> of the display panel in the vertical direction.

Specifically, the center line of the display panel parallel to the horizontal direction is a line which is parallel to the horizontal direction and which passes through the center point of the display panel. In this case, the difference in thickness between the combination layers of adjacent pixel units <NUM> on the same vertical line is Δh<NUM>. According to an optional embodiment of the present disclosure, the combination layers of the respective pixel units <NUM> on the same horizontal line are equal in thickness so as to reduce the manufacturing complexity.

Generally, the display panel has a size between <NUM> inches and <NUM> inches. Assuming that a viewing distance is in a range between <NUM> and <NUM> meters, the thickness of the combination layer can be obtained using an optical cavity length of the pixel unit <NUM> according to a formula Lcosα = pλ, where L is related to the optical cavity length, α is a viewing angle, λ is an emission wavelength of the organic light-emitting device, and p is a positive integer. Then, Δh<NUM> or Δh<NUM> can be calculated based the thicknesses of the combination layers of the pixel units <NUM> at the central position and at the edge position. According to an optional embodiment of the present disclosure, Δh<NUM> or Δh<NUM> has a value ranging from <NUM> to <NUM>.

In the OLED display panel provided by the embodiments of the present disclosure, the thickness of the combination layer gradually increases from the central position to the edge position. When the viewing angle α is kept unchanged, increasing the optical cavity length can cause a red shift of the wavelength of the resonance, so that gradually increasing the thickness of the encapsulation layer <NUM> from the central position to the edge position can achieve the purpose of suppressing the blue shift of the luminescence peak of the pixels at the edge of the OLED display panel.

Furthermore, embodiments of the present disclosure further provide an OLED display device including the OLED display panel in the above embodiments.

As shown in <FIG>, embodiments of the present disclosure further provide a method for manufacturing an OLED display panel, including:
a step <NUM> of forming an encapsulation layer <NUM> that has a gradually increasing thickness in a direction from a central position of the display panel to an edge position of the display panel.

Prior to this step, one or more pixel units <NUM> are formed on a base substrate <NUM>, and then covered by the encapsulation layer <NUM> in such a manner that the encapsulation layer <NUM> on the pixel unit(s) <NUM> has the gradually increasing thickness in the direction from the central position of the display panel to the edge position of the display panel.

According to the manufacturing method of the OLED display panel provided by the embodiments of the present disclosure, by forming the encapsulation layer <NUM> which has the thickness that gradually increases in the direction from the central position of the display panel to the edge position of the display panel, it is possible to achieve the purpose of suppressing the blue shift of the luminescence peak of the pixels at the edge of the OLED display panel.

Further, according to the claimed invention as shown in <FIG>, prior to step <NUM>, the method further includes:
a step 101a of forming a pixel-defining layer <NUM> that has a gradually increasing thickness in the direction from the central position of the display panel to the edge position of the display panel. Since the encapsulation layer <NUM> covered on the pixel units <NUM> has certain fluidity, the pixel-defining layer <NUM> of the pixel units <NUM> can play an important role of supporting the encapsulation layer <NUM> covered on the pixel units <NUM>. By gradually increasing the thickness of the pixel-defining layer <NUM> on the pixel units <NUM> in the direction from the central position of the display panel to the edge position of the display panel, it is possible to enable the thickness of the encapsulation layer <NUM> covered on the pixel units <NUM> to gradually increase.

Further, as shown in <FIG>, after step 101a and before step <NUM>, the manufacturing method further includes step 101b:
forming, on the pixel-defining layer <NUM>, an etched spacer <NUM> that has an equal or gradually increasing thickness in the direction from the central position of the display panel to the edge position of the display panel.

When the thickness of the one or more spacers <NUM> provided on the pixel-defining layer <NUM> is consistent, the thickness of the encapsulation layer <NUM> covered on the pixel units <NUM> is associated with the thickness of the pixel-defining layer <NUM>. When the thickness of the one or more spacers <NUM> provided on the pixel-defining layer <NUM> is not consistent, the thickness of the encapsulation layer <NUM> covered on the pixel units <NUM> is associated with the thicknesses of the pixel-defining layer <NUM> and of the spacer <NUM>, and the spacer <NUM> will also function to support the encapsulation layer <NUM>.

In this embodiment, the thickness of the encapsulation layer <NUM> covered on the pixel unit <NUM> is determined by the thicknesses of both the pixel-defining layer <NUM> and the spacer <NUM>. Thus, the resonant cavity length of the pixel unit <NUM> at the edge position of the display panel is increased to enable the wavelength of the luminescence spectrum peak of the OLED to be gradually increased, thereby suppressing the phenomenon of the blue shift of the luminescence peak position of the pixels at the edge of the display panel.

Claim 1:
A display panel, comprising:
a display panel body (<NUM>, <NUM>); and
an encapsulation layer (<NUM>) disposed on the display panel body (<NUM>, <NUM>),
wherein the encapsulation layer (<NUM>) has a gradually increasing thickness in a direction from a central position of the display panel to an edge position of the display panel,
wherein the display panel body (<NUM>, <NUM>) comprises a base substrate (<NUM>) and one or more pixel units (<NUM>) disposed on the base substrate (<NUM>),
the display panel being characterized by further comprising: a pixel-defining layer (<NUM>) being configured to define a light emitting element (<NUM>) of the one or more pixel units (<NUM>) and that has a gradually increasing thickness in the direction from the central position of the display panel to the edge position of the display panel.