JP2005108540A - Self-luminous display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a self-luminous display panel capable of absorbing external light without deteriorating light using efficiency. <P>SOLUTION: This self-luminous display panel comprises an organic EL layer 1 provided on a glass substrate 2, in which a light emitted from a light emitting layer 11 of the organic EL layer 1 is radiated through a positive electrode 14 and the glass substrate 2. A first polarizing and selective reflecting layer 3 and a straight polarizing plate 5 are laminated on the outside of the glass substrate 2, and a λ/4-phase difference plate 6, a second polarizing and selective reflecting layer 7 and a visible light absorbing layer 8 are laminated on the outside of a negative electrode 16. The second polarizing and selective reflecting layer 7 transmits a light component with λ/4-phase difference given to S component and reflects a light component with λ/4-phase difference given to P component. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a self-luminous display panel such as an organic EL (electroluminescence) display.

In recent years, an organic EL display has been developed, and it has been studied to employ the organic EL display for a display panel of a mobile phone, for example.
As shown in FIG. 6, the organic EL display is formed by forming an organic EL layer (1) on a glass substrate (2). In the organic EL layer (1), a hole transport layer (12) and an electron transport layer (13) are arranged on both sides of the light emitting layer (11) to form an organic layer, and ITO (indium tin) is formed on both sides of the organic layer. An anode (14) made of oxide) and a cathode (16) made of metal are arranged, and the surface of the anode (14) is provided with a TFT portion (15) having an opening (17). By applying a voltage between (14) and the cathode (16), the light emitting layer (11) is caused to emit light, and the light is directed from the opening (17) of the TFT section (15) to the front where the observer is. The light is emitted (see, for example, Patent Document 1).

  In the organic EL display shown in FIG. 6, a λ / 4 retardation plate (9) and a linear polarizing plate (91) are arranged on the surface of the glass substrate (2), and the contrast is lowered by absorbing external light. It is preventing. The linearly polarizing plate (91) transmits the light component (S + λ / 4) in which the phase difference of λ / 4 is given to the S component of the light emitted from the light emitting layer (11), while from the light emitting layer (11). It absorbs a light component (P + λ / 4) in which a phase difference of λ / 4 is given to the P component of the emitted light.

FIG. 7 shows how light (S component and P component) emitted from the light emitting layer (11) is emitted forward, and FIG. 8 absorbs light (external light) incident from the outside. It shows a state.
As shown in FIG. 7, the S component of the light traveling forward from the light emitting layer (11) passes through the λ / 4 phase difference plate (9) to give a phase difference of λ / 4, and the light component (S + λ / 4) through the linearly polarizing plate (91) and emitted forward. The P component of the light traveling forward from the light emitting layer (11) passes through the λ / 4 phase difference plate (9) and is given a phase difference of λ / 4, and then the linearly polarizing plate (91). Is absorbed by.
On the other hand, the S component of the light traveling backward from the light emitting layer (11) is reflected by the cathode (16), and then passes through the λ / 4 phase difference plate (9) so that the phase difference of λ / 4 is obtained. Then, the light component (S + λ / 4) passes through the linear polarizing plate (91) and is emitted forward. The P component of the light traveling backward from the light emitting layer (11) is reflected by the cathode (16) and then passes through the λ / 4 phase difference plate (9) to obtain a phase difference of λ / 4. Given and absorbed by the linear polarizer (91).

  As shown in FIG. 8, the light component (S + λ / 4) of the incident external light passes through the linear polarizing plate (91), and further passes through the λ / 4 phase difference plate (9). After being given a phase difference of / 4, the light component P is propagated in the light emitting layer (11) and then reflected by the cathode (16). The reflected light component P passes through the λ / 4 phase difference plate (9), is given a phase difference of λ / 4, becomes a light component (P + λ / 4), and enters the linearly polarizing plate (91). Absorbed by the linear polarizing plate (91). Of the incident external light, the light component (P + λ / 4) is absorbed by the linearly polarizing plate (91).

As shown in FIG. 6, in an organic EL display having a λ / 4 retardation plate (9) and a linearly polarizing plate (91) on the surface of a glass substrate (2), external light is absorbed as described above, and the anode ( 14) and the cathode (16) are not reflected, so the contrast is not lowered by the reflected light.
US Pat. No. 15,260,026 JP 2002-215067 A

However, in the conventional organic EL display shown in FIG. 6, as shown in FIG. 7, the P component of the light generated in the light emitting layer (11) is generated by the linearly polarizing plate (91) in both the front emission and the rear emission. Since the light is absorbed, there is a problem that the light use efficiency is reduced by half.
Accordingly, an object of the present invention is to provide a self-luminous display panel that can absorb external light without reducing the light utilization efficiency.

In the self-luminous display panel according to the present invention, on the glass substrate (2), a pair of positive and negative electrodes (14) and (16) for causing the light emitting layer to emit light are arranged on both sides of the light emitting layer (11). An organic EL layer (1) is provided, and light emitted from the light emitting layer (11) of the organic EL layer (1) is transmitted through one electrode (14) and the glass substrate (2) and emitted in the vertical direction. The
A first polarization selective reflection layer (3) and a linearly polarizing plate (5) are sequentially laminated on the outside of the glass substrate (2), and a λ / 4 retardation plate (6) is placed on the outside of the other electrode (16). The second polarization selective reflection layer (7) and the visible light absorption layer (8) are sequentially laminated.
Here, the first polarization selective reflection layer (3) transmits the first light component (S component or P component) that is transmitted through the linear polarizing plate (5), while being absorbed by the linear polarizing plate (5). The second light component (P component or S component) is reflected, and the second polarization selective reflection layer (7) has a phase difference of λ / 4 in the first light component (S component or P component). While the given signal component is transmitted, the signal component to which the phase difference of λ / 4 is given to the second light component (P component or S component) is reflected.

  In the self-luminous display panel of the present invention, the first light component of the internal light traveling from the light emitting layer (11) toward the front of the viewer is the first polarization selective reflection layer (3) and the straight line. The light passes through the polarizing plate (5) and is emitted forward. Of the internal light traveling forward from the light emitting layer (11), the second light component is reflected by the first polarization selective reflection layer (3) and then the λ / 4 phase difference plate (6). Is given a phase difference of λ / 4 and reflected by the second polarization selective reflection layer (7). The reflected light passes through the λ / 4 retardation plate (6), is given a phase difference of λ / 4, travels in the light emitting layer (11) as a first light component, and further selects the first polarization. The light passes through the reflective layer (3) and the linearly polarizing plate (5) and is emitted forward.

  On the other hand, of the internal light traveling backward from the light emitting layer (11), the first light component passes through the λ / 4 retardation plate (6) and is given a phase difference of λ / 4, and the second polarization selection After passing through the reflective layer (7), it enters the visible light absorbing layer (8) and is absorbed by the visible light absorbing layer (8). The second light component of the internal light traveling backward from the light emitting layer (11) passes through the λ / 4 retardation plate (6) and is given a phase difference of λ / 4. Reflected by the reflective layer (7). The reflected light passes through the λ / 4 retardation plate (6), is given a phase difference of λ / 4, travels in the light emitting layer (11) as a first light component, and further selects the first polarization. The light passes through the reflective layer (3) and the linearly polarizing plate (5) and is emitted forward.

  Of the incident external light, the first light component is transmitted through the linearly polarizing plate (5) and the first polarization selective reflection layer (3), and further travels through the light emitting layer (11), so that λ / 4 After passing through the phase difference plate (6) and given a phase difference of λ / 4, it passes through the second polarization selective reflection layer (7) and is finally absorbed by the visible light absorption layer (8). Of the incident external light, the second light component is absorbed by the linearly polarizing plate (5).

In a specific configuration, the second polarization selective reflection layer (7) is constituted by a retroreflection layer (4) for reflecting incident light from the light emitting layer in a direction opposite to the incident direction.
According to the specific configuration, of the internal light generated in the light emitting layer (11), the second light component is incident on the retroreflective layer (4), so that the light component is in the direction opposite to the incident direction. The reflected light is emitted toward the observer through the same path as the incident light to the retroreflective layer. Therefore, crosstalk and color blur do not occur.

  According to the self-luminous display panel according to the present invention, not only all the external light can be absorbed, but also the first light component of the internal light traveling backward from the light emitting layer (11) is visible. Since it is only absorbed by the light absorption layer (8), both the second light component of the internal light traveling forward from the light emitting layer and the second light component of the internal light traveling backward are present. Compared with the conventional self-luminous display panel that is absorbed by the linear polarizing plate, the light utilization efficiency is improved.

Hereinafter, the embodiment in which the present invention is implemented in an organic EL display will be specifically described with reference to the drawings.
The organic EL display according to the present invention is configured by forming an organic EL layer (1) on a glass substrate (2) as shown in FIG. The organic EL layer (1) has an organic layer formed by arranging a hole transport layer (12) and an electron transport layer (13) on both sides of the light emitting layer (11), and an anode made of ITO on both sides of the organic layer. (14) and a cathode (16) made of a transparent metal are arranged, and a TFT section (15) having an opening (17) is provided on the surface of the anode (14) to constitute a see-through type organic EL display. ing.

On the outside of the glass substrate (2), a first polarization selective reflection layer (3) and a linear polarizing plate (5) are sequentially laminated. On the outside of the cathode (16), a λ / 4 retardation plate (6), a second polarization selective reflection layer (7), and a visible light absorption layer (8) are sequentially laminated.
Here, the linearly polarizing plate (5) transmits the S component of light while absorbing the P component. The first polarization selective reflection layer (3) transmits the S component while reflecting the P component. Further, the second polarization selective reflection layer (7) transmits the light component (S + λ / 4) having a phase difference of λ / 4 in the S component, while providing a phase difference of λ / 4 in the P component. The light component (P + λ / 4) is reflected.

FIG. 2 shows a state in which internal light (S component and P component) emitted from the light emitting layer (11) is emitted forward, and FIG. 3 shows that light incident from outside (external light) is absorbed. It shows how it works.
As shown in FIG. 2, among the internal light traveling from the light emitting layer (11) toward the front where the observer is, the S component is transmitted through the first polarization selective reflection layer (3) and the linear polarizing plate (5). , Emitted forward. Of the light traveling forward from the light emitting layer (11), the P component is reflected by the first polarization selective reflection layer (3), and then the cathode (16) and the λ / 4 retardation plate (6). ) / 4, a phase difference of λ / 4 is given, and the light component (P + λ / 4) is reflected by the second polarization selective reflection layer (7). The reflected light passes through the λ / 4 phase difference plate (6) and is given a phase difference of λ / 4, becomes an S component, passes through the cathode (16) and the light emitting layer (11), and further passes through the first polarized light. The light passes through the selective reflection layer (3) and the linear polarizing plate (5) and is emitted forward.

  On the other hand, of the internal light traveling backward from the light emitting layer (11), the S component passes through the cathode (16) and the λ / 4 phase difference plate (6) and is given a phase difference of λ / 4. After passing through the second polarization selective reflection layer (7) as (S + λ / 4), it enters the visible light absorption layer (8) and is absorbed by the visible light absorption layer (8). Of the internal light traveling backward from the light emitting layer (11), the P component passes through the cathode (16) and the λ / 4 retardation plate (6) and is given a phase difference of λ / 4. (P + λ / 4) is reflected by the second polarization selective reflection layer (7). The reflected light passes through the λ / 4 phase difference plate (6) and is given a phase difference of λ / 4, becomes an S component, passes through the cathode (16) and the light emitting layer (11), and further passes through the first. The light passes through the polarization selective reflection layer (3) and the linear polarizing plate (5) and is emitted forward.

  As shown in FIG. 3, in the incident external light, the S component passes through the linearly polarizing plate (5) and the first polarized light selective reflection layer (3), and further passes through the light emitting layer (11) and the cathode (16). Then, after passing through the λ / 4 phase difference plate (6) and being given a phase difference of λ / 4, it is transmitted through the second polarization selective reflection layer (7) and finally the visible light absorption layer (8). Is absorbed by. Of the incident external light, the P component is absorbed by the linearly polarizing plate (5).

In the organic EL display shown in FIG. 4, a retroreflective layer (4) is disposed as the second polarization selective reflection layer (7).
While the retroreflective layer (4) has a number of hemispherical recesses formed on the surface of the base (41) as shown in FIG. 5, the light component (S + λ / 4) is transmitted through the inner surface of the hemispherical recess. A polarization selective reflection layer (43) that reflects the light component (P + λ / 4) is formed, and a spherical glass bead (42) is placed on the inner surface of the reflection layer (43). The glass beads (42) are formed to have a particle size (for example, 40 to 90 μm) smaller than the pixel pitch, and are arranged at a pitch smaller than the pixel pitch.
The retroreflective layer (4) is bonded to the visible light absorbing layer (8), and the λ / 4 phase difference plate (6) is bonded to the glass beads (42) through an adhesive layer (44). It is joined.

In the retroreflective layer (4), as indicated by an arrow in the figure, when a light ray emitted from one light emitting point enters the retroreflective layer (4), the light ray enters the glass bead (42). In this case, the light is refracted and travels through the glass beads (42), and is then reflected by the surface of the reflective layer (43). The reflected light is refracted again when emitted from the glass bead (42), and is emitted in a direction opposite to the incident direction of the incident light. In this way, the light beam incident on the retroreflective layer (4) always returns to the original light emitting point position, following a path that is hardly deviated from the incident light path, regardless of the incident direction.
The progress of internal light and the absorption of external light in the organic EL display shown in FIG. 4 are as shown in FIGS.

  As described above, according to the organic EL display of the present invention, not only all the external light can be absorbed, but also the S component in the internal light traveling backward from the light emitting layer (11) as shown in FIG. Is only absorbed by the visible light absorbing layer (8). Therefore, as shown in FIG. 7, both the P component of the internal light traveling forward from the light emitting layer (11) and the P component of the internal light traveling backward are absorbed by the linearly polarizing plate (91). Compared with the conventional self-luminous display panel, the light utilization efficiency is improved.

  Furthermore, in the organic EL display shown in FIG. 4, when the P component of the internal light emitted from the light emitting layer (11) is incident on the retroreflective layer (4) (see FIG. 2), the P component is incident on the organic EL display. The reflected light is reflected in the direction opposite to the direction, and the reflected light is emitted forward through the same path as the incident light to the retroreflective layer (4). Accordingly, there is no occurrence of crosstalk or color blur due to the deviation of the optical path.

In addition, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim. For example, the same effect can be obtained by the configuration in which the S component and the P component of light described in the above embodiment are interchanged and the configuration in which the stacked structure of the organic EL layer (1) shown in FIGS. can get.
Further, the present invention is not limited to the see-through type organic EL display shown in FIGS. 1 and 4, and may be implemented in a bottom emission type or top emission type organic EL display.

It is sectional drawing which shows the laminated structure of the organic electroluminescent display which concerns on this invention. It is a figure explaining the advancing condition of the internal light in this organic EL display. It is a figure explaining the absorption condition of the external light in this organic EL display. It is sectional drawing which shows the other laminated structure of the organic electroluminescent display which concerns on this invention. It is sectional drawing which expands and shows the structure of a retroreflection layer. It is sectional drawing which shows the laminated structure of the conventional organic EL display. It is a figure explaining the advancing condition of the internal light in this organic EL display. It is a figure explaining the absorption condition of the external light in this organic EL display.

Explanation of symbols

(1) Organic EL layer
(2) Glass substrate
(3) First polarization selective reflection layer
(4) Retroreflective layer
(5) Linear polarizing plate
(6) λ / 4 retardation plate
(7) Second polarization selective reflection layer
(8) Visible light absorption layer

Claims (3)

  In a display panel in which a pair of positive and negative electrodes for causing the light emitting layer to emit light is provided on both sides of the light emitting layer, and a light beam emitted from the light emitting layer passes through one electrode and is emitted in a vertical direction, A first polarization selective reflection layer (3) and a linearly polarizing plate (5) are sequentially laminated on the outside, and a λ / 4 phase difference plate (6) and a second polarization selective reflection layer (7) are placed outside the other electrode. And the visible light absorption layer (8) are sequentially laminated, and the first polarization selective reflection layer (3) transmits the first light component that passes through the linear polarizing plate (5), while the linear polarizing plate (5) The second polarization selective reflection layer (7) reflects the absorbed second light component. The second polarization selective reflection layer (7) transmits the first light component having a phase difference of λ / 4, while transmitting the first light component. A self-luminous display panel which reflects a light component in which a phase difference of λ / 4 is given to the light component of 2.   An organic EL layer (1) comprising a pair of positive and negative electrodes (14) and (16) for causing the light emitting layer to emit light is provided on both sides of the light emitting layer (11) on the glass substrate (2). In a display panel that emits light emitted from the light-emitting layer (11) of the organic EL layer (1) through one electrode (14) and the glass substrate (2) in the vertical direction, the outside of the glass substrate (2) The first polarization selective reflection layer (3) and the linearly polarizing plate (5) are sequentially laminated, and on the outside of the other electrode (16) is a λ / 4 phase difference plate (6) and a second polarization selective reflection layer ( 7) and a visible light absorption layer (8) are sequentially laminated, and the first polarization selective reflection layer (3) transmits the first light component that passes through the linear polarizing plate (5), while the linear polarizing plate (5 ) Is reflected, and the second polarization selective reflection layer (7) transmits a light component having a phase difference of λ / 4 given to the first light component. The second Self-luminous display panel which is characterized in that for reflecting a light component phase difference of lambda / 4 is applied to the component. The second polarized light selective reflection layer (7) is constituted by a retroreflective layer (4) for reflecting incident light from the light emitting layer in a direction opposite to its incident direction. Self-luminous display panel.

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