JP2554059B2 - Thin-film EL display unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to a thin film used in, for example, an image display device.
The present invention relates to an EL display unit, particularly a structure for reducing the generation of sound due to vibration.

<Outline of the Invention> The present invention is a thin film formed by forming a thin film EL element on a glass substrate and protecting the thin film EL element from moisture by a seal plate.
In a thin film EL display unit including an EL panel and a housing for accommodating the thin film EL panel, the housing includes a translucent plate, a frame body and a back plate, and the translucent plate has a peripheral portion at an upper portion of the frame plate. The thin film EL panel is fixed to the frame body by a spacer made of a soft material outside the effective display area of the glass substrate of the thin film EL panel without directly contacting the housing. Then, by fixing the peripheral part of the back plate to the lower part of the frame body by abutting it, the sound from the thin film EL panel is confined in the space surrounded by the translucent plate, the frame body and the back plate. It is designed so that the sound due to vibration is not transmitted.

<Prior Art> As shown in FIG. 3, the thin film EL element is composed of a glass substrate 1,
It has a transparent electrode 2, a first dielectric layer 3, a light emitting layer 4, a second dielectric layer 5 and a back electrode 6, which are sequentially stacked on top of each other, and the transparent electrode 2 and the back electrode 6 are perpendicular to each other. Is formed in. The transparent electrode 2 is made of ITO (Insium Tin Oxide) or the like, and the back electrode 6 is made of aluminum or the like. The light emitting layer 4 is formed of a semiconductor material such as ZnS or ZnSe, and particularly ZnS with Mn added as a light emitting center provides practically sufficient brightness. In addition, the first dielectric layer 3
And the second dielectric layer 5 is made of Y ₂ O ₃ , TiO ₂ , Ta ₂ O ₅ , Si ₃ N ₄ , SiO ₂ and SiO.
N, Al ₂ O _3, etc. are known, especially Si ₃ N ₄ , SiO ₂ , SiON and Al.
_A practical thin-film EL device can be realized by using a composite dielectric composed of ₂ O ₃ .

In such a thin film EL element, an AC power source 7 is connected to the transparent electrode 2 and the back electrode 6, and an AC voltage is applied between both electrodes 2 and 6 to emit light at a voltage higher than the light emission start voltage from the light emitting layer 4. The light is extracted from the glass substrate 1 side.

In addition, as a driving circuit of the thin film EL display device, for example, a fourth
The one shown in the figure is known.

In FIG. 4, the thin film EL display device 101 has an X-direction electrode X ₁
The ~Xj the data side electrodes, only the electrode is shown the Y-direction electrodes Y ₁ ～Yj as the scanning electrode. The Y-direction electrodes Y _{1 to} Yi are divided into an odd line and an even line, and an odd line scan side N-ch high breakdown voltage MOSIC 102 having MOS transistors NT _{1 to} NTi individually connected to each line and an even line. while connected to the use scanning side N-ch high-voltage MOSIC103, an odd line scanning side P-ch high-voltage MOSIC104 with MOS transistors PT ₁ ~PTi connected individually to each line, even-line scanning side It is connected to the P-ch high voltage MOSIC 105.
The X-direction electrodes X _{1 to} Xj have individually connected MOS transistors NT _{1 to} NTi, and the data side N-ch high breakdown voltage MOSI.
While being connected to C106, they are connected to the cathodes of the corresponding diodes of the diode array 107 for separating the data side drive lines and protecting the switching elements from reverse bias. A pre-charging drive circuit 108 is connected to the anode of each diode of the diode array 107, and is connected to the scanning side P-c.
h The sources of the MOS transistors PT _{1 to} PTi of the high breakdown voltage MOSICs 104, 105 are commonly connected to the pull-up charging drive circuit 109 and the write drive circuit 110. Moreover, the sources of the MOS transistors NT ₁ ~NTi the scanning side N-ch high-voltage MOSIC102,103 usually are connected in common to the source potential switching circuit 111 is maintained at ground potential.

That is, as a driving circuit for the scanning side electrode, an N-ch high withstand voltage is provided.
It is provided with MOSICs 102 and 103 and P-ch high voltage MOSICs 104 and 105, performs so-called field inversion drive in which the polarity is inverted for each field, and further changes the polarity of the write waveform applied to the picture element for each scanning line, thereby thin film EL The flicker is reduced by averaging the asymmetry of the light emission intensity depending on the polarity of the voltage applied to the device.

By the way, a thin film EL as shown in FIGS.
In the display unit, the thin film EL panel 8 comprises a glass substrate 1 and a seal plate 9 for protecting the thin film EL element from moisture.
It is fixed with double-sided adhesive tape on top. The thin film EL
Each electrode terminal on the data side and scanning side of panel 8 (not shown)
Is connected to a flexible printed circuit board (FPC) 11 on which a plurality of driving ICs 11a are mounted, and the FPC 11 is connected to a circuit board 12 by a sumi card (not shown) on the back side of the base plate. Incidentally, FIG. 5 (b) is a sectional view taken along line AA of FIG. 5 (a).

Alternatively, as shown in FIGS. 6 (a) and 6 (b), the thin film EL
The panel 8 is fixed to a display frame 13 made of Al or the like via a rubber pad 14. An FPC 11 is connected to each electrode terminal of the thin film EL panel 8 in the same manner as in FIG. 5, and further connected to a circuit board 12 fixed to a display frame 13 by a sumic card (not shown). The display filter 15 is attached to the display surface side of the thin-film EL panel 8, and the display frame
It is pressed by a part of 13 and fixed so as to come into contact with the glass substrate 1. 6 (b) is the same as FIG. 6 (a).
FIG.

<Problems to be Solved by the Invention> However, ZnS of the light emitting layer 4 constituting the thin film EL panel is a piezoelectric semiconductor, and is a material having a piezoelectric effect or an inverse piezoelectric effect (electrostriction). Electrostriction is a phenomenon in which a slight deformation (strain) occurs when an electric field is applied to a crystal body, and AC electric displacement is converted into mechanical vibration. There are several types of vibration modes such as vertical vibration, thickness vibration, and flexural vibration, and these vibrations are propagated in the solid and from the solid into the air, and reach the human ear as sound.

Here, in the line-sequential driving method as shown in FIG. 4 described above, the voltage waveform shown in FIG. 7 is applied to each picture element, and the vibration mode of the light emitting layer 4 also repeats the vibration like this waveform. There is. In particular, apply modulation voltage ± 1 / 2VM (raise,
Since the reduction period) is performed for all display picture elements, individual vibrations are superimposed and become large. In such a PN inversion symmetric drive, the number of vibrations is {frame frequency ×
(Number of scanning electrodes + α)} / 2 times, depending on the data signal, the frame frequency is 60 Hz, the number of scanning electrodes is 256, α = 4
In the case of, a sound is generated due to vibration having a fundamental frequency of 7.8 kHz.

In the case of FIGS. 5A and 5B, this sound is caused by the vibration of the light emitting layer being propagated from the display side of the glass substrate 1 into the air. A part of the vibration is propagated to the back surface through the seal plate 9, but as for the vibration that is propagated to the seal plate 9, JP-A-54-1465.
Sound is reduced by interposing a vibration absorber like No. 93 “Thin-film EL display panel”. However, the vibration sound propagating from the display surface and the side surface of the glass substrate 1 is not taken, and reaches the ears as it is.

Also, as shown in FIGS. 6 (a) and 6 (b), a display filter
Even in the thin film EL display unit equipped with 15,
Since the display filter 15 is in direct contact with the display surface of the glass substrate 1, the vibration of the glass substrate 1 propagates to the display filter 15 and is transmitted as sound from the display surface of the display filter 15 into the air. Further, even when not touching, the sound circulates from the periphery of the display filter 15 and is propagated, so that the sound from the thin film EL panel 8 is transmitted to the air and reaches the ear.

Thus, the sound generated by the vibration generated from the thin film EL panel 8 may impair the function of the display device.

The present invention has been tried in view of the above points, and thin film EL
It is an object of the present invention to provide a thin film EL display unit in which sound propagating from a panel to the air is reduced to an extremely low level.

<Means for Explaining Problems> The present invention has a double insulating structure in which, for example, a transparent electrode, a first dielectric layer, a light emitting layer, a second dielectric layer, and a back electrode are sequentially laminated on a glass substrate. In a thin film EL panel in which the thin film EL element is formed and the thin film EL element is protected from moisture by a seal plate, and a thin film EL display unit in which the thin film EL panel is housed, the case is transparent. The thin film EL panel is composed of a light plate, a frame, and a back plate, and the light transmissive plate is fixed by abutting the peripheral portion thereof to the upper part of the frame, without directly contacting the casing. Outside the effective display area of the glass substrate of the EL panel, it is fixed by abutting on the frame by a spacer made of a soft material, and the back plate is fixed by abutting its peripheral portion on the lower part of the frame. is there.

<Operation> With the above structure, the sound emitted from the thin-film EL panel into the air is difficult to propagate into the hard material, and is reflected by the housing, and the soft spacers directly transmit the vibration from the glass substrate. A thin film in the space surrounded by the translucent plate, frame, and back plate so that it does not reach the plate, frame, and back plate.
The sound from the EL panel can be contained.

<Example> Hereinafter, different examples of the present invention will be described in detail with reference to the drawings.

1 (a) and 1 (b) show an embodiment of the present invention. The same reference numerals as those in FIGS. 5A and 5B have the same functions.

In FIGS. 1 (a) and 1 (b), the housing is composed of a transparent plate 16, a frame body 17, and a back plate 18, and the transparent plate 16 has an acrylic plate, a glass plate, a vinyl chloride plate, or a dimming effect. It is a hard material such as a circularly polarizing plate, and the frame 17 and the back plate 18 are made of a hard material such as ABS, acrylic, and aluminum.

The translucent plate 16 is fixed to the holding part 17a provided on the upper part of the frame body 17 so that there is no gap all around the translucent plate 16 and fixed with an adhesive or the like. Next, the thin film EL panel 8 is formed on the frame body 17 by a spacer 19 such as a double-sided adhesive sponge tape having a thickness of 1 mm or more, rubber, foam resin or the like which is hard to transmit mechanical vibration outside the effective display area of the glass substrate 1. The inner surface is abutted and fixed, and the circuit board 12 is fixed to the fixing boss 17b provided on the frame body 17 with screws 20 ... After that, the back plate 18 is brought into contact with the L-shaped angle 17c provided in the lower portion of the frame body 17 so that a gap is formed around the back plate 18 and fixed by the screws 20. In this way, the thin film EL panel 8 is completely sealed in the space surrounded by the translucent plate 16, the frame body 17, and the back plate 18.

Reference numeral 21 is a hole through which a signal and a power supply line for driving the thin film EL panel 8 pass, and it is more effective if a cable or the like is passed through this hole 21 and then sealed with silicon resin or the like.

In this structure, the sound emitted from the thin film EL panel 8 is reflected on the surface of the housing without passing through the housing, and is confined in the space surrounded by the translucent plate 16, the frame body 17, and the back plate 18. The sound passing through is very low. Further, since the frame body 17 fixes the glass substrate 1 with the soft spacer 19, and the translucent plate 16 and the back plate 18 are connected only to the frame body 17, the glass substrate 1
The vibration of is not directly transmitted to the translucent plate 16, the frame body 17 and the back plate 18.

The sound pressure level of the thin film EL panel having the above structure is shown in FIG. In the figure, curve A shows the sound pressure level of the conventional structure (Fig. 5), and curve B shows the sound pressure level of the structure of the present invention (Fig. 1).

In FIG. 2, the conventional structure has a large angle dependence like the curve A and has a peak near ± 50 °, but the structure of the present invention has almost no angle dependence like the curve B, and Sound pressure level is extremely low in all directions.
This is because the sound emitted from the thin film EL panel 8 is transmitted through the translucent plate 16, the frame body 17,
Since it is confined in the space surrounded by the back plate 18 and reflected and attenuated in the housing, an excellent sound reduction effect is obtained.

The transparent plate 16, the frame body 17, and the back plate 18 may be made of acrylic plates laminated with a soft material such as sponge as long as at least a part of them is made of a hard material. The plate 16 and the frame body 17 may be integrated. Further, the spacer 17 may be a double-sided adhesive tape attached to an acrylic plate as long as at least a part thereof is made of a soft material.

<Effects of the Invention> As described above, according to the present invention, by confining the sound in the space surrounded by the translucent plate, the frame, and the back plate, the vibration sound emitted from the thin film EL panel is reduced to an extremely low level. It is possible to provide a good thin-film EL display unit in which the function as a display device is prevented from being transmitted to the air.

[Brief description of drawings]

1 (a) and 1 (b) are exploded perspective views and sectional views showing an embodiment of the present invention, FIG. 2 is a graph showing the sound pressure level of FIG. 1, and FIG. 3 is a thin film EL device. Sectional view, FIG. 4 is a drive circuit diagram of a thin film EL display device, FIGS. 5 and 6 are different conventional examples, and FIG. 5A is a plan view and FIG.
Is a cross-sectional view taken along the line AA in FIG. 7A, and FIG. 7 is a picture element A in FIG.
FIG. 6 is a waveform diagram showing an applied waveform in B. 1 ... glass substrate, 8 ... thin film EL panel, 9 ... seal plate, 16 ... transparent plate, 17 ... frame body, 18 ... rear plate, 19 ... spacer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hisashi Uede 22-22 Nagaike-cho, Abeno-ku, Osaka City Sharp Corporation (56) References JP-A-53-64497 (JP, A) JP-A-61- 13594 (JP, A) JP 61-87190 (JP, A) Actually open 52-150978 (JP, U) Actually open 57-157980 (JP, U)

Claims (1)

(57) [Claims] 1. A thin film formed by forming a thin film EL element on a glass substrate and protecting the thin film EL element from moisture by a seal plate.
A thin film EL display unit comprising an EL panel and a housing for accommodating the thin film EL panel, wherein the housing comprises a translucent plate, a frame and a back plate, and the translucent plate has a peripheral portion on the upper part of the frame. The thin film EL panel is fixed to the frame body by a spacer made of a soft material outside the effective display area of the glass substrate of the thin film EL panel without directly contacting the housing. A thin film EL display unit is characterized in that the back plate is fixed by abutting a peripheral portion of the back plate to a lower portion of the frame body to seal the thin film EL panel by the housing.